Anders Roxell [Tue, 7 Dec 2021 11:02:28 +0000 (12:02 +0100)]
powerpc/cell: Fix clang -Wimplicit-fallthrough warning
Clang warns:
arch/powerpc/platforms/cell/pervasive.c:81:2: error: unannotated fall-through between switch labels
case SRR1_WAKEEE:
^
arch/powerpc/platforms/cell/pervasive.c:81:2: note: insert 'break;' to avoid fall-through
case SRR1_WAKEEE:
^
break;
1 error generated.
Clang is more pedantic than GCC, which does not warn when failing
through to a case that is just break or return. Clang's version is more
in line with the kernel's own stance in deprecated.rst. Add athe missing
break to silence the warning.
Fixes:
6e83985b0f6e ("powerpc/cbe: Do not process external or decremeter interrupts from sreset")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211207110228.698956-1-anders.roxell@linaro.org
Xiang wangx [Sun, 5 Dec 2021 13:09:25 +0000 (21:09 +0800)]
macintosh: Add const to of_device_id
struct of_device_id should normally be const.
Signed-off-by: Xiang wangx <wangxiang@cdjrlc.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211205130925.28389-1-wangxiang@cdjrlc.com
Christophe Leroy [Mon, 29 Nov 2021 17:49:41 +0000 (18:49 +0100)]
powerpc/inst: Optimise copy_inst_from_kernel_nofault()
copy_inst_from_kernel_nofault() uses copy_from_kernel_nofault() to
copy one or two 32bits words. This means calling an out-of-line
function which itself calls back copy_from_kernel_nofault_allowed()
then performs a generic copy with loops.
Rewrite copy_inst_from_kernel_nofault() to do everything at a
single place and use __get_kernel_nofault() directly to perform
single accesses without loops.
Allthough the generic function uses pagefault_disable(), it is not
required on powerpc because do_page_fault() bails earlier when a
kernel mode fault happens on a kernel address.
As the function has now become very small, inline it.
With this change, on an 8xx the time spent in the loop in
ftrace_replace_code() is reduced by 23% at function tracer activation
and 27% at nop tracer activation.
The overall time to activate function tracer (measured with shell
command 'time') is 570ms before the patch and 470ms after the patch.
Even vmlinux size is reduced (by 152 instruction).
Before the patch:
00000018 <copy_inst_from_kernel_nofault>:
18: 94 21 ff e0 stwu r1,-32(r1)
1c: 7c 08 02 a6 mflr r0
20: 38 a0 00 04 li r5,4
24: 93 e1 00 1c stw r31,28(r1)
28: 7c 7f 1b 78 mr r31,r3
2c: 38 61 00 08 addi r3,r1,8
30: 90 01 00 24 stw r0,36(r1)
34: 48 00 00 01 bl 34 <copy_inst_from_kernel_nofault+0x1c>
34: R_PPC_REL24 copy_from_kernel_nofault
38: 2c 03 00 00 cmpwi r3,0
3c: 40 82 00 0c bne 48 <copy_inst_from_kernel_nofault+0x30>
40: 81 21 00 08 lwz r9,8(r1)
44: 91 3f 00 00 stw r9,0(r31)
48: 80 01 00 24 lwz r0,36(r1)
4c: 83 e1 00 1c lwz r31,28(r1)
50: 38 21 00 20 addi r1,r1,32
54: 7c 08 03 a6 mtlr r0
58: 4e 80 00 20 blr
After the patch (before inlining):
00000018 <copy_inst_from_kernel_nofault>:
18: 3d 20 b0 00 lis r9,-20480
1c: 7c 04 48 40 cmplw r4,r9
20: 7c 69 1b 78 mr r9,r3
24: 41 80 00 14 blt 38 <copy_inst_from_kernel_nofault+0x20>
28: 81 44 00 00 lwz r10,0(r4)
2c: 38 60 00 00 li r3,0
30: 91 49 00 00 stw r10,0(r9)
34: 4e 80 00 20 blr
38: 38 60 ff de li r3,-34
3c: 4e 80 00 20 blr
40: 38 60 ff f2 li r3,-14
44: 4e 80 00 20 blr
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Add clang workaround, with version check as suggested by Nathan]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0d5b12183d5176dd702d29ad94c39c384e51c78f.1638208156.git.christophe.leroy@csgroup.eu
Christophe Leroy [Mon, 29 Nov 2021 17:49:40 +0000 (18:49 +0100)]
powerpc/inst: Move ppc_inst_t definition in asm/reg.h
Because of circular inclusion of asm/hw_breakpoint.h, we
need to move definition of asm/reg.h outside of inst.h
so that asm/hw_breakpoint.h gets it without including
asm/inst.h
Also remove asm/inst.h from asm/uprobes.h as it's not
needed anymore.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4b79f1491118af96b1ac0735e74aeca02ea4c04e.1638208156.git.christophe.leroy@csgroup.eu
Christophe Leroy [Mon, 29 Nov 2021 17:49:39 +0000 (18:49 +0100)]
powerpc/inst: Define ppc_inst_t as u32 on PPC32
Unlike PPC64 ABI, PPC32 uses the stack to pass a parameter defined
as a struct, even when the struct has a single simple element.
To avoid that, define ppc_inst_t as u32 on PPC32.
Keep it as 'struct ppc_inst' when __CHECKER__ is defined so that
sparse can perform type checking.
Also revert commit
511eea5e2ccd ("powerpc/kprobes: Fix Oops by passing
ppc_inst as a pointer to emulate_step() on ppc32") as now the
instruction to be emulated is passed as a register to emulate_step().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c6d0c46f598f76ad0b0a88bc0d84773bd921b17c.1638208156.git.christophe.leroy@csgroup.eu
Christophe Leroy [Mon, 29 Nov 2021 17:49:38 +0000 (18:49 +0100)]
powerpc/inst: Define ppc_inst_t
In order to stop using 'struct ppc_inst' on PPC32,
define a ppc_inst_t typedef.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fe5baa2c66fea9db05a8b300b3e8d2880a42596c.1638208156.git.christophe.leroy@csgroup.eu
Christophe Leroy [Mon, 29 Nov 2021 17:49:37 +0000 (18:49 +0100)]
powerpc/inst: Refactor ___get_user_instr()
PPC64 version of ___get_user_instr() can be used for PPC32 as well,
by simply disabling the suffix part with IS_ENABLED(CONFIG_PPC64).
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1f0ede830ccb33a659119a55cb590820c27004db.1638208156.git.christophe.leroy@csgroup.eu
Christophe Leroy [Fri, 26 Nov 2021 12:40:35 +0000 (13:40 +0100)]
powerpc/32s: Allocate one 256k IBAT instead of two consecutives 128k IBATs
Today we have the following IBATs allocated:
---[ Instruction Block Address Translation ]---
0: 0xc0000000-0xc03fffff 0x00000000 4M Kernel x m
1: 0xc0400000-0xc05fffff 0x00400000 2M Kernel x m
2: 0xc0600000-0xc06fffff 0x00600000 1M Kernel x m
3: 0xc0700000-0xc077ffff 0x00700000 512K Kernel x m
4: 0xc0780000-0xc079ffff 0x00780000 128K Kernel x m
5: 0xc07a0000-0xc07bffff 0x007a0000 128K Kernel x m
6: -
7: -
The two 128K should be a single 256K instead.
When _etext is not aligned to 128Kbytes, the system will allocate
all necessary BATs to the lower 128Kbytes boundary, then allocate
an additional 128Kbytes BAT for the remaining block.
Instead, align the top to 128Kbytes so that the function directly
allocates a 256Kbytes last block:
---[ Instruction Block Address Translation ]---
0: 0xc0000000-0xc03fffff 0x00000000 4M Kernel x m
1: 0xc0400000-0xc05fffff 0x00400000 2M Kernel x m
2: 0xc0600000-0xc06fffff 0x00600000 1M Kernel x m
3: 0xc0700000-0xc077ffff 0x00700000 512K Kernel x m
4: 0xc0780000-0xc07bffff 0x00780000 256K Kernel x m
5: -
6: -
7: -
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ab58b296832b0ec650e2203200e060adbcb2677d.1637930421.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:33 +0000 (09:29 +0200)]
powerpc: Remove CONFIG_PPC_HAVE_KUAP and CONFIG_PPC_HAVE_KUEP
All platforms now have KUAP and KUEP so remove CONFIG_PPC_HAVE_KUAP
and CONFIG_PPC_HAVE_KUEP.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a3c007ad0951965199e6ab2ef1035966bc66e771.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:32 +0000 (09:29 +0200)]
powerpc/kuap: Wire-up KUAP on book3e/64
This adds KUAP support to book3e/64.
This is done by reading the content of SPRN_MAS1 and checking
the TID at the time user pgtable is loaded.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e2c2c9375afd4bbc06aa904d0103a5f5102a2b1a.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:31 +0000 (09:29 +0200)]
powerpc/kuap: Wire-up KUAP on 85xx in 32 bits mode.
This adds KUAP support to 85xx in 32 bits mode.
This is done by reading the content of SPRN_MAS1 and checking
the TID at the time user pgtable is loaded.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f8696f8980ca1532ada3a2f0e0a03e756269c7fe.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:30 +0000 (09:29 +0200)]
powerpc/kuap: Wire-up KUAP on 40x
This adds KUAP support to 40x. This is done by checking
the content of SPRN_PID at the time user pgtable is loaded.
40x doesn't have KUEP, but KUAP implies KUEP because when the
PID doesn't match the page's PID, the page cannot be read nor
executed.
So KUEP is now automatically selected when KUAP is selected and
disabled when KUAP is disabled.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/aaefa91897ddc42ac11019dc0e1d1a525bd08e90.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:29 +0000 (09:29 +0200)]
powerpc/kuap: Wire-up KUAP on 44x
This adds KUAP support to 44x. This is done by checking
the content of SPRN_PID at the time it is read and written
into SPRN_MMUCR.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7d6c3f1978a26feada74b084f651e8cf1e3b3a47.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:28 +0000 (09:29 +0200)]
powerpc: Add KUAP support for BOOKE and 40x
On booke/40x we don't have segments like book3s/32.
On booke/40x we don't have access protection groups like 8xx.
Use the PID register to provide user access protection.
Kernel address space can be accessed with any PID.
User address space has to be accessed with the PID of the user.
User PID is always not null.
Everytime the kernel is entered, set PID register to 0 and
restore PID register when returning to user.
Everytime kernel needs to access user data, PID is restored
for the access.
In TLB miss handlers, check the PID and bail out to data storage
exception when PID is 0 and accessed address is in user space.
Note that also forbids execution of user text by kernel except
when user access is unlocked. But this shouldn't be a problem
as the kernel is not supposed to ever run user text.
This patch prepares the infrastructure but the real activation of KUAP
is done by following patches for each processor type one by one.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5d65576a8e31e9480415785a180c92dd4e72306d.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:27 +0000 (09:29 +0200)]
powerpc/kuap: Make PPC_KUAP_DEBUG depend on PPC_KUAP only
PPC_KUAP_DEBUG is supported by all platforms doing PPC_KUAP,
it doesn't depend on Radix on book3s/64.
This will avoid adding one more dependency when implementing
KUAP on book3e/64.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a5ff6228a36e51783b83d8c10d058db76e450f63.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:26 +0000 (09:29 +0200)]
powerpc/kuap: Prepare for supporting KUAP on BOOK3E/64
Also call kuap_lock() and kuap_save_and_lock() from
interrupt functions with CONFIG_PPC64.
For book3s/64 we keep them empty as it is done in assembly.
Also do the locked assert when switching task unless it is
book3s/64.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1cbf94e26e6d6e2e028fd687588a7e6622d454a6.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:25 +0000 (09:29 +0200)]
powerpc/config: Add CONFIG_BOOKE_OR_40x
We have many functionnalities common to 40x and BOOKE, it leads to
many places with #if defined(CONFIG_BOOKE) || defined(CONFIG_40x).
We are going to add a few more with KUAP for booke/40x, so create
a new symbol which is defined when either BOOKE or 40x is defined.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9a3dbd60924cb25c9f944d3d8205ac5a0d15e229.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:24 +0000 (09:29 +0200)]
powerpc/nohash: Move setup_kuap out of 8xx.c
In order to reuse it on booke/4xx, move KUAP
setup routine out of 8xx.c
Make them usable on SMP by removing the __init tag
as it is called for each CPU.
And use __prevent_user_access() instead of hard
coding initial lock.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ae35eec3426509efc2b8ae69586c822e2fe2642a.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:23 +0000 (09:29 +0200)]
powerpc/kuap: Add kuap_lock()
Add kuap_lock() and call it when entering interrupts from user.
It is called kuap_lock() as it is similar to kuap_save_and_lock()
without the save.
However book3s/32 already have a kuap_lock(). Rename it
kuap_lock_addr().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4437e2deb9f6f549f7089d45e9c6f96a7e77905a.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:22 +0000 (09:29 +0200)]
powerpc/kuap: Remove __kuap_assert_locked()
__kuap_assert_locked() is redundant with
__kuap_get_and_assert_locked().
Move the verification of CONFIG_PPC_KUAP_DEBUG in kuap_assert_locked()
and make it call __kuap_get_and_assert_locked() directly.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1a60198a25d2ba38a37f1b92bc7d096435df4224.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:21 +0000 (09:29 +0200)]
powerpc/kuap: Check KUAP activation in generic functions
Today, every platform checks that KUAP is not de-activated
before doing the real job.
Move the verification out of platform specific functions.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/894f110397fcd248e125fb855d1e863e4e633a0d.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:20 +0000 (09:29 +0200)]
powerpc/kuap: Add a generic intermediate layer
Make the following functions generic to all platforms.
- bad_kuap_fault()
- kuap_assert_locked()
- kuap_save_and_lock() (PPC32 only)
- kuap_kernel_restore()
- kuap_get_and_assert_locked()
And for all platforms except book3s/64
- allow_user_access()
- prevent_user_access()
- prevent_user_access_return()
- restore_user_access()
Prepend __ in front of the name of platform specific ones.
For now the generic just calls the platform specific, but
next patch will move redundant parts of specific functions
into the generic one.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/eaef143a8dae7288cd34565ffa7b49c16aee1ec3.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:19 +0000 (09:29 +0200)]
powerpc/kuep: Remove 'nosmep' boot time parameter except for book3s/64
Deactivating KUEP at boot time is unrelevant for PPC32 and BOOK3E/64.
Remove it.
It allows to refactor setup_kuep() via a __weak function
that only PPC64s will overide for now.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix CONFIG_PPC_BOOKS_64 -> CONFIG_PPC_BOOK3S_64 typo]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4c36df18b41c988c4512f45d96220486adbe4c99.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:18 +0000 (09:29 +0200)]
powerpc/32s: Save content of sr0 to avoid 'mfsr'
Calling 'mfsr' to get the content of segment registers is heavy,
in addition it requires clearing of the 'reserved' bits.
In order to avoid this operation, save it in mm context and in
thread struct.
The saved sr0 is the one used by kernel, this means that on
locking entry it can be used as is.
For unlocking, the only thing to do is to clear SR_NX.
This improves null_syscall selftest by 12 cycles, ie 4%.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b02baf2ed8f09bad910dfaeeb7353b2ae6830525.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:17 +0000 (09:29 +0200)]
powerpc/32s: Do kuep_lock() and kuep_unlock() in assembly
When interrupt and syscall entries where converted to C, KUEP locking
and unlocking was also converted. It improved performance by unrolling
the loop, and allowed easily implementing boot time deactivation of
KUEP.
However, null_syscall selftest shows that KUEP is still heavy
(361 cycles with KUEP, 212 cycles without).
A way to improve more is to group 'mtsr's together, instead of
repeating 'addi' + 'mtsr' several times.
In order to do that, more registers need to be available. In C, GCC
will always be able to provide the requested number of registers, but
at the cost of saving some data on the stack, which is counter
performant here.
So let's do it in assembly, when we have full control of which
register can be used. It also has the advantage of locking earlier
and unlocking later and it helps GCC generating less tricky code.
The only drawback is to make boot time deactivation less straight
forward and require 'hand' instruction patching.
Group 'mtsr's by 4.
With this change, null_syscall selftest reports 336 cycles. Without
the change it was 361 cycles, that's a 7% reduction.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/115cb279e9b9948dfd93a065e047081c59e3a2a6.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:16 +0000 (09:29 +0200)]
powerpc/32s: Remove capability to disable KUEP at boottime
Disabling KUEP at boottime makes things unnecessarily complex.
Still allow disabling KUEP at build time, but when it's built-in
it is always there.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/96f583f82423a29a4205c60b9721079111b35567.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:15 +0000 (09:29 +0200)]
powerpc/book3e: Activate KUEP at all time
On book3e,
- When using 64 bits PTE: User pages don't have the SX bit defined
so KUEP is always active.
- When using 32 bits PTE: Implement KUEP by clearing SX bit during
TLB miss for user pages. The impact is minimal and worth neither
boot time nor build time selection.
Activate it at all time.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e376b114283fb94504e2aa2de846780063252cde.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:14 +0000 (09:29 +0200)]
powerpc/44x: Activate KUEP at all time
On 44x, KUEP is implemented by clearing SX bit during TLB miss
for user pages. The impact is minimal and not worth neither
boot time nor build time selection.
Activate it at all time.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2414d662558e7fb27d1ed41c8e47c591d576acac.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:13 +0000 (09:29 +0200)]
powerpc/8xx: Activate KUEP at all time
On the 8xx, there is absolutely no runtime impact with KUEP. Protection
against execution of user code in kernel mode is set up at boot time
by configuring the groups with contain all user pages as having swapped
protection rights, in extenso EX for user and NA for supervisor.
Configure KUEP at startup and force selection of CONFIG_PPC_KUEP.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2129e86944323ffe9ed07fffbeafdfd2e363690a.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 19 Oct 2021 07:29:12 +0000 (09:29 +0200)]
Revert "powerpc: Inline setup_kup()"
This reverts commit
1791ebd131c46539b024c0f2ebf12b6c88a265b9.
setup_kup() was inlined to manage conflict between PPC32 marking
setup_{kuap/kuep}() __init and PPC64 not marking them __init.
But in fact PPC32 has removed the __init mark for all but 8xx
in order to properly handle SMP.
In order to make setup_kup() grow a bit, revert the commit
mentioned above but remove __init for 8xx as well so that
we don't have to mark setup_kup() as __ref.
Also switch the order so that KUAP is initialised before KUEP
because on the 40x, KUEP will depend on the activation of KUAP.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7691088fd0994ee3c8db6298dc8c00259e3f6a7f.1634627931.git.christophe.leroy@csgroup.eu
Christophe Leroy [Mon, 27 Sep 2021 15:12:39 +0000 (17:12 +0200)]
powerpc/40x: Map 32Mbytes of memory at startup
As reported by Carlo, 16Mbytes is not enough with modern kernels
that tend to be a bit big, so map another 16M page at boot.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/89b5f974a7fa5011206682cd092e2c905530ff46.1632755552.git.christophe.leroy@csgroup.eu
Nicholas Piggin [Wed, 1 Dec 2021 14:41:53 +0000 (00:41 +1000)]
powerpc/microwatt: add POWER9_CPU, clear PPC_64S_HASH_MMU
Microwatt implements a subset of ISA v3.0 (which is equivalent to
the POWER9_CPU option). It is radix-only, so does not require hash
MMU support.
This saves 20kB compressed dtbImage and 56kB vmlinux size.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-19-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:52 +0000 (00:41 +1000)]
powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMU
Compiling out hash support code when CONFIG_PPC_64S_HASH_MMU=n saves
128kB kernel image size (90kB text) on powernv_defconfig minus KVM,
350kB on pseries_defconfig minus KVM, 40kB on a tiny config.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fixup defined(ARCH_HAS_MEMREMAP_COMPAT_ALIGN), which needs CONFIG.
Fix radix_enabled() use in setup_initial_memory_limit(). Add some
stubs to reduce number of ifdefs.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-18-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:51 +0000 (00:41 +1000)]
powerpc/64s: Make hash MMU support configurable
This adds Kconfig selection which allows 64s hash MMU support to be
disabled. It can be disabled if radix support is enabled, the minimum
supported CPU type is POWER9 (or higher), and KVM is not selected.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-17-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:50 +0000 (00:41 +1000)]
powerpc/64s: Always define arch unmapped area calls
To avoid any functional changes to radix paths when building with hash
MMU support disabled (and CONFIG_PPC_MM_SLICES=n), always define the
arch get_unmapped_area calls on 64s platforms.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-16-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:49 +0000 (00:41 +1000)]
powerpc/64s: Fix radix MMU when MMU_FTR_HPTE_TABLE is clear
There are a few places that require MMU_FTR_HPTE_TABLE to be set even
when running in radix mode. Fix those up.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-15-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:48 +0000 (00:41 +1000)]
powerpc/64e: remove mmu_linear_psize
mmu_linear_psize is only set at boot once on 64e, is not necessarily
the correct size of the linear map pages, and is never used anywhere.
Remove it.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Retain the extern, so we can use IS_ENABLED() for related code]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-14-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:47 +0000 (00:41 +1000)]
powerpc: make memremap_compat_align 64s-only
memremap_compat_align is only relevant when ZONE_DEVICE is selected.
ZONE_DEVICE depends on ARCH_HAS_PTE_DEVMAP, which is only selected
by PPC_BOOK3S_64.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-13-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:46 +0000 (00:41 +1000)]
powerpc/64: pcpu setup avoid reading mmu_linear_psize on 64e or radix
Radix never sets mmu_linear_psize so it's always 4K, which causes pcpu
atom_size to always be PAGE_SIZE. 64e sets it to 1GB always.
Make paths for these platforms to be explicit about what value they set
atom_size to.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-12-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:45 +0000 (00:41 +1000)]
powerpc/64s: Rename hash_hugetlbpage.c to hugetlbpage.c
This file contains functions and data common to radix, so rename it to
remove the hash_ prefix.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-11-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:44 +0000 (00:41 +1000)]
powerpc/64s: move page size definitions from hash specific file
The radix code uses some of the psize variables. Move the common
ones from hash_utils.c to pgtable.c.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-10-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:43 +0000 (00:41 +1000)]
powerpc/64s: Make flush_and_reload_slb a no-op when radix is enabled
The radix test can exclude slb_flush_all_realmode() from being called
because flush_and_reload_slb() is only expected to flush ERAT when
called by flush_erat(), which is only on pre-ISA v3.0 CPUs that do not
support radix.
This helps the later change to make hash support configurable to not
introduce runtime changes to radix mode behaviour.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-9-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:42 +0000 (00:41 +1000)]
powerpc/64s: move THP trace point creation out of hash specific file
In preparation for making hash MMU support configurable, move THP
trace point function definitions out of an otherwise hash-specific
file.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-8-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:41 +0000 (00:41 +1000)]
powerpc/pseries: lparcfg don't include slb_size line in radix mode
This avoids a change in behaviour in the later patch making hash
support configurable. This is possibly a user interface change, so
the alternative would be a hard-coded slb_size=0 here.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-7-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:40 +0000 (00:41 +1000)]
powerpc/pseries: move process table registration away from hash-specific code
This reduces ifdefs in a later change which makes hash support configurable.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-6-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:39 +0000 (00:41 +1000)]
powerpc/64s: Move and rename do_bad_slb_fault as it is not hash specific
slb.c is hash-specific SLB management, but do_bad_slb_fault deals with
segment interrupts that occur with radix MMU as well.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-5-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:38 +0000 (00:41 +1000)]
powerpc/pseries: Stop selecting PPC_HASH_MMU_NATIVE
The pseries platform does not use the native hash code but the PAPR
virtualised hash interfaces, so remove PPC_HASH_MMU_NATIVE.
This requires moving tlbiel code from hash_native.c to hash_utils.c.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-4-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:37 +0000 (00:41 +1000)]
powerpc: Rename PPC_NATIVE to PPC_HASH_MMU_NATIVE
PPC_NATIVE now only controls the native HPT code, so rename it to be
more descriptive. Restrict it to Book3S only.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-3-npiggin@gmail.com
Nicholas Piggin [Wed, 1 Dec 2021 14:41:36 +0000 (00:41 +1000)]
powerpc: Remove unused FW_FEATURE_NATIVE references
FW_FEATURE_NATIVE_ALWAYS and FW_FEATURE_NATIVE_POSSIBLE are always
zero and never do anything. Remove them.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-2-npiggin@gmail.com
Cédric Le Goater [Wed, 1 Dec 2021 16:54:18 +0000 (17:54 +0100)]
powerpc/xive: Fix compile when !CONFIG_PPC_POWERNV.
The automatic "save & restore" of interrupt context is a POWER10/XIVE2
feature exploited by KVM under the PowerNV platform. It is not
available under pSeries and the associated toggle should not be
exposed under the XIVE debugfs directory.
Introduce a platform handler for debugfs initialization and move the
'save-restore' entry under the native (PowerNV) backend to fix compile
when !CONFIG_PPC_POWERNV.
Fixes:
1e7684dc4fc7 ("powerpc/xive: Add a debugfs toggle for save-restore")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201165418.1041842-1-clg@kaod.org
Kees Cook [Thu, 18 Nov 2021 20:36:04 +0000 (12:36 -0800)]
powerpc/signal32: Use struct_group() to zero spe regs
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.
Add a struct_group() for the spe registers so that memset() can correctly reason
about the size:
In function 'fortify_memset_chk',
inlined from 'restore_user_regs.part.0' at arch/powerpc/kernel/signal_32.c:539:3:
>> include/linux/fortify-string.h:195:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
195 | __write_overflow_field();
| ^~~~~~~~~~~~~~~~~~~~~~~~
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211118203604.1288379-1-keescook@chromium.org
Christophe Leroy [Tue, 30 Nov 2021 08:42:37 +0000 (09:42 +0100)]
powerpc/32s: Fix shift-out-of-bounds in KASAN init
================================================================================
UBSAN: shift-out-of-bounds in arch/powerpc/mm/kasan/book3s_32.c:22:23
shift exponent -1 is negative
CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.5-gentoo-PowerMacG4 #9
Call Trace:
[
c214be60] [
c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable)
[
c214be80] [
c0b99288] ubsan_epilogue+0x10/0x5c
[
c214be90] [
c0b98fe0] __ubsan_handle_shift_out_of_bounds+0x94/0x138
[
c214bf00] [
c1c0f010] kasan_init_region+0xd8/0x26c
[
c214bf30] [
c1c0ed84] kasan_init+0xc0/0x198
[
c214bf70] [
c1c08024] setup_arch+0x18/0x54c
[
c214bfc0] [
c1c037f0] start_kernel+0x90/0x33c
[
c214bff0] [
00003610] 0x3610
================================================================================
This happens when the directly mapped memory is a power of 2.
Fix it by checking the shift and set the result to 0 when shift is -1
Fixes:
7974c4732642 ("powerpc/32s: Implement dedicated kasan_init_region()")
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215169
Link: https://lore.kernel.org/r/15cbc3439d4ad988b225e2119ec99502a5cc6ad3.1638261744.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 30 Nov 2021 09:32:42 +0000 (10:32 +0100)]
powerpc/powermac: Add missing lockdep_register_key()
KeyWest i2c @0xf8001003 irq 42 /uni-n@
f8000000/i2c@
f8001000
BUG: key
c2d00cbc has not been registered!
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:4801 lockdep_init_map_type+0x4c0/0xb4c
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.5-gentoo-PowerMacG4 #9
NIP:
c01a9428 LR:
c01a9428 CTR:
00000000
REGS:
e1033cf0 TRAP: 0700 Not tainted (5.15.5-gentoo-PowerMacG4)
MSR:
00029032 <EE,ME,IR,DR,RI> CR:
24002002 XER:
00000000
GPR00:
c01a9428 e1033db0 c2d1cf20 00000016 00000004 00000001 c01c0630 e1033a73
GPR08:
00000000 00000000 00000000 e1033db0 24002004 00000000 f8729377 00000003
GPR16:
c1829a9c 00000000 18305357 c1416fc0 c1416f80 c006ac60 c2d00ca8 c1416f00
GPR24:
00000000 c21586f0 c2160000 00000000 c2d00cbc c2170000 c216e1a0 c2160000
NIP [
c01a9428] lockdep_init_map_type+0x4c0/0xb4c
LR [
c01a9428] lockdep_init_map_type+0x4c0/0xb4c
Call Trace:
[
e1033db0] [
c01a9428] lockdep_init_map_type+0x4c0/0xb4c (unreliable)
[
e1033df0] [
c1c177b8] kw_i2c_add+0x334/0x424
[
e1033e20] [
c1c18294] pmac_i2c_init+0x9ec/0xa9c
[
e1033e80] [
c1c1a790] smp_core99_probe+0xbc/0x35c
[
e1033eb0] [
c1c03cb0] kernel_init_freeable+0x190/0x5a4
[
e1033f10] [
c000946c] kernel_init+0x28/0x154
[
e1033f30] [
c0035148] ret_from_kernel_thread+0x14/0x1c
Add missing lockdep_register_key()
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/69e4f55565bb45ebb0843977801b245af0c666fe.1638264741.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 30 Nov 2021 10:10:43 +0000 (11:10 +0100)]
powerpc/modules: Don't WARN on first module allocation attempt
module_alloc() first tries to allocate module text within 24 bits direct
jump from kernel text, and tries a wider allocation if first one fails.
When first allocation fails the following is observed in kernel logs:
vmap allocation for size
2400256 failed: use vmalloc=<size> to increase size
systemd-udevd: vmalloc error: size
2395133, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null)
CPU: 0 PID: 127 Comm: systemd-udevd Tainted: G W 5.15.5-gentoo-PowerMacG4 #9
Call Trace:
[
e2a53a50] [
c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable)
[
e2a53a70] [
c0540128] warn_alloc+0x11c/0x2b4
[
e2a53b50] [
c0531be8] __vmalloc_node_range+0xd8/0x64c
[
e2a53c10] [
c00338c0] module_alloc+0xa0/0xac
[
e2a53c40] [
c027a368] load_module+0x2ae0/0x8148
[
e2a53e30] [
c027fc78] sys_finit_module+0xfc/0x130
[
e2a53f30] [
c0035098] ret_from_syscall+0x0/0x28
...
Add __GFP_NOWARN flag to first allocation so that no warning appears
when it fails.
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Fixes:
2ec13df16704 ("powerpc/modules: Load modules closer to kernel text")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/93c9b84d6ec76aaf7b4f03468e22433a6d308674.1638267035.git.christophe.leroy@csgroup.eu
Nicholas Piggin [Mon, 29 Nov 2021 03:09:15 +0000 (13:09 +1000)]
powerpc/64s: Get LPID bit width from device tree
Allow the LPID bit width and partition table size to be set at runtime
from the device tree.
Move the PID bit width detection into the same place.
KVM does not support using the extra bits yet, this is mainly required
to get the PTCR register values correct (so KVM will run but it will
not allocate > 4096 LPIDs).
OPAL firmware provides this property for POWER10 CPUs since skiboot
commit
9b85f7d961f2 ("hdata: add mmu-pid-bits and mmu-lpid-bits for
POWER10 CPUs").
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211129030915.1888332-1-npiggin@gmail.com
Athira Rajeev [Wed, 21 Jul 2021 05:48:29 +0000 (01:48 -0400)]
powerpc/perf: Fix PMU callbacks to clear pending PMI before resetting an overflown PMC
Running perf fuzzer showed below in dmesg logs:
"Can't find PMC that caused IRQ"
This means a PMU exception happened, but none of the PMC's (Performance
Monitor Counter) were found to be overflown. There are some corner cases
that clears the PMCs after PMI gets masked. In such cases, the perf
interrupt handler will not find the active PMC values that had caused
the overflow and thus leads to this message while replaying.
Case 1: PMU Interrupt happens during replay of other interrupts and
counter values gets cleared by PMU callbacks before replay:
During replay of interrupts like timer, __do_irq() and doorbell
exception, we conditionally enable interrupts via may_hard_irq_enable().
This could potentially create a window to generate a PMI. Since irq soft
mask is set to ALL_DISABLED, the PMI will get masked here. We could get
IPIs run before perf interrupt is replayed and the PMU events could
be deleted or stopped. This will change the PMU SPR values and resets
the counters. Snippet of ftrace log showing PMU callbacks invoked in
__do_irq():
<idle>-0 [051] dns.
132025441306354: __do_irq <-call_do_irq
<idle>-0 [051] dns.
132025441306430: irq_enter <-__do_irq
<idle>-0 [051] dns.
132025441306503: irq_enter_rcu <-__do_irq
<idle>-0 [051] dnH.
132025441306599: xive_get_irq <-__do_irq
<<>>
<idle>-0 [051] dnH.
132025441307770: generic_smp_call_function_single_interrupt <-smp_ipi_demux_relaxed
<idle>-0 [051] dnH.
132025441307839: flush_smp_call_function_queue <-smp_ipi_demux_relaxed
<idle>-0 [051] dnH.
132025441308057: _raw_spin_lock <-event_function
<idle>-0 [051] dnH.
132025441308206: power_pmu_disable <-perf_pmu_disable
<idle>-0 [051] dnH.
132025441308337: power_pmu_del <-event_sched_out
<idle>-0 [051] dnH.
132025441308407: power_pmu_read <-power_pmu_del
<idle>-0 [051] dnH.
132025441308477: read_pmc <-power_pmu_read
<idle>-0 [051] dnH.
132025441308590: isa207_disable_pmc <-power_pmu_del
<idle>-0 [051] dnH.
132025441308663: write_pmc <-power_pmu_del
<idle>-0 [051] dnH.
132025441308787: power_pmu_event_idx <-perf_event_update_userpage
<idle>-0 [051] dnH.
132025441308859: rcu_read_unlock_strict <-perf_event_update_userpage
<idle>-0 [051] dnH.
132025441308975: power_pmu_enable <-perf_pmu_enable
<<>>
<idle>-0 [051] dnH.
132025441311108: irq_exit <-__do_irq
<idle>-0 [051] dns.
132025441311319: performance_monitor_exception <-replay_soft_interrupts
Case 2: PMI's masked during local_* operations, example local_add(). If
the local_add() operation happens within a local_irq_save(), replay of
PMI will be during local_irq_restore(). Similar to case 1, this could
also create a window before replay where PMU events gets deleted or
stopped.
Fix it by updating the PMU callback function power_pmu_disable() to
check for pending perf interrupt. If there is an overflown PMC and
pending perf interrupt indicated in paca, clear the PMI bit in paca to
drop that sample. Clearing of PMI bit is done in power_pmu_disable()
since disable is invoked before any event gets deleted/stopped. With
this fix, if there are more than one event running in the PMU, there is
a chance that we clear the PMI bit for the event which is not getting
deleted/stopped. The other events may still remain active. Hence to make
sure we don't drop valid sample in such cases, another check is added in
power_pmu_enable. This checks if there is an overflown PMC found among
the active events and if so enable back the PMI bit. Two new helper
functions are introduced to clear/set the PMI, ie
clear_pmi_irq_pending() and set_pmi_irq_pending(). Helper function
pmi_irq_pending() is introduced to give a warning if there is pending
PMI bit in paca, but no PMC is overflown.
Also there are corner cases which result in performance monitor
interrupts being triggered during power_pmu_disable(). This happens
since PMXE bit is not cleared along with disabling of other MMCR0 bits
in the pmu_disable. Such PMI's could leave the PMU running and could
trigger PMI again which will set MMCR0 PMAO bit. This could lead to
spurious interrupts in some corner cases. Example, a timer after
power_pmu_del() which will re-enable interrupts and triggers a PMI again
since PMAO bit is still set. But fails to find valid overflow since PMC
was cleared in power_pmu_del(). Fix that by disabling PMXE along with
disabling of other MMCR0 bits in power_pmu_disable().
We can't just replay PMI any time. Hence this approach is preferred
rather than replaying PMI before resetting overflown PMC. Patch also
documents core-book3s on a race condition which can trigger these PMC
messages during idle path in PowerNV.
Fixes:
f442d004806e ("powerpc/64s: Add support to mask perf interrupts and replay them")
Reported-by: Nageswara R Sastry <nasastry@in.ibm.com>
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Suggested-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make pmi_irq_pending() return bool, reflow/reword some comments]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1626846509-1350-2-git-send-email-atrajeev@linux.vnet.ibm.com
Christophe Leroy [Tue, 21 Sep 2021 15:09:49 +0000 (17:09 +0200)]
powerpc/atomics: Remove atomic_inc()/atomic_dec() and friends
Now that atomic_add() and atomic_sub() handle immediate operands,
atomic_inc() and atomic_dec() have no added value compared to the
generic fallback which calls atomic_add(1) and atomic_sub(1).
Also remove atomic_inc_not_zero() which fallsback to
atomic_add_unless() which itself fallsback to
atomic_fetch_add_unless() which now handles immediate operands.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0bc64a2f18726055093dbb2e479cefc60a409cfd.1632236981.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 21 Sep 2021 15:09:48 +0000 (17:09 +0200)]
powerpc/atomics: Use immediate operand when possible
Today we get the following code generation for atomic operations:
c001bb2c: 39 20 00 01 li r9,1
c001bb30: 7d 40 18 28 lwarx r10,0,r3
c001bb34: 7d 09 50 50 subf r8,r9,r10
c001bb38: 7d 00 19 2d stwcx. r8,0,r3
c001c7a8: 39 40 00 01 li r10,1
c001c7ac: 7d 00 18 28 lwarx r8,0,r3
c001c7b0: 7c ea 42 14 add r7,r10,r8
c001c7b4: 7c e0 19 2d stwcx. r7,0,r3
By allowing GCC to choose between immediate or regular operation,
we get:
c001bb2c: 7d 20 18 28 lwarx r9,0,r3
c001bb30: 39 49 ff ff addi r10,r9,-1
c001bb34: 7d 40 19 2d stwcx. r10,0,r3
--
c001c7a4: 7d 40 18 28 lwarx r10,0,r3
c001c7a8: 39 0a 00 01 addi r8,r10,1
c001c7ac: 7d 00 19 2d stwcx. r8,0,r3
For "and", the dot form has to be used because "andi" doesn't exist.
For logical operations we use unsigned 16 bits immediate.
For arithmetic operations we use signed 16 bits immediate.
On pmac32_defconfig, it reduces the text by approx another 8 kbytes.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2ec558d44db8045752fe9dbd29c9ba84bab6030b.1632236981.git.christophe.leroy@csgroup.eu
Christophe Leroy [Tue, 21 Sep 2021 15:09:47 +0000 (17:09 +0200)]
powerpc/bitops: Use immediate operand when possible
Today we get the following code generation for bitops like
set or clear bit:
c0009fe0: 39 40 08 00 li r10,2048
c0009fe4: 7c e0 40 28 lwarx r7,0,r8
c0009fe8: 7c e7 53 78 or r7,r7,r10
c0009fec: 7c e0 41 2d stwcx. r7,0,r8
c000d568: 39 00 18 00 li r8,6144
c000d56c: 7c c0 38 28 lwarx r6,0,r7
c000d570: 7c c6 40 78 andc r6,r6,r8
c000d574: 7c c0 39 2d stwcx. r6,0,r7
Most set bits are constant on lower 16 bits, so it can easily
be replaced by the "immediate" version of the operation. Allow
GCC to choose between the normal or immediate form.
For clear bits, on 32 bits 'rlwinm' can be used instead of 'andc' for
when all bits to be cleared are consecutive.
On 64 bits we don't have any equivalent single operation for clearing,
single bits or a few bits, we'd need two 'rldicl' so it is not
worth it, the li/andc sequence is doing the same.
With this patch we get:
c0009fe0: 7d 00 50 28 lwarx r8,0,r10
c0009fe4: 61 08 08 00 ori r8,r8,2048
c0009fe8: 7d 00 51 2d stwcx. r8,0,r10
c000d558: 7c e0 40 28 lwarx r7,0,r8
c000d55c: 54 e7 05 64 rlwinm r7,r7,0,21,18
c000d560: 7c e0 41 2d stwcx. r7,0,r8
On pmac32_defconfig, it reduces the text by approx 10 kbytes.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e6f815d9181bab09df3b350af51149437863e9f9.1632236981.git.christophe.leroy@csgroup.eu
Nicholas Piggin [Fri, 22 Oct 2021 06:13:22 +0000 (16:13 +1000)]
powerpc: flexible GPR range save/restore macros
Introduce macros that operate on a (start, end) range of GPRs, which
reduces lines of code and need to do mental arithmetic while reading the
code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211022061322.2671178-1-npiggin@gmail.com
Nicholas Piggin [Fri, 19 Nov 2021 11:31:46 +0000 (21:31 +1000)]
powerpc/watchdog: help remote CPUs to flush NMI printk output
The printk layer at the moment does not seem to have a good way to force
flush printk messages that are created in NMI context, except in the
panic path.
NMI-context printk messages normally get to the console with irq_work,
but that won't help if the CPU is stuck with irqs disabled, as can be
the case for hard lockup watchdog messages.
The watchdog currently flushes the printk buffers after detecting a
lockup on remote CPUs, but they may not have processed their NMI IPI
yet by that stage, or they may have self-detected a lockup in which
case they won't go via this NMI IPI path.
Improve the situation by having NMI-context mark a flag if it called
printk, and have watchdog timer interrupts check if that flag was set
and try to flush if it was. Latency is not a big problem because we
were already stuck for a while, just need to try to make sure the
messages eventually make it out.
Depends-on:
5d5e4522a7f4 ("printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211119113146.752759-6-npiggin@gmail.com
Christophe Leroy [Thu, 25 Nov 2021 11:43:33 +0000 (12:43 +0100)]
powerpc: Don't bother about .data..Lubsan sections
Since commit
9a427556fb8e ("vmlinux.lds.h: catch compound literals
into data and BSS") .data..Lubsan sections are taken into account
in DATA_MAIN which is included in DATA_DATA macro.
No need to take care of them anymore in powerpc vmlinux.lds.S
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3eb14570612eef17e01bb67f14a4450136001794.1637840601.git.christophe.leroy@csgroup.eu
Christophe Leroy [Fri, 26 Nov 2021 10:30:03 +0000 (11:30 +0100)]
powerpc/ptdump: Fix display a BAT's size unit
We have wrong units on BAT's sizes (G instead of M, M instead of ...)
---[ Instruction Block Address Translation ]---
0: 0xc0000000-0xc03fffff 0x00000000 4G Kernel x m
1: 0xc0400000-0xc05fffff 0x00400000 2G Kernel x m
2: 0xc0600000-0xc06fffff 0x00600000 1G Kernel x m
3: 0xc0700000-0xc077ffff 0x00700000 512M Kernel x m
4: 0xc0780000-0xc079ffff 0x00780000 128M Kernel x m
5: 0xc07a0000-0xc07bffff 0x007a0000 128M Kernel x m
6: -
7: -
This is because pt_dump_size() expects a size in Kbytes but
bat_show_603() gives the size in bytes.
To avoid risk of confusion, change pt_dump_size() to take bytes.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f16c30f5c9185a63335322cf1a8b22f189d335ef.1637922595.git.christophe.leroy@csgroup.eu
Christophe Leroy [Thu, 28 Oct 2021 12:24:04 +0000 (14:24 +0200)]
powerpc/ftrace: Activate HAVE_DYNAMIC_FTRACE_WITH_REGS on PPC32
Unlike PPC64, PPC32 doesn't require any special compiler option
to get _mcount() call not clobbering registers.
Provide ftrace_regs_caller() and ftrace_regs_call() and activate
HAVE_DYNAMIC_FTRACE_WITH_REGS.
That's heavily copied from ftrace_64_mprofile.S
For the time being leave livepatching aside, it will come with
following patch.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1862dc7719855cc2a4eec80920d94c955877557e.1635423081.git.christophe.leroy@csgroup.eu
Christophe Leroy [Thu, 28 Oct 2021 12:24:03 +0000 (14:24 +0200)]
powerpc/ftrace: Add module_trampoline_target() for PPC32
module_trampoline_target() is used by __ftrace_modify_call().
Implement it for PPC32 so that CONFIG_DYNAMIC_FTRACE_WITH_REGS
can be activated on PPC32 as well.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/42345f464fb465f0fc76f3090e250be8fc1729f0.1635423081.git.christophe.leroy@csgroup.eu
Christophe Leroy [Thu, 28 Oct 2021 12:24:02 +0000 (14:24 +0200)]
powerpc/ftrace: No need to read LR from stack in _mcount()
All functions calling _mcount do it exactly the same way, with the
following sequence of instructions:
c07de788: 7c 08 02 a6 mflr r0
c07de78c: 90 01 00 04 stw r0,4(r1)
c07de790: 4b 84 13 65 bl
c001faf4 <_mcount>
Allthough LR is pushed on stack, it is still in r0 while entering
_mcount().
Function arguments are in r3-r10, so r11 and r12 are still available
at that point.
Do like PPC64 and use r12 to move LR into CTR, so that r0 is preserved
and doesn't need to be restored from the stack.
While at it, bring back the EXPORT_SYMBOL at the end of _mcount.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/24a3ba7db388537c44a038026f926d885372e6d3.1635423081.git.christophe.leroy@csgroup.eu
Michael Ellerman [Wed, 24 Nov 2021 09:32:54 +0000 (20:32 +1100)]
powerpc: Mark probe_machine() __init and static
Prior to commit
b1923caa6e64 ("powerpc: Merge 32-bit and 64-bit
setup_arch()") probe_machine() was called from setup_32/64.c and lived
in setup-common.c. But now it's only called from setup-common.c so it
can be static and __init, and we don't need the declaration in
machdep.h either.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-6-mpe@ellerman.id.au
Michael Ellerman [Wed, 24 Nov 2021 09:32:53 +0000 (20:32 +1100)]
powerpc/smp: Move setup_profiling_timer() under CONFIG_PROFILING
setup_profiling_timer() is only needed when CONFIG_PROFILING is enabled.
Fixes the following W=1 warning when CONFIG_PROFILING=n:
linux/arch/powerpc/kernel/smp.c:1638:5: error: no previous prototype for ‘setup_profiling_timer’
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-5-mpe@ellerman.id.au
Michael Ellerman [Wed, 24 Nov 2021 09:32:52 +0000 (20:32 +1100)]
powerpc/mm: Move tlbcam_sz() and make it static
Building with W=1 we see a warning:
linux/arch/powerpc/mm/nohash/fsl_book3e.c:63:15: error: no previous prototype for ‘tlbcam_sz’
tlbcam_sz() is not used outside this file, so we can make it static.
However it's only used inside #ifdef CONFIG_PPC32, so move it within
that ifdef, otherwise we would get a defined but not used error.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-4-mpe@ellerman.id.au
Michael Ellerman [Wed, 24 Nov 2021 09:32:51 +0000 (20:32 +1100)]
powerpc/85xx: Make c293_pcie_pic_init() static
To fix the W=1 warning:
linux/arch/powerpc/platforms/85xx/c293pcie.c:22:13: error: no previous prototype for ‘c293_pcie_pic_init’
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-3-mpe@ellerman.id.au
Michael Ellerman [Wed, 24 Nov 2021 09:32:50 +0000 (20:32 +1100)]
powerpc/85xx: Make mpc85xx_smp_kexec_cpu_down() static
To fix the W=1 warning:
arch/powerpc/platforms/85xx/smp.c:369:6: error: no previous prototype for ‘mpc85xx_smp_kexec_cpu_down’
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-2-mpe@ellerman.id.au
Michael Ellerman [Wed, 24 Nov 2021 09:32:49 +0000 (20:32 +1100)]
powerpc/85xx: Fix no previous prototype warning for mpc85xx_setup_pmc()
Fixes the following W=1 warning:
arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c:89:12: warning: no previous prototype for 'mpc85xx_setup_pmc'
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211124093254.1054750-1-mpe@ellerman.id.au
Nicholas Piggin [Fri, 5 Nov 2021 03:50:42 +0000 (13:50 +1000)]
powerpc: select CPUMASK_OFFSTACK if NR_CPUS >= 8192
Some core kernel code starts to go beyond the 2048 byte stack size
warning at NR_CPUS=8192, so select CPUMASK_OFFSTACK in that case.
x86 does similarly for very large NR_CPUS.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211105035042.1398309-2-npiggin@gmail.com
Nicholas Piggin [Fri, 5 Nov 2021 03:50:41 +0000 (13:50 +1000)]
powerpc: remove cpu_online_cores_map function
This function builds the cores online map with on-stack cpumasks which
can cause high stack usage with large NR_CPUS.
It is not used in any performance sensitive paths, so instead just check
for first thread sibling.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211105035042.1398309-1-npiggin@gmail.com
Michael Ellerman [Mon, 29 Nov 2021 06:41:52 +0000 (17:41 +1100)]
Revert "powerpc/code-patching: Improve verification of patchability"
This reverts commit
8b8a8f0ab3f5519e45c526f826a655817486c5bb.
As reported[1] by Sachin this causes problems with ftrace, and it also
causes the code patching selftests to fail as reported[2] by Stephen.
So revert it for now.
1: https://lore.kernel.org/linuxppc-dev/
3668743C-09DF-4673-B15C-
2FFE2A57F7D7@linux.vnet.ibm.com/
2: https://lore.kernel.org/linuxppc-dev/
20211126161747.
1f7795b0@canb.auug.org.au/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nicholas Piggin [Thu, 25 Nov 2021 10:33:46 +0000 (20:33 +1000)]
powerpc/watchdog: Fix wd_smp_last_reset_tb reporting
wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of
marking CPUs stuck and removing them from the pending mask before it
begins any printing. This causes last reset times reported to be off.
Fix this by reading it into a local variable before it gets reset.
Fixes:
76521c4b0291 ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com
Michael Ellerman [Thu, 18 Nov 2021 00:44:15 +0000 (11:44 +1100)]
powerpc/microwatt: Make microwatt_get_random_darn() static
Make microwatt_get_random_darn() static, because it can be.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211118004415.1706863-1-mpe@ellerman.id.au
Nicholas Piggin [Wed, 10 Nov 2021 02:50:56 +0000 (12:50 +1000)]
powerpc/watchdog: read TB close to where it is used
When taking watchdog actions, printing messages, comparing and
re-setting wd_smp_last_reset_tb, etc., read TB close to the point of use
and under wd_smp_lock or printing lock (if applicable).
This should keep timebase mostly monotonic with kernel log messages, and
could prevent (in theory) a laggy CPU updating wd_smp_last_reset_tb to
something a long way in the past, and causing other CPUs to appear to be
stuck.
These additional TB reads are all slowpath (lockup has been detected),
so performance does not matter.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211110025056.2084347-5-npiggin@gmail.com
Nicholas Piggin [Wed, 10 Nov 2021 02:50:55 +0000 (12:50 +1000)]
powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi
There is a deadlock with the console_owner lock and the wd_smp_lock:
CPU x takes the console_owner lock
CPU y takes a watchdog timer interrupt and takes __wd_smp_lock
CPU x takes a soft-NMI interrupt, detects deadlock, spins on __wd_smp_lock
CPU y detects deadlock, tries to print something and spins on console_owner
-> deadlock
Change the watchdog locking scheme so wd_smp_lock protects the watchdog
internal data, but "reporting" (printing, issuing NMI IPIs, taking any
action outside of watchdog) uses a non-waiting exclusion. If a CPU detects
a problem but can not take the reporting lock, it just returns because
something else is already reporting. It will try again at some point.
Typically hard lockup watchdog report usefulness is not impacted due to
failure to spewing a large enough amount of data in as short a time as
possible, but by messages getting garbled.
Laurent debugged this and found the deadlock, and this patch is based on
his general approach to avoid expensive operations while holding the lock.
With the addition of the reporting exclusion.
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
[np: rework to add reporting exclusion update changelog]
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211110025056.2084347-4-npiggin@gmail.com
Nicholas Piggin [Wed, 10 Nov 2021 02:50:54 +0000 (12:50 +1000)]
powerpc/watchdog: tighten non-atomic read-modify-write access
Most updates to wd_smp_cpus_pending are under lock except the watchdog
interrupt bit clear.
This can race with non-atomic RMW updates to the mask under lock, which
can happen in two instances:
Firstly, if another CPU detects this one is stuck, removes it from the
mask, mask becomes empty and is re-filled with non-atomic stores. This
is okay because it would re-fill the mask with this CPU's bit clear
anyway (because this CPU is now stuck), so it doesn't matter that the
bit clear update got "lost". Add a comment for this.
Secondly, if another CPU detects a different CPU is stuck and removes it
from the pending mask with a non-atomic store to bytes which also
include the bit of this CPU. This case can result in the bit clear being
lost and the end result being the bit is set. This should be so rare it
hardly matters, but to make things simpler to reason about just avoid
the non-atomic access for that case.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211110025056.2084347-3-npiggin@gmail.com
Nicholas Piggin [Wed, 10 Nov 2021 02:50:53 +0000 (12:50 +1000)]
powerpc/watchdog: Fix missed watchdog reset due to memory ordering race
It is possible for all CPUs to miss the pending cpumask becoming clear,
and then nobody resetting it, which will cause the lockup detector to
stop working. It will eventually expire, but watchdog_smp_panic will
avoid doing anything if the pending mask is clear and it will never be
reset.
Order the cpumask clear vs the subsequent test to close this race.
Add an extra check for an empty pending mask when the watchdog fires and
finds its bit still clear, to try to catch any other possible races or
bugs here and keep the watchdog working. The extra test in
arch_touch_nmi_watchdog is required to prevent the new warning from
firing off.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Debugged-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211110025056.2084347-2-npiggin@gmail.com
Peiwei Hu [Fri, 19 Nov 2021 09:12:18 +0000 (17:12 +0800)]
powerpc/prom_init: Fix improper check of prom_getprop()
prom_getprop() can return PROM_ERROR. Binary operator can not identify
it.
Fixes:
94d2dde738a5 ("[POWERPC] Efika: prune fixups and make them more carefull")
Signed-off-by: Peiwei Hu <jlu.hpw@foxmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/tencent_BA28CC6897B7C95A92EB8C580B5D18589105@qq.com
Nathan Lynch [Wed, 17 Nov 2021 06:02:59 +0000 (00:02 -0600)]
powerpc/rtas: rtas_busy_delay_time() kernel-doc
Provide API documentation for rtas_busy_delay_time(), explaining why we
return the same value for 9900 and -2.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211117060259.957178-3-nathanl@linux.ibm.com
Nathan Lynch [Wed, 17 Nov 2021 06:02:58 +0000 (00:02 -0600)]
powerpc/rtas: rtas_busy_delay() improvements
Generally RTAS cannot block, and in PAPR it is required to return control
to the OS within a few tens of microseconds. In order to support operations
which may take longer to complete, many RTAS primitives can return
intermediate -2 ("busy") or 990x ("extended delay") values, which indicate
that the OS should reattempt the same call with the same arguments at some
point in the future.
Current versions of PAPR are less than clear about this, but the intended
meanings of these values in more detail are:
RTAS_BUSY (-2): RTAS has suspended a potentially long-running operation in
order to meet its latency obligation and give the OS the opportunity to
perform other work. RTAS can resume making progress as soon as the OS
reattempts the call.
RTAS_EXTENDED_DELAY_{MIN...MAX} (9900-9905): RTAS must wait for an external
event to occur or for internal contention to resolve before it can complete
the requested operation. The value encodes a non-binding hint as to roughly
how long the OS should wait before calling again, but the OS is allowed to
reattempt the call sooner or even immediately.
Linux of course must take its own CPU scheduling obligations into account
when handling these statuses; e.g. a task which receives an RTAS_BUSY
status should check whether to reschedule before it attempts the RTAS call
again to avoid starving other tasks.
rtas_busy_delay() is a helper function that "consumes" a busy or extended
delay status. Common usage:
int rc;
do {
rc = rtas_call(rtas_token("some-function"), ...);
} while (rtas_busy_delay(rc));
/* convert rc to Linux error value, etc */
If rc is a busy or extended delay status, the caller can rely on
rtas_busy_delay() to perform an appropriate sleep or reschedule and return
nonzero. Other statuses are handled normally by the caller.
The current implementation of rtas_busy_delay() both oversleeps and
overuses the CPU:
* It performs msleep() for all 990x and even when no delay is
suggested (-2), but this is understood to actually sleep for two jiffies
minimum in practice (20ms with HZ=100). 9900 (1ms) and 9901 (10ms)
appear to be the most common extended delay statuses, and the
oversleeping measurably lengthens DLPAR operations, which perform
many RTAS calls.
* It does not sleep on 990x unless need_resched() is true, causing code
like the loop above to needlessly retry, wasting CPU time.
Alter the logic to align better with the intended meanings:
* When passed RTAS_BUSY, perform cond_resched() and return without
sleeping. The caller should reattempt immediately
* Always sleep when passed an extended delay status, using usleep_range()
for precise shorter sleeps. Limit the sleep time to one second even
though there are higher architected values.
Change rtas_busy_delay()'s return type to bool to better reflect its usage,
and add kernel-doc.
rtas_busy_delay_time() is unchanged, even though it "incorrectly" returns 1
for RTAS_BUSY. There are users of that API with open-coded delay loops in
sensitive contexts that will have to be taken on an individual basis.
Brief results for addition and removal of 5GB memory on a small P9 PowerVM
partition follow. Load was generated with stress-ng --cpu N. For add,
elapsed time is greatly reduced without significant change in the number of
RTAS calls or time spent on CPU. For remove, elapsed time is modestly
reduced, with significant reductions in RTAS calls and time spent on CPU.
With no competing workload (- before, + after):
Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs):
- 1,935 probe:rtas_call # 0.003 M/sec ( +- 0.22% )
- 609.99 msec task-clock # 0.183 CPUs utilized ( +- 0.19% )
+ 1,956 probe:rtas_call # 0.003 M/sec ( +- 0.17% )
+ 618.56 msec task-clock # 0.278 CPUs utilized ( +- 0.11% )
- 3.3322 +- 0.0670 seconds time elapsed ( +- 2.01% )
+ 2.2222 +- 0.0416 seconds time elapsed ( +- 1.87% )
Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs):
- 6,224 probe:rtas_call # 0.008 M/sec ( +- 2.57% )
- 750.36 msec task-clock # 0.190 CPUs utilized ( +- 2.01% )
+ 843 probe:rtas_call # 0.003 M/sec ( +- 0.12% )
+ 250.66 msec task-clock # 0.068 CPUs utilized ( +- 0.17% )
- 3.9394 +- 0.0890 seconds time elapsed ( +- 2.26% )
+ 3.678 +- 0.113 seconds time elapsed ( +- 3.07% )
With all CPUs 100% busy (- before, + after):
Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs):
- 2,979 probe:rtas_call # 0.003 M/sec ( +- 0.12% )
- 1,096.62 msec task-clock # 0.105 CPUs utilized ( +- 0.10% )
+ 2,981 probe:rtas_call # 0.003 M/sec ( +- 0.22% )
+ 1,095.26 msec task-clock # 0.154 CPUs utilized ( +- 0.21% )
- 10.476 +- 0.104 seconds time elapsed ( +- 1.00% )
+ 7.1124 +- 0.0865 seconds time elapsed ( +- 1.22% )
Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs):
- 2,702 probe:rtas_call # 0.004 M/sec ( +- 4.00% )
- 722.71 msec task-clock # 0.067 CPUs utilized ( +- 2.41% )
+ 1,246 probe:rtas_call # 0.003 M/sec ( +- 0.25% )
+ 487.73 msec task-clock # 0.049 CPUs utilized ( +- 0.20% )
- 10.829 +- 0.163 seconds time elapsed ( +- 1.51% )
+ 9.9887 +- 0.0866 seconds time elapsed ( +- 0.87% )
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211117060259.957178-2-nathanl@linux.ibm.com
Nathan Lynch [Mon, 20 Sep 2021 17:32:03 +0000 (12:32 -0500)]
powerpc/pseries: delete scanlog
Remove the pseries scanlog driver.
This code supports functions from Power4-era servers that are not present
on targets currently supported by arch/powerpc. System manuals from this
time have this description:
Scan Dump data is a set of chip data that the service processor gathers
after a system malfunction. It consists of chip scan rings, chip trace
arrays, and Scan COM (SCOM) registers. This data is stored in the
scan-log partition of the system’s Nonvolatile Random Access
Memory (NVRAM).
PowerVM partition firmware development doesn't recognize the associated
function call or property, and they don't see any references to them in
their codebase. It seems to have been specific to non-virtualized pseries.
References:
Historical Linux commit from February 2003 (interesting to note this seems
to be the source of non-GPL exports for rtas_call etc):
https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=
f92e361842d5251e50562b09664082dcbd0548bb
IntelliStation and pSeries docs which refer to the feature:
http://ps-2.retropc.se/basil.holloway/ALL%20PDF/380635.pdf
http://ps-2.kev009.com/rs6000/manuals/p/p615-6C3-6E3/6C3_and_6E3_Users_Guide_SA38-0629.pdf
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210920173203.1800475-1-nathanl@linux.ibm.com
Nathan Lynch [Tue, 16 Nov 2021 21:58:06 +0000 (15:58 -0600)]
powerpc/rtas: kernel-doc fixes
Fix the following issues reported by kernel-doc:
$ scripts/kernel-doc -v -none arch/powerpc/kernel/rtas.c
arch/powerpc/kernel/rtas.c:810: info: Scanning doc for function rtas_activate_firmware
arch/powerpc/kernel/rtas.c:818: warning: contents before sections
arch/powerpc/kernel/rtas.c:841: info: Scanning doc for function rtas_call_reentrant
arch/powerpc/kernel/rtas.c:893: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Find a specific pseries error log in an RTAS extended event log.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211116215806.928235-1-nathanl@linux.ibm.com
Christophe Leroy [Mon, 15 Nov 2021 10:12:22 +0000 (11:12 +0100)]
powerpc/code-patching: Improve verification of patchability
Today, patch_instruction() assumes that it is called exclusively on
valid addresses, and only checks that it is not called on an init
address after init section has been freed.
Improve verification by calling kernel_text_address() instead.
kernel_text_address() already includes a verification of
initmem release.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bc683d499a411730504b132a924de0ccc2ef1f79.1636971137.git.christophe.leroy@csgroup.eu
Jason Wang [Sun, 14 Nov 2021 11:56:16 +0000 (19:56 +0800)]
powerpc/tsi108: make EXPORT_SYMBOL follow its function immediately
EXPORT_SYMBOL(foo); should immediately follow its function/variable.
Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211114115616.493815-1-wangborong@cdjrlc.com
Hari Bathini [Tue, 12 Oct 2021 12:30:56 +0000 (18:00 +0530)]
bpf ppc32: Access only if addr is kernel address
With KUAP enabled, any kernel code which wants to access userspace
needs to be surrounded by disable-enable KUAP. But that is not
happening for BPF_PROBE_MEM load instruction. Though PPC32 does not
support read protection, considering the fact that PTR_TO_BTF_ID
(which uses BPF_PROBE_MEM mode) could either be a valid kernel pointer
or NULL but should never be a pointer to userspace address, execute
BPF_PROBE_MEM load only if addr is kernel address, otherwise set
dst_reg=0 and move on.
This will catch NULL, valid or invalid userspace pointers. Only bad
kernel pointer will be handled by BPF exception table.
[Alexei suggested for x86]
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-9-hbathini@linux.ibm.com
Hari Bathini [Tue, 12 Oct 2021 12:30:55 +0000 (18:00 +0530)]
bpf ppc32: Add BPF_PROBE_MEM support for JIT
BPF load instruction with BPF_PROBE_MEM mode can cause a fault
inside kernel. Append exception table for such instructions
within BPF program.
Unlike other archs which uses extable 'fixup' field to pass dest_reg
and nip, BPF exception table on PowerPC follows the generic PowerPC
exception table design, where it populates both fixup and extable
sections within BPF program. fixup section contains 3 instructions,
first 2 instructions clear dest_reg (lower & higher 32-bit registers)
and last instruction jumps to next instruction in the BPF code.
extable 'insn' field contains relative offset of the instruction and
'fixup' field contains relative offset of the fixup entry. Example
layout of BPF program with extable present:
+------------------+
| |
| |
0x4020 -->| lwz r28,4(r4) |
| |
| |
0x40ac -->| lwz r3,0(r24) |
| lwz r4,4(r24) |
| |
| |
|------------------|
0x4278 -->| li r28,0 | \
| li r27,0 | | fixup entry
| b 0x4024 | /
0x4284 -->| li r4,0 |
| li r3,0 |
| b 0x40b4 |
|------------------|
0x4290 -->| insn=0xfffffd90 | \ extable entry
| fixup=0xffffffe4 | /
0x4298 -->| insn=0xfffffe14 |
| fixup=0xffffffe8 |
+------------------+
(Addresses shown here are chosen random, not real)
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-8-hbathini@linux.ibm.com
Ravi Bangoria [Tue, 12 Oct 2021 12:30:54 +0000 (18:00 +0530)]
bpf ppc64: Access only if addr is kernel address
On PPC64 with KUAP enabled, any kernel code which wants to
access userspace needs to be surrounded by disable-enable KUAP.
But that is not happening for BPF_PROBE_MEM load instruction.
So, when BPF program tries to access invalid userspace address,
page-fault handler considers it as bad KUAP fault:
Kernel attempted to read user page (
d0000000) - exploit attempt? (uid: 0)
Considering the fact that PTR_TO_BTF_ID (which uses BPF_PROBE_MEM
mode) could either be a valid kernel pointer or NULL but should
never be a pointer to userspace address, execute BPF_PROBE_MEM load
only if addr is kernel address, otherwise set dst_reg=0 and move on.
This will catch NULL, valid or invalid userspace pointers. Only bad
kernel pointer will be handled by BPF exception table.
[Alexei suggested for x86]
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-7-hbathini@linux.ibm.com
Ravi Bangoria [Tue, 12 Oct 2021 12:30:53 +0000 (18:00 +0530)]
bpf ppc64: Add BPF_PROBE_MEM support for JIT
BPF load instruction with BPF_PROBE_MEM mode can cause a fault
inside kernel. Append exception table for such instructions
within BPF program.
Unlike other archs which uses extable 'fixup' field to pass dest_reg
and nip, BPF exception table on PowerPC follows the generic PowerPC
exception table design, where it populates both fixup and extable
sections within BPF program. fixup section contains two instructions,
first instruction clears dest_reg and 2nd jumps to next instruction
in the BPF code. extable 'insn' field contains relative offset of
the instruction and 'fixup' field contains relative offset of the
fixup entry. Example layout of BPF program with extable present:
+------------------+
| |
| |
0x4020 -->| ld r27,4(r3) |
| |
| |
0x40ac -->| lwz r3,0(r4) |
| |
| |
|------------------|
0x4280 -->| li r27,0 | \ fixup entry
| b 0x4024 | /
0x4288 -->| li r3,0 |
| b 0x40b0 |
|------------------|
0x4290 -->| insn=0xfffffd90 | \ extable entry
| fixup=0xffffffec | /
0x4298 -->| insn=0xfffffe14 |
| fixup=0xffffffec |
+------------------+
(Addresses shown here are chosen random, not real)
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-6-hbathini@linux.ibm.com
Hari Bathini [Tue, 12 Oct 2021 12:30:52 +0000 (18:00 +0530)]
powerpc/ppc-opcode: introduce PPC_RAW_BRANCH() macro
Define and use PPC_RAW_BRANCH() macro instead of open coding it. This
macro is used while adding BPF_PROBE_MEM support.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-5-hbathini@linux.ibm.com
Hari Bathini [Tue, 12 Oct 2021 12:30:51 +0000 (18:00 +0530)]
bpf powerpc: refactor JIT compiler code
Refactor powerpc LDX JITing code to simplify adding BPF_PROBE_MEM
support.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-4-hbathini@linux.ibm.com
Ravi Bangoria [Tue, 12 Oct 2021 12:30:50 +0000 (18:00 +0530)]
bpf powerpc: Remove extra_pass from bpf_jit_build_body()
In case of extra_pass, usual JIT passes are always skipped. So,
extra_pass is always false while calling bpf_jit_build_body() and
can be removed.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-3-hbathini@linux.ibm.com
Ravi Bangoria [Tue, 12 Oct 2021 12:30:49 +0000 (18:00 +0530)]
bpf powerpc: Remove unused SEEN_STACK
SEEN_STACK is unused on PowerPC. Remove it. Also, have
SEEN_TAILCALL use 0x40000000.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211012123056.485795-2-hbathini@linux.ibm.com
Oliver O'Halloran [Fri, 15 Oct 2021 07:06:28 +0000 (18:06 +1100)]
powerpc/eeh: Use a goto for recovery failures
The EEH recovery logic in eeh_handle_normal_event() has some pretty strange
flow control. If we remove all the actual recovery logic we're left with
the following skeleton:
if (result != PCI_ERS_RESULT_DISCONNECT) {
...
}
if (result != PCI_ERS_RESULT_DISCONNECT) {
...
}
if (result == PCI_ERS_RESULT_NONE) {
...
}
if (result == PCI_ERS_RESULT_CAN_RECOVER) {
...
}
if (result == PCI_ERS_RESULT_CAN_RECOVER) {
...
}
if (result == PCI_ERS_RESULT_NEED_RESET) {
...
}
if ((result == PCI_ERS_RESULT_RECOVERED) ||
(result == PCI_ERS_RESULT_NONE)) {
...
goto out;
}
/*
* unsuccessful recovery / PCI_ERS_RESULT_DISCONECTED
* handling is here.
*/
...
out:
...
Most of the "if () { ... }" blocks above change "result" to
PCI_ERS_RESULT_DISCONNECTED if an error occurs in that recovery step. This
makes the control flow a bit confusing since it breaks the early-exit
pattern that is generally used in Linux. In any case we end up handling the
error in the final else block so why not just jump there directly? Doing so
also allows us to de-indent a bunch of code.
No functional changes.
[dja: rebase on top of linux-next + my preceeding refactor,
move clearing the EEH_DEV_NO_HANDLER bit above the first goto so that
it is always clear in the error handler code as it was before.]
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015070628.1331635-2-dja@axtens.net
Daniel Axtens [Fri, 15 Oct 2021 07:06:27 +0000 (18:06 +1100)]
powerpc/eeh: Small refactor of eeh_handle_normal_event()
The control flow of eeh_handle_normal_event() is a bit tricky.
Break out one of the error handling paths - rather than be in an else
block, we'll make it part of the regular body of the function and put a
'goto out;' in the true limb of the if.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015070628.1331635-1-dja@axtens.net
Cédric Le Goater [Fri, 5 Nov 2021 10:26:35 +0000 (11:26 +0100)]
powerpc/xive: Add a debugfs toggle for save-restore
On POWER10, the automatic "save & restore" of interrupt context is
always available. Provide a way to deactivate it for tests or
performance.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211105102636.1016378-11-clg@kaod.org
Cédric Le Goater [Fri, 5 Nov 2021 10:26:34 +0000 (11:26 +0100)]
powerpc/xive: Add a kernel parameter for StoreEOI
StoreEOI is activated by default on platforms supporting the feature
(POWER10) and will be used as soon as firmware advertises its
availability. The kernel parameter provides a way to deactivate its
use. It can be still be reactivated through debugfs.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211105102636.1016378-10-clg@kaod.org
projects / linux-2.6-microblaze.git / log