x86/paravirt: Match paravirt patchlet field definition ordering to initialization...
authorIngo Molnar <mingo@kernel.org>
Thu, 25 Apr 2019 08:10:12 +0000 (10:10 +0200)
committerIngo Molnar <mingo@kernel.org>
Thu, 25 Apr 2019 10:00:44 +0000 (12:00 +0200)
commitfc93dfd9345bb8b29a62b21cb0447dd1a3815f91
tree3a8a19683e0b205facc4725d0a3236b7d9589d1b
parent0b9d2fc1d0d628c94c6866a2ed3005c6730db512
x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering

Here's the objdump -D output of the PATCH_XXL data table:

0000000000000010 <patch_data_xxl>:
  10:   fa                      cli
  11:   fb                      sti
  12:   57                      push   %rdi
  13:   9d                      popfq
  14:   9c                      pushfq
  15:   58                      pop    %rax
  16:   0f 20 d0                mov    %cr2,%rax
  19:   0f 20 d8                mov    %cr3,%rax
  1c:   0f 22 df                mov    %rdi,%cr3
  1f:   0f 09                   wbinvd
  21:   0f 01 f8                swapgs
  24:   48 0f 07                sysretq
  27:   0f 01 f8                swapgs
  2a:   48 89 f8                mov    %rdi,%rax

Note how this doesn't match up to the source code:

static const struct patch_xxl patch_data_xxl = {
        .irq_irq_disable        = { 0xfa },             // cli
        .irq_irq_enable         = { 0xfb },             // sti
        .irq_save_fl            = { 0x9c, 0x58 },       // pushf; pop %[re]ax
        .mmu_read_cr2           = { 0x0f, 0x20, 0xd0 }, // mov %cr2, %[re]ax
        .mmu_read_cr3           = { 0x0f, 0x20, 0xd8 }, // mov %cr3, %[re]ax
        .irq_restore_fl         = { 0x57, 0x9d },       // push %rdi; popfq
        .mmu_write_cr3          = { 0x0f, 0x22, 0xdf }, // mov %rdi, %cr3
        .cpu_wbinvd             = { 0x0f, 0x09 },       // wbinvd
        .cpu_usergs_sysret64    = { 0x0f, 0x01, 0xf8,
                                    0x48, 0x0f, 0x07 }, // swapgs; sysretq
        .cpu_swapgs             = { 0x0f, 0x01, 0xf8 }, // swapgs
        .mov64                  = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax
        .irq_restore_fl         = { 0x50, 0x9d },       // push %eax; popf
        .mmu_write_cr3          = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3
        .cpu_iret               = { 0xcf },             // iret
};

Note how they are reordered: in the generated code .irq_restore_fl comes
before .irq_save_fl, etc. This is because the field ordering in struct
patch_xxl does not match the initialization ordering of patch_data_xxl.

Match up the initialization order with the definition order - this makes
the disassembly easily reviewable:

0000000000000010 <patch_data_xxl>:
  10:   fa                      cli
  11:   fb                      sti
  12:   9c                      pushfq
  13:   58                      pop    %rax
  14:   0f 20 d0                mov    %cr2,%rax
  17:   0f 20 d8                mov    %cr3,%rax
  1a:   0f 22 df                mov    %rdi,%cr3
  1d:   57                      push   %rdi
  1e:   9d                      popfq
  1f:   0f 09                   wbinvd
  21:   0f 01 f8                swapgs
  24:   48 0f 07                sysretq
  27:   0f 01 f8                swapgs
  2a:   48 89 f8                mov    %rdi,%rax

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190425081012.GA115378@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/paravirt_patch.c