Revert "powerpc/64s: Remove PROT_SAO support"

This reverts commit 5c9fa16e8abd342ce04dc830c1ebb2a03abf6c05.

Since PROT_SAO can still be useful for certain classes of software,
reintroduce it. Concerns about guest migration for LPARs using SAO
will be addressed next.

Signed-off-by: Shawn Anastasio <shawn@anastas.io>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200821185558.35561-2-shawn@anastas.io

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 6de56c3..495fc0c 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -20,13 +20,9 @@
 #define _PAGE_RW               (_PAGE_READ | _PAGE_WRITE)
 #define _PAGE_RWX              (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)
 #define _PAGE_PRIVILEGED       0x00008 /* kernel access only */
-
-#define _PAGE_CACHE_CTL                0x00030 /* Bits for the folowing cache modes */
-                       /*      No bits set is normal cacheable memory */
-                       /*      0x00010 unused, is SAO bit on radix POWER9 */
+#define _PAGE_SAO              0x00010 /* Strong access order */
 #define _PAGE_NON_IDEMPOTENT   0x00020 /* non idempotent memory */
 #define _PAGE_TOLERANT         0x00030 /* tolerant memory, cache inhibited */
-
 #define _PAGE_DIRTY            0x00080 /* C: page changed */
 #define _PAGE_ACCESSED         0x00100 /* R: page referenced */
 /*
@@ -828,6 +824,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
        return hash__set_pte_at(mm, addr, ptep, pte, percpu);
 }
 
+#define _PAGE_CACHE_CTL        (_PAGE_SAO | _PAGE_NON_IDEMPOTENT | _PAGE_TOLERANT)
+
 #define pgprot_noncached pgprot_noncached
 static inline pgprot_t pgprot_noncached(pgprot_t prot)
 {

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index e005b45..32a15dc 100644 (file)
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -196,7 +196,7 @@ static inline void cpu_feature_keys_init(void) { }
 #define CPU_FTR_SPURR                  LONG_ASM_CONST(0x0000000001000000)
 #define CPU_FTR_DSCR                   LONG_ASM_CONST(0x0000000002000000)
 #define CPU_FTR_VSX                    LONG_ASM_CONST(0x0000000004000000)
-// Free                                        LONG_ASM_CONST(0x0000000008000000)
+#define CPU_FTR_SAO                    LONG_ASM_CONST(0x0000000008000000)
 #define CPU_FTR_CP_USE_DCBTZ           LONG_ASM_CONST(0x0000000010000000)
 #define CPU_FTR_UNALIGNED_LD_STD       LONG_ASM_CONST(0x0000000020000000)
 #define CPU_FTR_ASYM_SMT               LONG_ASM_CONST(0x0000000040000000)
@@ -441,7 +441,7 @@ static inline void cpu_feature_keys_init(void) { }
            CPU_FTR_MMCRA | CPU_FTR_SMT | \
            CPU_FTR_COHERENT_ICACHE | \
            CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
-           CPU_FTR_DSCR | CPU_FTR_ASYM_SMT | \
+           CPU_FTR_DSCR | CPU_FTR_SAO  | CPU_FTR_ASYM_SMT | \
            CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
            CPU_FTR_CFAR | CPU_FTR_HVMODE | \
            CPU_FTR_VMX_COPY | CPU_FTR_HAS_PPR | CPU_FTR_DABRX )
@@ -450,7 +450,7 @@ static inline void cpu_feature_keys_init(void) { }
            CPU_FTR_MMCRA | CPU_FTR_SMT | \
            CPU_FTR_COHERENT_ICACHE | \
            CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
-           CPU_FTR_DSCR | \
+           CPU_FTR_DSCR | CPU_FTR_SAO  | \
            CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
            CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
            CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_DAWR | \
@@ -461,7 +461,7 @@ static inline void cpu_feature_keys_init(void) { }
            CPU_FTR_MMCRA | CPU_FTR_SMT | \
            CPU_FTR_COHERENT_ICACHE | \
            CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
-           CPU_FTR_DSCR | \
+           CPU_FTR_DSCR | CPU_FTR_SAO  | \
            CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
            CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
            CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
@@ -479,7 +479,7 @@ static inline void cpu_feature_keys_init(void) { }
            CPU_FTR_MMCRA | CPU_FTR_SMT | \
            CPU_FTR_COHERENT_ICACHE | \
            CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
-           CPU_FTR_DSCR | \
+           CPU_FTR_DSCR | CPU_FTR_SAO  | \
            CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
            CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
            CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \

diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
index 7c07728..4ba303e 100644 (file)
--- a/arch/powerpc/include/asm/mman.h
+++ b/arch/powerpc/include/asm/mman.h
@@ -13,20 +13,38 @@
 #include <linux/pkeys.h>
 #include <asm/cpu_has_feature.h>
 
-#ifdef CONFIG_PPC_MEM_KEYS
 static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
                unsigned long pkey)
 {
-       return pkey_to_vmflag_bits(pkey);
+#ifdef CONFIG_PPC_MEM_KEYS
+       return (((prot & PROT_SAO) ? VM_SAO : 0) | pkey_to_vmflag_bits(pkey));
+#else
+       return ((prot & PROT_SAO) ? VM_SAO : 0);
+#endif
 }
 #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
 
 static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
 {
-       return __pgprot(vmflag_to_pte_pkey_bits(vm_flags));
+#ifdef CONFIG_PPC_MEM_KEYS
+       return (vm_flags & VM_SAO) ?
+               __pgprot(_PAGE_SAO | vmflag_to_pte_pkey_bits(vm_flags)) :
+               __pgprot(0 | vmflag_to_pte_pkey_bits(vm_flags));
+#else
+       return (vm_flags & VM_SAO) ? __pgprot(_PAGE_SAO) : __pgprot(0);
+#endif
 }
 #define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags)
-#endif
+
+static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
+{
+       if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO))
+               return false;
+       if ((prot & PROT_SAO) && !cpu_has_feature(CPU_FTR_SAO))
+               return false;
+       return true;
+}
+#define arch_validate_prot arch_validate_prot
 
 #endif /* CONFIG_PPC64 */
 #endif /* _ASM_POWERPC_MMAN_H */

diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index 59ee9fa..6cb8aa3 100644 (file)
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -82,6 +82,8 @@
  */
 #include <asm/nohash/pte-book3e.h>
 
+#define _PAGE_SAO      0
+
 #define PTE_RPN_MASK   (~((1UL << PTE_RPN_SHIFT) - 1))
 
 /*

diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
index 3a70035..c0c7372 100644 (file)
--- a/arch/powerpc/include/uapi/asm/mman.h
+++ b/arch/powerpc/include/uapi/asm/mman.h
@@ -11,7 +11,7 @@
 #include <asm-generic/mman-common.h>
 
 
-#define PROT_SAO       0x10            /* Unsupported since v5.9 */
+#define PROT_SAO       0x10            /* Strong Access Ordering */
 
 #define MAP_RENAME      MAP_ANONYMOUS   /* In SunOS terminology */
 #define MAP_NORESERVE   0x40            /* don't reserve swap pages */

diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 8dc46f3..f204ad7 100644 (file)
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -653,7 +653,7 @@ static struct dt_cpu_feature_match __initdata
        {"processor-control-facility-v3", feat_enable_dbell, CPU_FTR_DBELL},
        {"processor-utilization-of-resources-register", feat_enable_purr, 0},
        {"no-execute", feat_enable, 0},
-       /* strong-access-ordering is unused */
+       {"strong-access-ordering", feat_enable, CPU_FTR_SAO},
        {"cache-inhibited-large-page", feat_enable_large_ci, 0},
        {"coprocessor-icswx", feat_enable, 0},
        {"hypervisor-virtualization-interrupt", feat_enable_hvi, 0},

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 890a71c..c663e7b 100644 (file)
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -232,6 +232,8 @@ unsigned long htab_convert_pte_flags(unsigned long pteflags)
                rflags |= HPTE_R_I;
        else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_NON_IDEMPOTENT)
                rflags |= (HPTE_R_I | HPTE_R_G);
+       else if ((pteflags & _PAGE_CACHE_CTL) == _PAGE_SAO)
+               rflags |= (HPTE_R_W | HPTE_R_I | HPTE_R_M);
        else
                /*
                 * Add memory coherence if cache inhibited is not set

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1983e08..5abe6df 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -321,6 +321,8 @@ extern unsigned int kobjsize(const void *objp);
 
 #if defined(CONFIG_X86)
 # define VM_PAT                VM_ARCH_1       /* PAT reserves whole VMA at once (x86) */
+#elif defined(CONFIG_PPC)
+# define VM_SAO                VM_ARCH_1       /* Strong Access Ordering (powerpc) */
 #elif defined(CONFIG_PARISC)
 # define VM_GROWSUP    VM_ARCH_1
 #elif defined(CONFIG_IA64)

diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 939092d..5fb7520 100644 (file)
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -114,6 +114,8 @@ IF_HAVE_PG_IDLE(PG_idle,            "idle"          )
 
 #if defined(CONFIG_X86)
 #define __VM_ARCH_SPECIFIC_1 {VM_PAT,     "pat"           }
+#elif defined(CONFIG_PPC)
+#define __VM_ARCH_SPECIFIC_1 {VM_SAO,     "sao"           }
 #elif defined(CONFIG_PARISC) || defined(CONFIG_IA64)
 #define __VM_ARCH_SPECIFIC_1 {VM_GROWSUP,      "growsup"       }
 #elif !defined(CONFIG_MMU)

diff --git a/mm/ksm.c b/mm/ksm.c
index 0aa2247..90a625b 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2453,6 +2453,10 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
                if (vma_is_dax(vma))
                        return 0;
 
+#ifdef VM_SAO
+               if (*vm_flags & VM_SAO)
+                       return 0;
+#endif
 #ifdef VM_SPARC_ADI
                if (*vm_flags & VM_SPARC_ADI)
                        return 0;

diff --git a/tools/testing/selftests/powerpc/mm/.gitignore b/tools/testing/selftests/powerpc/mm/.gitignore
index 91c775c..aac4a59 100644 (file)
--- a/tools/testing/selftests/powerpc/mm/.gitignore
+++ b/tools/testing/selftests/powerpc/mm/.gitignore
@@ -2,6 +2,7 @@
 hugetlb_vs_thp_test
 subpage_prot
 tempfile
+prot_sao
 segv_errors
 wild_bctr
 large_vm_fork_separation

diff --git a/tools/testing/selftests/powerpc/mm/Makefile b/tools/testing/selftests/powerpc/mm/Makefile
index 250ce17..defe488 100644 (file)
--- a/tools/testing/selftests/powerpc/mm/Makefile
+++ b/tools/testing/selftests/powerpc/mm/Makefile
@@ -2,7 +2,7 @@
 noarg:
        $(MAKE) -C ../
 
-TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot segv_errors wild_bctr \
+TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr \
                  large_vm_fork_separation bad_accesses pkey_exec_prot \
                  pkey_siginfo stack_expansion_signal stack_expansion_ldst
 
@@ -14,6 +14,8 @@ include ../../lib.mk
 
 $(TEST_GEN_PROGS): ../harness.c ../utils.c
 
+$(OUTPUT)/prot_sao: ../utils.c
+
 $(OUTPUT)/wild_bctr: CFLAGS += -m64
 $(OUTPUT)/large_vm_fork_separation: CFLAGS += -m64
 $(OUTPUT)/bad_accesses: CFLAGS += -m64

diff --git a/tools/testing/selftests/powerpc/mm/prot_sao.c b/tools/testing/selftests/powerpc/mm/prot_sao.c
new file mode 100644 (file)
index 0000000..e2eed65
--- /dev/null
+++ b/tools/testing/selftests/powerpc/mm/prot_sao.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2016, Michael Ellerman, IBM Corp.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include <asm/cputable.h>
+
+#include "utils.h"
+
+#define SIZE (64 * 1024)
+
+int test_prot_sao(void)
+{
+       char *p;
+
+       /* 2.06 or later should support SAO */
+       SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
+
+       /*
+        * Ensure we can ask for PROT_SAO.
+        * We can't really verify that it does the right thing, but at least we
+        * confirm the kernel will accept it.
+        */
+       p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE | PROT_SAO,
+                MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+       FAIL_IF(p == MAP_FAILED);
+
+       /* Write to the mapping, to at least cause a fault */
+       memset(p, 0xaa, SIZE);
+
+       return 0;
+}
+
+int main(void)
+{
+       return test_harness(test_prot_sao, "prot-sao");
+}