Revert "mm: x86, arm64: add arch_has_hw_pte_young()"

This reverts commit b480620.
xanmod · Dec 15, 2021 · bcde0eb · bcde0eb
1 parent d704d88
commit bcde0eb
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Showing 7 changed files with 21 additions and 41 deletions.
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
@@ -779,11 +779,6 @@ static inline bool system_supports_tlb_range(void)
 		cpus_have_const_cap(ARM64_HAS_TLB_RANGE);
 }
 
-static inline bool system_has_hw_af(void)
-{
-	return IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && cpus_have_const_cap(ARM64_HW_AF);
-}
-
 extern int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
 
 static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
@@ -999,24 +999,21 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
  * page after fork() + CoW for pfn mappings. We don't always have a
  * hardware-managed access flag on arm64.
  */
-static inline bool arch_has_hw_pte_young(bool local)
+static inline bool arch_faults_on_old_pte(void)
 {
-	if (local) {
-		WARN_ON(preemptible());
-		return cpu_has_hw_af();
-	}
+	WARN_ON(preemptible());
 
-	return system_has_hw_af();
+	return !cpu_has_hw_af();
 }
-#define arch_has_hw_pte_young		arch_has_hw_pte_young
+#define arch_faults_on_old_pte		arch_faults_on_old_pte
 
 /*
  * Experimentally, it's cheap to set the access flag in hardware and we
  * benefit from prefaulting mappings as 'old' to start with.
  */
 static inline bool arch_wants_old_prefaulted_pte(void)
 {
-	return arch_has_hw_pte_young(true);
+	return !arch_faults_on_old_pte();
 }
 #define arch_wants_old_prefaulted_pte	arch_wants_old_prefaulted_pte
 

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
@@ -2161,16 +2161,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.matches = has_hw_dbm,
 		.cpu_enable = cpu_enable_hw_dbm,
 	},
-	{
-		.desc = "Hardware update of the Access flag",
-		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
-		.capability = ARM64_HW_AF,
-		.sys_reg = SYS_ID_AA64MMFR1_EL1,
-		.sign = FTR_UNSIGNED,
-		.field_pos = ID_AA64MMFR1_HADBS_SHIFT,
-		.min_field_value = 1,
-		.matches = has_cpuid_feature,
-	},
 #endif
 	{
 		.desc = "CRC32 instructions",

diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
@@ -35,7 +35,6 @@ HAS_STAGE2_FWB
 HAS_SYSREG_GIC_CPUIF
 HAS_TLB_RANGE
 HAS_VIRT_HOST_EXTN
-HW_AF
 HW_DBM
 KVM_PROTECTED_MODE
 MISMATCHED_CACHE_TYPE

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
@@ -1398,10 +1398,10 @@ static inline bool arch_has_pfn_modify_check(void)
 	return boot_cpu_has_bug(X86_BUG_L1TF);
 }
 
-#define arch_has_hw_pte_young arch_has_hw_pte_young
-static inline bool arch_has_hw_pte_young(bool local)
+#define arch_faults_on_old_pte arch_faults_on_old_pte
+static inline bool arch_faults_on_old_pte(void)
 {
-	return true;
+	return false;
 }
 
 #endif	/* __ASSEMBLY__ */

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
@@ -258,19 +258,6 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif
 
-#ifndef arch_has_hw_pte_young
-/*
- * Return whether the accessed bit is supported by the local CPU or all CPUs.
- *
- * Those arches which have hw access flag feature need to implement their own
- * helper. By default, "false" means pagefault will be hit on old pte.
- */
-static inline bool arch_has_hw_pte_young(bool local)
-{
-	return false;
-}
-#endif
-
 #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 				       unsigned long address,

diff --git a/mm/memory.c b/mm/memory.c
@@ -121,6 +121,18 @@ int randomize_va_space __read_mostly =
 					2;
 #endif
 
+#ifndef arch_faults_on_old_pte
+static inline bool arch_faults_on_old_pte(void)
+{
+	/*
+	 * Those arches which don't have hw access flag feature need to
+	 * implement their own helper. By default, "true" means pagefault
+	 * will be hit on old pte.
+	 */
+	return true;
+}
+#endif
+
 #ifndef arch_wants_old_prefaulted_pte
 static inline bool arch_wants_old_prefaulted_pte(void)
 {
@@ -2758,7 +2770,7 @@ static inline bool cow_user_page(struct page *dst, struct page *src,
 	 * On architectures with software "accessed" bits, we would
 	 * take a double page fault, so mark it accessed here.
 	 */
-	if (!arch_has_hw_pte_young(true) && !pte_young(vmf->orig_pte)) {
+	if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
 		pte_t entry;
 
 		vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);