arm64 fixes for -rc2

- Disable interrupts during page-table walk in show_pte()
 
 - Fix kexec_file_load() with 52-bit capable kernels on machines without
   52-bit addressing
 
 - Fix MIDR matching in CPU errata handling for KVM guests
 
 - Avoid reading MTE-specific ID registers when MTE support is disabled
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "Nothing Earth-shattering, but worthwhile fixes nonetheless:

   - Disable interrupts during page-table walk in show_pte()

   - Fix kexec_file_load() with 52-bit capable kernels on machines
     without 52-bit addressing

   - Fix MIDR matching in CPU errata handling for KVM guests

   - Avoid reading MTE-specific ID registers when MTE support is
     disabled"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Don't read GMID_EL1 when MTE is disabled
  arm64: errata: pass REVIDR when matching target implementation CPUs
  arm64: trans_pgd: clone only the linear map that exists at runtime
  arm64: mm: Fix the lockless page-table walk in show_pte()

arch/arm64/include/asm/cpu.h

@@ -78,5 +78,6 @@ void __init cpuinfo_store_boot_cpu(void);
 void __init init_cpu_features(struct cpuinfo_arm64 *info);
 void update_cpu_features(int cpu, struct cpuinfo_arm64 *info,
 				 struct cpuinfo_arm64 *boot);
+bool gmid_el1_accessible(const struct cpuinfo_arm64 *info);
 
 #endif /* __ASM_CPU_H */

arch/arm64/include/asm/cpufeature.h

@@ -627,13 +627,6 @@ static inline bool id_aa64pfr1_mpamfrac(u64 pfr1)
 	return val > 0;
 }
 
-static inline bool id_aa64pfr1_mte(u64 pfr1)
-{
-	u32 val = cpuid_feature_extract_unsigned_field(pfr1, ID_AA64PFR1_EL1_MTE_SHIFT);
-
-	return val >= ID_AA64PFR1_EL1_MTE_MTE2;
-}
-
 void __init setup_boot_cpu_features(void);
 void __init setup_system_features(void);
 void __init setup_user_features(void);

arch/arm64/kernel/cpu_errata.c

@@ -82,7 +82,7 @@ is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
 
 	for (i = 0; i < target_impl_cpu_num; i++) {
 		if (__is_affected_midr_range(entry, target_impl_cpus[i].midr,
-					     target_impl_cpus[i].midr))
+					     target_impl_cpus[i].revidr))
 			return true;
 	}
 	return false;

arch/arm64/kernel/cpufeature.c

@@ -1178,6 +1178,33 @@ static bool detect_ftr_has_mpam(void)
 	return id_aa64pfr0_mpam(pfr0) || id_aa64pfr1_mpamfrac(pfr1);
 }
 
+bool gmid_el1_accessible(const struct cpuinfo_arm64 *info)
+{
+	const struct arm64_ftr_bits *ftrp;
+	s64 mte, ovr;
+	u64 ftr_mask;
+
+	/* No ID register reflects CONFIG_ARM64_MTE. */
+	if (!IS_ENABLED(CONFIG_ARM64_MTE))
+		return false;
+
+	for (ftrp = ftr_id_aa64pfr1; ftrp->width; ftrp++) {
+		if (ftrp->shift == ID_AA64PFR1_EL1_MTE_SHIFT)
+			break;
+	}
+
+	ftr_mask = arm64_ftr_mask(ftrp);
+	mte = arm64_ftr_value(ftrp, info->reg_id_aa64pfr1);
+
+	/* The boot CPU runs before init_cpu_ftr_reg() strips unsafe overrides. */
+	if ((id_aa64pfr1_override.mask & ftr_mask) == ftr_mask) {
+		ovr = arm64_ftr_value(ftrp, id_aa64pfr1_override.val);
+		mte = arm64_ftr_safe_value(ftrp, ovr, mte);
+	}
+
+	return mte >= ID_AA64PFR1_EL1_MTE_MTE2;
+}
+
 void __init init_cpu_features(struct cpuinfo_arm64 *info)
 {
 	/* Before we start using the tables, make sure it is sorted */
@@ -1230,7 +1257,7 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
 		init_cpu_ftr_reg(SYS_MPAMIDR_EL1, info->reg_mpamidr);
 	}
 
-	if (id_aa64pfr1_mte(info->reg_id_aa64pfr1))
+	if (gmid_el1_accessible(info))
 		init_cpu_ftr_reg(SYS_GMID_EL1, info->reg_gmid);
 }
 
@@ -1492,11 +1519,9 @@ void update_cpu_features(int cpu,
 	 * they read/write depends on the GMID_EL1.BS field. Check that the
 	 * value is the same on all CPUs.
 	 */
-	if (IS_ENABLED(CONFIG_ARM64_MTE) &&
-	    id_aa64pfr1_mte(info->reg_id_aa64pfr1)) {
+	if (gmid_el1_accessible(info))
 		taint |= check_update_ftr_reg(SYS_GMID_EL1, cpu,
 					      info->reg_gmid, boot->reg_gmid);
-	}
 
 	/*
 	 * If we don't have AArch32 at all then skip the checks entirely

arch/arm64/kernel/cpuinfo.c

@@ -502,7 +502,7 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 	info->reg_id_aa64smfr0 = read_cpuid(ID_AA64SMFR0_EL1);
 	info->reg_id_aa64fpfr0 = read_cpuid(ID_AA64FPFR0_EL1);
 
-	if (id_aa64pfr1_mte(info->reg_id_aa64pfr1))
+	if (gmid_el1_accessible(info))
 		info->reg_gmid = read_cpuid(GMID_EL1);
 
 	if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0))

arch/arm64/kernel/machine_kexec.c

@@ -129,7 +129,8 @@ int machine_kexec_post_load(struct kimage *kimage)
 	}
 
 	/* Create a copy of the linear map */
-	rc = trans_pgd_create_copy(&info, &trans_pgd, PAGE_OFFSET, PAGE_END);
+	rc = trans_pgd_create_copy(&info, &trans_pgd,
+				   _PAGE_OFFSET(vabits_actual), PAGE_END);
 	if (rc)
 		return rc;
 	kimage->arch.ttbr1 = __pa(trans_pgd);

arch/arm64/mm/fault.c

@@ -16,6 +16,7 @@
 #include <linux/mm.h>
 #include <linux/hardirq.h>
 #include <linux/init.h>
+#include <linux/irqflags.h>
 #include <linux/kasan.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
@@ -154,6 +155,9 @@ static void show_pte(unsigned long addr)
 	pr_alert("%s pgtable: %luk pages, %llu-bit VAs, pgdp=%016lx\n",
 		 mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
 		 vabits_actual, mm_to_pgd_phys(mm));
+
+	guard(irqsave)();
+
 	pgdp = pgd_offset(mm, addr);
 	pgd = READ_ONCE(*pgdp);
 	pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
@@ -167,25 +171,25 @@ static void show_pte(unsigned long addr)
 		if (pgd_none(pgd) || pgd_bad(pgd))
 			break;
 
-		p4dp = p4d_offset(pgdp, addr);
+		p4dp = p4d_offset_lockless(pgdp, pgd, addr);
 		p4d = READ_ONCE(*p4dp);
 		pr_cont(", p4d=%016llx", p4d_val(p4d));
 		if (p4d_none(p4d) || p4d_bad(p4d))
 			break;
 
-		pudp = pud_offset(p4dp, addr);
+		pudp = pud_offset_lockless(p4dp, p4d, addr);
 		pud = READ_ONCE(*pudp);
 		pr_cont(", pud=%016llx", pud_val(pud));
 		if (pud_none(pud) || pud_bad(pud))
 			break;
 
-		pmdp = pmd_offset(pudp, addr);
+		pmdp = pmd_offset_lockless(pudp, pud, addr);
 		pmd = READ_ONCE(*pmdp);
 		pr_cont(", pmd=%016llx", pmd_val(pmd));
 		if (pmd_none(pmd) || pmd_bad(pmd))
 			break;
 
-		ptep = pte_offset_map(pmdp, addr);
+		ptep = pte_offset_map(&pmd, addr);
 		if (!ptep)
 			break;