Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "Another handful of arm64 fixes here. Most of the complication comes
  from improving our kpti code to avoid lengthy pauses (30+ seconds)
  during boot when we rewrite the page tables. There are also a couple
  of IORT fixes that came in via Lorenzo.

  Summary:

   - Don't error in kexec_file_load if kaslr-seed is missing in
     device-tree

   - Fix incorrect argument type passed to iort_match_node_callback()

   - Fix IORT build failure when CONFIG_IOMMU_API=n

   - Fix kpti performance regression with new rodata default option

   - Typo fix"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: kexec_file: return successfully even if kaslr-seed doesn't exist
  ACPI/IORT: Fix rc_dma_get_range()
  arm64: kpti: Avoid rewriting early page tables when KASLR is enabled
  arm64: asm-prototypes: Fix fat-fingered typo in comment
  ACPI/IORT: Fix build when CONFIG_IOMMU_API=n

3 files changed, 44 insertions, 3 deletions

diff --git a/arch/arm64/include/asm/asm-prototypes.h b/arch/arm64/include/asm/asm-prototypes.h
index 2173ad32d550..1c9a3a0c5fa5 100644
--- a/arch/arm64/include/asm/asm-prototypes.h
+++ b/arch/arm64/include/asm/asm-prototypes.h
@@ -2,7 +2,7 @@
 #ifndef __ASM_PROTOTYPES_H
 #define __ASM_PROTOTYPES_H
 /*
- * CONFIG_MODEVERIONS requires a C declaration to generate the appropriate CRC
+ * CONFIG_MODVERSIONS requires a C declaration to generate the appropriate CRC
  * for each symbol. Since commit:
  *
  *   4efca4ed05cbdfd1 ("kbuild: modversions for EXPORT_SYMBOL() for asm")
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 7689c7aa1d77..ac352accb3d9 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -16,6 +16,8 @@
 #ifndef __ASM_MMU_H
 #define __ASM_MMU_H
 
+#include <asm/cputype.h>
+
 #define MMCF_AARCH32	0x1	/* mm context flag for AArch32 executables */
 #define USER_ASID_BIT	48
 #define USER_ASID_FLAG	(UL(1) << USER_ASID_BIT)
@@ -44,6 +46,45 @@ static inline bool arm64_kernel_unmapped_at_el0(void)
 	       cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
 }
 
+static inline bool arm64_kernel_use_ng_mappings(void)
+{
+	bool tx1_bug;
+
+	/* What's a kpti? Use global mappings if we don't know. */
+	if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0))
+		return false;
+
+	/*
+	 * Note: this function is called before the CPU capabilities have
+	 * been configured, so our early mappings will be global. If we
+	 * later determine that kpti is required, then
+	 * kpti_install_ng_mappings() will make them non-global.
+	 */
+	if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
+		return arm64_kernel_unmapped_at_el0();
+
+	/*
+	 * KASLR is enabled so we're going to be enabling kpti on non-broken
+	 * CPUs regardless of their susceptibility to Meltdown. Rather
+	 * than force everybody to go through the G -> nG dance later on,
+	 * just put down non-global mappings from the beginning.
+	 */
+	if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
+		tx1_bug = false;
+#ifndef MODULE
+	} else if (!static_branch_likely(&arm64_const_caps_ready)) {
+		extern const struct midr_range cavium_erratum_27456_cpus[];
+
+		tx1_bug = is_midr_in_range_list(read_cpuid_id(),
+						cavium_erratum_27456_cpus);
+#endif
+	} else {
+		tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456);
+	}
+
+	return !tx1_bug && kaslr_offset() > 0;
+}
+
 typedef void (*bp_hardening_cb_t)(void);
 
 struct bp_hardening_data {
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 78b942c1bea4..986e41c4c32b 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -37,8 +37,8 @@
 #define _PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
 #define _PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
 
-#define PTE_MAYBE_NG		(arm64_kernel_unmapped_at_el0() ? PTE_NG : 0)
-#define PMD_MAYBE_NG		(arm64_kernel_unmapped_at_el0() ? PMD_SECT_NG : 0)
+#define PTE_MAYBE_NG		(arm64_kernel_use_ng_mappings() ? PTE_NG : 0)
+#define PMD_MAYBE_NG		(arm64_kernel_use_ng_mappings() ? PMD_SECT_NG : 0)
 
 #define PROT_DEFAULT		(_PROT_DEFAULT | PTE_MAYBE_NG)
 #define PROT_SECT_DEFAULT	(_PROT_SECT_DEFAULT | PMD_MAYBE_NG)