arm64 fixes for -rc2

- 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
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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:
 "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

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")

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 {

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)

arch/arm64/kernel/cpu_errata.c

@@ -553,7 +553,7 @@ static const struct midr_range arm64_repeat_tlbi_cpus[] = {
 #endif
 
 #ifdef CONFIG_CAVIUM_ERRATUM_27456
-static const struct midr_range cavium_erratum_27456_cpus[] = {
+const struct midr_range cavium_erratum_27456_cpus[] = {
 	/* Cavium ThunderX, T88 pass 1.x - 2.1 */
 	MIDR_RANGE(MIDR_THUNDERX, 0, 0, 1, 1),
 	/* Cavium ThunderX, T81 pass 1.0 */

arch/arm64/kernel/cpufeature.c

@@ -983,7 +983,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 
 	/* Useful for KASLR robustness */
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
-		return true;
+		return kaslr_offset() > 0;
 
 	/* Don't force KPTI for CPUs that are not vulnerable */
 	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
@@ -1003,7 +1003,12 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
 	static bool kpti_applied = false;
 	int cpu = smp_processor_id();
 
-	if (kpti_applied)
+	/*
+	 * We don't need to rewrite the page-tables if either we've done
+	 * it already or we have KASLR enabled and therefore have not
+	 * created any global mappings at all.
+	 */
+	if (kpti_applied || kaslr_offset() > 0)
 		return;
 
 	remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);

arch/arm64/kernel/head.S

@@ -475,6 +475,7 @@ ENDPROC(__primary_switched)
 
 ENTRY(kimage_vaddr)
 	.quad		_text - TEXT_OFFSET
+EXPORT_SYMBOL(kimage_vaddr)
 
 /*
  * If we're fortunate enough to boot at EL2, ensure that the world is

arch/arm64/kernel/machine_kexec_file.c

@@ -87,7 +87,9 @@ static int setup_dtb(struct kimage *image,
 
 	/* add kaslr-seed */
 	ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
-	if (ret && (ret != -FDT_ERR_NOTFOUND))
+	if  (ret == -FDT_ERR_NOTFOUND)
+		ret = 0;
+	else if (ret)
 		goto out;
 
 	if (rng_is_initialized()) {

drivers/acpi/arm64/iort.c

@@ -876,7 +876,7 @@ int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
 	return (resv == its->its_count) ? resv : -ENODEV;
 }
 #else
-static inline const struct iommu_ops *iort_fwspec_iommu_ops(struct device *dev);
+static inline const struct iommu_ops *iort_fwspec_iommu_ops(struct device *dev)
 { return NULL; }
 static inline int iort_add_device_replay(const struct iommu_ops *ops,
 					 struct device *dev)
@@ -952,9 +952,10 @@ static int rc_dma_get_range(struct device *dev, u64 *size)
 {
 	struct acpi_iort_node *node;
 	struct acpi_iort_root_complex *rc;
+	struct pci_bus *pbus = to_pci_dev(dev)->bus;
 
 	node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
-			      iort_match_node_callback, dev);
+			      iort_match_node_callback, &pbus->dev);
 	if (!node || node->revision < 1)
 		return -ENODEV;