[PATCHv6 7/8] arm64: efi: Use ioremap_exec for code sections

[Laura Abbott]

ioremap is not guaranteed to return memory with proper
execution permissions. Introduce ioremap_exec which will
ensure that permission bits are set as expected for EFI
code sections.

Tested-by: Kees Cook <keescook at chromium.org>
Signed-off-by: Laura Abbott <lauraa at codeaurora.org>
---
 arch/arm64/include/asm/io.h      |  1 +
 arch/arm64/include/asm/pgtable.h |  1 +
 arch/arm64/kernel/efi.c          | 12 +++++++++++-
 arch/arm64/mm/ioremap.c          | 11 +++++++++++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 79f1d519..7dd8465 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -230,6 +230,7 @@ extern void __memset_io(volatile void __iomem *, int, size_t);
 extern void __iomem *__ioremap(phys_addr_t phys_addr, size_t size, pgprot_t prot);
 extern void __iounmap(volatile void __iomem *addr);
 extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
+extern void __iomem *ioremap_exec(phys_addr_t phys_addr, size_t size);
 
 #define ioremap(addr, size)		__ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE))
 #define ioremap_nocache(addr, size)	__ioremap((addr), (size), __pgprot(PROT_DEVICE_nGnRE))
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 41a43bf..9b1d9d0 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -65,6 +65,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
 #define PROT_DEVICE_nGnRE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
 #define PROT_NORMAL_NC		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL_NC))
 #define PROT_NORMAL		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL))
+#define PROT_NORMAL_EXEC	(PROT_DEFAULT | PTE_UXN | PTE_ATTRINDX(MT_NORMAL))
 
 #define PROT_SECT_DEVICE_nGnRE	(PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE))
 #define PROT_SECT_NORMAL	(PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL))
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 95c49eb..9e41f95 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -47,6 +47,14 @@ static int __init is_normal_ram(efi_memory_desc_t *md)
 	return 0;
 }
 
+static int __init is_code(efi_memory_desc_t *md)
+{
+	if (md->attribute & EFI_RUNTIME_SERVICES_CODE)
+		return 1;
+	return 0;
+}
+
+
 static void __init efi_setup_idmap(void)
 {
 	struct memblock_region *r;
@@ -338,7 +346,9 @@ static int __init remap_region(efi_memory_desc_t *md, void **new)
 	memrange_efi_to_native(&paddr, &npages);
 	size = npages << PAGE_SHIFT;
 
-	if (is_normal_ram(md))
+	if (is_code(md))
+		vaddr = (__force u64)ioremap_exec(paddr, size);
+	else if (is_normal_ram(md))
 		vaddr = (__force u64)ioremap_cache(paddr, size);
 	else
 		vaddr = (__force u64)ioremap(paddr, size);
diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index cbb99c8..b998441 100644
--- a/arch/arm64/mm/ioremap.c
+++ b/arch/arm64/mm/ioremap.c
@@ -103,6 +103,17 @@ void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
 }
 EXPORT_SYMBOL(ioremap_cache);
 
+void __iomem *ioremap_exec(phys_addr_t phys_addr, size_t size)
+{
+	/* For normal memory we already have a cacheable mapping. */
+	if (pfn_valid(__phys_to_pfn(phys_addr)))
+		return (void __iomem *)__phys_to_virt(phys_addr);
+
+	return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL_EXEC),
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_exec);
+
 /*
  * Must be called after early_fixmap_init
  */
-- 
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