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Subject[PATCH 07/13] efi/arm-init: Use read-only early mappings
Date
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

The early mappings of the EFI system table contents and the UEFI memory
map are read-only from the OS point of view. So map them read-only to
protect them from inadvertent modification.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
drivers/firmware/efi/arm-init.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 9e15d571b53c..aa1f743152a2 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -61,8 +61,8 @@ static int __init uefi_init(void)
char vendor[100] = "unknown";
int i, retval;

- efi.systab = early_memremap(efi_system_table,
- sizeof(efi_system_table_t));
+ efi.systab = early_memremap_ro(efi_system_table,
+ sizeof(efi_system_table_t));
if (efi.systab == NULL) {
pr_warn("Unable to map EFI system table.\n");
return -ENOMEM;
@@ -86,8 +86,8 @@ static int __init uefi_init(void)
efi.systab->hdr.revision & 0xffff);

/* Show what we know for posterity */
- c16 = early_memremap(efi_to_phys(efi.systab->fw_vendor),
- sizeof(vendor) * sizeof(efi_char16_t));
+ c16 = early_memremap_ro(efi_to_phys(efi.systab->fw_vendor),
+ sizeof(vendor) * sizeof(efi_char16_t));
if (c16) {
for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
vendor[i] = c16[i];
@@ -100,8 +100,8 @@ static int __init uefi_init(void)
efi.systab->hdr.revision & 0xffff, vendor);

table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
- config_tables = early_memremap(efi_to_phys(efi.systab->tables),
- table_size);
+ config_tables = early_memremap_ro(efi_to_phys(efi.systab->tables),
+ table_size);
if (config_tables == NULL) {
pr_warn("Unable to map EFI config table array.\n");
retval = -ENOMEM;
@@ -185,7 +185,7 @@ void __init efi_init(void)
efi_system_table = params.system_table;

memmap.phys_map = params.mmap;
- memmap.map = early_memremap(params.mmap, params.mmap_size);
+ memmap.map = early_memremap_ro(params.mmap, params.mmap_size);
if (memmap.map == NULL) {
/*
* If we are booting via UEFI, the UEFI memory map is the only
--
2.6.2
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