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efi/arm64: Check for h/w support before booting a >4 KB granular kernel

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A kernel built with support for a page size that is not supported by the
hardware it runs on cannot boot to a state where it can inform the user
about the failure.

If we happen to be booting via UEFI, we can fail gracefully so check
if the currently configured page size is supported by the hardware before
entering the kernel proper. Note that UEFI mandates support for 4 KB pages,
so in that case, no check is needed.

Tested-by: Suzuki K Poulose <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Matt Fleming <[email protected]>
Reviewed-by: Jeremy Linton <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Ard Biesheuvel 2016-02-17 12:36:02 +00:00 • committed by Ingo Molnar
commit 42b5573403
1 changed files with 20 additions and 0 deletions
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20
drivers/firmware/efi/libstub/arm64-stub.c
View file

@ -12,6 +12,26 @@
#include <linux/efi.h>
#include <asm/efi.h>
#include <asm/sections.h>
#include <asm/sysreg.h>
efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
{
u64 tg;
/* UEFI mandates support for 4 KB granularity, no need to check */
if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
return EFI_SUCCESS;
tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n");
else
pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n");
return EFI_UNSUPPORTED;
}
return EFI_SUCCESS;
}
efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg,
unsigned long *image_addr,