Commit-ID: 42b55734030c1f724d5f47aeb872e2cccd650d79 Gitweb: http://git.kernel.org/tip/42b55734030c1f724d5f47aeb872e2cccd650d79 Author: Ard Biesheuvel <[email protected]> AuthorDate: Wed, 17 Feb 2016 12:36:02 +0000 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 22 Feb 2016 08:26:27 +0100
efi/arm64: Check for h/w support before booting a >4 KB granular kernel 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]> --- drivers/firmware/efi/libstub/arm64-stub.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 9e03427..047fc34 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -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,
