[PATCH 2/3] arm64: efistub: check for h/w support before booting a >4 KB granule kernel
From: Ard Biesheuvel <hidden>
Date: 2016-01-28 17:02:28
Subsystem:
extensible firmware interface (efi), the rest · Maintainers:
Ard Biesheuvel, Linus Torvalds
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 it. 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. Suggested-by: Jeremy Linton <redacted> Signed-off-by: Ard Biesheuvel <redacted> --- 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 9e0342745e4f..aef04ad60e0d 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 granule, 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 granule kernel is not supported by your CPU\n"); + else + pr_efi_err(sys_table_arg, "This 16 KB granule 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,
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2.5.0