diff mbox

[v2,6/7] arm64: efistub: check for h/w support before booting a >4 KB granule kernel

Message ID 1454601030-9093-7-git-send-email-ard.biesheuvel@linaro.org
State Accepted
Commit 42b55734030c1f724d5f47aeb872e2cccd650d79
Headers show

Commit Message

Ard Biesheuvel Feb. 4, 2016, 3:50 p.m. UTC 
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.

Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>

Tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 drivers/firmware/efi/libstub/arm64-stub.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

-- 
2.5.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff mbox

Patch

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,