linux-kernel - [tip:efi/core] efi/arm64: Check for h/w support before booting a >4 KB granular kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-42b55734030c1f724d5f47aeb872e2cccd650d79@git.kernel.org>
Date:	Mon, 22 Feb 2016 04:16:07 -0800
From:	tip-bot for Ard Biesheuvel <tipbot@...or.com>@zytor.com
To:	linux-tip-commits@...r.kernel.org@...or.com
Cc:	peterz@...radead.org, jeremy.linton@....com, mingo@...nel.org,
	matt@...eblueprint.co.uk, ard.biesheuvel@...aro.org,
	mark.rutland@....com, torvalds@...ux-foundation.org, hpa@...or.com,
	linux-kernel@...r.kernel.org, suzuki.poulose@....com,
	tglx@...utronix.de
Subject: [tip:efi/core] efi/arm64: Check for h/w support before booting a >4 KB granular kernel

Commit-ID:  42b55734030c1f724d5f47aeb872e2cccd650d79
Gitweb:     http://git.kernel.org/tip/42b55734030c1f724d5f47aeb872e2cccd650d79
Author:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
AuthorDate: Wed, 17 Feb 2016 12:36:02 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
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 <suzuki.poulose@....com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Reviewed-by: Jeremy Linton <jeremy.linton@....com>
Acked-by: Mark Rutland <mark.rutland@....com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-efi@...r.kernel.org
Link: http://lkml.kernel.org/r/1455712566-16727-10-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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,