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1d04ba1796
The UEFI spec allows runtime services to be called with interrupts masked or unmasked, and if a runtime service function needs to mask interrupts, it must restore the mask to its original state before returning (i.e. from the PoV of the OS, this does not change across a call). Firmware should never unmask exceptions, as these may then be taken by the OS unexpectedly. Unfortunately, some firmware has been seen to unmask IRQs (and potentially other maskable exceptions) across runtime services calls, leaving IRQ flags corrupted after returning from a runtime services function call. This may be detected by the IRQ tracing code, but often goes unnoticed, leaving a potentially disastrous bug hidden. This patch detects when the IRQ flags are corrupted by an EFI runtime services call, logging the call and specific corruption to the console. While restoring the expected value of the flags is insufficient to avoid problems, we do so to avoid redundant warnings from elsewhere (e.g. IRQ tracing). The set of bits in flags which we want to check is architecture-specific (e.g. we want to check FIQ on arm64, but not the zero flag on x86), so each arch must provide ARCH_EFI_IRQ_FLAGS_MASK to describe those. In the absence of this mask, the check is a no-op, and we redundantly save the flags twice, but that will be short-lived as subsequent patches will implement this and remove the scaffolding. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Leif Lindholm <leif.lindholm@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1461614832-17633-37-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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| .. | ||
| broadcom | ||
| efi | ||
| arm_scpi.c | ||
| dcdbas.c | ||
| dcdbas.h | ||
| dell_rbu.c | ||
| dmi-id.c | ||
| dmi-sysfs.c | ||
| dmi_scan.c | ||
| edd.c | ||
| iscsi_ibft.c | ||
| iscsi_ibft_find.c | ||
| Kconfig | ||
| Makefile | ||
| memmap.c | ||
| pcdp.c | ||
| pcdp.h | ||
| psci.c | ||
| qcom_scm-32.c | ||
| qcom_scm-64.c | ||
| qcom_scm.c | ||
| qcom_scm.h | ||
| qemu_fw_cfg.c | ||
| raspberrypi.c | ||