Some firmware erroneously unmask IRQs (and potentially other architecture specific exceptions) during runtime services functions, in violation of both common sense and the UEFI specification. This can result in a number of issues if said exceptions are taken when they are expected to be masked, and additionally can confuse IRQ tracing if the original mask state is not restored prior to returning from firmware. In practice it's difficult to check that firmware never unmasks exceptions, but we can at least check that the IRQ flags are at least consistent upon entry to and return from a runtime services function call. This series implements said check in the shared EFI runtime wrappers code, after an initial round of refactoring such that this can be generic. I have left ia64 as-is, without this check, as ia64 doesn't currently use the generic runtime wrappers, has many special cases for the runtime calls which don't fit well with the generic code, and I don't expect a new, buggy ia64 firmware to appear soon. The first time corruption of the IRQ flags is detected, we dump a stack trace, and set TAINT_FIRMWARE_WORKAROUND. Additionally, and in all subsequent cases, we log (with ratelimiting) the specific corruption of the flags, and restore the expected flags to avoid redundant warnings elsewhere. Since v1 [1]: * Fix thinko: s/local_irq_save/local_save_flags/ * Remove ifdefs after conversion * Remove reundant semicolon from x86 patch * Move efi_call_virt_check_flags before first use * Add Acked-bys and Reviewed-bys Ard, I assume that your Reviewed-by still stands for the final patch, even though efi_call_virt_check_flags moved. Please shout if that's not the case! Hopefully you're also happy to extend that to the new patch removing the ifdefs once they become superfluous. Thanks, Mark. [1] https://lkml.org/lkml/2016/4/21/260 Mark Rutland (6): efi/runtime-wrappers: add {__,}efi_call_virt templates arm64/efi: move to generic {__,}efi_call_virt arm/efi: move to generic {__,}efi_call_virt x86/efi: move to generic {__,}efi_call_virt efi/runtime-wrappers: remove redundant ifdefs efi/runtime-wrappers: detect FW irq flag corruption arch/arm/include/asm/efi.h | 20 ++++------------ arch/arm64/include/asm/efi.h | 21 ++++++----------- arch/x86/include/asm/efi.h | 41 ++++++++++----------------------- drivers/firmware/efi/runtime-wrappers.c | 38 ++++++++++++++++++++++++++++++ 4 files changed, 61 insertions(+), 59 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
