Commit-ID: 18c46461d9e42d398536055f31f58cdcd2c6347e Gitweb: http://git.kernel.org/tip/18c46461d9e42d398536055f31f58cdcd2c6347e Author: Matt Fleming <matt.fleming@xxxxxxxxx> AuthorDate: Mon, 24 Feb 2014 18:07:26 +0000 Committer: Matt Fleming <matt.fleming@xxxxxxxxx> CommitDate: Tue, 4 Mar 2014 21:44:00 +0000 x86/efi: Re-disable interrupts after calling firmware services Some firmware appears to enable interrupts during boot service calls, even if we've explicitly disabled them prior to the call. This is actually allowed per the UEFI spec because boottime services expect to be called with interrupts enabled. So that's fine, we just need to ensure that we disable them again in efi_enter32() before switching to a 64-bit GDT, otherwise an interrupt may fire causing a 32-bit IRQ handler to run after we've left compatibility mode. Despite efi_enter32() being called both for boottime and runtime services, this really only affects boottime because the runtime services callchain is executed with interrupts disabled. See efi_thunk(). Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> --- arch/x86/platform/efi/efi_stub_64.S | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/platform/efi/efi_stub_64.S b/arch/x86/platform/efi/efi_stub_64.S index e811514..65b787a 100644 --- a/arch/x86/platform/efi/efi_stub_64.S +++ b/arch/x86/platform/efi/efi_stub_64.S @@ -261,6 +261,12 @@ ENTRY(efi_enter32) /* We must preserve return value */ movl %eax, %edi + /* + * Some firmware will return with interrupts enabled. Be sure to + * disable them before we switch GDTs. + */ + cli + movl 44(%esp), %eax movl %eax, 2(%eax) lgdtl (%eax) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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