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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-02-01 22:06:58 (GMT) |
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committer | Ingo Molnar <mingo@kernel.org> | 2016-02-03 10:31:04 (GMT) |
commit | ca0e30dcaa53a3fcb2dfdf74252d30bc40603eea (patch) | |
tree | ff97b9475eaeca4fb8007dc1ba10836fe4f21373 /arch/x86/platform | |
parent | d3cac1f83c631b9fe5edaebcba49f6989bfff089 (diff) | |
download | linux-ca0e30dcaa53a3fcb2dfdf74252d30bc40603eea.tar.xz |
efi: Add nonblocking option to efi_query_variable_store()
The function efi_query_variable_store() may be invoked by
efivar_entry_set_nonblocking(), which itself takes care to only
call a non-blocking version of the SetVariable() runtime
wrapper. However, efi_query_variable_store() may call the
SetVariable() wrapper directly, as well as the wrapper for
QueryVariableInfo(), both of which could deadlock in the same
way we are trying to prevent by calling
efivar_entry_set_nonblocking() in the first place.
So instead, modify efi_query_variable_store() to use the
non-blocking variants of QueryVariableInfo() (and give up rather
than free up space if the available space is below
EFI_MIN_RESERVE) if invoked with the 'nonblocking' argument set
to true.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1454364428-494-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/platform')
-rw-r--r-- | arch/x86/platform/efi/quirks.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 4535046..2326bf5 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -57,13 +57,41 @@ void efi_delete_dummy_variable(void) } /* + * In the nonblocking case we do not attempt to perform garbage + * collection if we do not have enough free space. Rather, we do the + * bare minimum check and give up immediately if the available space + * is below EFI_MIN_RESERVE. + * + * This function is intended to be small and simple because it is + * invoked from crash handler paths. + */ +static efi_status_t +query_variable_store_nonblocking(u32 attributes, unsigned long size) +{ + efi_status_t status; + u64 storage_size, remaining_size, max_size; + + status = efi.query_variable_info_nonblocking(attributes, &storage_size, + &remaining_size, + &max_size); + if (status != EFI_SUCCESS) + return status; + + if (remaining_size - size < EFI_MIN_RESERVE) + return EFI_OUT_OF_RESOURCES; + + return EFI_SUCCESS; +} + +/* * Some firmware implementations refuse to boot if there's insufficient space * in the variable store. Ensure that we never use more than a safe limit. * * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable * store. */ -efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) +efi_status_t efi_query_variable_store(u32 attributes, unsigned long size, + bool nonblocking) { efi_status_t status; u64 storage_size, remaining_size, max_size; @@ -71,6 +99,9 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) if (!(attributes & EFI_VARIABLE_NON_VOLATILE)) return 0; + if (nonblocking) + return query_variable_store_nonblocking(attributes, size); + status = efi.query_variable_info(attributes, &storage_size, &remaining_size, &max_size); if (status != EFI_SUCCESS) |