diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2022-10-28 16:39:14 +0200 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2023-01-16 15:27:31 +0100 |
| commit | 8a9a1a18731eb123e35f48176380a18b9782845e (patch) | |
| tree | f575285adbe808f8a4b9b7346a6e88a266d4b304 /arch/arm64/include/asm/efi.h | |
| parent | d3f450533bbcb6dd4d7d59cadc9b61b7321e4ac1 (diff) | |
arm64: efi: Avoid workqueue to check whether EFI runtime is live
Comparing current_work() against efi_rts_work.work is sufficient to
decide whether current is currently running EFI runtime services code at
any level in its call stack.
However, there are other potential users of the EFI runtime stack, such
as the ACPI subsystem, which may invoke efi_call_virt_pointer()
directly, and so any sync exceptions occurring in firmware during those
calls are currently misidentified.
So instead, let's check whether the stashed value of the thread stack
pointer points into current's thread stack. This can only be the case if
current was interrupted while running EFI runtime code. Note that this
implies that we should clear the stashed value after switching back, to
avoid false positives.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'arch/arm64/include/asm/efi.h')
| -rw-r--r-- | arch/arm64/include/asm/efi.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 31d13a6001df..de4ff90785b2 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -48,8 +48,17 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md); }) extern spinlock_t efi_rt_lock; +extern u64 *efi_rt_stack_top; efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...); +/* + * efi_rt_stack_top[-1] contains the value the stack pointer had before + * switching to the EFI runtime stack. + */ +#define current_in_efi() \ + (!preemptible() && efi_rt_stack_top != NULL && \ + on_task_stack(current, READ_ONCE(efi_rt_stack_top[-1]), 1)) + #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) /* |