diff options
Diffstat (limited to 'arch/arm64/kernel/efi-rt-wrapper.S')
| -rw-r--r-- | arch/arm64/kernel/efi-rt-wrapper.S | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S new file mode 100644 index 000000000..05235ebb3 --- /dev/null +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -0,0 +1,41 @@ +/* + * Copyright (C) 2018 Linaro Ltd <ard.biesheuvel@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/linkage.h> + +ENTRY(__efi_rt_asm_wrapper) + stp x29, x30, [sp, #-32]! + mov x29, sp + + /* + * Register x18 is designated as the 'platform' register by the AAPCS, + * which means firmware running at the same exception level as the OS + * (such as UEFI) should never touch it. + */ + stp x1, x18, [sp, #16] + + /* + * We are lucky enough that no EFI runtime services take more than + * 5 arguments, so all are passed in registers rather than via the + * stack. + */ + mov x8, x0 + mov x0, x2 + mov x1, x3 + mov x2, x4 + mov x3, x5 + mov x4, x6 + blr x8 + + ldp x1, x2, [sp, #16] + cmp x2, x18 + ldp x29, x30, [sp], #32 + b.ne 0f + ret +0: b efi_handle_corrupted_x18 // tail call +ENDPROC(__efi_rt_asm_wrapper) |