| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
| 2 | /* |
| 3 | * Copyright (C) 2018 Linaro Ltd <ard.biesheuvel@linaro.org> |
| 4 | */ |
| 5 | |
| 6 | #include <linux/linkage.h> |
| 7 | |
| 8 | ENTRY(__efi_rt_asm_wrapper) |
| 9 | stp x29, x30, [sp, #-32]! |
| 10 | mov x29, sp |
| 11 | |
| 12 | /* |
| 13 | * Register x18 is designated as the 'platform' register by the AAPCS, |
| 14 | * which means firmware running at the same exception level as the OS |
| 15 | * (such as UEFI) should never touch it. |
| 16 | */ |
| 17 | stp x1, x18, [sp, #16] |
| 18 | |
| 19 | /* |
| 20 | * We are lucky enough that no EFI runtime services take more than |
| 21 | * 5 arguments, so all are passed in registers rather than via the |
| 22 | * stack. |
| 23 | */ |
| 24 | mov x8, x0 |
| 25 | mov x0, x2 |
| 26 | mov x1, x3 |
| 27 | mov x2, x4 |
| 28 | mov x3, x5 |
| 29 | mov x4, x6 |
| 30 | blr x8 |
| 31 | |
| 32 | ldp x1, x2, [sp, #16] |
| 33 | cmp x2, x18 |
| 34 | ldp x29, x30, [sp], #32 |
| 35 | b.ne 0f |
| 36 | ret |
| 37 | 0: |
| 38 | #ifdef CONFIG_SHADOW_CALL_STACK |
| 39 | /* |
| 40 | * Restore x18 before returning to instrumented code. This is |
| 41 | * safe because the wrapper is called with preemption disabled and |
| 42 | * a separate shadow stack is used for interrupts. |
| 43 | */ |
| 44 | mov x18, x2 |
| 45 | #endif |
| 46 | b efi_handle_corrupted_x18 // tail call |
| 47 | ENDPROC(__efi_rt_asm_wrapper) |