From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/arm64/kernel/efi-rt-wrapper.S | 87 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 arch/arm64/kernel/efi-rt-wrapper.S (limited to 'arch/arm64/kernel/efi-rt-wrapper.S') diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S new file mode 100644 index 000000000..e8ae80366 --- /dev/null +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -0,0 +1,87 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2018 Linaro Ltd + */ + +#include +#include + +SYM_FUNC_START(__efi_rt_asm_wrapper) + stp x29, x30, [sp, #-112]! + 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] + + /* + * Preserve all callee saved registers and preserve the stack pointer + * value at the base of the EFI runtime stack so we can recover from + * synchronous exceptions occurring while executing the firmware + * routines. + */ + stp x19, x20, [sp, #32] + stp x21, x22, [sp, #48] + stp x23, x24, [sp, #64] + stp x25, x26, [sp, #80] + stp x27, x28, [sp, #96] + + ldr_l x16, efi_rt_stack_top + mov sp, x16 + stp x18, x29, [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 + + mov x16, sp + mov sp, x29 + str xzr, [x16, #8] // clear recorded task SP value + + ldp x1, x2, [sp, #16] + cmp x2, x18 + ldp x29, x30, [sp], #112 + b.ne 0f + ret +0: + /* + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a + * shadow stack pointer, which we need to restore before returning to + * potentially instrumented code. This is safe because the wrapper is + * called with preemption disabled and a separate shadow stack is used + * for interrupts. + */ +#ifdef CONFIG_SHADOW_CALL_STACK + ldr_l x18, efi_rt_stack_top + ldr x18, [x18, #-16] +#endif + + b efi_handle_corrupted_x18 // tail call +SYM_FUNC_END(__efi_rt_asm_wrapper) + +SYM_CODE_START(__efi_rt_asm_recover) + mov sp, x30 + + ldr_l x16, efi_rt_stack_top // clear recorded task SP value + str xzr, [x16, #-8] + + ldp x19, x20, [sp, #32] + ldp x21, x22, [sp, #48] + ldp x23, x24, [sp, #64] + ldp x25, x26, [sp, #80] + ldp x27, x28, [sp, #96] + ldp x29, x30, [sp], #112 + ret +SYM_CODE_END(__efi_rt_asm_recover) -- cgit v1.2.3