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Message-ID: <20260118170507.711576-1-brgerst@gmail.com> Date: Sun, 18 Jan 2026 12:05:07 -0500 From: Brian Gerst <brgerst@...il.com> To: linux-kernel@...r.kernel.org, x86@...nel.org Cc: Ingo Molnar <mingo@...nel.org>, "H . Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, Brian Gerst <brgerst@...il.com>, Ard Biesheuvel <ardb@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org> Subject: [PATCH] x86/acpi: Remove indirect jump from wakeup_long64() wakeup_long64() is called from common_startup_64() via inital_code, so it is already running on the normal virtual mapping. There is no need to use an indirect jump since it is not switching mappings. Remove the indirect jump by embedding wakeup_long64() as an inner label of do_suspend_lowlevel(). Remove saved_rip is which is now unused. No functional change. Signed-off-by: Brian Gerst <brgerst@...il.com> Cc: Ard Biesheuvel <ardb@...nel.org> Cc: "Rafael J. Wysocki" <rafael@...nel.org> --- arch/x86/kernel/acpi/wakeup_64.S | 64 +++++++++++++------------------- 1 file changed, 26 insertions(+), 38 deletions(-) diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S index 04f561f75e99..a256cdd03ab5 100644 --- a/arch/x86/kernel/acpi/wakeup_64.S +++ b/arch/x86/kernel/acpi/wakeup_64.S @@ -13,39 +13,6 @@ # Copyright 2003 Pavel Machek <pavel@...e.cz .code64 - /* - * Hooray, we are in Long 64-bit mode (but still running in low memory) - */ -SYM_FUNC_START(wakeup_long64) - ANNOTATE_NOENDBR - movq saved_magic(%rip), %rax - movq $0x123456789abcdef0, %rdx - cmpq %rdx, %rax - je 2f - - /* stop here on a saved_magic mismatch */ - movq $0xbad6d61676963, %rcx -1: - jmp 1b -2: - movw $__KERNEL_DS, %ax - movw %ax, %ss - movw %ax, %ds - movw %ax, %es - movw %ax, %fs - movw %ax, %gs - movq saved_rsp(%rip), %rsp - - movq saved_rbx(%rip), %rbx - movq saved_rdi(%rip), %rdi - movq saved_rsi(%rip), %rsi - movq saved_rbp(%rip), %rbp - - movq saved_rip(%rip), %rax - ANNOTATE_RETPOLINE_SAFE - jmp *%rax -SYM_FUNC_END(wakeup_long64) - SYM_FUNC_START(do_suspend_lowlevel) FRAME_BEGIN subq $8, %rsp @@ -71,8 +38,6 @@ SYM_FUNC_START(do_suspend_lowlevel) pushfq popq pt_regs_flags(%rax) - movq $.Lresume_point, saved_rip(%rip) - movq %rsp, saved_rsp(%rip) movq %rbp, saved_rbp(%rip) movq %rbx, saved_rbx(%rip) @@ -86,9 +51,27 @@ SYM_FUNC_START(do_suspend_lowlevel) /* in case something went wrong, restore the machine status and go on */ jmp .Lresume_point - .align 4 -.Lresume_point: +SYM_INNER_LABEL_ALIGN(wakeup_long64, SYM_L_GLOBAL) ANNOTATE_NOENDBR + movq saved_magic(%rip), %rax + movq $0x123456789abcdef0, %rdx + cmpq %rdx, %rax + jne .Lbad_saved_magic + + movw $__KERNEL_DS, %ax + movw %ax, %ss + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movq saved_rsp(%rip), %rsp + + movq saved_rbx(%rip), %rbx + movq saved_rdi(%rip), %rdi + movq saved_rsi(%rip), %rsi + movq saved_rbp(%rip), %rbp + +.Lresume_point: /* We don't restore %rax, it must be 0 anyway */ movq $saved_context, %rax movq saved_context_cr4(%rax), %rbx @@ -130,6 +113,12 @@ SYM_FUNC_START(do_suspend_lowlevel) addq $8, %rsp FRAME_END jmp restore_processor_state + +.Lbad_saved_magic: + /* stop here on a saved_magic mismatch */ + movq $0xbad6d61676963, %rcx +1: + jmp 1b SYM_FUNC_END(do_suspend_lowlevel) STACK_FRAME_NON_STANDARD do_suspend_lowlevel @@ -139,7 +128,6 @@ saved_rsi: .quad 0 saved_rdi: .quad 0 saved_rbx: .quad 0 -saved_rip: .quad 0 saved_rsp: .quad 0 SYM_DATA(saved_magic, .quad 0) base-commit: 72249a0533c63e77e4bf56012b7b4f8fb3066317 -- 2.52.0
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