From 2333f3c473c1562633cd17ac2eb743c29c3b2d9d Mon Sep 17 00:00:00 2001 From: "Peter Zijlstra (Intel)" Date: Tue, 5 Dec 2023 02:50:19 -0800 Subject: x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code PUSH_AND_CLEAR_REGS could be used besides actual entry code; in that case %rbp shouldn't be cleared (otherwise the frame pointer is destroyed) and UNWIND_HINT shouldn't be added. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Xin Li Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Tested-by: Shan Kang Link: https://lore.kernel.org/r/20231205105030.8698-31-xin3.li@intel.com --- arch/x86/entry/calling.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'arch/x86/entry') diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 9f1d94790a54..3ff925b17b7e 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -65,7 +65,7 @@ For 32-bit we have the following conventions - kernel is built with * for assembly code: */ -.macro PUSH_REGS rdx=%rdx rcx=%rcx rax=%rax save_ret=0 +.macro PUSH_REGS rdx=%rdx rcx=%rcx rax=%rax save_ret=0 unwind_hint=1 .if \save_ret pushq %rsi /* pt_regs->si */ movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ @@ -87,14 +87,17 @@ For 32-bit we have the following conventions - kernel is built with pushq %r13 /* pt_regs->r13 */ pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ + + .if \unwind_hint UNWIND_HINT_REGS + .endif .if \save_ret pushq %rsi /* return address on top of stack */ .endif .endm -.macro CLEAR_REGS +.macro CLEAR_REGS clear_bp=1 /* * Sanitize registers of values that a speculation attack might * otherwise want to exploit. The lower registers are likely clobbered @@ -109,7 +112,9 @@ For 32-bit we have the following conventions - kernel is built with xorl %r10d, %r10d /* nospec r10 */ xorl %r11d, %r11d /* nospec r11 */ xorl %ebx, %ebx /* nospec rbx */ + .if \clear_bp xorl %ebp, %ebp /* nospec rbp */ + .endif xorl %r12d, %r12d /* nospec r12 */ xorl %r13d, %r13d /* nospec r13 */ xorl %r14d, %r14d /* nospec r14 */ @@ -117,9 +122,9 @@ For 32-bit we have the following conventions - kernel is built with .endm -.macro PUSH_AND_CLEAR_REGS rdx=%rdx rcx=%rcx rax=%rax save_ret=0 - PUSH_REGS rdx=\rdx, rcx=\rcx, rax=\rax, save_ret=\save_ret - CLEAR_REGS +.macro PUSH_AND_CLEAR_REGS rdx=%rdx rcx=%rcx rax=%rax save_ret=0 clear_bp=1 unwind_hint=1 + PUSH_REGS rdx=\rdx, rcx=\rcx, rax=\rax, save_ret=\save_ret unwind_hint=\unwind_hint + CLEAR_REGS clear_bp=\clear_bp .endm .macro POP_REGS pop_rdi=1 -- cgit v1.2.3