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x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code

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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) <peterz@infradead.org>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Shan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-31-xin3.li@intel.com
This commit is contained in:
Peter Zijlstra (Intel) 2023-12-05 02:50:19 -08:00 committed by Borislav Petkov (AMD)
parent 5105e7687a
commit 2333f3c473
1 changed files with 10 additions and 5 deletions
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15
arch/x86/entry/calling.h
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@ -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