Commit 2333f3c4 authored by Peter Zijlstra (Intel)'s avatar Peter Zijlstra (Intel) Committed by Borislav Petkov (AMD)
Browse files

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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarXin Li <xin3.li@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarShan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-31-xin3.li@intel.com
parent 5105e768

arch/x86/entry/calling.h

+10 −5
Original line number Diff line number Diff line
@@ -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