From 41662a9f9207545714f0dd3e71cbd8b5a49d148b Mon Sep 17 00:00:00 2001
From: deraadt <deraadt@openbsd.org>
Date: Sun, 21 Jul 2024 16:19:25 +0000
Subject: [PATCH] A few manual ret-cleans.  Seeing as these pertain to
 interrupt servicing, the stack utilization ends up near the the deep end of
 the stack where, retcleans are useful. tested for a while in snaps ok bluhm

---
 sys/arch/amd64/amd64/vector.S | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/sys/arch/amd64/amd64/vector.S b/sys/arch/amd64/amd64/vector.S
index de24a291fd7..c51f872f061 100644
--- a/sys/arch/amd64/amd64/vector.S
+++ b/sys/arch/amd64/amd64/vector.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vector.S,v 1.95 2024/02/12 01:18:17 guenther Exp $	*/
+/*	$OpenBSD: vector.S,v 1.96 2024/07/21 16:19:25 deraadt Exp $	*/
 /*	$NetBSD: vector.S,v 1.5 2004/06/28 09:13:11 fvdl Exp $	*/
 
 /*
@@ -145,6 +145,7 @@ INTRENTRY_LABEL(calltrap_specstk):
 	SMAP_CLAC
 	movq	%rsp,%rdi
 	call	kerntrap
+	movq	$0,-8(%rsp)
 	movl	$MSR_GSBASE,%ecx	# restore GS.base
 	movq	%r12,%rax
 	movq	%r13,%rdx
@@ -157,6 +158,7 @@ INTRENTRY_LABEL(calltrap_specstk):
 	wrmsr
 	CODEPATCH_END(CPTAG_IBPB_NOP)
 	call	pku_xonly
+	movq	$0,-8(%rsp)
 	popq	%rdi
 	popq	%rsi
 	popq	%rdx
@@ -199,6 +201,7 @@ INTRENTRY_LABEL(trap03):
 	leaq	dt_prov_kprobe, %rdi
 	movq	%rsp, %rsi
 	call	dt_prov_kprobe_hook
+	movq	$0,-8(%rsp)
 	cmpl    $0, %eax
 	je     .Lreal_kern_trap
 
@@ -451,6 +454,7 @@ GENTRY(alltraps)
 recall_trap:
 	movq	%rsp, %rdi
 	call	usertrap
+	movq	$0,-8(%rsp)
 	cli
 	jmp	intr_user_exit
 END(alltraps)
@@ -476,6 +480,7 @@ GENTRY(alltraps_kern_meltdown)
 #endif /* DIAGNOSTIC */
 	movq	%rsp, %rdi
 	call	kerntrap
+	movq	$0,-8(%rsp)
 2:	cli
 #ifndef DIAGNOSTIC
 	INTRFASTEXIT
@@ -489,6 +494,7 @@ GENTRY(alltraps_kern_meltdown)
 	movl	%ebx,%edx
 	xorq	%rax,%rax
 	call	printf
+	movq	$0,-8(%rsp)
 #ifdef DDB
 	int	$3
 #endif /* DDB */
@@ -567,6 +573,7 @@ KIDTVEC_FALLTHROUGH(resume_lapic_ipi)
 	SMAP_CLAC
 	movq	%rbx,IF_PPL(%rsp)
 	call	x86_ipi_handler
+	movq	$0,-8(%rsp)
 	jmp	Xdoreti
 2:
 	movq	$(1 << LIR_IPI),%rax
@@ -775,6 +782,7 @@ KIDTVEC_FALLTHROUGH(resume_lapic_ltimer)
 	movq	%rbx,IF_PPL(%rsp)
 	xorq	%rdi,%rdi
 	call	lapic_clockintr
+	movq	$0,-8(%rsp)
 	jmp	Xdoreti
 2:
 	movq	$(1 << LIR_TIMER),%rax
@@ -794,6 +802,7 @@ END(Xrecurse_xen_upcall)
 IDTVEC(intr_xen_upcall)
 	INTRENTRY(intr_xen_upcall)
 	call	xen_intr_ack
+	movq	$0,-8(%rsp)
 	movl	CPUVAR(ILEVEL),%ebx
 	cmpl	$IPL_NET,%ebx
 	jae	2f
@@ -808,6 +817,7 @@ KIDTVEC_FALLTHROUGH(resume_xen_upcall)
 	SMAP_CLAC
 	movq	%rbx,IF_PPL(%rsp)
 	call	xen_intr
+	movq	$0,-8(%rsp)
 	jmp	Xdoreti
 2:
 	movq	$(1 << LIR_XEN),%rax
@@ -841,6 +851,7 @@ KIDTVEC_FALLTHROUGH(resume_hyperv_upcall)
 	SMAP_CLAC
 	movq	%rbx,IF_PPL(%rsp)
 	call	hv_intr
+	movq	$0,-8(%rsp)
 	jmp	Xdoreti
 2:
 	movq	$(1 << LIR_HYPERV),%rax
@@ -898,6 +909,7 @@ IDTVEC(intr_##name##num)						;\
 	movq	%rbx, %rsi						;\
 	movq	%rsp, %rdi						;\
 	call	intr_handler		/* call it */			;\
+	movq	$0,-8(%rsp)						;\
 	orl	%eax,%eax		/* should it be counted? */	;\
 	jz	4f			/* no, skip it */		;\
 	incq	IH_COUNT(%rbx)		/* count the intrs */		;\
@@ -1288,6 +1300,7 @@ KIDTVEC(softtty)
 	incl	CPUVAR(IDEPTH)
 	movl	$X86_SOFTINTR_SOFTTTY,%edi
 	call	softintr_dispatch
+	movq	$0,-8(%rsp)
 	decl	CPUVAR(IDEPTH)
 	CODEPATCH_START
 	jmp	retpoline_r13
@@ -1301,6 +1314,7 @@ KIDTVEC(softnet)
 	incl	CPUVAR(IDEPTH)
 	movl	$X86_SOFTINTR_SOFTNET,%edi
 	call	softintr_dispatch
+	movq	$0,-8(%rsp)
 	decl	CPUVAR(IDEPTH)
 	CODEPATCH_START
 	jmp	retpoline_r13
@@ -1314,6 +1328,7 @@ KIDTVEC(softclock)
 	incl	CPUVAR(IDEPTH)
 	movl	$X86_SOFTINTR_SOFTCLOCK,%edi
 	call	softintr_dispatch
+	movq	$0,-8(%rsp)
 	decl	CPUVAR(IDEPTH)
 	CODEPATCH_START
 	jmp	retpoline_r13
-- 
2.20.1