From d33c1d168c21cc363ad385b8c5a2cea928affa92 Mon Sep 17 00:00:00 2001
From: jake <jake@FreeBSD.org>
Date: Sun, 3 Dec 2000 01:09:59 +0000
Subject: [PATCH] Change cpu_switch to explicitly popl the callers program
 counter and pushl that of the new process, rather than doing a movl (%esp)
 and assuming that the stack has been setup right.  This make the initial
 stack setup slightly more sane, and will make it easier to stick an
 interrupted process onto the run queue without its knowing.

---
 sys/amd64/amd64/cpu_switch.S | 6 ++----
 sys/amd64/amd64/swtch.s      | 6 ++----
 sys/amd64/amd64/vm_machdep.c | 2 +-
 sys/i386/i386/swtch.s        | 6 ++----
 sys/i386/i386/vm_machdep.c   | 2 +-
 5 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 2d315fc5f787..f19a7fb4a69e 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -103,8 +103,7 @@ ENTRY(cpu_switch)
 
 	movl	P_ADDR(%ecx),%edx
 
-	movl	(%esp),%eax			/* Hardware registers */
-	movl	%eax,PCB_EIP(%edx)
+	popl	PCB_EIP(%edx)			/* Hardware registers */
 	movl	%ebx,PCB_EBX(%edx)
 	movl	%esp,PCB_ESP(%edx)
 	movl	%ebp,PCB_EBP(%edx)
@@ -254,8 +253,7 @@ sw1b:
 	movl	PCB_EBP(%edx),%ebp
 	movl	PCB_ESI(%edx),%esi
 	movl	PCB_EDI(%edx),%edi
-	movl	PCB_EIP(%edx),%eax
-	movl	%eax,(%esp)
+	pushl	PCB_EIP(%edx)
 
 #ifdef SMP
 #ifdef GRAB_LOPRIO				/* hold LOPRIO for INTs */
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index 2d315fc5f787..f19a7fb4a69e 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -103,8 +103,7 @@ ENTRY(cpu_switch)
 
 	movl	P_ADDR(%ecx),%edx
 
-	movl	(%esp),%eax			/* Hardware registers */
-	movl	%eax,PCB_EIP(%edx)
+	popl	PCB_EIP(%edx)			/* Hardware registers */
 	movl	%ebx,PCB_EBX(%edx)
 	movl	%esp,PCB_ESP(%edx)
 	movl	%ebp,PCB_EBP(%edx)
@@ -254,8 +253,7 @@ sw1b:
 	movl	PCB_EBP(%edx),%ebp
 	movl	PCB_ESI(%edx),%esi
 	movl	PCB_EDI(%edx),%edi
-	movl	PCB_EIP(%edx),%eax
-	movl	%eax,(%esp)
+	pushl	PCB_EIP(%edx)
 
 #ifdef SMP
 #ifdef GRAB_LOPRIO				/* hold LOPRIO for INTs */
diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index 294a5838def0..befe6fee5199 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -168,7 +168,7 @@ cpu_fork(p1, p2, flags)
 	pcb2->pcb_edi = 0;
 	pcb2->pcb_esi = (int)fork_return;	/* fork_trampoline argument */
 	pcb2->pcb_ebp = 0;
-	pcb2->pcb_esp = (int)p2->p_md.md_regs - sizeof(void *);
+	pcb2->pcb_esp = (int)p2->p_md.md_regs;
 	pcb2->pcb_ebx = (int)p2;		/* fork_trampoline argument */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	/*
diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s
index 2d315fc5f787..f19a7fb4a69e 100644
--- a/sys/i386/i386/swtch.s
+++ b/sys/i386/i386/swtch.s
@@ -103,8 +103,7 @@ ENTRY(cpu_switch)
 
 	movl	P_ADDR(%ecx),%edx
 
-	movl	(%esp),%eax			/* Hardware registers */
-	movl	%eax,PCB_EIP(%edx)
+	popl	PCB_EIP(%edx)			/* Hardware registers */
 	movl	%ebx,PCB_EBX(%edx)
 	movl	%esp,PCB_ESP(%edx)
 	movl	%ebp,PCB_EBP(%edx)
@@ -254,8 +253,7 @@ sw1b:
 	movl	PCB_EBP(%edx),%ebp
 	movl	PCB_ESI(%edx),%esi
 	movl	PCB_EDI(%edx),%edi
-	movl	PCB_EIP(%edx),%eax
-	movl	%eax,(%esp)
+	pushl	PCB_EIP(%edx)
 
 #ifdef SMP
 #ifdef GRAB_LOPRIO				/* hold LOPRIO for INTs */
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index 294a5838def0..befe6fee5199 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -168,7 +168,7 @@ cpu_fork(p1, p2, flags)
 	pcb2->pcb_edi = 0;
 	pcb2->pcb_esi = (int)fork_return;	/* fork_trampoline argument */
 	pcb2->pcb_ebp = 0;
-	pcb2->pcb_esp = (int)p2->p_md.md_regs - sizeof(void *);
+	pcb2->pcb_esp = (int)p2->p_md.md_regs;
 	pcb2->pcb_ebx = (int)p2;		/* fork_trampoline argument */
 	pcb2->pcb_eip = (int)fork_trampoline;
 	/*