runtime: use gp->sched.sp for stack overflow check
On x86 it is a few words lower on the stack than m->morebuf.sp
so it is a more precise check. Enabling the check requires recording
a valid gp->sched in reflect.call too. This is a good thing in general,
since it will make stack traces during reflect.call work better, and it
may be useful for preemption too.
R=dvyukov
CC=golang-dev
https://golang.org/cl/10709043
diff --git a/src/pkg/runtime/asm_386.s b/src/pkg/runtime/asm_386.s
index cd1514e..630f006 100644
--- a/src/pkg/runtime/asm_386.s
+++ b/src/pkg/runtime/asm_386.s
@@ -254,6 +254,11 @@
MOVL g(CX), AX
MOVL AX, (m_morebuf+gobuf_g)(BX)
+ // Save our own state as the PC and SP to restore
+ // if this goroutine needs to be restarted.
+ MOVL $reflect·call(SB), (g_sched+gobuf_pc)(AX)
+ MOVL SP, (g_sched+gobuf_sp)(AX)
+
// Set up morestack arguments to call f on a new stack.
// We set f's frame size to 1, as a hint to newstack
// that this is a call from reflect·call.
diff --git a/src/pkg/runtime/asm_amd64.s b/src/pkg/runtime/asm_amd64.s
index 0b7c3de..d43eb02 100644
--- a/src/pkg/runtime/asm_amd64.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -231,6 +231,11 @@
MOVQ AX, (m_morebuf+gobuf_sp)(BX)
MOVQ g(CX), AX
MOVQ AX, (m_morebuf+gobuf_g)(BX)
+
+ // Save our own state as the PC and SP to restore
+ // if this goroutine needs to be restarted.
+ MOVQ $reflect·call(SB), (g_sched+gobuf_pc)(AX)
+ MOVQ SP, (g_sched+gobuf_sp)(AX)
// Set up morestack arguments to call f on a new stack.
// We set f's frame size to 1, as a hint to newstack
diff --git a/src/pkg/runtime/asm_arm.s b/src/pkg/runtime/asm_arm.s
index fd88b46..31bbca6 100644
--- a/src/pkg/runtime/asm_arm.s
+++ b/src/pkg/runtime/asm_arm.s
@@ -207,6 +207,13 @@
MOVW SP, (m_morebuf+gobuf_sp)(m) // our caller's SP
MOVW g, (m_morebuf+gobuf_g)(m)
+ // Save our own state as the PC and SP to restore
+ // if this goroutine needs to be restarted.
+ MOVW $reflect·call(SB), R11
+ MOVW R11, (g_sched+gobuf_pc)(g)
+ MOVW LR, (g_sched+gobuf_lr)(g)
+ MOVW SP, (g_sched+gobuf_sp)(g)
+
// Set up morestack arguments to call f on a new stack.
// We set f's frame size to 1, as a hint to newstack
// that this is a call from reflect·call.
diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c
index 5480c46..16dfa04 100644
--- a/src/pkg/runtime/stack.c
+++ b/src/pkg/runtime/stack.c
@@ -215,7 +215,7 @@
if(!reflectcall)
runtime·rewindmorestack(&gp->sched);
- sp = m->morebuf.sp;
+ sp = gp->sched.sp;
if(thechar == '6' || thechar == '8') {
// The call to morestack cost a word.
sp -= sizeof(uintptr);
