stack overflow debugging and fix.
* in 6l, -K already meant check for stack underflow.
add -KK to mean double-check stack overflows
even in nosplit functions.
* comment out print locks; they deadlock too easily
but are still useful to put back for special occasions.
* let runcgo assembly switch to scheduler stack
without involving scheduler directly. because runcgo
gets called from matchmg, it is too hard to keep it
from being called on other stacks.
R=r
DELTA=94 (65 added, 18 deleted, 11 changed)
OCL=35591
CL=35604
diff --git a/src/cmd/6l/pass.c b/src/cmd/6l/pass.c
index e5b948a..7a95f74 100644
--- a/src/cmd/6l/pass.c
+++ b/src/cmd/6l/pass.c
@@ -638,6 +638,9 @@
q = P;
q1 = P;
+ if((p->from.scale & NOSPLIT) && autoffset >= StackSmall)
+ diag("nosplit func likely to overflow stack");
+
if(!(p->from.scale & NOSPLIT)) {
if(debug['K']) {
// 6l -K means check not only for stack
@@ -792,8 +795,44 @@
if(q != P)
q->pcond = p;
}
-
deltasp = autoffset;
+
+ if(debug['K'] > 1 && autoffset) {
+ // 6l -KK means double-check for stack overflow
+ // even after calling morestack and even if the
+ // function is marked as nosplit.
+ p = appendp(p);
+ p->as = AMOVQ;
+ p->from.type = D_INDIR+D_R15;
+ p->from.offset = 0;
+ p->to.type = D_BX;
+
+ p = appendp(p);
+ p->as = ASUBQ;
+ p->from.type = D_CONST;
+ p->from.offset = StackSmall+32;
+ p->to.type = D_BX;
+
+ p = appendp(p);
+ p->as = ACMPQ;
+ p->from.type = D_SP;
+ p->to.type = D_BX;
+
+ p = appendp(p);
+ p->as = AJHI;
+ p->to.type = D_BRANCH;
+ q1 = p;
+
+ p = appendp(p);
+ p->as = AINT;
+ p->from.type = D_CONST;
+ p->from.offset = 3;
+
+ p = appendp(p);
+ p->as = ANOP;
+ q1->pcond = p;
+ q1 = P;
+ }
}
pcsize = p->mode/8;
a = p->from.type;
@@ -844,13 +883,12 @@
goto become;
if(autoffset) {
- q = p;
+ p->as = AADJSP;
+ p->from.type = D_CONST;
+ p->from.offset = -autoffset;
+
p = appendp(p);
p->as = ARET;
-
- q->as = AADJSP;
- q->from.type = D_CONST;
- q->from.offset = -autoffset;
}
continue;
diff --git a/src/pkg/runtime/386/asm.s b/src/pkg/runtime/386/asm.s
index 5aa73a6..9df7fb1 100644
--- a/src/pkg/runtime/386/asm.s
+++ b/src/pkg/runtime/386/asm.s
@@ -300,12 +300,22 @@
INT $0x3
// runcgo(void(*fn)(void*), void *arg)
-// Just call fn(arg), but first align the stack
-// appropriately for the gcc ABI.
+// Call fn(arg) on the scheduler stack,
+// aligned appropriately for the gcc ABI.
TEXT runcgo(SB),7,$16
MOVL fn+0(FP), AX
MOVL arg+4(FP), BX
MOVL SP, CX
+
+ // Figure out if we need to switch to m->g0 stack.
+ MOVL m, DX
+ MOVL m_g0(DX), SI
+ CMPL g, SI
+ JEQ 2(PC)
+ MOVL (m_sched+gobuf_sp)(DX), SP
+
+ // Now on a scheduling stack (a pthread-created stack).
+ SUBL $16, SP
ANDL $~15, SP // alignment for gcc ABI
MOVL CX, 4(SP)
MOVL BX, 0(SP)
diff --git a/src/pkg/runtime/amd64/asm.s b/src/pkg/runtime/amd64/asm.s
index 6cb6d5c..87bc222 100644
--- a/src/pkg/runtime/amd64/asm.s
+++ b/src/pkg/runtime/amd64/asm.s
@@ -272,20 +272,32 @@
JMP AX // but first run the deferred function
// runcgo(void(*fn)(void*), void *arg)
-// Call fn(arg), but align the stack
-// appropriately for the gcc ABI
-// and also save g and m across the call,
+// Call fn(arg) on the scheduler stack,
+// aligned appropriately for the gcc ABI.
+// Save g and m across the call,
// since the foreign code might reuse them.
TEXT runcgo(SB),7,$32
+ // Save old registers.
MOVQ fn+0(FP),AX
MOVQ arg+8(FP),DI // DI = first argument in AMD64 ABI
MOVQ SP, CX
+
+ // Figure out if we need to switch to m->g0 stack.
+ MOVQ m_g0(m), R8
+ CMPQ R8, g
+ JEQ 2(PC)
+ MOVQ (m_sched+gobuf_sp)(m), SP
+
+ // Now on a scheduling stack (a pthread-created stack).
+ SUBQ $32, SP
ANDQ $~15, SP // alignment for gcc ABI
MOVQ g, 24(SP) // save old g, m, SP
MOVQ m, 16(SP)
MOVQ CX, 8(SP)
CALL AX
- MOVQ 16(SP), m // restore
+
+ // Restore registers, stack pointer.
+ MOVQ 16(SP), m
MOVQ 24(SP), g
MOVQ 8(SP), SP
RET
diff --git a/src/pkg/runtime/cgocall.c b/src/pkg/runtime/cgocall.c
index a475603..70382ce 100644
--- a/src/pkg/runtime/cgocall.c
+++ b/src/pkg/runtime/cgocall.c
@@ -25,10 +25,7 @@
* foreign code.
*/
sys·entersyscall();
- g->cgofn = fn;
- g->cgoarg = arg;
- g->status = Gcgocall;
- gosched();
+ runcgo(fn, arg);
sys·exitsyscall();
return;
}
diff --git a/src/pkg/runtime/print.c b/src/pkg/runtime/print.c
index fb2881b..4a358a8 100644
--- a/src/pkg/runtime/print.c
+++ b/src/pkg/runtime/print.c
@@ -4,7 +4,7 @@
#include "runtime.h"
-static Lock debuglock;
+//static Lock debuglock;
void
dump(byte *p, int32 n)
@@ -37,7 +37,7 @@
int8 *p, *lp;
byte *arg, *narg;
- lock(&debuglock);
+// lock(&debuglock);
lp = p = s;
arg = (byte*)(&s+1);
@@ -100,7 +100,7 @@
if(p > lp)
write(1, lp, p-lp);
- unlock(&debuglock);
+// unlock(&debuglock);
}
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index f6f2bb2..4113002 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -95,7 +95,7 @@
{
int32 n;
byte *p;
-
+
allm = m;
mallocinit();
@@ -452,15 +452,6 @@
lock(&sched);
if(gosave(&m->sched) != 0){
gp = m->curg;
- if(gp->status == Gcgocall){
- // Runtime call into external code (FFI).
- // When running with FFI, the scheduler stack is a
- // native pthread stack, so it suffices to switch to the
- // scheduler stack and make the call.
- runcgo(gp->cgofn, gp->cgoarg);
- gp->status = Grunning;
- gogo(&gp->sched, 1);
- }
// Jumped here via gosave/gogo, so didn't
// execute lock(&sched) above.
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index b44eb92..b560d68 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -94,7 +94,6 @@
Gwaiting,
Gmoribund,
Gdead,
- Gcgocall,
};
enum
{
