Revert "liblink, cmd/ld, runtime: remove stackguard1"
This reverts commit ab0535ae3fb45ba734d47542cc4845f27f708d1b.
I think it will remain useful to distinguish code that must
run on a system stack from code that can run on either stack,
even if that distinction is no
longer based on the implementation language.
That is, I expect to add a //go:systemstack comment that,
in terms of the old implementation, tells the compiler,
to pretend this function was written in C.
Change-Id: I33d2ebb2f99ae12496484c6ec8ed07233d693275
Reviewed-on: https://go-review.googlesource.com/2275
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/include/link.h b/include/link.h
index 8a23822..9e75350 100644
--- a/include/link.h
+++ b/include/link.h
@@ -131,6 +131,7 @@
short type;
short version;
uchar dupok;
+ uchar cfunc;
uchar external;
uchar nosplit;
uchar reachable;
diff --git a/src/cmd/ld/lib.c b/src/cmd/ld/lib.c
index 9c58c22..925274b 100644
--- a/src/cmd/ld/lib.c
+++ b/src/cmd/ld/lib.c
@@ -1564,3 +1564,56 @@
errorexit();
}
}
+
+void
+checkgo(void)
+{
+ LSym *s;
+ Reloc *r;
+ int i;
+ int changed;
+
+ if(!debug['C'])
+ return;
+
+ // TODO(rsc,khr): Eventually we want to get to no Go-called C functions at all,
+ // which would simplify this logic quite a bit.
+
+ // Mark every Go-called C function with cfunc=2, recursively.
+ do {
+ changed = 0;
+ for(s = ctxt->textp; s != nil; s = s->next) {
+ if(s->cfunc == 0 || (s->cfunc == 2 && s->nosplit)) {
+ for(i=0; i<s->nr; i++) {
+ r = &s->r[i];
+ if(r->sym == nil)
+ continue;
+ if((r->type == R_CALL || r->type == R_CALLARM) && r->sym->type == STEXT) {
+ if(r->sym->cfunc == 1) {
+ changed = 1;
+ r->sym->cfunc = 2;
+ }
+ }
+ }
+ }
+ }
+ }while(changed);
+
+ // Complain about Go-called C functions that can split the stack
+ // (that can be preempted for garbage collection or trigger a stack copy).
+ for(s = ctxt->textp; s != nil; s = s->next) {
+ if(s->cfunc == 0 || (s->cfunc == 2 && s->nosplit)) {
+ for(i=0; i<s->nr; i++) {
+ r = &s->r[i];
+ if(r->sym == nil)
+ continue;
+ if((r->type == R_CALL || r->type == R_CALLARM) && r->sym->type == STEXT) {
+ if(s->cfunc == 0 && r->sym->cfunc == 2 && !r->sym->nosplit)
+ print("Go %s calls C %s\n", s->name, r->sym->name);
+ else if(s->cfunc == 2 && s->nosplit && !r->sym->nosplit)
+ print("Go calls C %s calls %s\n", s->name, r->sym->name);
+ }
+ }
+ }
+ }
+}
diff --git a/src/cmd/ld/lib.h b/src/cmd/ld/lib.h
index cf397ee..17483e0 100644
--- a/src/cmd/ld/lib.h
+++ b/src/cmd/ld/lib.h
@@ -183,6 +183,7 @@
uint32 be32(uchar *b);
uint64 be64(uchar *b);
void callgraph(void);
+void checkgo(void);
void cflush(void);
void codeblk(int64 addr, int64 size);
vlong cpos(void);
diff --git a/src/cmd/ld/pobj.c b/src/cmd/ld/pobj.c
index 5b5942c..b86ddfe 100644
--- a/src/cmd/ld/pobj.c
+++ b/src/cmd/ld/pobj.c
@@ -172,6 +172,7 @@
mark(linklookup(ctxt, "runtime.read_tls_fallback", 0));
}
+ checkgo();
deadcode();
callgraph();
paramspace = "SP"; /* (FP) now (SP) on output */
diff --git a/src/liblink/obj5.c b/src/liblink/obj5.c
index ff1ef0f..d7f2714 100644
--- a/src/liblink/obj5.c
+++ b/src/liblink/obj5.c
@@ -474,7 +474,7 @@
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
- p->from.offset = 3*ctxt->arch->ptrsize; // G.panic
+ p->from.offset = 4*ctxt->arch->ptrsize; // G.panic
p->to.type = D_REG;
p->to.reg = 1;
@@ -783,7 +783,9 @@
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
- p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->from.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
p->to.type = D_REG;
p->to.reg = 1;
@@ -876,7 +878,10 @@
p->as = ABL;
p->scond = C_SCOND_LS;
p->to.type = D_BRANCH;
- p->to.sym = ctxt->symmorestack[noctxt];
+ if(ctxt->cursym->cfunc)
+ p->to.sym = linklookup(ctxt, "runtime.morestackc", 0);
+ else
+ p->to.sym = ctxt->symmorestack[noctxt];
// BLS start
p = appendp(ctxt, p);
diff --git a/src/liblink/obj6.c b/src/liblink/obj6.c
index 2dc1315..2acfd2f 100644
--- a/src/liblink/obj6.c
+++ b/src/liblink/obj6.c
@@ -452,7 +452,7 @@
p = appendp(ctxt, p);
p->as = AMOVQ;
p->from.type = D_INDIR+D_CX;
- p->from.offset = 3*ctxt->arch->ptrsize; // G.panic
+ p->from.offset = 4*ctxt->arch->ptrsize; // G.panic
p->to.type = D_BX;
if(ctxt->headtype == Hnacl) {
p->as = AMOVL;
@@ -689,7 +689,9 @@
p->as = cmp;
p->from.type = D_SP;
indir_cx(ctxt, &p->to);
- p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->to.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
} else if(framesize <= StackBig) {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAQ -xxx(SP), AX
@@ -704,7 +706,9 @@
p->as = cmp;
p->from.type = D_AX;
indir_cx(ctxt, &p->to);
- p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->to.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
} else {
// Such a large stack we need to protect against wraparound.
// If SP is close to zero:
@@ -724,7 +728,9 @@
p = appendp(ctxt, p);
p->as = mov;
indir_cx(ctxt, &p->from);
- p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->from.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
p->to.type = D_SI;
p = appendp(ctxt, p);
@@ -765,7 +771,10 @@
p = appendp(ctxt, p);
p->as = ACALL;
p->to.type = D_BRANCH;
- p->to.sym = ctxt->symmorestack[noctxt];
+ if(ctxt->cursym->cfunc)
+ p->to.sym = linklookup(ctxt, "runtime.morestackc", 0);
+ else
+ p->to.sym = ctxt->symmorestack[noctxt];
p = appendp(ctxt, p);
p->as = AJMP;
diff --git a/src/liblink/obj8.c b/src/liblink/obj8.c
index 023bea6..f54153a 100644
--- a/src/liblink/obj8.c
+++ b/src/liblink/obj8.c
@@ -335,7 +335,7 @@
p = appendp(ctxt, p);
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
- p->from.offset = 3*ctxt->arch->ptrsize; // G.panic
+ p->from.offset = 4*ctxt->arch->ptrsize; // G.panic
p->to.type = D_BX;
p = appendp(ctxt, p);
@@ -538,7 +538,9 @@
p->as = ACMPL;
p->from.type = D_SP;
p->to.type = D_INDIR+D_CX;
- p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->to.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
} else if(framesize <= StackBig) {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAL -(framesize-StackSmall)(SP), AX
@@ -553,7 +555,9 @@
p->as = ACMPL;
p->from.type = D_AX;
p->to.type = D_INDIR+D_CX;
- p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->to.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->to.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
} else {
// Such a large stack we need to protect against wraparound
// if SP is close to zero.
@@ -573,7 +577,9 @@
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
p->from.offset = 0;
- p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->from.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
p->to.type = D_SI;
p = appendp(ctxt, p);
@@ -616,7 +622,10 @@
p = appendp(ctxt, p);
p->as = ACALL;
p->to.type = D_BRANCH;
- p->to.sym = ctxt->symmorestack[noctxt];
+ if(ctxt->cursym->cfunc)
+ p->to.sym = linklookup(ctxt, "runtime.morestackc", 0);
+ else
+ p->to.sym = ctxt->symmorestack[noctxt];
p = appendp(ctxt, p);
p->as = AJMP;
diff --git a/src/liblink/obj9.c b/src/liblink/obj9.c
index 120bced..2b6456d 100644
--- a/src/liblink/obj9.c
+++ b/src/liblink/obj9.c
@@ -492,7 +492,7 @@
q->as = AMOVD;
q->from.type = D_OREG;
q->from.reg = REGG;
- q->from.offset = 3*ctxt->arch->ptrsize; // G.panic
+ q->from.offset = 4*ctxt->arch->ptrsize; // G.panic
q->to.type = D_REG;
q->to.reg = 3;
@@ -724,7 +724,9 @@
p->as = AMOVD;
p->from.type = D_OREG;
p->from.reg = REGG;
- p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard
+ p->from.offset = 2*ctxt->arch->ptrsize; // G.stackguard0
+ if(ctxt->cursym->cfunc)
+ p->from.offset = 3*ctxt->arch->ptrsize; // G.stackguard1
p->to.type = D_REG;
p->to.reg = 3;
@@ -832,7 +834,10 @@
p = appendp(ctxt, p);
p->as = ABL;
p->to.type = D_BRANCH;
- p->to.sym = ctxt->symmorestack[noctxt];
+ if(ctxt->cursym->cfunc)
+ p->to.sym = linklookup(ctxt, "runtime.morestackc", 0);
+ else
+ p->to.sym = ctxt->symmorestack[noctxt];
// BR start
p = appendp(ctxt, p);
diff --git a/src/liblink/objfile.c b/src/liblink/objfile.c
index e47263d..aa701f4 100644
--- a/src/liblink/objfile.c
+++ b/src/liblink/objfile.c
@@ -332,6 +332,8 @@
Bprint(ctxt->bso, "t=%d ", s->type);
if(s->dupok)
Bprint(ctxt->bso, "dupok ");
+ if(s->cfunc)
+ Bprint(ctxt->bso, "cfunc ");
if(s->nosplit)
Bprint(ctxt->bso, "nosplit ");
Bprint(ctxt->bso, "size=%lld value=%lld", (vlong)s->size, (vlong)s->value);
@@ -397,7 +399,7 @@
wrint(b, s->args);
wrint(b, s->locals);
wrint(b, s->nosplit);
- wrint(b, s->leaf);
+ wrint(b, s->leaf | s->cfunc<<1);
n = 0;
for(a = s->autom; a != nil; a = a->link)
n++;
@@ -641,6 +643,7 @@
s->nosplit = rdint(f);
v = rdint(f);
s->leaf = v&1;
+ s->cfunc = v&2;
n = rdint(f);
for(i=0; i<n; i++) {
a = emallocz(sizeof *a);
@@ -696,6 +699,8 @@
Bprint(ctxt->bso, "t=%d ", s->type);
if(s->dupok)
Bprint(ctxt->bso, "dupok ");
+ if(s->cfunc)
+ Bprint(ctxt->bso, "cfunc ");
if(s->nosplit)
Bprint(ctxt->bso, "nosplit ");
Bprint(ctxt->bso, "size=%lld value=%lld", (vlong)s->size, (vlong)s->value);
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s
index 43f92b2..14e4360 100644
--- a/src/runtime/asm_386.s
+++ b/src/runtime/asm_386.s
@@ -20,7 +20,8 @@
// _cgo_init may update stackguard.
MOVL $runtime·g0(SB), BP
LEAL (-64*1024+104)(SP), BX
- MOVL BX, g_stackguard(BP)
+ MOVL BX, g_stackguard0(BP)
+ MOVL BX, g_stackguard1(BP)
MOVL BX, (g_stack+stack_lo)(BP)
MOVL SP, (g_stack+stack_hi)(BP)
@@ -50,7 +51,8 @@
MOVL $runtime·g0(SB), CX
MOVL (g_stack+stack_lo)(CX), AX
ADDL $const__StackGuard, AX
- MOVL AX, g_stackguard(CX)
+ MOVL AX, g_stackguard0(CX)
+ MOVL AX, g_stackguard1(CX)
// skip runtime·ldt0setup(SB) and tls test after _cgo_init for non-windows
CMPL runtime·iswindows(SB), $0
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 4061e99..5a94e11 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -20,7 +20,8 @@
// _cgo_init may update stackguard.
MOVQ $runtime·g0(SB), DI
LEAQ (-64*1024+104)(SP), BX
- MOVQ BX, g_stackguard(DI)
+ MOVQ BX, g_stackguard0(DI)
+ MOVQ BX, g_stackguard1(DI)
MOVQ BX, (g_stack+stack_lo)(DI)
MOVQ SP, (g_stack+stack_hi)(DI)
@@ -48,7 +49,8 @@
MOVQ $runtime·g0(SB), CX
MOVQ (g_stack+stack_lo)(CX), AX
ADDQ $const__StackGuard, AX
- MOVQ AX, g_stackguard(CX)
+ MOVQ AX, g_stackguard0(CX)
+ MOVQ AX, g_stackguard1(CX)
CMPL runtime·iswindows(SB), $0
JEQ ok
diff --git a/src/runtime/asm_amd64p32.s b/src/runtime/asm_amd64p32.s
index b919734..20fb5df 100644
--- a/src/runtime/asm_amd64p32.s
+++ b/src/runtime/asm_amd64p32.s
@@ -22,7 +22,8 @@
// create istack out of the given (operating system) stack.
MOVL $runtime·g0(SB), DI
LEAL (-64*1024+104)(SP), BX
- MOVL BX, g_stackguard(DI)
+ MOVL BX, g_stackguard0(DI)
+ MOVL BX, g_stackguard1(DI)
MOVL BX, (g_stack+stack_lo)(DI)
MOVL SP, (g_stack+stack_hi)(DI)
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index 6fe931bd..fdcc0e6 100644
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -32,7 +32,8 @@
// create istack out of the OS stack
MOVW $(-8192+104)(R13), R0
- MOVW R0, g_stackguard(g)
+ MOVW R0, g_stackguard0(g)
+ MOVW R0, g_stackguard1(g)
MOVW R0, (g_stack+stack_lo)(g)
MOVW R13, (g_stack+stack_hi)(g)
@@ -55,7 +56,8 @@
// update stackguard after _cgo_init
MOVW (g_stack+stack_lo)(g), R0
ADD $const__StackGuard, R0
- MOVW R0, g_stackguard(g)
+ MOVW R0, g_stackguard0(g)
+ MOVW R0, g_stackguard1(g)
BL runtime·checkgoarm(SB)
BL runtime·check(SB)
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 86cf6857..1360c6e 100644
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -22,7 +22,8 @@
MOVD $runtime·g0(SB), g
MOVD $(-64*1024), R31
ADD R31, R1, R3
- MOVD R3, g_stackguard(g)
+ MOVD R3, g_stackguard0(g)
+ MOVD R3, g_stackguard1(g)
MOVD R3, (g_stack+stack_lo)(g)
MOVD R1, (g_stack+stack_hi)(g)
diff --git a/src/runtime/lock_futex.go b/src/runtime/lock_futex.go
index d1a45eb..6e1f1e9 100644
--- a/src/runtime/lock_futex.go
+++ b/src/runtime/lock_futex.go
@@ -114,7 +114,7 @@
throw("runtime·unlock: lock count")
}
if gp.m.locks == 0 && gp.preempt { // restore the preemption request in case we've cleared it in newstack
- gp.stackguard = stackPreempt
+ gp.stackguard0 = stackPreempt
}
}
diff --git a/src/runtime/lock_sema.go b/src/runtime/lock_sema.go
index 556551f..c995e08 100644
--- a/src/runtime/lock_sema.go
+++ b/src/runtime/lock_sema.go
@@ -115,7 +115,7 @@
throw("runtime·unlock: lock count")
}
if gp.m.locks == 0 && gp.preempt { // restore the preemption request in case we've cleared it in newstack
- gp.stackguard = stackPreempt
+ gp.stackguard0 = stackPreempt
}
}
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index bb23b80..99420c8 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -64,7 +64,7 @@
}
mp.mallocing = 1
if mp.curg != nil {
- mp.curg.stackguard = ^uintptr(0xfff) | 0xbad
+ mp.curg.stackguard0 = ^uintptr(0xfff) | 0xbad
}
}
@@ -127,7 +127,7 @@
}
mp.mallocing = 0
if mp.curg != nil {
- mp.curg.stackguard = mp.curg.stack.lo + _StackGuard
+ mp.curg.stackguard0 = mp.curg.stack.lo + _StackGuard
}
// Note: one releasem for the acquirem just above.
// The other for the acquirem at start of malloc.
@@ -319,7 +319,7 @@
}
mp.mallocing = 0
if mp.curg != nil {
- mp.curg.stackguard = mp.curg.stack.lo + _StackGuard
+ mp.curg.stackguard0 = mp.curg.stack.lo + _StackGuard
}
// Note: one releasem for the acquirem just above.
// The other for the acquirem at start of malloc.
diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go
index 118351c..3cb91ee 100644
--- a/src/runtime/proc1.go
+++ b/src/runtime/proc1.go
@@ -179,6 +179,9 @@
sched.mcount++
checkmcount()
mpreinit(mp)
+ if mp.gsignal != nil {
+ mp.gsignal.stackguard1 = mp.gsignal.stack.lo + _StackGuard
+ }
// Add to allm so garbage collector doesn't free g->m
// when it is just in a register or thread-local storage.
@@ -210,7 +213,7 @@
}
_g_.m.locks--
if _g_.m.locks == 0 && _g_.preempt { // restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
}
}
@@ -460,7 +463,7 @@
if !gp.gcworkdone {
gp.preemptscan = true
gp.preempt = true
- gp.stackguard = stackPreempt
+ gp.stackguard0 = stackPreempt
}
// Unclaim.
@@ -542,7 +545,7 @@
gp.gcworkdone = true // scan is a noop
break
}
- if status == _Grunning && gp.stackguard == uintptr(stackPreempt) && notetsleep(&sched.stopnote, 100*1000) { // nanosecond arg
+ if status == _Grunning && gp.stackguard0 == uintptr(stackPreempt) && notetsleep(&sched.stopnote, 100*1000) { // nanosecond arg
noteclear(&sched.stopnote)
} else {
stopscanstart(gp)
@@ -701,7 +704,7 @@
}
_g_.m.locks--
if _g_.m.locks == 0 && _g_.preempt { // restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
}
}
@@ -722,7 +725,8 @@
}
// Initialize stack guards so that we can start calling
// both Go and C functions with stack growth prologues.
- _g_.stackguard = _g_.stack.lo + _StackGuard
+ _g_.stackguard0 = _g_.stack.lo + _StackGuard
+ _g_.stackguard1 = _g_.stackguard0
mstart1()
}
@@ -802,7 +806,7 @@
}
_g_.m.locks--
if _g_.m.locks == 0 && _g_.preempt { // restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
}
return mp
@@ -879,7 +883,7 @@
_g_ := getg()
_g_.stack.hi = uintptr(noescape(unsafe.Pointer(&x))) + 1024
_g_.stack.lo = uintptr(noescape(unsafe.Pointer(&x))) - 32*1024
- _g_.stackguard = _g_.stack.lo + _StackGuard
+ _g_.stackguard0 = _g_.stack.lo + _StackGuard
// Initialize this thread to use the m.
asminit()
@@ -1217,7 +1221,7 @@
casgstatus(gp, _Grunnable, _Grunning)
gp.waitsince = 0
gp.preempt = false
- gp.stackguard = gp.stack.lo + _StackGuard
+ gp.stackguard0 = gp.stack.lo + _StackGuard
_g_.m.p.schedtick++
_g_.m.curg = gp
gp.m = _g_.m
@@ -1613,7 +1617,7 @@
// (See details in comment above.)
// Catch calls that might, by replacing the stack guard with something that
// will trip any stack check and leaving a flag to tell newstack to die.
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
_g_.throwsplit = true
// Leave SP around for GC and traceback.
@@ -1644,7 +1648,7 @@
// Goroutines must not split stacks in Gsyscall status (it would corrupt g->sched).
// We set _StackGuard to StackPreempt so that first split stack check calls morestack.
// Morestack detects this case and throws.
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
_g_.m.locks--
}
@@ -1682,7 +1686,7 @@
_g_.m.locks++ // see comment in entersyscall
_g_.throwsplit = true
- _g_.stackguard = stackPreempt // see comment in entersyscall
+ _g_.stackguard0 = stackPreempt // see comment in entersyscall
// Leave SP around for GC and traceback.
pc := getcallerpc(unsafe.Pointer(&dummy))
@@ -1748,10 +1752,10 @@
_g_.m.locks--
if _g_.preempt {
// restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
} else {
// otherwise restore the real _StackGuard, we've spoiled it in entersyscall/entersyscallblock
- _g_.stackguard = _g_.stack.lo + _StackGuard
+ _g_.stackguard0 = _g_.stack.lo + _StackGuard
}
_g_.throwsplit = false
return
@@ -1869,7 +1873,7 @@
// Code between fork and exec must not allocate memory nor even try to grow stack.
// Here we spoil g->_StackGuard to reliably detect any attempts to grow stack.
// runtime_AfterFork will undo this in parent process, but not in child.
- gp.stackguard = stackFork
+ gp.stackguard0 = stackFork
}
// Called from syscall package before fork.
@@ -1883,7 +1887,7 @@
gp := getg().m.curg
// See the comment in beforefork.
- gp.stackguard = gp.stack.lo + _StackGuard
+ gp.stackguard0 = gp.stack.lo + _StackGuard
hz := sched.profilehz
if hz != 0 {
@@ -1907,7 +1911,8 @@
systemstack(func() {
newg.stack = stackalloc(uint32(stacksize))
})
- newg.stackguard = newg.stack.lo + _StackGuard
+ newg.stackguard0 = newg.stack.lo + _StackGuard
+ newg.stackguard1 = ^uintptr(0)
}
return newg
}
@@ -2003,7 +2008,7 @@
}
_g_.m.locks--
if _g_.m.locks == 0 && _g_.preempt { // restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
}
return newg
}
@@ -2022,7 +2027,7 @@
stackfree(gp.stack)
gp.stack.lo = 0
gp.stack.hi = 0
- gp.stackguard = 0
+ gp.stackguard0 = 0
}
gp.schedlink = _p_.gfree
@@ -2068,7 +2073,7 @@
systemstack(func() {
gp.stack = stackalloc(_FixedStack)
})
- gp.stackguard = gp.stack.lo + _StackGuard
+ gp.stackguard0 = gp.stack.lo + _StackGuard
} else {
if raceenabled {
racemalloc(unsafe.Pointer(gp.stack.lo), gp.stack.hi-gp.stack.lo)
@@ -2773,10 +2778,10 @@
gp.preempt = true
// Every call in a go routine checks for stack overflow by
- // comparing the current stack pointer to gp->stackguard.
- // Setting gp->stackguard to StackPreempt folds
+ // comparing the current stack pointer to gp->stackguard0.
+ // Setting gp->stackguard0 to StackPreempt folds
// preemption into the normal stack overflow check.
- gp.stackguard = stackPreempt
+ gp.stackguard0 = stackPreempt
return true
}
diff --git a/src/runtime/runtime1.go b/src/runtime/runtime1.go
index 4c61751..b3e6e7b 100644
--- a/src/runtime/runtime1.go
+++ b/src/runtime/runtime1.go
@@ -386,7 +386,7 @@
mp.locks--
if mp.locks == 0 && _g_.preempt {
// restore the preemption request in case we've cleared it in newstack
- _g_.stackguard = stackPreempt
+ _g_.stackguard0 = stackPreempt
}
}
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 8425729..3b7db1e 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -154,10 +154,14 @@
type g struct {
// Stack parameters.
// stack describes the actual stack memory: [stack.lo, stack.hi).
- // stackguard is the stack pointer compared in the Go stack growth prologue.
+ // stackguard0 is the stack pointer compared in the Go stack growth prologue.
// It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption.
- stack stack // offset known to runtime/cgo
- stackguard uintptr // offset known to liblink
+ // stackguard1 is the stack pointer compared in the C stack growth prologue.
+ // It is stack.lo+StackGuard on g0 and gsignal stacks.
+ // It is ~0 on other goroutine stacks, to trigger a call to morestackc (and crash).
+ stack stack // offset known to runtime/cgo
+ stackguard0 uintptr // offset known to liblink
+ stackguard1 uintptr // offset known to liblink
_panic *_panic // innermost panic - offset known to liblink
_defer *_defer // innermost defer
@@ -171,7 +175,7 @@
waitreason string // if status==gwaiting
schedlink *g
issystem bool // do not output in stack dump, ignore in deadlock detector
- preempt bool // preemption signal, duplicates stackguard = stackpreempt
+ preempt bool // preemption signal, duplicates stackguard0 = stackpreempt
paniconfault bool // panic (instead of crash) on unexpected fault address
preemptscan bool // preempted g does scan for gc
gcworkdone bool // debug: cleared at begining of gc work phase cycle, set by gcphasework, tested at end of cycle
diff --git a/src/runtime/stack1.go b/src/runtime/stack1.go
index 8b32eb6d..6c34642 100644
--- a/src/runtime/stack1.go
+++ b/src/runtime/stack1.go
@@ -26,13 +26,13 @@
poisonStack = uintptrMask & 0x6868686868686868
// Goroutine preemption request.
- // Stored into g->stackguard to cause split stack check failure.
+ // Stored into g->stackguard0 to cause split stack check failure.
// Must be greater than any real sp.
// 0xfffffade in hex.
stackPreempt = uintptrMask & -1314
// Thread is forking.
- // Stored into g->stackguard to cause split stack check failure.
+ // Stored into g->stackguard0 to cause split stack check failure.
// Must be greater than any real sp.
stackFork = uintptrMask & -1234
)
@@ -566,7 +566,7 @@
// Swap out old stack for new one
gp.stack = new
- gp.stackguard = new.lo + _StackGuard // NOTE: might clobber a preempt request
+ gp.stackguard0 = new.lo + _StackGuard // NOTE: might clobber a preempt request
gp.sched.sp = new.hi - used
// free old stack
@@ -611,7 +611,7 @@
func newstack() {
thisg := getg()
// TODO: double check all gp. shouldn't be getg().
- if thisg.m.morebuf.g.stackguard == stackFork {
+ if thisg.m.morebuf.g.stackguard0 == stackFork {
throw("stack growth after fork")
}
if thisg.m.morebuf.g != thisg.m.curg {
@@ -674,7 +674,7 @@
writebarrierptr_nostore((*uintptr)(unsafe.Pointer(&gp.sched.ctxt)), uintptr(gp.sched.ctxt))
}
- if gp.stackguard == stackPreempt {
+ if gp.stackguard0 == stackPreempt {
if gp == thisg.m.g0 {
throw("runtime: preempt g0")
}
@@ -689,7 +689,7 @@
gcphasework(gp)
casfrom_Gscanstatus(gp, _Gscanwaiting, _Gwaiting)
casgstatus(gp, _Gwaiting, _Grunning)
- gp.stackguard = gp.stack.lo + _StackGuard
+ gp.stackguard0 = gp.stack.lo + _StackGuard
gp.preempt = false
gp.preemptscan = false // Tells the GC premption was successful.
gogo(&gp.sched) // never return
@@ -700,7 +700,7 @@
if thisg.m.locks != 0 || thisg.m.mallocing != 0 || thisg.m.gcing != 0 || thisg.m.p.status != _Prunning {
// Let the goroutine keep running for now.
// gp->preempt is set, so it will be preempted next time.
- gp.stackguard = gp.stack.lo + _StackGuard
+ gp.stackguard0 = gp.stack.lo + _StackGuard
casgstatus(gp, _Gwaiting, _Grunning)
gogo(&gp.sched) // never return
}
@@ -804,3 +804,10 @@
s = t
}
}
+
+//go:nosplit
+func morestackc() {
+ systemstack(func() {
+ throw("attempt to execute C code on Go stack")
+ })
+}
diff --git a/src/runtime/stack2.go b/src/runtime/stack2.go
index 8cc7496..8a78b1a 100644
--- a/src/runtime/stack2.go
+++ b/src/runtime/stack2.go
@@ -97,7 +97,7 @@
)
// Goroutine preemption request.
-// Stored into g->stackguard to cause split stack check failure.
+// Stored into g->stackguard0 to cause split stack check failure.
// Must be greater than any real sp.
// 0xfffffade in hex.
const (
diff --git a/src/runtime/sys_plan9_386.s b/src/runtime/sys_plan9_386.s
index 13ead5d..b9db8cb 100644
--- a/src/runtime/sys_plan9_386.s
+++ b/src/runtime/sys_plan9_386.s
@@ -148,7 +148,8 @@
MOVL AX, (g_stack+stack_hi)(DX)
SUBL $(64*1024), AX // stack size
MOVL AX, (g_stack+stack_lo)(DX)
- MOVL AX, g_stackguard(DX)
+ MOVL AX, g_stackguard0(DX)
+ MOVL AX, g_stackguard1(DX)
// Initialize procid from TOS struct.
MOVL _tos(SB), AX
diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
index a958ce8..02c7c87 100644
--- a/src/runtime/sys_plan9_amd64.s
+++ b/src/runtime/sys_plan9_amd64.s
@@ -145,7 +145,8 @@
MOVQ AX, (g_stack+stack_hi)(DX)
SUBQ $(64*1024), AX // stack size
MOVQ AX, (g_stack+stack_lo)(DX)
- MOVQ AX, g_stackguard(DX)
+ MOVQ AX, g_stackguard0(DX)
+ MOVQ AX, g_stackguard1(DX)
// Initialize procid from TOS struct.
MOVQ _tos(SB), AX
diff --git a/src/runtime/sys_solaris_amd64.s b/src/runtime/sys_solaris_amd64.s
index 64a5224..54aeaea 100644
--- a/src/runtime/sys_solaris_amd64.s
+++ b/src/runtime/sys_solaris_amd64.s
@@ -134,7 +134,8 @@
SUBQ $(0x100000), AX // stack size
MOVQ AX, (g_stack+stack_lo)(DX)
ADDQ $const__StackGuard, AX
- MOVQ AX, g_stackguard(DX)
+ MOVQ AX, g_stackguard0(DX)
+ MOVQ AX, g_stackguard1(DX)
// Someday the convention will be D is always cleared.
CLD
diff --git a/src/runtime/sys_windows_386.s b/src/runtime/sys_windows_386.s
index eee6573..c8a830c 100644
--- a/src/runtime/sys_windows_386.s
+++ b/src/runtime/sys_windows_386.s
@@ -209,7 +209,8 @@
LEAL -8192(SP), CX
MOVL CX, (g_stack+stack_lo)(SP)
ADDL $const__StackGuard, CX
- MOVL CX, g_stackguard(SP)
+ MOVL CX, g_stackguard0(SP)
+ MOVL CX, g_stackguard1(SP)
MOVL DX, (g_stack+stack_hi)(SP)
PUSHL 16(BP) // arg for handler
@@ -314,7 +315,8 @@
SUBL $(64*1024), AX // stack size
MOVL AX, (g_stack+stack_lo)(DX)
ADDL $const__StackGuard, AX
- MOVL AX, g_stackguard(DX)
+ MOVL AX, g_stackguard0(DX)
+ MOVL AX, g_stackguard1(DX)
// Set up tls.
LEAL m_tls(CX), SI
diff --git a/src/runtime/sys_windows_amd64.s b/src/runtime/sys_windows_amd64.s
index aa8100e..68f7cd3 100644
--- a/src/runtime/sys_windows_amd64.s
+++ b/src/runtime/sys_windows_amd64.s
@@ -246,7 +246,8 @@
LEAQ -8192(SP), CX
MOVQ CX, (g_stack+stack_lo)(SP)
ADDQ $const__StackGuard, CX
- MOVQ CX, g_stackguard(SP)
+ MOVQ CX, g_stackguard0(SP)
+ MOVQ CX, g_stackguard1(SP)
MOVQ DX, (g_stack+stack_hi)(SP)
PUSHQ 32(BP) // arg for handler
@@ -355,7 +356,8 @@
SUBQ $(64*1024), AX // stack size
MOVQ AX, (g_stack+stack_lo)(DX)
ADDQ $const__StackGuard, AX
- MOVQ AX, g_stackguard(DX)
+ MOVQ AX, g_stackguard0(DX)
+ MOVQ AX, g_stackguard1(DX)
// Set up tls.
LEAQ m_tls(CX), SI
