qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-23 07:10:05 -07:00
Code Releases Activity

runtime: stop scanning stack frames/args conservatively

Browse Source 
The goal here is to commit fully to having precise information
about stack frames. If we need information we don't have,
crash instead of assuming we should scan conservatively.

Since the stack copying assumes fully precise information,
any crashes during garbage collection that are introduced by
this CL are crashes that could have happened during stack
copying instead. Those are harder to find because stacks are
copied much less often than the garbage collector is invoked.

In service of that goal, remove ARGSIZE macros from
asm_*.s, change switchtoM to have no arguments
(it doesn't have any live arguments), and add
args and locals information to some frames that
can call back into Go.

LGTM=khr
R=khr, rlh
CC=golang-codereviews
https://golang.org/cl/137540043
This commit is contained in:
Russ Cox 2014-09-12 07:46:11 -04:00
parent a7c6d89166
commit e844f53a01
8 changed files with 64 additions and 100 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/runtime/asm_386.s
View File

@ -102,9 +102,7 @@ ok:
// create a new goroutine to start program
PUSHL $runtime·main·f(SB) // entry
PUSHL $0 // arg size
ARGSIZE(8)
CALL runtime·newproc(SB)
ARGSIZE(-1)
POPL AX
POPL AX
@ -206,7 +204,7 @@ TEXT runtime·mcall(SB), NOSPLIT, $0-4
// lives at the bottom of the G stack from the one that lives
// at the top of the M stack because the one at the top of
// the M stack terminates the stack walk (see topofstack()).
TEXT runtime·switchtoM(SB), NOSPLIT, $0-4
TEXT runtime·switchtoM(SB), NOSPLIT, $0-0
RET
// func onM_signalok(fn func())
@ -263,7 +261,6 @@ oncurg:
MOVL BX, SP
// call target function
ARGSIZE(0)
MOVL DI, DX
MOVL 0(DI), DI
CALL DI
@ -656,6 +653,7 @@ TEXT runtime·asmcgocall(SB),NOSPLIT,$0-8
RET
TEXT runtime·asmcgocall_errno(SB),NOSPLIT,$0-12
GO_ARGS
MOVL fn+0(FP), AX
MOVL arg+4(FP), BX
CALL asmcgocall<>(SB)
@ -716,6 +714,9 @@ TEXT runtime·cgocallback(SB),NOSPLIT,$12-12
// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback_gofunc(SB),NOSPLIT,$12-12
GO_ARGS
NO_LOCAL_POINTERS
// If g is nil, Go did not create the current thread.
// Call needm to obtain one for temporary use.
// In this case, we're running on the thread stack, so there's

10
src/runtime/asm_amd64.s
View File

@ -98,9 +98,7 @@ ok:
MOVQ $runtime·main·f(SB), BP // entry
PUSHQ BP
PUSHQ $0 // arg size
ARGSIZE(16)
CALL runtime·newproc(SB)
ARGSIZE(-1)
POPQ AX
POPQ AX
@ -183,7 +181,6 @@ TEXT runtime·mcall(SB), NOSPLIT, $0-8
MOVQ SI, g(CX) // g = m->g0
MOVQ (g_sched+gobuf_sp)(SI), SP // sp = m->g0->sched.sp
PUSHQ AX
ARGSIZE(8)
MOVQ DI, DX
MOVQ 0(DI), DI
CALL DI
@ -197,7 +194,7 @@ TEXT runtime·mcall(SB), NOSPLIT, $0-8
// lives at the bottom of the G stack from the one that lives
// at the top of the M stack because the one at the top of
// the M stack terminates the stack walk (see topofstack()).
TEXT runtime·switchtoM(SB), NOSPLIT, $0-8
TEXT runtime·switchtoM(SB), NOSPLIT, $0-0
RET
// func onM_signalok(fn func())
@ -255,7 +252,6 @@ oncurg:
MOVQ BX, SP
// call target function
ARGSIZE(0)
MOVQ DI, DX
MOVQ 0(DI), DI
CALL DI
@ -634,6 +630,7 @@ TEXT runtime·asmcgocall(SB),NOSPLIT,$0-16
RET
TEXT runtime·asmcgocall_errno(SB),NOSPLIT,$0-20
GO_ARGS
MOVQ fn+0(FP), AX
MOVQ arg+8(FP), BX
CALL asmcgocall<>(SB)
@ -703,6 +700,9 @@ TEXT runtime·cgocallback(SB),NOSPLIT,$24-24
// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback_gofunc(SB),NOSPLIT,$8-24
GO_ARGS
NO_LOCAL_POINTERS
// If g is nil, Go did not create the current thread.
// Call needm to obtain one m for temporary use.
// In this case, we're running on the thread stack, so there's

6
src/runtime/asm_amd64p32.s
View File

@ -75,9 +75,7 @@ ok:
MOVL $runtime·main·f(SB), AX // entry
MOVL $0, 0(SP)
MOVL AX, 4(SP)
ARGSIZE(8)
CALL runtime·newproc(SB)
ARGSIZE(-1)
// start this M
CALL runtime·mstart(SB)
@ -158,7 +156,6 @@ TEXT runtime·mcall(SB), NOSPLIT, $0-4
MOVL SI, g(CX) // g = m->g0
MOVL (g_sched+gobuf_sp)(SI), SP // sp = m->g0->sched.sp
PUSHQ AX
ARGSIZE(8)
MOVL DI, DX
MOVL 0(DI), DI
CALL DI
@ -172,7 +169,7 @@ TEXT runtime·mcall(SB), NOSPLIT, $0-4
// lives at the bottom of the G stack from the one that lives
// at the top of the M stack because the one at the top of
// the M stack terminates the stack walk (see topofstack()).
TEXT runtime·switchtoM(SB), NOSPLIT, $0-4
TEXT runtime·switchtoM(SB), NOSPLIT, $0-0
RET
// func onM_signalok(fn func())
@ -225,7 +222,6 @@ oncurg:
MOVL (g_sched+gobuf_sp)(DX), SP
// call target function
ARGSIZE(0)
MOVL DI, DX
MOVL 0(DI), DI
CALL DI

9
src/runtime/asm_arm.s
View File

@ -77,9 +77,7 @@ nocgo:
MOVW.W R0, -4(R13)
MOVW $0, R0
MOVW.W R0, -4(R13) // push $0 as guard
ARGSIZE(12)
BL runtime·newproc(SB)
ARGSIZE(-1)
MOVW $12(R13), R13 // pop args and LR
// start this M
@ -197,7 +195,7 @@ TEXT runtime·mcall(SB),NOSPLIT,$-4-4
// lives at the bottom of the G stack from the one that lives
// at the top of the M stack because the one at the top of
// the M stack terminates the stack walk (see topofstack()).
TEXT runtime·switchtoM(SB),NOSPLIT,$0-4
TEXT runtime·switchtoM(SB),NOSPLIT,$0-0
MOVW $0, R0
BL (R0) // clobber lr to ensure push {lr} is kept
RET
@ -258,7 +256,6 @@ oncurg:
MOVW R3, SP
// call target function
ARGSIZE(0)
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
@ -490,6 +487,7 @@ TEXT runtime·asmcgocall(SB),NOSPLIT,$0-8
RET
TEXT runtime·asmcgocall_errno(SB),NOSPLIT,$0-12
GO_ARGS
MOVW fn+0(FP), R1
MOVW arg+4(FP), R0
BL asmcgocall<>(SB)
@ -553,6 +551,9 @@ TEXT runtime·cgocallback(SB),NOSPLIT,$12-12
// cgocallback_gofunc(void (*fn)(void*), void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback_gofunc(SB),NOSPLIT,$8-12
GO_ARGS
NO_LOCAL_POINTERS
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R0
CMP $0, R0

74
src/runtime/mgc0.c
View File

@ -65,7 +65,6 @@
enum {
Debug = 0,
ConcurrentSweep = 1,
PreciseScan = 1,
WorkbufSize = 4*1024,
FinBlockSize = 4*1024,
@ -239,16 +238,6 @@ scanblock(byte *b, uintptr n, byte *ptrmask)
ptrmask = nil; // use GC bitmap for pointer info
scanobj:
if(!PreciseScan) {
if(ptrmask == nil) {
// Heap obj, obtain real size.
if(!runtime·mlookup(b, &p, &n, nil))
continue; // not an allocated obj
if(b != p)
runtime·throw("bad heap object");
}
ptrmask = ScanConservatively;
}
// Find bits of the beginning of the object.
if(ptrmask == nil) {
off = (uintptr*)b - (uintptr*)arena_start;
@ -620,7 +609,7 @@ scanframe(Stkframe *frame, void *unused)
Func *f;
StackMap *stackmap;
BitVector bv;
uintptr size;
uintptr size, minsize;
uintptr targetpc;
int32 pcdata;
@ -644,25 +633,21 @@ scanframe(Stkframe *frame, void *unused)
}
// Scan local variables if stack frame has been allocated.
// Use pointer information if known.
stackmap = runtime·funcdata(f, FUNCDATA_LocalsPointerMaps);
if(stackmap == nil) {
// No locals information, scan everything.
size = frame->varp - frame->sp;
if(Debug > 2)
runtime·printf("frame %s unsized locals %p+%p\n", runtime·funcname(f), (byte*)(frame->varp-size), size);
scanblock((byte*)(frame->varp - size), size, ScanConservatively);
} else if(stackmap->n < 0) {
// Locals size information, scan just the locals.
size = -stackmap->n;
if(Debug > 2)
runtime·printf("frame %s conservative locals %p+%p\n", runtime·funcname(f), (byte*)(frame->varp-size), size);
scanblock((byte*)(frame->varp - size), size, ScanConservatively);
} else if(stackmap->n > 0) {
size = frame->varp - frame->sp;
minsize = 0;
if(thechar != '6' && thechar != '8')
minsize = sizeof(uintptr);
if(size > minsize) {
stackmap = runtime·funcdata(f, FUNCDATA_LocalsPointerMaps);
if(stackmap == nil || stackmap->n <= 0) {
runtime·printf("runtime: frame %s untyped locals %p+%p\n", runtime·funcname(f), (byte*)(frame->varp-size), size);
runtime·throw("missing stackmap");
}
// Locals bitmap information, scan just the pointers in locals.
if(pcdata < 0 || pcdata >= stackmap->n) {
// don't know where we are
runtime·printf("pcdata is %d and %d stack map entries for %s (targetpc=%p)\n",
runtime·printf("runtime: pcdata is %d and %d locals stack map entries for %s (targetpc=%p)\n",
pcdata, stackmap->n, runtime·funcname(f), targetpc);
runtime·throw("scanframe: bad symbol table");
}
@ -672,19 +657,26 @@ scanframe(Stkframe *frame, void *unused)
}
// Scan arguments.
// Use pointer information if known.
if(frame->argmap != nil) {
bv = *frame->argmap;
scanblock((byte*)frame->argp, bv.n/BitsPerPointer*PtrSize, bv.bytedata);
} else if((stackmap = runtime·funcdata(f, FUNCDATA_ArgsPointerMaps)) != nil) {
bv = runtime·stackmapdata(stackmap, pcdata);
scanblock((byte*)frame->argp, bv.n/BitsPerPointer*PtrSize, bv.bytedata);
} else {
if(Debug > 2)
runtime·printf("frame %s conservative args %p+%p\n", runtime·funcname(f), frame->argp, (uintptr)frame->arglen);
scanblock((byte*)frame->argp, frame->arglen, ScanConservatively);
}
return true;
if(frame->arglen > 0) {
if(frame->argmap != nil)
bv = *frame->argmap;
else {
stackmap = runtime·funcdata(f, FUNCDATA_ArgsPointerMaps);
if(stackmap == nil || stackmap->n <= 0) {
runtime·printf("runtime: frame %s untyped args %p+%p\n", runtime·funcname(f), frame->argp, (uintptr)frame->arglen);
runtime·throw("missing stackmap");
}
if(pcdata < 0 || pcdata >= stackmap->n) {
// don't know where we are
runtime·printf("runtime: pcdata is %d and %d args stack map entries for %s (targetpc=%p)\n",
pcdata, stackmap->n, runtime·funcname(f), targetpc);
runtime·throw("scanframe: bad symbol table");
}
bv = runtime·stackmapdata(stackmap, pcdata);
}
scanblock((byte*)frame->argp, bv.n/BitsPerPointer*PtrSize, bv.bytedata);
}
return true;
}
static void

1
src/runtime/runtime.h
View File

@ -806,7 +806,6 @@ void runtime·signalstack(byte*, int32);
void runtime·symtabinit(void);
Func* runtime·findfunc(uintptr);
int32 runtime·funcline(Func*, uintptr, String*);
int32 runtime·funcarglen(Func*, uintptr);
int32 runtime·funcspdelta(Func*, uintptr);
int8* runtime·funcname(Func*);
int32 runtime·pcdatavalue(Func*, int32, uintptr);

7
src/runtime/symtab.go
View File

@ -237,13 +237,6 @@ func pcdatavalue(f *_func, table int32, targetpc uintptr) int32 {
return pcvalue(f, off, targetpc, true)
}
func funcarglen(f *_func, targetpc uintptr) int32 {
if targetpc == f.entry {
return 0
}
return pcdatavalue(f, _PCDATA_ArgSize, targetpc-_PCQuantum)
}
func funcdata(f *_func, i int32) unsafe.Pointer {
if i < 0 || i >= f.nfuncdata {
return nil

48
src/runtime/traceback.go
View File

@ -187,41 +187,23 @@ func gentraceback(pc0 uintptr, sp0 uintptr, lr0 uintptr, gp *g, skip int, pcbuf
if usesLR {
frame.argp += ptrSize
}
if f.args != _ArgsSizeUnknown {
frame.arglen = uintptr(f.args)
} else if callback != nil && (gofuncname(f) == "reflect.makeFuncStub" || gofuncname(f) == "reflect.methodValueCall") {
// NOTE: Two calls to gofuncname on line above will be
// collapsed to one when we pull out all the imprecise fallback code.
arg0 := frame.sp
if usesLR {
arg0 += ptrSize
}
fn := *(**[2]uintptr)(unsafe.Pointer(arg0))
if fn[0] != f.entry {
print("runtime: confused by ", gofuncname(f), "\n")
gothrow("reflect mismatch")
}
bv := (*bitvector)(unsafe.Pointer(fn[1]))
frame.arglen = uintptr(bv.n / 2 * ptrSize)
frame.argmap = bv
} else if flr == nil {
frame.arglen = 0
} else {
i := funcarglen(flr, frame.lr)
if i >= 0 {
frame.arglen = uintptr(i)
} else {
var tmp string
if flr != nil {
tmp = gofuncname(flr)
} else {
tmp = "?"
frame.arglen = uintptr(f.args)
if callback != nil && f.args == _ArgsSizeUnknown {
// Extract argument bitmaps for reflect stubs from the calls they made to reflect.
switch gofuncname(f) {
case "reflect.makeFuncStub", "reflect.methodValueCall":
arg0 := frame.sp
if usesLR {
arg0 += ptrSize
}
print("runtime: unknown argument frame size for ", gofuncname(f), " called from ", hex(frame.lr), " [", tmp, "]\n")
if callback != nil {
gothrow("invalid stack")
fn := *(**[2]uintptr)(unsafe.Pointer(arg0))
if fn[0] != f.entry {
print("runtime: confused by ", gofuncname(f), "\n")
gothrow("reflect mismatch")
}
frame.arglen = 0
bv := (*bitvector)(unsafe.Pointer(fn[1]))
frame.arglen = uintptr(bv.n / 2 * ptrSize)
frame.argmap = bv
}
}
}