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Diffstat (limited to 'src/pkg/runtime/traceback_x86.c')
-rw-r--r--src/pkg/runtime/traceback_x86.c207
1 files changed, 189 insertions, 18 deletions
diff --git a/src/pkg/runtime/traceback_x86.c b/src/pkg/runtime/traceback_x86.c
index 8e3063f43..851504f52 100644
--- a/src/pkg/runtime/traceback_x86.c
+++ b/src/pkg/runtime/traceback_x86.c
@@ -2,14 +2,23 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// +build amd64 386
+// +build amd64 amd64p32 386
#include "runtime.h"
#include "arch_GOARCH.h"
#include "malloc.h"
#include "funcdata.h"
+#ifdef GOOS_windows
+#include "defs_GOOS_GOARCH.h"
+#endif
void runtime·sigpanic(void);
+void runtime·newproc(void);
+void runtime·deferproc(void);
+
+#ifdef GOOS_windows
+void runtime·sigtramp(void);
+#endif
// This code is also used for the 386 tracebacks.
// Use uintptr for an appropriate word-sized integer.
@@ -19,18 +28,22 @@ void runtime·sigpanic(void);
// collector (callback != nil). A little clunky to merge these, but avoids
// duplicating the code and all its subtlety.
int32
-runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip, uintptr *pcbuf, int32 max, void (*callback)(Stkframe*, void*), void *v, bool printall)
+runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip, uintptr *pcbuf, int32 max, bool (*callback)(Stkframe*, void*), void *v, bool printall)
{
- int32 i, n, nprint, line;
- uintptr tracepc;
- bool waspanic, printing;
+ int32 i, n, nprint, line, gotraceback;
+ uintptr tracepc, sparg;
+ bool waspanic, wasnewproc, printing;
Func *f, *flr;
Stkframe frame;
Stktop *stk;
String file;
+ Panic *panic;
+ Defer *defer;
USED(lr0);
+ gotraceback = runtime·gotraceback(nil);
+
if(pc0 == ~(uintptr)0 && sp0 == ~(uintptr)0) { // Signal to fetch saved values from gp.
if(gp->syscallstack != (uintptr)nil) {
pc0 = gp->syscallpc;
@@ -46,13 +59,21 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
frame.pc = pc0;
frame.sp = sp0;
waspanic = false;
+ wasnewproc = false;
printing = pcbuf==nil && callback==nil;
-
+ panic = gp->panic;
+ defer = gp->defer;
+
+ while(defer != nil && defer->argp == NoArgs)
+ defer = defer->link;
+ while(panic != nil && panic->defer == nil)
+ panic = panic->link;
+
// If the PC is zero, it's likely a nil function call.
// Start in the caller's frame.
if(frame.pc == 0) {
frame.pc = *(uintptr*)frame.sp;
- frame.sp += sizeof(uintptr);
+ frame.sp += sizeof(uintreg);
}
f = runtime·findfunc(frame.pc);
@@ -95,20 +116,63 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
frame.fn = f;
continue;
}
+
f = frame.fn;
+#ifdef GOOS_windows
+ // Windows exception handlers run on the actual g stack (there is room
+ // dedicated to this below the usual "bottom of stack"), not on a separate
+ // stack. As a result, we have to be able to unwind past the exception
+ // handler when called to unwind during stack growth inside the handler.
+ // Recognize the frame at the call to sighandler in sigtramp and unwind
+ // using the context argument passed to the call. This is awful.
+ if(f != nil && f->entry == (uintptr)runtime·sigtramp && frame.pc > f->entry) {
+ Context *r;
+
+ // Invoke callback so that stack copier sees an uncopyable frame.
+ if(callback != nil) {
+ frame.continpc = frame.pc;
+ frame.argp = nil;
+ frame.arglen = 0;
+ if(!callback(&frame, v))
+ return n;
+ }
+ r = (Context*)((uintptr*)frame.sp)[1];
+#ifdef GOARCH_amd64
+ frame.pc = r->Rip;
+ frame.sp = r->Rsp;
+#else
+ frame.pc = r->Eip;
+ frame.sp = r->Esp;
+#endif
+ frame.lr = 0;
+ frame.fp = 0;
+ frame.fn = nil;
+ if(printing && runtime·showframe(nil, gp))
+ runtime·printf("----- exception handler -----\n");
+ f = runtime·findfunc(frame.pc);
+ if(f == nil) {
+ runtime·printf("runtime: unknown pc %p after exception handler\n", frame.pc);
+ if(callback != nil)
+ runtime·throw("unknown pc");
+ }
+ frame.fn = f;
+ continue;
+ }
+#endif
+
// Found an actual function.
// Derive frame pointer and link register.
if(frame.fp == 0) {
frame.fp = frame.sp + runtime·funcspdelta(f, frame.pc);
- frame.fp += sizeof(uintptr); // caller PC
+ frame.fp += sizeof(uintreg); // caller PC
}
if(runtime·topofstack(f)) {
frame.lr = 0;
flr = nil;
} else {
if(frame.lr == 0)
- frame.lr = ((uintptr*)frame.fp)[-1];
+ frame.lr = ((uintreg*)frame.fp)[-1];
flr = runtime·findfunc(frame.lr);
if(flr == nil) {
runtime·printf("runtime: unexpected return pc for %s called from %p\n", runtime·funcname(f), frame.lr);
@@ -117,7 +181,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
}
}
- frame.varp = (byte*)frame.fp - sizeof(uintptr);
+ frame.varp = (byte*)frame.fp - sizeof(uintreg);
// Derive size of arguments.
// Most functions have a fixed-size argument block,
@@ -143,6 +207,40 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
frame.arglen = 0;
}
}
+
+ // Determine function SP where deferproc would find its arguments.
+ // On x86 that's just the standard bottom-of-stack, so SP exactly.
+ // If the previous frame was a direct call to newproc/deferproc, however,
+ // the SP is two words lower than normal.
+ sparg = frame.sp;
+ if(wasnewproc)
+ sparg += 2*sizeof(uintreg);
+
+ // Determine frame's 'continuation PC', where it can continue.
+ // Normally this is the return address on the stack, but if sigpanic
+ // is immediately below this function on the stack, then the frame
+ // stopped executing due to a trap, and frame.pc is probably not
+ // a safe point for looking up liveness information. In this panicking case,
+ // the function either doesn't return at all (if it has no defers or if the
+ // defers do not recover) or it returns from one of the calls to
+ // deferproc a second time (if the corresponding deferred func recovers).
+ // It suffices to assume that the most recent deferproc is the one that
+ // returns; everything live at earlier deferprocs is still live at that one.
+ frame.continpc = frame.pc;
+ if(waspanic) {
+ if(panic != nil && panic->defer->argp == (byte*)sparg)
+ frame.continpc = (uintptr)panic->defer->pc;
+ else if(defer != nil && defer->argp == (byte*)sparg)
+ frame.continpc = (uintptr)defer->pc;
+ else
+ frame.continpc = 0;
+ }
+
+ // Unwind our local panic & defer stacks past this frame.
+ while(panic != nil && (panic->defer == nil || panic->defer->argp == (byte*)sparg || panic->defer->argp == NoArgs))
+ panic = panic->link;
+ while(defer != nil && (defer->argp == (byte*)sparg || defer->argp == NoArgs))
+ defer = defer->link;
if(skip > 0) {
skip--;
@@ -151,8 +249,10 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
if(pcbuf != nil)
pcbuf[n] = frame.pc;
- if(callback != nil)
- callback(&frame, v);
+ if(callback != nil) {
+ if(!callback(&frame, v))
+ return n;
+ }
if(printing) {
if(printall || runtime·showframe(f, gp)) {
// Print during crash.
@@ -164,7 +264,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
tracepc--;
runtime·printf("%s(", runtime·funcname(f));
for(i = 0; i < frame.arglen/sizeof(uintptr); i++) {
- if(i >= 5) {
+ if(i >= 10) {
runtime·prints(", ...");
break;
}
@@ -177,8 +277,8 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
runtime·printf("\t%S:%d", file, line);
if(frame.pc > f->entry)
runtime·printf(" +%p", (uintptr)(frame.pc - f->entry));
- if(m->throwing > 0 && gp == m->curg)
- runtime·printf(" fp=%p", frame.fp);
+ if(m->throwing > 0 && gp == m->curg || gotraceback >= 2)
+ runtime·printf(" fp=%p sp=%p", frame.fp, frame.sp);
runtime·printf("\n");
nprint++;
}
@@ -187,6 +287,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
skipped:
waspanic = f->entry == (uintptr)runtime·sigpanic;
+ wasnewproc = f->entry == (uintptr)runtime·newproc || f->entry == (uintptr)runtime·deferproc;
// Do not unwind past the bottom of the stack.
if(flr == nil)
@@ -202,7 +303,72 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
if(pcbuf == nil && callback == nil)
n = nprint;
-
+
+ // If callback != nil, we're being called to gather stack information during
+ // garbage collection or stack growth. In that context, require that we used
+ // up the entire defer stack. If not, then there is a bug somewhere and the
+ // garbage collection or stack growth may not have seen the correct picture
+ // of the stack. Crash now instead of silently executing the garbage collection
+ // or stack copy incorrectly and setting up for a mysterious crash later.
+ //
+ // Note that panic != nil is okay here: there can be leftover panics,
+ // because the defers on the panic stack do not nest in frame order as
+ // they do on the defer stack. If you have:
+ //
+ // frame 1 defers d1
+ // frame 2 defers d2
+ // frame 3 defers d3
+ // frame 4 panics
+ // frame 4's panic starts running defers
+ // frame 5, running d3, defers d4
+ // frame 5 panics
+ // frame 5's panic starts running defers
+ // frame 6, running d4, garbage collects
+ // frame 6, running d2, garbage collects
+ //
+ // During the execution of d4, the panic stack is d4 -> d3, which
+ // is nested properly, and we'll treat frame 3 as resumable, because we
+ // can find d3. (And in fact frame 3 is resumable. If d4 recovers
+ // and frame 5 continues running, d3, d3 can recover and we'll
+ // resume execution in (returning from) frame 3.)
+ //
+ // During the execution of d2, however, the panic stack is d2 -> d3,
+ // which is inverted. The scan will match d2 to frame 2 but having
+ // d2 on the stack until then means it will not match d3 to frame 3.
+ // This is okay: if we're running d2, then all the defers after d2 have
+ // completed and their corresponding frames are dead. Not finding d3
+ // for frame 3 means we'll set frame 3's continpc == 0, which is correct
+ // (frame 3 is dead). At the end of the walk the panic stack can thus
+ // contain defers (d3 in this case) for dead frames. The inversion here
+ // always indicates a dead frame, and the effect of the inversion on the
+ // scan is to hide those dead frames, so the scan is still okay:
+ // what's left on the panic stack are exactly (and only) the dead frames.
+ //
+ // We require callback != nil here because only when callback != nil
+ // do we know that gentraceback is being called in a "must be correct"
+ // context as opposed to a "best effort" context. The tracebacks with
+ // callbacks only happen when everything is stopped nicely.
+ // At other times, such as when gathering a stack for a profiling signal
+ // or when printing a traceback during a crash, everything may not be
+ // stopped nicely, and the stack walk may not be able to complete.
+ // It's okay in those situations not to use up the entire defer stack:
+ // incomplete information then is still better than nothing.
+ if(callback != nil && n < max && defer != nil) {
+ if(defer != nil)
+ runtime·printf("runtime: g%D: leftover defer argp=%p pc=%p\n", gp->goid, defer->argp, defer->pc);
+ if(panic != nil)
+ runtime·printf("runtime: g%D: leftover panic argp=%p pc=%p\n", gp->goid, panic->defer->argp, panic->defer->pc);
+ for(defer = gp->defer; defer != nil; defer = defer->link)
+ runtime·printf("\tdefer %p argp=%p pc=%p\n", defer, defer->argp, defer->pc);
+ for(panic = gp->panic; panic != nil; panic = panic->link) {
+ runtime·printf("\tpanic %p defer %p", panic, panic->defer);
+ if(panic->defer != nil)
+ runtime·printf(" argp=%p pc=%p", panic->defer->argp, panic->defer->pc);
+ runtime·printf("\n");
+ }
+ runtime·throw("traceback has leftover defers or panics");
+ }
+
return n;
}
@@ -232,6 +398,8 @@ runtime·printcreatedby(G *gp)
void
runtime·traceback(uintptr pc, uintptr sp, uintptr lr, G *gp)
{
+ int32 n;
+
USED(lr);
if(gp->status == Gsyscall) {
@@ -242,8 +410,11 @@ runtime·traceback(uintptr pc, uintptr sp, uintptr lr, G *gp)
// Print traceback. By default, omits runtime frames.
// If that means we print nothing at all, repeat forcing all frames printed.
- if(runtime·gentraceback(pc, sp, 0, gp, 0, nil, 100, nil, nil, false) == 0)
- runtime·gentraceback(pc, sp, 0, gp, 0, nil, 100, nil, nil, true);
+ n = runtime·gentraceback(pc, sp, 0, gp, 0, nil, TracebackMaxFrames, nil, nil, false);
+ if(n == 0)
+ n = runtime·gentraceback(pc, sp, 0, gp, 0, nil, TracebackMaxFrames, nil, nil, true);
+ if(n == TracebackMaxFrames)
+ runtime·printf("...additional frames elided...\n");
runtime·printcreatedby(gp);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-03 18:36:55 +0000