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author | Russ Cox <rsc@golang.org> | 2014-02-27 22:43:47 -0500 |
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committer | Russ Cox <rsc@golang.org> | 2014-02-27 22:43:47 -0500 |
commit | 6dc75d34f149ee58c1c77fc1d45d7a9ff3d1ddd4 (patch) | |
tree | 01451e3b1cae69b075675934383b131858b5953f | |
parent | 8632586cdc31ae61d0d7ef0ca7f13f7d481a9bfa (diff) | |
download | go-6dc75d34f149ee58c1c77fc1d45d7a9ff3d1ddd4.tar.gz |
[release-branch.go1.2] runtime: if traceback sees a breakpoint, don't change the PC
??? CL 49580044 / 38cd458b1dfe
runtime: if traceback sees a breakpoint, don't change the PC
Changing the PC confuses gdb, because execution does not
continue where gdb expects it. Not changing the PC has the
potential to confuse a stack dump, but when running under gdb
it seems better to confuse a stack dump than to confuse gdb.
Fixes issue 6776.
LGTM=rsc
R=golang-codereviews, dvyukov, rsc
CC=golang-codereviews
https://codereview.appspot.com/49580044
???
LGTM=r
R=golang-codereviews, r
CC=golang-dev
https://codereview.appspot.com/69800043
-rw-r--r-- | src/pkg/runtime/sys_x86.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/pkg/runtime/sys_x86.c b/src/pkg/runtime/sys_x86.c index e68ff514a..0df6dfbbd 100644 --- a/src/pkg/runtime/sys_x86.c +++ b/src/pkg/runtime/sys_x86.c @@ -37,6 +37,19 @@ runtime·rewindmorestack(Gobuf *gobuf) gobuf->pc = gobuf->pc + 2 + *(int8*)(pc+1); return; } + if(pc[0] == 0xcc) { + // This is a breakpoint inserted by gdb. We could use + // runtime·findfunc to find the function. But if we + // do that, then we will continue execution at the + // function entry point, and we will not hit the gdb + // breakpoint. So for this case we don't change + // gobuf->pc, so that when we return we will execute + // the jump instruction and carry on. This means that + // stack unwinding may not work entirely correctly + // (http://golang.org/issue/5723) but the user is + // running under gdb anyhow. + return; + } runtime·printf("runtime: pc=%p %x %x %x %x %x\n", pc, pc[0], pc[1], pc[2], pc[3], pc[4]); runtime·throw("runtime: misuse of rewindmorestack"); } |