Hello Go experts,
Could someone please help to resolve this issue?
Best Regards
Mariappan
On Thu, Mar 30, 2023 at 2:52 PM mariappan balraj <mariappan.bal...@gmail.com>
wrote:
> Hello Go Experts,
>
> When panic() is called from Go function, in the below call sequence,
> runtime.unwindm() [which is defer function of runtime.cgocallbackg1] is
> called. This function is unwinding the system stack. Later, as part of the
> function addOneOpenDeferFrame(), systemstack() is called to run a function
> in the system stack. This will use the stack which is allocated for C
> function calls. This makes stack unwinding impossible in case of panic() is
> called. Can someone please help me to fix this issue?
>
> (dlv) bt
> 0 0x00000000004054e6 in runtime.unwindm
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:326
> 1 0x0000000000405446 in runtime.cgocallbackg1.func3
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:304
> 2 0x00000000004340c8 in runtime.deferCallSave
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:796
> 3 0x0000000000433fa5 in runtime.runOpenDeferFrame
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:769
> 4 0x0000000000434332 in runtime.gopanic
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:884
> 5 0x00000000004642a7 in main.Test4
> at ./export.go:7
> at ./export.go:7
> 6 0x000000000046431c in _cgoexp_78b81bbf688e_Test4
> at _cgo_gotypes.go:61
> 7 0x000000000040535b in runtime.cgocallbackg1
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315
> 8 0x0000000000405079 in runtime.cgocallbackg
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234
> 9 0x0000000000461b0f in runtime.cgocallbackg
> at <autogenerated>:1
> 10 0x000000000045f3f4 in runtime.cgocallback
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998
> 11 0x00000000004641bd in crosscall2
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s:30
> 12 0x0000000000464386 in C.Test4
> at /tmp/go-build/_cgo_export.c:33
> 13 0x0000000000464432 in C.test1
> at ./hello.go:9
> 14 0x000000000046444d in C.test2
> at ./hello.go:14
> 15 0x0000000000464468 in C.test3
> 15 0x0000000000464468 in C.test3
> at ./hello.go:19
> 16 0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3
> at /tmp/go-build/cgo-gcc-prolog:49
> 17 0x000000000045f2e4 in runtime.asmcgocall
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:848
> 18 0x000000000046448a in C._cgo_78b81bbf688e_Cfunc_test3
> at /tmp/go-build/cgo-gcc-prolog:44
> 19 0x0000000000404f0a in runtime.cgocall
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167
> 20 0x0000000000464245 in main._Cfunc_test3
> at _cgo_gotypes.go:39
> 21 0x00000000004642d7 in main.main
> at ./hello.go:33
> 22 0x0000000000437073 in runtime.main
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250
> 23 0x000000000045f5e1 in runtime.goexit
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598
>
> 254 func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) {
> 304 defer unwindm(&restore)
>
> 326 func unwindm(restore *bool) {
> 327 if *restore {
> 328 // Restore sp saved by cgocallback during
> 329 // unwind of g's stack (see comment at top of file).
> 330 mp := acquirem()
> 331 sched := &mp.g0.sched
> 332 sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp +
> alignUp(sys.MinFrameSize, sys.StackAlign)))
>
> (dlv)
> > runtime.addOneOpenDeferFrame()
> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:642 (PC:
> 0x433a45)
> Warning: debugging optimized function
> 637: func addOneOpenDeferFrame(gp *g, pc uintptr, sp unsafe.Pointer) {
> 638: var prevDefer *_defer
> 639: if sp == nil {
> 640: prevDefer = gp._defer
> 641: pc = prevDefer.framepc
> => 642: sp = unsafe.Pointer(prevDefer.sp)
> 643: }
> 644: systemstack(func() {
> 645: gentraceback(pc, uintptr(sp), 0, gp, 0, nil,
> 0x7fffffff,
> 646: func(frame *stkframe, unused
> unsafe.Pointer) bool {
> 647: if prevDefer != nil &&
> prevDefer.sp == frame.sp {
> (dlv) bt
> 0 0x0000000000433a45 in runtime.addOneOpenDeferFrame
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:642
> 1 0x0000000000434357 in runtime.gopanic
> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886
> 2 0x00000000004642a7 in main.Test4
> at ./export.go:7
>
> On Tue, Mar 28, 2023 at 4:14 PM mariappan balraj <
> mariappan.bal...@gmail.com> wrote:
>
>> Hello Go Experts,
>>
>> I am observing system stack corruption when panic() is called from go
>> function. When panic is called from Test4(), as part of
>> runtime.systemstack_switch(), the RSP and RBP is set in such a way that it
>> will corrupt the stack.
>>
>> Rbp = 0x00007ffdb188bd20===> This should be less than 0x7ffdb188bc50. But
>> it is set to the value which is already used for CGO calls. So it is making
>> the system stack to corrupt. When the core file is generated, it makes it
>> unable to debug from the core file using dlv. Can someone please help on
>> this issue?
>>
>> RBP 0x7ffdb188bc50 RA 0x45f3f4 runtime.cgocallback
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1003
>> RBP 0x7ffdb188bca0 RA 0x4641bd crosscall2
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s 32
>> RBP 0x7ffdb188bcd0 RA 0x464386 C.Test4 /tmp/go-build/_cgo_export.c 35
>> RBP 0x7ffdb188bce0 RA 0x464432 C.test1
>> /home/soomohan/mbalraj/test/hello.go 10
>> RBP 0x7ffdb188bd00 RA 0x46444d C.test2
>> /home/soomohan/mbalraj/test/hello.go 15
>> RBP 0x7ffdb188bd20 RA 0x464468 C.test3
>> /home/soomohan/mbalraj/test/hello.go 20
>> RBP 0x7ffdb188bd50 RA 0x4644a7 C._cgo_78b81bbf688e_Cfunc_test3
>> /tmp/go-build/cgo-gcc-prolog 51
>>
>> go version
>> go version go1.20.2 linux/amd64
>>
>> //hello.go
>> package main
>>
>> /*
>> #include <stdio.h>
>>
>> extern void Test4(void);
>>
>> void test1(void) {
>> Test4();
>> }
>>
>> void test2(void) {
>> int val = 2;
>> test1();
>> }
>>
>> void test3(void) {
>> int val = 3;
>> test2();
>> }
>>
>> void test4(void) {
>> printf("Test4()");
>> }
>> */
>> import "C"
>>
>> func Test5() {
>> C.test4()
>> }
>>
>> func main() {
>> C.test3()
>> }
>>
>> //export.go
>> package main
>>
>> import "C"
>>
>> //export Test4
>> func Test4() {
>> panic("Panic inside Test4")
>> //Test5()
>> }
>>
>> I have written the following script test.start to debug this issue
>> further in DLV.
>> def command_goroutine_start_line(args):
>> regs = registers().Regs
>> rip = 0
>> for reg in regs:
>> if reg.Name == "Rbp":
>> rbp = int(reg.Value, 16)
>> elif reg.Name == "Rip":
>> rip = int(reg.Value, 16)
>>
>> da = disassemble(StartPC=rip, EndPC=rip+1).Disassemble
>> print("RBP 0x%x RIP 0x%x %s %s %s" % (rbp, rip,
>> da[0].Loc.Function.Name_, da[0].Loc.File, da[0].Loc.Line))
>>
>> while True:
>> mem = examine_memory(rbp, 8).Mem
>> val = 0
>> for i in range(len(mem)):
>> val <<= 8
>> val += mem[len(mem) - i - 1]
>> prbp = val
>>
>> mem = examine_memory(rbp + 8, 8).Mem
>> val = 0
>> for i in range(len(mem)):
>> val <<= 8
>> val += mem[len(mem) - i - 1]
>> ra = val
>>
>> da = disassemble(StartPC=ra, EndPC=ra+1).Disassemble
>> print("RBP 0x%x RA 0x%x %s %s %s" % (prbp, ra,
>> da[0].Loc.Function.Name_, da[0].Loc.File, da[0].Loc.Line))
>> if prbp == 0:
>> break
>> rbp = prbp
>>
>> def main():
>> dlv_command("config alias goroutine_start_line gsl")
>>
>> (dlv)bt
>> RBP 0x0 RA 0x45f5e1 runtime.goexit
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1599
>>
>> 0 0x0000000000433b04 in runtime.addOneOpenDeferFrame.func1
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:646
>> 1 0x000000000045f0c0 in runtime.systemstack_switch
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463
>> 2 0x0000000000433a89 in runtime.addOneOpenDeferFrame
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:644
>> 3 0x0000000000434357 in runtime.gopanic
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886
>> 4 0x00000000004642a7 in main.Test4
>> at ./export.go:7
>> 5 0x000000000046431c in _cgoexp_78b81bbf688e_Test4
>> at _cgo_gotypes.go:61
>> 6 0x000000000040535b in runtime.cgocallbackg1
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315
>> 7 0x0000000000405079 in runtime.cgocallbackg
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234
>> 8 0x0000000000461b0f in runtime.cgocallbackg
>> at <autogenerated>:1
>> 9 0x000000000045f3f4 in runtime.cgocallback
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998
>> 10 0x0000000000000001 in ???
>> at ?:-1
>> 11 0x0000000000464386 in C.Test4
>> at /tmp/go-build/_cgo_export.c:33
>> 12 0x0000000000464432 in C.test1
>> at ./hello.go:9
>> 13 0x000000000046444d in C.test2
>> at ./hello.go:14
>> 14 0x0000000000464468 in C.test3
>> at ./hello.go:19
>> 15 0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3
>> 15 0x00000000004644a7 in C._cgo_78b81bbf688e_Cfunc_test3
>> at /tmp/go-build/cgo-gcc-prolog:49
>> 16 0x000000000045f2e4 in runtime.asmcgocall
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:848
>> 17 0x000000000046448a in C._cgo_78b81bbf688e_Cfunc_test3
>> at /tmp/go-build/cgo-gcc-prolog:44
>> 18 0x0000000000404f0a in runtime.cgocall
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167
>> 19 0x0000000000464245 in main._Cfunc_test3
>> at _cgo_gotypes.go:39
>> 20 0x00000000004642d7 in main.main
>> at ./hello.go:33
>> 21 0x0000000000437073 in runtime.main
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250
>> 22 0x000000000045f5e1 in runtime.goexit
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598
>>
>> (dlv)source test.star
>> (dlv)gsl
>> (dlv) gsl
>> RBP 0xc000048c68 RIP 0x433b04 runtime.addOneOpenDeferFrame.func1
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go 646
>> RBP 0xc000048d28 RA 0x434357 runtime.gopanic
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go 905
>> RBP 0xc000048d48 RA 0x4642a7 main.Test4
>> /home/soomohan/mbalraj/test/export.go 7
>> RBP 0xc000048d58 RA 0x46431c _cgoexp_78b81bbf688e_Test4 _cgo_gotypes.go 62
>> RBP 0xc000048e18 RA 0x40535b runtime.cgocallbackg1
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go 323
>> RBP 0xc000048ea8 RA 0x405079 runtime.cgocallbackg
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go 240
>> RBP 0xc000048ed0 RA 0x461b0f runtime.cgocallbackg <autogenerated> 1
>> RBP 0x7ffdb188bc50 RA 0x45f3f4 runtime.cgocallback
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1003
>> RBP 0x7ffdb188bca0 RA 0x4641bd crosscall2
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgo/asm_amd64.s 32
>> RBP 0x7ffdb188bcd0 RA 0x464386 C.Test4 /tmp/go-build/_cgo_export.c 35
>> RBP 0x7ffdb188bce0 RA 0x464432 C.test1
>> /home/soomohan/mbalraj/test/hello.go 10
>> RBP 0x7ffdb188bd00 RA 0x46444d C.test2
>> /home/soomohan/mbalraj/test/hello.go 15
>> RBP 0x7ffdb188bd20 RA 0x464468 C.test3
>> /home/soomohan/mbalraj/test/hello.go 20
>> RBP 0x7ffdb188bd50 RA 0x4644a7 C._cgo_78b81bbf688e_Cfunc_test3
>> /tmp/go-build/cgo-gcc-prolog 51
>> RBP 0xc000048f38 RA 0x45f2e4 runtime.asmcgocall
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 852
>> RBP 0xc000048f60 RA 0x464245 main._Cfunc_test3 _cgo_gotypes.go 40
>> RBP 0xc000048f70 RA 0x4642d7 main.main
>> /home/soomohan/mbalraj/test/hello.go 33
>> RBP 0xc000048fd0 RA 0x437073 runtime.main
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go 260
>> RBP 0x0 RA 0x45f5e1 runtime.goexit
>> /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s 1599
>>
>> (dlv)si
>>
>> (dlv)bt
>> 0 0x000000000045587f in runtime.gentraceback
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/traceback.go:32
>> 1 0x000000000045f0c0 in runtime.systemstack_switch
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463
>> 2 0x0000000000433a89 in runtime.addOneOpenDeferFrame
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:644
>> 3 0x0000000000434357 in runtime.gopanic
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:886
>> 4 0x00000000004642a7 in main.Test4
>> at ./export.go:7
>> 5 0x000000000046431c in _cgoexp_78b81bbf688e_Test4
>> at _cgo_gotypes.go:61
>> 6 0x000000000040535b in runtime.cgocallbackg1
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315
>> 7 0x0000000000405079 in runtime.cgocallbackg
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234
>> 8 0x0000000000461b0f in runtime.cgocallbackg
>> at <autogenerated>:1
>> 9 0x000000000045f3f4 in runtime.cgocallback
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998
>> 10 0x0000000000000001 in ???
>> at ?:-1
>> 11 0x0000000000464386 in C.Test4
>> at /tmp/go-build/_cgo_export.c:33
>> 12 0x0000000000464432 in C.test1
>> at ./hello.go:9
>> 13 0x000000000046444d in C.test2
>> at ./hello.go:14
>> 14 0x0000000000464468 in C.test3
>> at ./hello.go:19
>> 15 0x0000000000433b4b in runtime.addOneOpenDeferFrame.func1
>> 15 0x0000000000433b4b in runtime.addOneOpenDeferFrame.func1
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/panic.go:645
>> 16 0x000000000045f129 in runtime.systemstack
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:496
>> 17 0x0000000000461da5 in runtime.newproc
>> at <autogenerated>:1
>> 18 0x00000000004cc720 in ???
>> at ?:-1
>> 19 0x000000000046431c in _cgoexp_78b81bbf688e_Test4
>> at _cgo_gotypes.go:61
>> 20 0x000000000040535b in runtime.cgocallbackg1
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:315
>> 21 0x0000000000405079 in runtime.cgocallbackg
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:234
>> 22 0x0000000000461b0f in runtime.cgocallbackg
>> at <autogenerated>:1
>> 23 0x000000000045f3f4 in runtime.cgocallback
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:998
>> 24 0x000000000045f0c0 in runtime.systemstack_switch
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:463
>> 25 0x0000000000404f0a in runtime.cgocall
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/cgocall.go:167
>> 26 0x0000000000464245 in main._Cfunc_test3
>> at _cgo_gotypes.go:39
>> 27 0x00000000004642d7 in main.main
>> at ./hello.go:33
>> 28 0x0000000000437073 in runtime.main
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/proc.go:250
>> 29 0x000000000045f5e1 in runtime.goexit
>> at /home/soomohan/mbalraj/GO/go1.20.2/go/src/runtime/asm_amd64.s:1598
>>
>> (dlv) regs
>> (dlv) regs
>> Rip = 0x000000000045587f
>> Rsp = 0x00007ffdb188ba08
>> Rax = 0x000000000040535b
>> Rbx = 0x000000c000048d68
>> Rcx = 0x0000000000000000
>> Rdx = 0x0000000000433b60
>> Rsi = 0x0000000000000000
>> Rdi = 0x000000c0000061a0
>> Rbp = 0x00007ffdb188bd20
>> R8 = 0x0000000000000000
>> R9 = 0x000000007fffffff
>> R10 = 0x00007ffdb188bd80
>> R11 = 0x0000000000000000
>> R12 = 0x00007ffdb188ba88
>> R13 = 0x000000c000048c18
>> R14 = 0x00000000004cc720
>> R15 = 0x0000000000000000
>> Rflags = 0x0000000000000246 [PF ZF IF IOPL=0]
>> Es = 0x0000000000000000
>> Cs = 0x0000000000000033
>> Ss = 0x000000000000002b
>> Ds = 0x0000000000000000
>> Fs = 0x0000000000000000
>> Gs = 0x0000000000000000
>> Fs_base = 0x000015128ba66740
>> Gs_base = 0x0000000000000000
>>
>> Best Regards
>> Mariappan
>>
>
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