code review 4203042: runtime: pass to signal handler value of g at time of signal

src/pkg/runtime/linux/amd64/signal.c

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
 #include "defs.h"
 #include "signals.h"
 #include "os.h"
 
 void
@@ skipping 32 matching lines @@
 
 String
 runtime·signame(int32 sig)
 {
         if(sig < 0 || sig >= NSIG)
                 return runtime·emptystring;
         return runtime·gostringnocopy((byte*)runtime·sigtab[sig].name);
 }
 
 void
-runtime·sighandler(int32 sig, Siginfo* info, void* context)
+runtime·sighandler(int32 sig, Siginfo *info, void *context, G *gp)
 {
         Ucontext *uc;
         Mcontext *mc;
         Sigcontext *r;
         uintptr *sp;
-        G *gp;
 
         uc = context;
         mc = &uc->uc_mcontext;
         r = (Sigcontext*)mc;    // same layout, more conveient names
 
-        if((gp = m->curg) != nil && (runtime·sigtab[sig].flags & SigPanic)) {
+        if(gp != nil && (runtime·sigtab[sig].flags & SigPanic)) {
                 // Make it look like a call to the signal func.
                 // Have to pass arguments out of band since
                 // augmenting the stack frame would break
                 // the unwinding code.
                 gp->sig = sig;
                 gp->sigcode0 = info->si_code;
                 gp->sigcode1 = ((uintptr*)info)[2];
                 gp->sigpc = r->rip;
 
                 // Only push runtime·sigpanic if r->rip != 0.
@@ skipping 23 matching lines @@
 
         if(sig < 0 || sig >= NSIG)
                 runtime·printf("Signal %d\n", sig);
         else
                 runtime·printf("%s\n", runtime·sigtab[sig].name);
 
         runtime·printf("PC=%X\n", r->rip);
         runtime·printf("\n");
 
         if(runtime·gotraceback()){
-                runtime·traceback((void*)r->rip, (void*)r->rsp, 0, g);
-                runtime·tracebackothers(g);
+                runtime·traceback((void*)r->rip, (void*)r->rsp, 0, gp);
+                runtime·tracebackothers(gp);
                 runtime·dumpregs(r);
         }
 
         runtime·breakpoint();
         runtime·exit(2);
 }
 
 void
 runtime·signalstack(byte *p, int32 n)
 {
@@ skipping 25 matching lines @@
                         else
                                 sa.sa_handler = (void*)runtime·sigignore;
                         if(runtime·sigtab[i].flags & SigRestart)
                                 sa.sa_flags |= SA_RESTART;
                         else
                                 sa.sa_flags &= ~SA_RESTART;
                         runtime·rt_sigaction(i, &sa, nil, 8);
                 }
         }
 }