Simplify "recovery" unwinding

process.cc

@@ -22,7 +22,17 @@
 #include <sys/wait.h>
 #include <signal.h>
 
-
+#if defined(__amd64__)
+#define BP(regs) (regs.rbp)
+#define SP(regs) (regs.rsp)
+#define IP(regs) (regs.rip)
+#elif defined(__i386__)
+#define BP(regs) regs.ebp
+#define SP(regs) regs.esp
+#define IP(regs) (regs.eip)
+#elif defined(__aarch64__)
+#define IP(regs) (regs.pc)
+#endif
 
 /*
  * convert a gregset_t to an Elf::CoreRegs
@@ -933,30 +943,17 @@ ThreadStack::unwind(Process &p, Elf::CoreRegisters &regs, unsigned maxFrames)
                 // For ARM, the concept is the same, but we look at the link
                 // register rather than a pushd return address
 
-#if defined(__amd64__)
-#define BP(regs) (regs.rbp)
-#define SP(regs) (regs.rsp)
-#define IP(regs) (regs.rip)
-#elif defined(__i386__)
-#define BP(regs) regs.ebp
-#define SP(regs) regs.esp
-#define IP(regs) (regs.eip)
-#elif defined(__aarch64__)
-#define IP(regs) (regs.pc)
-#endif
-
-                auto newRegs = prev.regs; // start with a copy of prev frames regs.
 
                 if (stack.size() == 1 || stack[stack.size() - 2].isSignalTrampoline) {
-                    Dwarf::ProcessLocation prevlocation = prev.scopeIP(p);
-                    Dwarf::ProcessLocation location(p, IP(newRegs));
-                    if (!prevlocation.valid() || (location.valid() && (location.codeloc->phdr_->p_flags & PF_X) == 0)) {
+                    Dwarf::ProcessLocation badip = { p, IP(prev.regs) };
+                    if (!badip.valid() || (badip.codeloc->phdr_->p_flags & PF_X) == 0) {
 
 #if defined(__amd64__) || defined(__i386__)
                         // get stack pointer in the current frame, and read content of TOS
                         auto sp = SP(prev.regs);
                         Elf::Addr ip;
                         auto in = p.io->read(sp, sizeof ip, (char *)&ip);
+                        auto newRegs = prev.regs; // start with a copy of prev frames regs.
                         if (in == sizeof ip) {
                             SP(newRegs) = sp + sizeof ip;
                             IP(newRegs) = ip;             // .. insn pointer.
@@ -983,6 +980,7 @@ ThreadStack::unwind(Process &p, Elf::CoreRegisters &regs, unsigned maxFrames)
                        ucontext_t uc;
                     };
                     auto sigframe = p.io->readObj<rt_sigframe>(prev.regs.sp);
+                    Elf::CoreRegs newRegs;
                     for (int i = 0; i < 31; ++i)
                        newRegs.regs[i] = sigframe.uc.uc_mcontext.regs[i];
                     newRegs.sp = sigframe.uc.uc_mcontext.sp;
@@ -1041,6 +1039,7 @@ ThreadStack::unwind(Process &p, Elf::CoreRegisters &regs, unsigned maxFrames)
                    p.io->readObj(oldBp + ELF_BYTES, &newIp);
                    p.io->readObj(oldBp, &newBp);
                    if (newBp > oldBp && newIp > 4096) {
+                       Elf::CoreRegisters newRegs = prev.regs;
                        SP(newRegs) = oldBp + ELF_BYTES * 2;
                        BP(newRegs) = newBp;
                        IP(newRegs) = newIp;