[unwind] Handle UNW_X86_64_RIP register

[vitalybuka]

Summary

In some binaries, built with clang/lld, libunwind crashes
with "unsupported x86_64 register" for regNum == 16:

#1 abort ()
#2  libunwind::DwarfInstructions<libunwind::LocalAddressSpace, libunwind::Registers_x86_64>::evaluateExpression(unsigned long, libunwind::LocalAddressSpace&, libunwind::Registers_x86_64 const&, unsigned long) () 
#3 libunwind::DwarfInstructions<libunwind::LocalAddressSpace, libunwind::Registers_x86_64>::stepWithDwarf(libunwind::LocalAddressSpace&, unsigned long, unsigned long, libunwind::Registers_x86_64&, bool&) ()
#4 libunwind::UnwindCursor<libunwind::LocalAddressSpace, libunwind::Registers_x86_64>::step()
#5  _Unwind_Backtrace ()
#6  UnwindSlow ()

[vitalybuka]

remode debug logging

[MaskRay]

libunwind/src/Registers.hpp

349–350

Add UNW_X86_64_RIP here

453–454

Add UNW_X86_64_RIP here

libunwind/test/libunwind_01.pass.cpp

67

I am thinking of making the function available on all arches:

int num_regs = 0;
#if defined(__x86_64__)
num_regs = 33;
#endif

for (int i = 0; i < num_regs; ++i) {
  ...
}

[vitalybuka]

MaskRay's comments

[MaskRay]

Looks great!

libunwind/test/libunwind_01.pass.cpp

66

-2

[vitalybuka]

libunwind/test/libunwind_01.pass.cpp

66

-2+1 does not work on line 79

libunwind/src/Registers.hpp

 
 inline bool Registers_x86_64::validRegister(int regNum) const {
   if (regNum == UNW_REG_IP)
     return true;
   if (regNum == UNW_REG_SP)
     return true;
   if (regNum < 0)
     return false;
-  if (regNum > 15)
+  if (regNum > 16)
     return false;
   return true;
 }
 
 inline uint64_t Registers_x86_64::getRegister(int regNum) const {
   switch (regNum) {
   case UNW_REG_IP:
+  case UNW_X86_64_RIP:
     return _registers.__rip;
   case UNW_REG_SP:
     return _registers.__rsp;
   case UNW_X86_64_RAX:
     return _registers.__rax;
   case UNW_X86_64_RDX:
     return _registers.__rdx;
   case UNW_X86_64_RCX:
case UNW_X86_64_R15:
     return _registers.__r15;
   }
   _LIBUNWIND_ABORT("unsupported x86_64 register");
 }
 
 inline void Registers_x86_64::setRegister(int regNum, uint64_t value) {
   switch (regNum) {
   case UNW_REG_IP:
+  case UNW_X86_64_RIP:
     _registers.__rip = value;
     return;
   case UNW_REG_SP:
     _registers.__rsp = value;
     return;
   case UNW_X86_64_RAX:
     _registers.__rax = value;
     return;
case UNW_X86_64_R15:
     _registers.__r15 = value;
     return;
   }
   _LIBUNWIND_ABORT("unsupported x86_64 register");
 }
 
 inline const char *Registers_x86_64::getRegisterName(int regNum) {
   switch (regNum) {
   case UNW_REG_IP:
+  case UNW_X86_64_RIP:
     return "rip";
   case UNW_REG_SP:
     return "rsp";
   case UNW_X86_64_RAX:
     return "rax";
   case UNW_X86_64_RDX:
     return "rdx";
   case UNW_X86_64_RCX:

libunwind/test/libunwind_01.pass.cpp

 #include <libunwind.h>
 #include <stdlib.h>
+#include <string.h>
 
 void backtrace(int lower_bound) {
   unw_context_t context;
   unw_getcontext(&context);
 
   unw_cursor_t cursor;
   unw_init_local(&cursor, &context);
 
void test_no_info() {
   // Set the IP to an address clearly outside any function.
   unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)0);
 
   ret = unw_get_proc_info(&cursor, &info);
   if (ret != UNW_ENOINFO)
     abort();
 }
 
+void test_reg_names() {
+  unw_context_t context;
+  unw_getcontext(&context);
+
+  unw_cursor_t cursor;
+  unw_init_local(&cursor, &context);
+
+  int max_reg_num = -100;
+#if defined(__i386__)
+  max_reg_num = 7;
+#elif defined(__x86_64__)
+  max_reg_num = 32;
+#endif
+
+  const char prefix[] = "unknown";
+  for (int i = -2; i < max_reg_num; ++i) {
+    if (strncmp(prefix, unw_regname(&cursor, i), sizeof(prefix) - 1) == 0)
+      abort();
+  }
+
+  if (strncmp(prefix, unw_regname(&cursor, max_reg_num + 1),
+              sizeof(prefix) - 1) != 0)
+    abort();
+}
+
+#if defined(__x86_64__)
+void test_reg_get_set() {
+  unw_context_t context;
+  unw_getcontext(&context);
+
+  unw_cursor_t cursor;
+  unw_init_local(&cursor, &context);
+
+  for (int i = 0; i < 17; ++i) {
+    const unw_word_t set_value = 7;
+    if (unw_set_reg(&cursor, i, set_value) != UNW_ESUCCESS)
+      abort();
+
+    unw_word_t get_value = 0;
+    if (unw_get_reg(&cursor, i, &get_value) != UNW_ESUCCESS)
+      abort();
+
+    if (set_value != get_value)
+      abort();
+  }
+}
+
+void test_fpreg_get_set() {
+  unw_context_t context;
+  unw_getcontext(&context);
+
+  unw_cursor_t cursor;
+  unw_init_local(&cursor, &context);
+
+  // get/set is not implemented for x86_64 fpregs.
+  for (int i = 17; i < 33; ++i) {
+    const unw_fpreg_t set_value = 7;
+    if (unw_set_fpreg(&cursor, i, set_value) != UNW_EBADREG)
+      abort();
+
+    unw_fpreg_t get_value = 0;
+    if (unw_get_fpreg(&cursor, i, &get_value) != UNW_EBADREG)
+      abort();
+  }
+}
+#else
+void test_reg_get_set() {}
+void test_fpreg_get_set() {}
+#endif
+
 int main(int, char**) {
   test1(1);
   test2(1, 2);
   test3(1, 2, 3);
   test_no_info();
+  test_reg_names();
+  test_reg_get_set();
+  test_fpreg_get_set();
   return 0;
 }