Copy the siginfo_t structure with as minimal differences as possible, and rework parsing and description generating code

Author: Jlalond

lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp

@@ -565,18 +565,37 @@ Status ELFLinuxSigInfo::Parse(const DataExtractor &data, const ArchSpec &arch,
   // Not every stop signal has a valid address, but that will get resolved in
   // the unix_signals_sp->GetSignalDescription() call below.
   if (unix_signals_sp->GetShouldStop(si_signo)) {
-    addr = data.GetAddress(&offset);
-    addr_lsb = data.GetU16(&offset);
+    // Instead of memcpy we call all these individually as the extractor will
+    // handle endianness for us.
+    _sigfault.sig_addr = data.GetAddress(&offset);
+    _sigfault.sig_addr_lsb = data.GetU16(&offset);
+    if (data.GetByteSize() - offset >= sizeof(_sigfault._bounds)) {
+      _sigfault._bounds._addr_bnd._lower = data.GetAddress(&offset);
+      _sigfault._bounds._addr_bnd._upper = data.GetAddress(&offset);
+      _sigfault._bounds._pkey = data.GetU32(&offset);
+    } else {
+      // Set these to 0 so we don't use bogus data for the description.
+      _sigfault._bounds._addr_bnd._lower = 0;
+      _sigfault._bounds._addr_bnd._upper = 0;
+      _sigfault._bounds._pkey = 0;
+    }
   }
 
   return error;
 }
 
 std::string
 ELFLinuxSigInfo::GetDescription(const lldb::UnixSignalsSP unix_signals_sp) {
-  if (unix_signals_sp->GetShouldStop(si_signo))
-    return unix_signals_sp->GetSignalDescription(
-        si_signo, si_code, addr);
+  if (unix_signals_sp->GetShouldStop(si_signo)) {
+    if (_sigfault._bounds._addr_bnd._upper != 0)
+      return unix_signals_sp->GetSignalDescription(
+          si_signo, si_code, _sigfault.sig_addr,
+          _sigfault._bounds._addr_bnd._lower,
+          _sigfault._bounds._addr_bnd._upper);
+    else
+      return unix_signals_sp->GetSignalDescription(si_signo, si_code,
+                                                   _sigfault.sig_addr);
+  }
 
   return unix_signals_sp->GetSignalDescription(si_signo, si_code);
 }

lldb/source/Plugins/Process/elf-core/ThreadElfCore.h

@@ -79,8 +79,22 @@ struct ELFLinuxSigInfo {
   int32_t si_signo; // Order matters for the first 3.
   int32_t si_errno;
   int32_t si_code;
-  lldb::addr_t addr; /* faulting insn/memory ref. */
-  int32_t addr_lsb;  /* Valid LSB of the reported address.  */
+  // Copied from siginfo_t so we don't have to include signal.h on non 'Nix
+  // builds, we add `g` to the si_ prefix because siginfo_t defines them as
+  // macros.
+  struct {
+    lldb::addr_t sig_addr;  /* faulting insn/memory ref. */
+    short int sig_addr_lsb; /* Valid LSB of the reported address.  */
+    union {
+      /* used when si_code=SEGV_BNDERR */
+      struct {
+        lldb::addr_t _lower;
+        lldb::addr_t _upper;
+      } _addr_bnd;
+      /* used when si_code=SEGV_PKUERR */
+      uint32_t _pkey;
+    } _bounds;
+  } _sigfault;
 
   ELFLinuxSigInfo();
 
@@ -98,7 +112,7 @@ struct ELFLinuxSigInfo {
   static size_t GetSize(const lldb_private::ArchSpec &arch);
 };
 
-static_assert(sizeof(ELFLinuxSigInfo) == 32,
+static_assert(sizeof(ELFLinuxSigInfo) == 48,
               "sizeof ELFLinuxSigInfo is not correct!");
 
 // PRPSINFO structure's size differs based on architecture.