[lldb] [Process/elf-core] Fix reading NetBSD/i386 core dumps

[mgorny]

Summary

Add support for extracting basic data from NetBSD/i386 core dumps.
FPU registers are not supported at the moment.

[mgorny]

Use split code branches for i386 and amd64.

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

if (name == "NetBSD-CORE") {
           if (!had_nt_regs || tid != thread_data.tid)
             return llvm::make_error<llvm::StringError>(
                 "Error parsing NetBSD core(5) notes: Unexpected order "
                 "of NOTEs PT_GETFPREG before PT_GETREG",
                 llvm::inconvertibleErrorCode());
           thread_data.notes.push_back(note);
         }
       } break;
+      case llvm::Triple::x86: {
+        // Assume order PT_GETREGS, PT_GETFPREGS
+        if (note.info.n_type == NETBSD::I386::NT_REGS) {
+          // If this is the next thread, push the previous one first.
+          if (had_nt_regs) {
+            m_thread_data.push_back(thread_data);
+            thread_data = ThreadData();
+            had_nt_regs = false;
+          }
+
+          thread_data.gpregset = note.data;
+          thread_data.tid = tid;
+          if (thread_data.gpregset.GetByteSize() == 0)
+            return llvm::make_error<llvm::StringError>(
+                "Could not find general purpose registers note in core file.",
+                llvm::inconvertibleErrorCode());
+          had_nt_regs = true;
+        } else if (note.info.n_type == NETBSD::I386::NT_FPREGS) {
+          if (!had_nt_regs || tid != thread_data.tid)
+            return llvm::make_error<llvm::StringError>(
+                "Error parsing NetBSD core(5) notes: Unexpected order "
+                "of NOTEs PT_GETFPREG before PT_GETREG",
+                llvm::inconvertibleErrorCode());
+          thread_data.notes.push_back(note);
+        }
+      } break;
       case llvm::Triple::x86_64: {
         // Assume order PT_GETREGS, PT_GETFPREGS
         if (note.info.n_type == NETBSD::AMD64::NT_REGS) {
           // If this is the next thread, push the previous one first.
           if (had_nt_regs) {
             m_thread_data.push_back(thread_data);
             thread_data = ThreadData();
             had_nt_regs = false;

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

 namespace AARCH64 {
 enum { NT_REGS = 32, NT_FPREGS = 34 };
 }
 
 namespace AMD64 {
 enum { NT_REGS = 33, NT_FPREGS = 35 };
 }
 
+namespace I386 {
+enum { NT_REGS = 33, NT_FPREGS = 35 };
+}
+
 } // namespace NETBSD
 
 namespace OPENBSD {
 enum {
   NT_PROCINFO = 10,
   NT_AUXV = 11,
   NT_REGS = 20,
   NT_FPREGS = 21,
constexpr RegsetDesc FPR_Desc[] = {
     {llvm::Triple::FreeBSD, llvm::Triple::x86, llvm::ELF::NT_X86_XSTATE},
     {llvm::Triple::FreeBSD, llvm::Triple::UnknownArch, llvm::ELF::NT_FPREGSET},
     // In a i386 core file NT_FPREGSET is present, but it's not the result
     // of the FXSAVE instruction like in 64 bit files.
     // The result from FXSAVE is in NT_PRXFPREG for i386 core files
     {llvm::Triple::Linux, llvm::Triple::x86, llvm::ELF::NT_PRXFPREG},
     {llvm::Triple::Linux, llvm::Triple::UnknownArch, llvm::ELF::NT_FPREGSET},
     {llvm::Triple::NetBSD, llvm::Triple::aarch64, NETBSD::AARCH64::NT_FPREGS},
+    {llvm::Triple::NetBSD, llvm::Triple::x86, NETBSD::I386::NT_FPREGS},
     {llvm::Triple::NetBSD, llvm::Triple::x86_64, NETBSD::AMD64::NT_FPREGS},
     {llvm::Triple::OpenBSD, llvm::Triple::UnknownArch, OPENBSD::NT_FPREGS},
 };
 
 constexpr RegsetDesc AARCH64_SVE_Desc[] = {
     {llvm::Triple::Linux, llvm::Triple::aarch64, llvm::ELF::NT_ARM_SVE},
 };
 

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

 
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_i386.h"
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_mips64.h"
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_powerpc.h"
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.h"
 #include "Plugins/Process/Utility/RegisterContextLinux_i386.h"
 #include "Plugins/Process/Utility/RegisterContextLinux_s390x.h"
 #include "Plugins/Process/Utility/RegisterContextLinux_x86_64.h"
+#include "Plugins/Process/Utility/RegisterContextNetBSD_i386.h"
 #include "Plugins/Process/Utility/RegisterContextNetBSD_x86_64.h"
 #include "Plugins/Process/Utility/RegisterContextOpenBSD_i386.h"
 #include "Plugins/Process/Utility/RegisterContextOpenBSD_x86_64.h"
 #include "Plugins/Process/Utility/RegisterInfoPOSIX_arm.h"
 #include "Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h"
 #include "Plugins/Process/Utility/RegisterInfoPOSIX_ppc64le.h"
 #include "ProcessElfCore.h"
 #include "RegisterContextPOSIXCore_arm.h"
case llvm::Triple::FreeBSD: {
       }
       break;
     }
 
     case llvm::Triple::NetBSD: {
       switch (arch.GetMachine()) {
       case llvm::Triple::aarch64:
         break;
+      case llvm::Triple::x86:
+        reg_interface = new RegisterContextNetBSD_i386(arch);
+        break;
       case llvm::Triple::x86_64:
         reg_interface = new RegisterContextNetBSD_x86_64(arch);
         break;
       default:
         break;
       }
       break;
     }

lldb/test/Shell/Register/Core/x86-32-netbsd-addr.test

+# RUN: %lldb -b -s %s -c %p/Inputs/x86-32-netbsd.core | FileCheck %s
+
+register read --all
+# CHECK-DAG: eip = 0x08048955
+# CHECK-DAG: eflags = 0x00010282
+# CHECK-DAG: cs = 0x00000037
+# CHECK-DAG: fs = 0x0000004f
+# CHECK-DAG: gs = 0x0000008b
+# CHECK-DAG: ss = 0x0000004f
+# CHECK-DAG: ds = 0x0000004f
+# CHECK-DAG: es = 0x0000004f
+
+# TODO: fix reading fp registers

lldb/test/Shell/Register/Core/x86-32-netbsd-gp.test

+# RUN: %lldb -b -s %s -c %p/Inputs/x86-32-netbsd.core | FileCheck %p/Inputs/x86-32-gp.check
+
+register read --all