Fix NativeProcessLinux Read/Write register operations for arm

[omjavaid]

Summary

ptrace on arm doesnt support PTRACE_PEEKUSER/PTRACE_POKEUSER operations for register read/write.

To work around this we use PTRACE_GETREGS/PTRACE_SETREGS ptrace operations.

This patch fixes ReadRegOperation and WriteRegOperation in NativeProcessLinux to make sure we use correct method for register access on arm.

[tberghammer]

The general concept looks good but the following types are not defined on android:

elf_greg_t
elf_gregset_t
elf_fpregset_t

Please add their definition to source/Plugins/Process/Linux/Procfs.h where we already define them for arm64.

Exactly what type of error you seen without this patch? On android I haven't seen any problem reading out the registers without this patch either but it works also after applying this change (and hacking around the compile issue).

[emaste]

ping?

[tberghammer]

Do you see any failure caused by the lack of this patch? On android-arm, register read works without any change, so I am not sure what is the original background of this change, and I prefer not to apply it for android as PTRACE_GETREGS is slower then PTRACE_POKEUSER.

source/Plugins/Process/Linux/NativeProcessLinux.cpp

#if defined (__arm64__) || defined (__aarch64__)
             {
                 ArchSpec arch;
                 if (monitor->GetArchitecture(arch))
                     m_value.SetBytes((void *)(((unsigned char *)(regs)) + m_offset), 8, arch.GetByteOrder());
                 else
                     m_error.SetErrorString("failed to get architecture");
             }
         }
-#elif defined (__mips__)
+#elif defined (__mips__) || defined (__arm__)
         elf_gregset_t regs;
         PTRACE(PTRACE_GETREGS, m_tid, NULL, &regs, sizeof regs, m_error);
         if (m_error.Success())
         {
             lldb_private::ArchSpec arch;
             if (monitor->GetArchitecture(arch))
-                m_value.SetBytes((void *)(((unsigned char *)(regs)) + m_offset), 8, arch.GetByteOrder());
+                m_value.SetBytes((void *)(((unsigned char *)(regs)) + m_offset), arch.GetAddressByteSize(), arch.GetByteOrder());
             else
                 m_error.SetErrorString("failed to get architecture");
         }
 #else
         Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
 
         lldb::addr_t data = static_cast<unsigned long>(PTRACE(PTRACE_PEEKUSER, m_tid, (void*)m_offset, nullptr, 0, m_error));
         if (m_error.Success())
#if defined (__arm64__) || defined (__aarch64__)
             ioVec.iov_len = sizeof regs;
             PTRACE(PTRACE_GETREGSET, m_tid, &regset, &ioVec, sizeof regs, m_error);
             if (m_error.Success())
             {
                 ::memcpy((void *)(((unsigned char *)(&regs)) + m_offset), m_value.GetBytes(), 8);
                 PTRACE(PTRACE_SETREGSET, m_tid, &regset, &ioVec, sizeof regs, m_error);
             }
         }
-#elif defined (__mips__)
+#elif defined (__mips__) || defined (__arm__)
         elf_gregset_t regs;
         PTRACE(PTRACE_GETREGS, m_tid, NULL, &regs, sizeof regs, m_error);
         if (m_error.Success())
         {
-            ::memcpy((void *)(((unsigned char *)(&regs)) + m_offset), m_value.GetBytes(), 8);
-            PTRACE(PTRACE_SETREGS, m_tid, NULL, &regs, sizeof regs, m_error);
+            lldb_private::ArchSpec arch;
+            if (monitor->GetArchitecture(arch))
+            {
+              ::memcpy((void *)(((unsigned char *)(&regs)) + m_offset), m_value.GetBytes(), arch.GetAddressByteSize());
+              PTRACE(PTRACE_SETREGS, m_tid, NULL, &regs, sizeof regs, m_error);
             }
+            else
+                m_error.SetErrorString("failed to get architecture");
+        }
 #else
         void* buf;
         Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
 
         buf = (void*) m_value.GetAsUInt64();
 
         if (log)
             log->Printf ("NativeProcessLinux::%s() reg %s: %p", __FUNCTION__, m_reg_name, buf);