This revision was automatically updated to reflect the committed changes.
Closed by commit rL256847: Fix for undefined behavior while updating PC value
on arm-linux (authored by omjavaid).
Changed prior to commit:
http://reviews.llvm.org/D15877?vs=43941&id=44015#toc
Repository:
rL LLVM
http://reviews.llvm.org/D15877
Files:
lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
Index:
lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
===================================================================
--- lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
+++ lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
@@ -973,7 +973,24 @@
if (error.Fail())
return error;
- m_gpr_arm[offset / sizeof(uint32_t)] = value.GetAsUInt32();
+ uint32_t reg_value = value.GetAsUInt32();
+ // As precaution for an undefined behavior encountered while setting PC we
+ // will clear thumb bit of new PC if we are already in thumb mode; that is
+ // CPSR thumb mode bit is set.
+ if (offset / sizeof(uint32_t) == gpr_pc_arm)
+ {
+ // Check if we are already in thumb mode and
+ // thumb bit of current PC is read out to be zero and
+ // thumb bit of next PC is read out to be one.
+ if ((m_gpr_arm[gpr_cpsr_arm] & 0x20) &&
+ !(m_gpr_arm[gpr_pc_arm] & 0x01) &&
+ (value.GetAsUInt32() & 0x01))
+ {
+ reg_value &= (~1ull);
+ }
+ }
+
+ m_gpr_arm[offset / sizeof(uint32_t)] = reg_value;
return DoWriteGPR(m_gpr_arm, sizeof(m_gpr_arm));
}
Index: lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
===================================================================
--- lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
+++ lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp
@@ -973,7 +973,24 @@
if (error.Fail())
return error;
- m_gpr_arm[offset / sizeof(uint32_t)] = value.GetAsUInt32();
+ uint32_t reg_value = value.GetAsUInt32();
+ // As precaution for an undefined behavior encountered while setting PC we
+ // will clear thumb bit of new PC if we are already in thumb mode; that is
+ // CPSR thumb mode bit is set.
+ if (offset / sizeof(uint32_t) == gpr_pc_arm)
+ {
+ // Check if we are already in thumb mode and
+ // thumb bit of current PC is read out to be zero and
+ // thumb bit of next PC is read out to be one.
+ if ((m_gpr_arm[gpr_cpsr_arm] & 0x20) &&
+ !(m_gpr_arm[gpr_pc_arm] & 0x01) &&
+ (value.GetAsUInt32() & 0x01))
+ {
+ reg_value &= (~1ull);
+ }
+ }
+
+ m_gpr_arm[offset / sizeof(uint32_t)] = reg_value;
return DoWriteGPR(m_gpr_arm, sizeof(m_gpr_arm));
}
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