Hi folks
Even with the register map fixed (see UserArea in RegisterContextLinux_i386.cpp)
an assertion failure occurs:
$ lldb hello
Current executable set to 'hello' (i386).
(lldb) log enable linux ptrace
(lldb) run
operation ptrace(PTRACE_SETOPTIONS, 2667, (nil), 0x58, 0)=0 called from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 1456
Process 2667 launching
operation ptrace(PTRACE_TRACEME, 0, (nil), (nil), 0)=0 called from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 1196
operation ptrace(PTRACE_PEEKDATA, 2667, 0x8048340, (nil), 0)=895EED31 called
from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 245
operation ptrace(PTRACE_PEEKDATA, 2667, 0x8048340, (nil), 0)=895EED31 called
from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 245
operation ptrace(PTRACE_POKEDATA, 2667, 0x8048340, 0x895eedcc, 0)=0 called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 319
operation ptrace(PTRACE_PEEKDATA, 2667, 0x8048340, (nil), 0)=895EEDCC called
from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 245
operation ptrace(PTRACE_POKEUSER, 2667, 0x114, 0xffffffff, 0)=0 called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 543
operation ptrace(PTRACE_POKEUSER, 2667, 0x118, 0xffffffff, 0)=0 called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 543
operation ptrace(PTRACE_PEEKUSER, 2667, 0x114, (nil), 0)=FFFFFFFF called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 494
operation ptrace(PTRACE_PEEKUSER, 2667, 0x114, (nil), 0)=FFFFFFFF called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 494
operation ptrace(PTRACE_POKEUSER, 2667, 0x114, 0xffffffff, 0)=0 called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 543
operation ptrace(PTRACE_PEEKUSER, 2667, 0x118, (nil), 0)=FFFFFFFF called from
file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 494
operation ptrace(PTRACE_PEEKUSER, 2667, 0xfc, (nil), 0)=0 called from file
/home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/Linux/ProcessMonitor.cpp
line 494
lldb: /home/mg11/src/heracles/llvm/tools/lldb/source/Plugins/Process/POSIX/POSIXThread.cpp:530: void POSIXThread::WatchNotify(const ProcessMessage&): Assertion `wp_sp.get() && "No watchpoint found"'
failed.
Aborted (core dumped)
The root cause of this is that 0xffffffff is written to dr6/7 originally from
RegisterContextPOSIXProcessMonitor_x86.cpp, whereas the programmer intended
0 to be written:
RegisterContextPOSIXProcessMonitor_x86_64::IsWatchpointHit(uint32_t hw_index)
{
<snip>
RegisterValue zero_bits = RegisterValue(uint64_t(0));
if (!WriteRegister(m_reg_info.first_dr + 6, zero_bits) ||
!WriteRegister(m_reg_info.first_dr + 7, zero_bits))
Construction of the RegisterValue as uint64_t and the subsequent conditional
compilation of 32-bit code within ProcessMonitor.cpp
void
WriteRegOperation::Execute(ProcessMonitor *monitor)
{
<snip>
#if __WORDSIZE == 32
buf = (void*) m_value.GetAsUInt32();
#else
combined with RegisterValue's implementation returning "fail_value" for
wrapped 64-bit data accessed as 32-bits.
Removal of the preprocessing step, relies on the compiler forcing truncation
to 32-bit, when compiled on 32-bit platform, more faithfully than the
explicit GetAsUInt32().
Please could someone apply the attached patch which fixes the fail_value
return. I tested this on 32-bit by launching a program, stopping, setting
a break, then resuming it. It was fine. I can't test 64-bit yet, but clearly
my proposed patch results in the 64-bit code being unchanged.
Index: source/Plugins/Process/Linux/ProcessMonitor.cpp
===================================================================
--- source/Plugins/Process/Linux/ProcessMonitor.cpp (revision 202675)
+++ source/Plugins/Process/Linux/ProcessMonitor.cpp (working copy)
@@ -532,11 +532,7 @@
void* buf;
Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
-#if __WORDSIZE == 32
- buf = (void*) m_value.GetAsUInt32();
-#else
buf = (void*) m_value.GetAsUInt64();
-#endif
if (log)
log->Printf ("ProcessMonitor::%s() reg %s: %p", __FUNCTION__,
m_reg_name, buf);
thanks
Matt
PS
(If this patch is applied *and* the debug register offset problem fixed -
I'm uploading separate patch - then 32-bit linux debug experience is
sane).
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Index: source/Plugins/Process/Linux/ProcessMonitor.cpp
===================================================================
--- source/Plugins/Process/Linux/ProcessMonitor.cpp (revision 202675)
+++ source/Plugins/Process/Linux/ProcessMonitor.cpp (working copy)
@@ -532,11 +532,7 @@
void* buf;
Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
-#if __WORDSIZE == 32
- buf = (void*) m_value.GetAsUInt32();
-#else
buf = (void*) m_value.GetAsUInt64();
-#endif
if (log)
log->Printf ("ProcessMonitor::%s() reg %s: %p", __FUNCTION__, m_reg_name, buf);
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