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ARM: Make sure the target process doesn't run away from statetrace.

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This commit is contained in:
Gabe Black 2009-07-29 00:14:43 -07:00
parent 0a9eb59e6f
commit 873112ea99
2 changed files with 25 additions and 14 deletions
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7
src/arch/arm/nativetrace.cc
View file

@ -104,8 +104,13 @@ Trace::ArmNativeTrace::ThreadState::update(ThreadContext *tc)
void
Trace::ArmNativeTrace::check(NativeTraceRecord *record)
{
ThreadContext *tc = record->getThread();
// This area is read only on the target. It can't stop there to tell us
// what's going on, so we should skip over anything there also.
if (tc->readNextPC() > 0xffff0000)
return;
nState.update(this);
mState.update(record->getThread());
mState.update(tc);
bool errorFound = false;
// Regular int regs

32
util/statetrace/arch/tracechild_arm.cc
View file

@ -203,22 +203,28 @@ ostream & ARMTraceChild::outputStartState(ostream & os)
bool ARMTraceChild::step()
{
const uint32_t bkpt_inst = 0xe7f001f0;
const uint32_t bkpt_inst = 0xE1200070;
const uint32_t bkpt_mask = 0xFFF000F0;
uint32_t lr = getRegVal(14);
uint32_t pc = getPC();
uint32_t lrOp;
const uint32_t swi_inst = 0x0F0000000;
const uint32_t swi_mask = 0x0F0000000;
// Since ARM uses software breakpoints behind the scenes, they don't work
// in read only areas like the page of routines provided by the kernel. The
// link register generally holds the address the process wants to the
// kernel to return to after it's done, so we'll install a software
// breakpoint there. If the lr happens to point to the next instruction
// we'll leave out our breakpoint to avoid an infinite loop. This isn't a
// fool proof strategy, but it should work well in all the reasonable
// scenarios I can think of right now.
uint32_t next_op = ptrace(PTRACE_PEEKDATA, pid, getPC(), 0);
if ((next_op & swi_mask) == swi_inst) {
ptrace(PTRACE_POKEDATA, pid, next_op + sizeof(uint32_t), bkpt_inst);
ptraceSingleStep();
ptrace(PTRACE_POKEDATA, pid, next_op + sizeof(uint32_t), next_op);
}
else
{
ptraceSingleStep();
if (pc != lr) {
lrOp = ptrace(PTRACE_PEEKDATA, pid, lr, 0);
ptrace(PTRACE_POKEDATA, pid, lr, bkpt_inst);
}
ptraceSingleStep();
if (pc != lr) {
ptrace(PTRACE_POKEDATA, pid, lr, lrOp);
}
}