arm: Fix broken page table permissions checks in remote GDB
The remote GDB interface currently doesn't check if translations are
valid before reading memory. This causes a panic when GDB tries to
access unmapped memory (e.g., when getting a stack trace). There are
two reasons for this: 1) The function used to check for valid
translations (virtvalid()) doesn't work and panics on invalid
translations. 2) The method in the GDB interface used to test if a
translation is valid (RemoteGDB::acc) always returns true regardless
of the return from virtvalid().
This changeset fixes both of these issues.
diff --git a/src/arch/arm/vtophys.cc b/src/arch/arm/vtophys.cc
index bed76ac..3aad358 100644
--- a/src/arch/arm/vtophys.cc
+++ b/src/arch/arm/vtophys.cc
@@ -63,8 +63,8 @@
fatal("VTOPHYS: Can't convert vaddr to paddr on ARM without a thread context");
}
-Addr
-ArmISA::vtophys(ThreadContext *tc, Addr addr)
+static std::pair<bool, Addr>
+try_translate(ThreadContext *tc, Addr addr)
{
Fault fault;
// Set up a functional memory Request to pass to the TLB
@@ -82,22 +82,33 @@
tlb = static_cast<ArmISA::TLB*>(tc->getDTBPtr());
fault = tlb->translateFunctional(&req, tc, BaseTLB::Read, TLB::NormalTran);
if (fault == NoFault)
- return req.getPaddr();
+ return std::make_pair(true, req.getPaddr());
tlb = static_cast<ArmISA::TLB*>(tc->getITBPtr());
fault = tlb->translateFunctional(&req, tc, BaseTLB::Read, TLB::NormalTran);
if (fault == NoFault)
- return req.getPaddr();
+ return std::make_pair(true, req.getPaddr());
- panic("Table walkers support functional accesses. We should never get here\n");
+ return std::make_pair(false, 0);
+}
+
+Addr
+ArmISA::vtophys(ThreadContext *tc, Addr addr)
+{
+ const std::pair<bool, Addr> translation(try_translate(tc, addr));
+
+ if (translation.first)
+ return translation.second;
+ else
+ panic("Table walkers support functional accesses. We should never get here\n");
}
bool
ArmISA::virtvalid(ThreadContext *tc, Addr vaddr)
{
- if (vtophys(tc, vaddr) != -1)
- return true;
- return false;
+ const std::pair<bool, Addr> translation(try_translate(tc, vaddr));
+
+ return translation.first;
}
