changeset f7d17d8a854c in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=f7d17d8a854c
description:
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.
diffstat:
src/arch/arm/remote_gdb.cc | 15 ++++++---------
src/arch/arm/vtophys.cc | 27 +++++++++++++++++++--------
2 files changed, 25 insertions(+), 17 deletions(-)
diffs (87 lines):
diff -r 4206946d60fe -r f7d17d8a854c src/arch/arm/remote_gdb.cc
--- a/src/arch/arm/remote_gdb.cc Thu Feb 26 09:58:26 2015 -0600
+++ b/src/arch/arm/remote_gdb.cc Mon Mar 02 04:00:27 2015 -0500
@@ -142,6 +142,7 @@
#include "arch/arm/system.hh"
#include "arch/arm/utility.hh"
#include "arch/arm/vtophys.hh"
+#include "base/chunk_generator.hh"
#include "base/intmath.hh"
#include "base/remote_gdb.hh"
#include "base/socket.hh"
@@ -172,16 +173,12 @@
RemoteGDB::acc(Addr va, size_t len)
{
if (FullSystem) {
- Addr last_va;
- va = truncPage(va);
- last_va = roundPage(va + len);
-
- do {
- if (virtvalid(context, va)) {
- return true;
+ for (ChunkGenerator gen(va, len, PageBytes); !gen.done(); gen.next()) {
+ if (!virtvalid(context, gen.addr())) {
+ DPRINTF(GDBAcc, "acc: %#x mapping is invalid\n", va);
+ return false;
}
- va += PageBytes;
- } while (va < last_va);
+ }
DPRINTF(GDBAcc, "acc: %#x mapping is valid\n", va);
return true;
diff -r 4206946d60fe -r f7d17d8a854c src/arch/arm/vtophys.cc
--- a/src/arch/arm/vtophys.cc Thu Feb 26 09:58:26 2015 -0600
+++ b/src/arch/arm/vtophys.cc Mon Mar 02 04:00:27 2015 -0500
@@ -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;
}
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