[compiler-rt] r271272 - [esan] Intercept and chain signal handlers
Derek Bruening via llvm-commits
llvm-commits at lists.llvm.org
Tue May 31 06:21:07 PDT 2016
Author: bruening
Date: Tue May 31 08:21:03 2016
New Revision: 271272
URL: http://llvm.org/viewvc/llvm-project?rev=271272&view=rev
Log:
[esan] Intercept and chain signal handlers
Summary:
In preparation for fault-based shadow memory iteration, we add support for
our own signal handler by adding app signal handler interception as well as
chaining for SIGSEGV. This is done in a simple manner: we do not honor the
app's alternate stack nor any sigaction flags for SIGSEGV.
Adds a new test of transparency in app signal handling.
Reviewers: aizatsky
Subscribers: filcab, kubabrecka, vitalybuka, zhaoqin, kcc, eugenis, llvm-commits
Differential Revision: http://reviews.llvm.org/D20577
Added:
compiler-rt/trunk/lib/esan/working_set_posix.cpp (with props)
compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp (with props)
Modified:
compiler-rt/trunk/lib/esan/CMakeLists.txt
compiler-rt/trunk/lib/esan/esan.cpp
compiler-rt/trunk/lib/esan/esan.h
compiler-rt/trunk/lib/esan/esan_interceptors.cpp
compiler-rt/trunk/lib/esan/working_set.cpp
compiler-rt/trunk/lib/esan/working_set.h
Modified: compiler-rt/trunk/lib/esan/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/CMakeLists.txt?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/CMakeLists.txt (original)
+++ compiler-rt/trunk/lib/esan/CMakeLists.txt Tue May 31 08:21:03 2016
@@ -14,7 +14,8 @@ set(ESAN_SOURCES
esan_interceptors.cpp
esan_linux.cpp
cache_frag.cpp
- working_set.cpp)
+ working_set.cpp
+ working_set_posix.cpp)
foreach (arch ${ESAN_SUPPORTED_ARCH})
add_compiler_rt_runtime(clang_rt.esan
Modified: compiler-rt/trunk/lib/esan/esan.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/esan.cpp?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/esan.cpp (original)
+++ compiler-rt/trunk/lib/esan/esan.cpp Tue May 31 08:21:03 2016
@@ -73,6 +73,18 @@ void processRangeAccess(uptr PC, uptr Ad
}
}
+bool processSignal(int SigNum, void (*Handler)(int), void (**Result)(int)) {
+ if (WhichTool == ESAN_WorkingSet)
+ return processWorkingSetSignal(SigNum, Handler, Result);
+ return true;
+}
+
+bool processSigaction(int SigNum, const void *Act, void *OldAct) {
+ if (WhichTool == ESAN_WorkingSet)
+ return processWorkingSetSigaction(SigNum, Act, OldAct);
+ return true;
+}
+
#if SANITIZER_DEBUG
static bool verifyShadowScheme() {
// Sanity checks for our shadow mapping scheme.
Modified: compiler-rt/trunk/lib/esan/esan.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/esan.h?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/esan.h (original)
+++ compiler-rt/trunk/lib/esan/esan.h Tue May 31 08:21:03 2016
@@ -49,6 +49,9 @@ void initializeInterceptors();
void verifyAddressSpace();
bool fixMmapAddr(void **Addr, SIZE_T Size, int Flags);
uptr checkMmapResult(uptr Addr, SIZE_T Size);
+// The return value indicates whether to call the real version or not.
+bool processSignal(int SigNum, void (*Handler)(int), void (**Result)(int));
+bool processSigaction(int SigNum, const void *Act, void *OldAct);
} // namespace __esan
Modified: compiler-rt/trunk/lib/esan/esan_interceptors.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/esan_interceptors.cpp?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/esan_interceptors.cpp (original)
+++ compiler-rt/trunk/lib/esan/esan_interceptors.cpp Tue May 31 08:21:03 2016
@@ -351,6 +351,43 @@ INTERCEPTOR(void *, mmap64, void *addr,
#define ESAN_MAYBE_INTERCEPT_MMAP64
#endif
+//===----------------------------------------------------------------------===//
+// Signal-related interceptors
+//===----------------------------------------------------------------------===//
+
+#if SANITIZER_LINUX
+typedef void (*signal_handler_t)(int);
+INTERCEPTOR(signal_handler_t, signal, int signum, signal_handler_t handler) {
+ void *ctx;
+ COMMON_INTERCEPTOR_ENTER(ctx, signal, signum, handler);
+ signal_handler_t result;
+ if (!processSignal(signum, handler, &result))
+ return result;
+ else
+ return REAL(signal)(signum, handler);
+}
+#define ESAN_MAYBE_INTERCEPT_SIGNAL INTERCEPT_FUNCTION(signal)
+#else
+#error Platform not supported
+#define ESAN_MAYBE_INTERCEPT_SIGNAL
+#endif
+
+#if SANITIZER_LINUX
+INTERCEPTOR(int, sigaction, int signum, const struct sigaction *act,
+ struct sigaction *oldact) {
+ void *ctx;
+ COMMON_INTERCEPTOR_ENTER(ctx, sigaction, signum, act, oldact);
+ if (!processSigaction(signum, act, oldact))
+ return 0;
+ else
+ return REAL(sigaction)(signum, act, oldact);
+}
+#define ESAN_MAYBE_INTERCEPT_SIGACTION INTERCEPT_FUNCTION(sigaction)
+#else
+#error Platform not supported
+#define ESAN_MAYBE_INTERCEPT_SIGACTION
+#endif
+
namespace __esan {
void initializeInterceptors() {
@@ -372,6 +409,9 @@ void initializeInterceptors() {
INTERCEPT_FUNCTION(mmap);
ESAN_MAYBE_INTERCEPT_MMAP64;
+ ESAN_MAYBE_INTERCEPT_SIGNAL;
+ ESAN_MAYBE_INTERCEPT_SIGACTION;
+
// TODO(bruening): we should intercept calloc() and other memory allocation
// routines that zero memory and update our shadow memory appropriately.
Modified: compiler-rt/trunk/lib/esan/working_set.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/working_set.cpp?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/working_set.cpp (original)
+++ compiler-rt/trunk/lib/esan/working_set.cpp Tue May 31 08:21:03 2016
@@ -78,6 +78,7 @@ void processRangeAccessWorkingSet(uptr P
void initializeWorkingSet() {
// The shadow mapping assumes 64 so this cannot be changed.
CHECK(getFlags()->cache_line_size == 64);
+ registerMemoryFaultHandler();
}
int finalizeWorkingSet() {
Modified: compiler-rt/trunk/lib/esan/working_set.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/working_set.h?rev=271272&r1=271271&r2=271272&view=diff
==============================================================================
--- compiler-rt/trunk/lib/esan/working_set.h (original)
+++ compiler-rt/trunk/lib/esan/working_set.h Tue May 31 08:21:03 2016
@@ -25,6 +25,12 @@ int finalizeWorkingSet();
void processRangeAccessWorkingSet(uptr PC, uptr Addr, SIZE_T Size,
bool IsWrite);
+// Platform-dependent.
+void registerMemoryFaultHandler();
+bool processWorkingSetSignal(int SigNum, void (*Handler)(int),
+ void (**Result)(int));
+bool processWorkingSetSigaction(int SigNum, const void *Act, void *OldAct);
+
} // namespace __esan
#endif // WORKING_SET_H
Added: compiler-rt/trunk/lib/esan/working_set_posix.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/esan/working_set_posix.cpp?rev=271272&view=auto
==============================================================================
--- compiler-rt/trunk/lib/esan/working_set_posix.cpp (added)
+++ compiler-rt/trunk/lib/esan/working_set_posix.cpp Tue May 31 08:21:03 2016
@@ -0,0 +1,106 @@
+//===-- working_set_posix.cpp -----------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of EfficiencySanitizer, a family of performance tuners.
+//
+// POSIX-specific working set tool code.
+//===----------------------------------------------------------------------===//
+
+#include "working_set.h"
+#include "esan_flags.h"
+#include "esan_shadow.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_linux.h"
+#include <signal.h>
+#include <sys/mman.h>
+
+namespace __esan {
+
+// We only support regular POSIX threads with a single signal handler
+// for the whole process == thread group.
+// Thus we only need to store one app signal handler.
+// FIXME: Store and use any alternate stack and signal flags set by
+// the app. For now we just call the app handler from our handler.
+static __sanitizer_sigaction AppSigAct;
+
+bool processWorkingSetSignal(int SigNum, void (*Handler)(int),
+ void (**Result)(int)) {
+ VPrintf(2, "%s: %d\n", __FUNCTION__, SigNum);
+ if (SigNum == SIGSEGV) {
+ *Result = AppSigAct.handler;
+ AppSigAct.sigaction = (void (*)(int, void*, void*))Handler;
+ return false; // Skip real call.
+ }
+ return true;
+}
+
+bool processWorkingSetSigaction(int SigNum, const void *ActVoid,
+ void *OldActVoid) {
+ VPrintf(2, "%s: %d\n", __FUNCTION__, SigNum);
+ if (SigNum == SIGSEGV) {
+ const struct sigaction *Act = (const struct sigaction *) ActVoid;
+ struct sigaction *OldAct = (struct sigaction *) OldActVoid;
+ if (OldAct)
+ internal_memcpy(OldAct, &AppSigAct, sizeof(OldAct));
+ if (Act)
+ internal_memcpy(&AppSigAct, Act, sizeof(AppSigAct));
+ return false; // Skip real call.
+ }
+ return true;
+}
+
+static void reinstateDefaultHandler(int SigNum) {
+ __sanitizer_sigaction SigAct;
+ internal_memset(&SigAct, 0, sizeof(SigAct));
+ SigAct.sigaction = (void (*)(int, void*, void*)) SIG_DFL;
+ int Res = internal_sigaction(SigNum, &SigAct, nullptr);
+ CHECK(Res == 0);
+ VPrintf(1, "Unregistered for %d handler\n", SigNum);
+}
+
+// If this is a shadow fault, we handle it here; otherwise, we pass it to the
+// app to handle it just as the app would do without our tool in place.
+static void handleMemoryFault(int SigNum, void *Info, void *Ctx) {
+ if (SigNum == SIGSEGV) {
+
+ // TODO: Add shadow memory fault detection and handling.
+
+ if (AppSigAct.sigaction) {
+ // FIXME: For simplicity we ignore app options including its signal stack
+ // (we just use ours) and all the delivery flags.
+ AppSigAct.sigaction(SigNum, Info, Ctx);
+ } else {
+ // Crash instead of spinning with infinite faults.
+ reinstateDefaultHandler(SigNum);
+ }
+ } else
+ UNREACHABLE("signal not registered");
+}
+
+void registerMemoryFaultHandler() {
+ // We do not use an alternate signal stack, as doing so would require
+ // setting it up for each app thread.
+ // FIXME: This could result in problems with emulating the app's signal
+ // handling if the app relies on an alternate stack for SIGSEGV.
+
+ // We assume SIGSEGV is not blocked and won't be blocked by the app, so
+ // we leave the mask alone.
+
+ __sanitizer_sigaction SigAct;
+ internal_memset(&SigAct, 0, sizeof(SigAct));
+ SigAct.sigaction = handleMemoryFault;
+ // We want to handle nested signals b/c we need to handle a
+ // shadow fault in an app signal handler.
+ SigAct.sa_flags = SA_SIGINFO | SA_NODEFER;
+ int Res = internal_sigaction(SIGSEGV, &SigAct, &AppSigAct);
+ CHECK(Res == 0);
+ VPrintf(1, "Registered for SIGSEGV handler\n");
+}
+
+} // namespace __esan
Propchange: compiler-rt/trunk/lib/esan/working_set_posix.cpp
------------------------------------------------------------------------------
svn:eol-style = LF
Added: compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp?rev=271272&view=auto
==============================================================================
--- compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp (added)
+++ compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp Tue May 31 08:21:03 2016
@@ -0,0 +1,59 @@
+// RUN: %clang_esan_wset -O0 %s -o %t 2>&1
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <assert.h>
+
+sigjmp_buf mark;
+
+static void SignalHandler(int Sig) {
+ if (Sig == SIGSEGV) {
+ fprintf(stderr, "Handling SIGSEGV for signal\n");
+ siglongjmp(mark, 1);
+ }
+ exit(1);
+}
+
+static void SigactionHandler(int Sig, siginfo_t *Info, void *Ctx) {
+ if (Sig == SIGSEGV) {
+ fprintf(stderr, "Handling SIGSEGV for sigaction\n");
+ siglongjmp(mark, 1);
+ }
+ exit(1);
+}
+
+int main(int argc, char **argv) {
+ __sighandler_t Prior = signal(SIGSEGV, SignalHandler);
+ assert(Prior == SIG_DFL);
+ if (sigsetjmp(mark, 1) == 0)
+ *((volatile int *)(ssize_t)argc) = 42; // Raise SIGSEGV
+ fprintf(stderr, "Past longjmp for signal\n");
+
+ Prior = signal(SIGSEGV, SIG_DFL);
+ assert(Prior == SignalHandler);
+
+ struct sigaction SigAct;
+ SigAct.sa_sigaction = SigactionHandler;
+ int Res = sigfillset(&SigAct.sa_mask);
+ assert(Res == 0);
+ SigAct.sa_flags = SA_SIGINFO;
+ Res = sigaction(SIGSEGV, &SigAct, NULL);
+ assert(Res == 0);
+
+ if (sigsetjmp(mark, 1) == 0)
+ *((volatile int *)(ssize_t)argc) = 42; // Raise SIGSEGV
+ fprintf(stderr, "Past longjmp for sigaction\n");
+
+ Res = sigaction(SIGSEGV, NULL, &SigAct);
+ assert(Res == 0);
+ assert(SigAct.sa_sigaction == SigactionHandler);
+
+ return 0;
+}
+// CHECK: Handling SIGSEGV for signal
+// CHECK-NEXT: Past longjmp for signal
+// CHECK-NEXT: Handling SIGSEGV for sigaction
+// CHECK-NEXT: Past longjmp for sigaction
Propchange: compiler-rt/trunk/test/esan/TestCases/workingset-signal-posix.cpp
------------------------------------------------------------------------------
svn:eol-style = LF
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