<div dir="ltr">I've stumbled upon this test while changing how the coverage logic works... <div>Do we need coverage to work after fork but before exec at all?</div><div>It actually doesn't fully work today either, but I want to break it even more... </div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jun 4, 2014 at 5:13 AM, Evgeniy Stepanov <span dir="ltr"><<a href="mailto:eugeni.stepanov@gmail.com" target="_blank">eugeni.stepanov@gmail.com</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: eugenis<br>
Date: Wed Jun 4 07:13:54 2014<br>
New Revision: 210180<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=210180&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=210180&view=rev</a><br>
Log:<br>
[sancov] Handle fork.<br>
<br>
Reset coverage data on fork().<br>
For memory-mapped mode (coverage_direct=1) this helps avoid loss of data<br>
(before this change two processes would write to the same file simultaneously).<br>
For normal mode, this reduces coverage dump size, because PCs from the parent<br>
process are no longer inherited by the child.<br>
<br>
Added:<br>
compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc (with props)<br>
compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc (with props)<br>
Modified:<br>
compiler-rt/trunk/lib/asan/asan_interceptors.cc<br>
compiler-rt/trunk/lib/asan/asan_interceptors.h<br>
compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h<br>
compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc<br>
compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_interceptors.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.cc?rev=210180&r1=210179&r2=210180&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.cc?rev=210180&r1=210179&r2=210180&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_interceptors.cc (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_interceptors.cc Wed Jun 4 07:13:54 2014<br>
@@ -697,6 +697,16 @@ INTERCEPTOR(int, __cxa_atexit, void (*fu<br>
}<br>
#endif // ASAN_INTERCEPT___CXA_ATEXIT<br>
<br>
+#if ASAN_INTERCEPT_FORK<br>
+INTERCEPTOR(int, fork, void) {<br>
+ ENSURE_ASAN_INITED();<br>
+ if (common_flags()->coverage) CovBeforeFork();<br>
+ int pid = REAL(fork)();<br>
+ if (common_flags()->coverage) CovAfterFork(pid);<br>
+ return pid;<br>
+}<br>
+#endif // ASAN_INTERCEPT_FORK<br>
+<br>
#if SANITIZER_WINDOWS<br>
INTERCEPTOR_WINAPI(DWORD, CreateThread,<br>
void* security, uptr stack_size,<br>
@@ -808,6 +818,10 @@ void InitializeAsanInterceptors() {<br>
ASAN_INTERCEPT_FUNC(__cxa_atexit);<br>
#endif<br>
<br>
+#if ASAN_INTERCEPT_FORK<br>
+ ASAN_INTERCEPT_FUNC(fork);<br>
+#endif<br>
+<br>
// Some Windows-specific interceptors.<br>
#if SANITIZER_WINDOWS<br>
InitializeWindowsInterceptors();<br>
<br>
Modified: compiler-rt/trunk/lib/asan/asan_interceptors.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.h?rev=210180&r1=210179&r2=210180&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.h?rev=210180&r1=210179&r2=210180&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/asan/asan_interceptors.h (original)<br>
+++ compiler-rt/trunk/lib/asan/asan_interceptors.h Wed Jun 4 07:13:54 2014<br>
@@ -27,6 +27,7 @@<br>
# define ASAN_INTERCEPT_INDEX 1<br>
# define ASAN_INTERCEPT_PTHREAD_CREATE 1<br>
# define ASAN_INTERCEPT_MLOCKX 1<br>
+# define ASAN_INTERCEPT_FORK 1<br>
#else<br>
# define ASAN_INTERCEPT_ATOLL_AND_STRTOLL 0<br>
# define ASAN_INTERCEPT__LONGJMP 0<br>
@@ -34,6 +35,7 @@<br>
# define ASAN_INTERCEPT_INDEX 0<br>
# define ASAN_INTERCEPT_PTHREAD_CREATE 0<br>
# define ASAN_INTERCEPT_MLOCKX 0<br>
+# define ASAN_INTERCEPT_FORK 0<br>
#endif<br>
<br>
#if SANITIZER_FREEBSD || SANITIZER_LINUX<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h?rev=210180&r1=210179&r2=210180&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h?rev=210180&r1=210179&r2=210180&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_common.h Wed Jun 4 07:13:54 2014<br>
@@ -193,6 +193,8 @@ void CovPrepareForSandboxing(__sanitizer<br>
void SetSandboxingCallback(void (*f)());<br>
<br>
void CovUpdateMapping();<br>
+void CovBeforeFork();<br>
+void CovAfterFork(int child_pid);<br>
<br>
void InitTlsSize();<br>
uptr GetTlsSize();<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc?rev=210180&r1=210179&r2=210180&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc?rev=210180&r1=210179&r2=210180&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_libcdep.cc Wed Jun 4 07:13:54 2014<br>
@@ -59,6 +59,8 @@ namespace __sanitizer {<br>
class CoverageData {<br>
public:<br>
void Init();<br>
+ void BeforeFork();<br>
+ void AfterFork(int child_pid);<br>
void Extend(uptr npcs);<br>
void Add(uptr pc);<br>
<br>
@@ -86,6 +88,7 @@ class CoverageData {<br>
StaticSpinMutex mu;<br>
<br>
void DirectOpen();<br>
+ void ReInit();<br>
};<br>
<br>
static CoverageData coverage_data;<br>
@@ -107,23 +110,47 @@ void CoverageData::DirectOpen() {<br>
void CoverageData::Init() {<br>
pc_array = reinterpret_cast<uptr *>(<br>
MmapNoReserveOrDie(sizeof(uptr) * kPcArrayMaxSize, "CovInit"));<br>
+ pc_fd = kInvalidFd;<br>
if (common_flags()->coverage_direct) {<br>
atomic_store(&pc_array_size, 0, memory_order_relaxed);<br>
atomic_store(&pc_array_index, 0, memory_order_relaxed);<br>
} else {<br>
- pc_fd = 0;<br>
atomic_store(&pc_array_size, kPcArrayMaxSize, memory_order_relaxed);<br>
atomic_store(&pc_array_index, 0, memory_order_relaxed);<br>
}<br>
}<br>
<br>
+void CoverageData::ReInit() {<br>
+ internal_munmap(pc_array, sizeof(uptr) * kPcArrayMaxSize);<br>
+ if (pc_fd != kInvalidFd) internal_close(pc_fd);<br>
+ if (common_flags()->coverage_direct) {<br>
+ // In memory-mapped mode we must extend the new file to the known array<br>
+ // size.<br>
+ uptr size = atomic_load(&pc_array_size, memory_order_relaxed);<br>
+ Init();<br>
+ if (size) Extend(size);<br>
+ } else {<br>
+ Init();<br>
+ }<br>
+}<br>
+<br>
+void CoverageData::BeforeFork() {<br>
+ mu.Lock();<br>
+}<br>
+<br>
+void CoverageData::AfterFork(int child_pid) {<br>
+ // We are single-threaded so it's OK to release the lock early.<br>
+ mu.Unlock();<br>
+ if (child_pid == 0) ReInit();<br>
+}<br>
+<br>
// Extend coverage PC array to fit additional npcs elements.<br>
void CoverageData::Extend(uptr npcs) {<br>
if (!common_flags()->coverage_direct) return;<br>
SpinMutexLock l(&mu);<br>
<br>
- if (!pc_fd) DirectOpen();<br>
- CHECK(pc_fd);<br>
+ if (pc_fd == kInvalidFd) DirectOpen();<br>
+ CHECK_NE(pc_fd, kInvalidFd);<br>
<br>
uptr size = atomic_load(&pc_array_size, memory_order_relaxed);<br>
size += npcs * sizeof(uptr);<br>
@@ -324,6 +351,15 @@ int MaybeOpenCovFile(const char *name) {<br>
if (!common_flags()->coverage) return -1;<br>
return CovOpenFile(true /* packed */, name);<br>
}<br>
+<br>
+void CovBeforeFork() {<br>
+ coverage_data.BeforeFork();<br>
+}<br>
+<br>
+void CovAfterFork(int child_pid) {<br>
+ coverage_data.AfterFork(child_pid);<br>
+}<br>
+<br>
} // namespace __sanitizer<br>
<br>
extern "C" {<br>
<br>
Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc?rev=210180&r1=210179&r2=210180&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc?rev=210180&r1=210179&r2=210180&view=diff</a><br>
==============================================================================<br>
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc (original)<br>
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc Wed Jun 4 07:13:54 2014<br>
@@ -36,8 +36,27 @@<br>
namespace __sanitizer {<br>
<br>
static const uptr kMaxNumberOfModules = 1 << 14;<br>
+static const uptr kMaxTextSize = 64 * 1024;<br>
<br>
-static char *last_mapping;<br>
+struct CachedMapping {<br>
+ public:<br>
+ bool TestAndUpdate(const char *new_mapping) {<br>
+ int new_pid = internal_getpid();<br>
+ if (last_mapping && last_pid == new_pid &&<br>
+ internal_strcmp(last_mapping, new_mapping) == 0)<br>
+ return false;<br>
+ if (!last_mapping) last_mapping = (char *)InternalAlloc(kMaxTextSize);<br>
+ last_pid = new_pid;<br>
+ internal_strncpy(last_mapping, new_mapping, kMaxTextSize);<br>
+ return true;<br>
+ }<br>
+<br>
+ private:<br>
+ char *last_mapping;<br>
+ int last_pid;<br>
+};<br>
+<br>
+static CachedMapping cached_mapping;<br>
static StaticSpinMutex mapping_mu;<br>
<br>
void CovUpdateMapping() {<br>
@@ -45,7 +64,6 @@ void CovUpdateMapping() {<br>
<br>
SpinMutexLock l(&mapping_mu);<br>
<br>
- const uptr kMaxTextSize = 64 * 1024;<br>
InternalScopedString text(kMaxTextSize);<br>
InternalScopedBuffer<char> modules_data(kMaxNumberOfModules *<br>
sizeof(LoadedModule));<br>
@@ -66,9 +84,8 @@ void CovUpdateMapping() {<br>
}<br>
<br>
// Do not write mapping if it is the same as the one we've wrote last time.<br>
- if (last_mapping && (internal_strcmp(last_mapping, text.data()) == 0)) return;<br>
- if (!last_mapping) last_mapping = (char *)InternalAlloc(kMaxTextSize);<br>
- internal_strncpy(last_mapping, text.data(), kMaxTextSize);<br>
+ if (!cached_mapping.TestAndUpdate(text.data()))<br>
+ return;<br>
<br>
int err;<br>
InternalScopedString tmp_path(64 +<br>
<br>
Added: compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc?rev=210180&view=auto" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc?rev=210180&view=auto</a><br>
==============================================================================<br>
--- compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc (added)<br>
+++ compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc Wed Jun 4 07:13:54 2014<br>
@@ -0,0 +1,38 @@<br>
+// RUN: %clangxx_asan -mllvm -asan-coverage=1 %s -o %t<br>
+// RUN: rm -rf %T/coverage-fork-direct<br>
+// RUN: mkdir -p %T/coverage-fork-direct && cd %T/coverage-fork-direct<br>
+// RUN: (ASAN_OPTIONS=coverage=1:coverage_direct=1:verbosity=1 %run %t; \<br>
+// RUN: %sancov rawunpack *.sancov.raw; %sancov print *.sancov) 2>&1<br>
+//<br>
+// XFAIL: android<br>
+<br>
+#include <stdio.h><br>
+#include <string.h><br>
+#include <unistd.h><br>
+<br>
+__attribute__((noinline))<br>
+void foo() { printf("foo\n"); }<br>
+<br>
+__attribute__((noinline))<br>
+void bar() { printf("bar\n"); }<br>
+<br>
+__attribute__((noinline))<br>
+void baz() { printf("baz\n"); }<br>
+<br>
+int main(int argc, char **argv) {<br>
+ pid_t child_pid = fork();<br>
+ if (child_pid == 0) {<br>
+ fprintf(stderr, "Child PID: %d\n", getpid());<br>
+ baz();<br>
+ } else {<br>
+ fprintf(stderr, "Parent PID: %d\n", getpid());<br>
+ foo();<br>
+ bar();<br>
+ }<br>
+ return 0;<br>
+}<br>
+<br>
+// CHECK-DAG: Child PID: [[ChildPID:[0-9]+]]<br>
+// CHECK-DAG: Parent PID: [[ParentPID:[0-9]+]]<br>
+// CHECK-DAG: read 3 PCs from {{.*}}.[[ParentPID]].sancov<br>
+// CHECK-DAG: read 1 PCs from {{.*}}.[[ChildPID]].sancov<br>
<br>
Propchange: compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork-direct.cc<br>
------------------------------------------------------------------------------<br>
svn:eol-style = LF<br>
<br>
Added: compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc?rev=210180&view=auto" target="_blank">http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc?rev=210180&view=auto</a><br>
==============================================================================<br>
--- compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc (added)<br>
+++ compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc Wed Jun 4 07:13:54 2014<br>
@@ -0,0 +1,38 @@<br>
+// RUN: %clangxx_asan -mllvm -asan-coverage=1 %s -o %t<br>
+// RUN: export ASAN_OPTIONS=coverage=1:coverage_direct=0:verbosity=1<br>
+// RUN: rm -rf %T/coverage-fork<br>
+// RUN: mkdir -p %T/coverage-fork && cd %T/coverage-fork<br>
+// RUN: %run %t 2>&1 | FileCheck %s<br>
+//<br>
+// XFAIL: android<br>
+<br>
+#include <stdio.h><br>
+#include <string.h><br>
+#include <unistd.h><br>
+<br>
+__attribute__((noinline))<br>
+void foo() { printf("foo\n"); }<br>
+<br>
+__attribute__((noinline))<br>
+void bar() { printf("bar\n"); }<br>
+<br>
+__attribute__((noinline))<br>
+void baz() { printf("baz\n"); }<br>
+<br>
+int main(int argc, char **argv) {<br>
+ pid_t child_pid = fork();<br>
+ if (child_pid == 0) {<br>
+ fprintf(stderr, "Child PID: %d\n", getpid());<br>
+ baz();<br>
+ } else {<br>
+ fprintf(stderr, "Parent PID: %d\n", getpid());<br>
+ foo();<br>
+ bar();<br>
+ }<br>
+ return 0;<br>
+}<br>
+<br>
+// CHECK-DAG: Child PID: [[ChildPID:[0-9]+]]<br>
+// CHECK-DAG: [[ChildPID]].sancov: 1 PCs written<br>
+// CHECK-DAG: Parent PID: [[ParentPID:[0-9]+]]<br>
+// CHECK-DAG: [[ParentPID]].sancov: 3 PCs written<br>
<br>
Propchange: compiler-rt/trunk/test/asan/TestCases/Linux/coverage-fork.cc<br>
------------------------------------------------------------------------------<br>
svn:eol-style = LF<br>
<br>
<br>
_______________________________________________<br>
llvm-commits mailing list<br>
<a href="mailto:llvm-commits@cs.uiuc.edu">llvm-commits@cs.uiuc.edu</a><br>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits" target="_blank">http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits</a><br>
</blockquote></div></div>