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executor: remap cover fd's to higher values

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Remap cover fd's to 24x range to prevent interference
with fd's used during fuzzing and also to make
fd number consistent with/without cover enabled.
This commit is contained in:
Dmitry Vyukov 2018-08-08 12:48:06 +02:00
parent ddeb9f8d88
commit 9a791c3992
3 changed files with 18 additions and 8 deletions
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12
executor/executor.cc
View File

@ -52,8 +52,10 @@ typedef unsigned char uint8;
// Note: zircon max fd is 256.
// Some common_OS.h files know about this constant for RLIMIT_NOFILE.
const int kMaxFd = 250;
const int kMaxThreads = 16;
const int kInPipeFd = kMaxFd - 1; // remapped from stdin
const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
const int kCoverFd = kOutPipeFd - kMaxThreads;
const int kMaxArgs = 9;
const int kCoverSize = 256 << 10;
const int kFailStatus = 67;
@ -127,7 +129,6 @@ int flag_fault_nth;
const int kMaxCommands = 1000;
const int kMaxInput = 2 << 20;
const int kMaxThreads = 16;
const uint64 instr_eof = -1;
const uint64 instr_copyin = -2;
@ -351,8 +352,10 @@ int main(int argc, char** argv)
receive_execute();
#endif
if (flag_cover) {
for (int i = 0; i < kMaxThreads; i++)
for (int i = 0; i < kMaxThreads; i++) {
threads[i].cov.fd = kCoverFd + i;
cover_open(&threads[i].cov);
}
}
int status = 0;
@ -679,11 +682,12 @@ retry:
}
}
// Write output coverage for unfinished calls.
if (flag_cover && running > 0) {
if (running > 0) {
for (int i = 0; i < kMaxThreads; i++) {
thread_t* th = &threads[i];
if (th->executing) {
cover_collect(&th->cov);
if (flag_cover)
cover_collect(&th->cov);
write_call_output(th, false);
}
}

7
executor/executor_bsd.h
View File

@ -58,9 +58,12 @@ static long execute_syscall(const call_t* c, long a[kMaxArgs])
static void cover_open(cover_t* cov)
{
cov->fd = open("/dev/kcov", O_RDWR);
if (cov->fd == -1)
int fd = open("/dev/kcov", O_RDWR);
if (fd == -1)
fail("open of /dev/kcov failed");
if (dup2(fd, cov->fd) < 0)
fail("filed to dup2(%d, %d) cover fd", fd, cov->fd);
close(fd);
if (ioctl(cov->fd, KIOSETBUFSIZE, &kCoverSize))
fail("ioctl init trace write failed");
size_t mmap_alloc_size = kCoverSize * (is_kernel_64_bit ? 8 : 4);

7
executor/executor_linux.h
View File

@ -40,9 +40,12 @@ static long execute_syscall(const call_t* c, long a[kMaxArgs])
static void cover_open(cover_t* cov)
{
cov->fd = open("/sys/kernel/debug/kcov", O_RDWR);
if (cov->fd == -1)
int fd = open("/sys/kernel/debug/kcov", O_RDWR);
if (fd == -1)
fail("open of /sys/kernel/debug/kcov failed");
if (dup2(fd, cov->fd) < 0)
fail("filed to dup2(%d, %d) cover fd", fd, cov->fd);
close(fd);
const int kcov_init_trace = is_kernel_64_bit ? KCOV_INIT_TRACE64 : KCOV_INIT_TRACE32;
if (ioctl(cov->fd, kcov_init_trace, kCoverSize))
fail("cover init trace write failed");