diff options
Diffstat (limited to 'tools/testing/selftests/bpf/urandom_read.c')
-rw-r--r-- | tools/testing/selftests/bpf/urandom_read.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c new file mode 100644 index 000000000..e92644d0f --- /dev/null +++ b/tools/testing/selftests/bpf/urandom_read.c @@ -0,0 +1,88 @@ +#include <stdbool.h> +#include <stdio.h> +#include <unistd.h> +#include <errno.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <stdlib.h> +#include <signal.h> + +#define _SDT_HAS_SEMAPHORES 1 +#include "sdt.h" + +#define SEC(name) __attribute__((section(name), used)) + +#define BUF_SIZE 256 + +/* defined in urandom_read_aux.c */ +void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz); +/* these are coming from urandom_read_lib{1,2}.c */ +void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz); +void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz); + +unsigned short urand_read_with_sema_semaphore SEC(".probes"); + +static __attribute__((noinline)) +void urandom_read(int fd, int count) +{ + char buf[BUF_SIZE]; + int i; + + for (i = 0; i < count; ++i) { + read(fd, buf, BUF_SIZE); + + /* trigger USDTs defined in executable itself */ + urand_read_without_sema(i, count, BUF_SIZE); + STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE); + + /* trigger USDTs defined in shared lib */ + urandlib_read_without_sema(i, count, BUF_SIZE); + urandlib_read_with_sema(i, count, BUF_SIZE); + } +} + +static volatile bool parent_ready; + +static void handle_sigpipe(int sig) +{ + parent_ready = true; +} + +int main(int argc, char *argv[]) +{ + int fd = open("/dev/urandom", O_RDONLY); + int count = 4; + bool report_pid = false; + + if (fd < 0) + return 1; + + if (argc >= 2) + count = atoi(argv[1]); + if (argc >= 3) { + report_pid = true; + /* install SIGPIPE handler to catch when parent closes their + * end of the pipe (on the other side of our stdout) + */ + signal(SIGPIPE, handle_sigpipe); + } + + /* report PID and wait for parent process to send us "signal" by + * closing stdout + */ + if (report_pid) { + while (!parent_ready) { + fprintf(stdout, "%d\n", getpid()); + fflush(stdout); + } + /* at this point stdout is closed, parent process knows our + * PID and is ready to trace us + */ + } + + urandom_read(fd, count); + + close(fd); + return 0; +} |