Re: [PATCH 5/7] perf test: test_intel_pt.sh: Add jitdump test

From: Arnaldo Carvalho de Melo
Date: Fri Oct 14 2022 - 13:29:12 EST


Em Fri, Oct 14, 2022 at 08:09:03PM +0300, Adrian Hunter escreveu:
> Add a test for decoding self-modifying code using a jitdump file.
>
> The test creates a workload that uses self-modifying code and generates its
> own jitdump file. The result is processed with perf inject --jit and
> checked for decoding errors.
>
> Note the test will fail without patch "perf inject: Fix GEN_ELF_TEXT_OFFSET
> for jit" applied.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> tools/perf/tests/shell/test_intel_pt.sh | 162 ++++++++++++++++++++++++
> 1 file changed, 162 insertions(+)
>
> diff --git a/tools/perf/tests/shell/test_intel_pt.sh b/tools/perf/tests/shell/test_intel_pt.sh
> index 79dde57b561d..e0bf75981b9c 100755
> --- a/tools/perf/tests/shell/test_intel_pt.sh
> +++ b/tools/perf/tests/shell/test_intel_pt.sh
> @@ -22,6 +22,7 @@ outfile="${temp_dir}/test-out.txt"
> errfile="${temp_dir}/test-err.txt"
> workload="${temp_dir}/workload"
> awkscript="${temp_dir}/awkscript"
> +jitdump_workload="${temp_dir}/jitdump_workload"
>
> cleanup()
> {
> @@ -50,6 +51,13 @@ perf_record_no_decode()
> perf record -B -N --no-bpf-event "$@"
> }
>
> +# perf record for testing should not need BPF events
> +perf_record_no_bpf()
> +{
> + # Options for no BPF events
> + perf record --no-bpf-event "$@"
> +}
> +
> have_workload=false
> cat << _end_of_file_ | /usr/bin/cc -o "${workload}" -xc - -pthread && have_workload=true
> #include <time.h>
> @@ -269,6 +277,159 @@ test_per_thread()
> return 0
> }
>
> +test_jitdump()
> +{
> + echo "--- Test tracing self-modifying code that uses jitdump ---"
> +
> + script_path=$(realpath "$0")
> + script_dir=$(dirname "$script_path")
> + jitdump_incl_dir="${script_dir}/../../util"
> + jitdump_h="${jitdump_incl_dir}/jitdump.h"

So this requires one to test this being on the kernel (perf) sources
dir? I think we should add this header to some 'perf test' directory to
remove this requirement, ok?

But this can be done on top, right now we just don't test jitdump:

fd 20 : idx 11: mmapping fd 20
Checking 16 fds
OK
--- Test tracing self-modifying code that uses jitdump ---
SKIP: Include file jitdump.h not found
--- Cleaning up ---
--- Done ---
test child finished with 0
---- end ----
Miscellaneous Intel PT testing: Ok


> + if [ ! -e "${jitdump_h}" ] ; then
> + echo "SKIP: Include file jitdump.h not found"
> + return 2
> + fi
> +
> + if [ -z "${have_jitdump_workload}" ] ; then
> + have_jitdump_workload=false
> + # Create a workload that uses self-modifying code and generates its own jitdump file
> + cat <<- "_end_of_file_" | /usr/bin/cc -o "${jitdump_workload}" -I "${jitdump_incl_dir}" -xc - -pthread && have_jitdump_workload=true
> + #define _GNU_SOURCE
> + #include <sys/mman.h>
> + #include <sys/types.h>
> + #include <stddef.h>
> + #include <stdio.h>
> + #include <stdint.h>
> + #include <unistd.h>
> + #include <string.h>
> +
> + #include "jitdump.h"
> +
> + #define CHK_BYTE 0x5a
> +
> + static inline uint64_t rdtsc(void)
> + {
> + unsigned int low, high;
> +
> + asm volatile("rdtsc" : "=a" (low), "=d" (high));
> +
> + return low | ((uint64_t)high) << 32;
> + }
> +
> + static FILE *open_jitdump(void)
> + {
> + struct jitheader header = {
> + .magic = JITHEADER_MAGIC,
> + .version = JITHEADER_VERSION,
> + .total_size = sizeof(header),
> + .pid = getpid(),
> + .timestamp = rdtsc(),
> + .flags = JITDUMP_FLAGS_ARCH_TIMESTAMP,
> + };
> + char filename[256];
> + FILE *f;
> + void *m;
> +
> + snprintf(filename, sizeof(filename), "jit-%d.dump", getpid());
> + f = fopen(filename, "w+");
> + if (!f)
> + goto err;
> + /* Create an MMAP event for the jitdump file. That is how perf tool finds it. */
> + m = mmap(0, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fileno(f), 0);
> + if (m == MAP_FAILED)
> + goto err_close;
> + munmap(m, 4096);
> + if (fwrite(&header,sizeof(header),1,f) != 1)
> + goto err_close;
> + return f;
> +
> + err_close:
> + fclose(f);
> + err:
> + return NULL;
> + }
> +
> + static int write_jitdump(FILE *f, void *addr, const uint8_t *dat, size_t sz, uint64_t *idx)
> + {
> + struct jr_code_load rec = {
> + .p.id = JIT_CODE_LOAD,
> + .p.total_size = sizeof(rec) + sz,
> + .p.timestamp = rdtsc(),
> + .pid = getpid(),
> + .tid = gettid(),
> + .vma = (unsigned long)addr,
> + .code_addr = (unsigned long)addr,
> + .code_size = sz,
> + .code_index = ++*idx,
> + };
> +
> + if (fwrite(&rec,sizeof(rec),1,f) != 1 ||
> + fwrite(dat, sz, 1, f) != 1)
> + return -1;
> + return 0;
> + }
> +
> + static void close_jitdump(FILE *f)
> + {
> + fclose(f);
> + }
> +
> + int main()
> + {
> + /* Get a memory page to store executable code */
> + void *addr = mmap(0, 4096, PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> + /* Code to execute: mov CHK_BYTE, %eax ; ret */
> + uint8_t dat[] = {0xb8, CHK_BYTE, 0x00, 0x00, 0x00, 0xc3};
> + FILE *f = open_jitdump();
> + uint64_t idx = 0;
> + int ret = 1;
> +
> + if (!f)
> + return 1;
> + /* Copy executable code to executable memory page */
> + memcpy(addr, dat, sizeof(dat));
> + /* Record it in the jitdump file */
> + if (write_jitdump(f, addr, dat, sizeof(dat), &idx))
> + goto out_close;
> + /* Call it */
> + ret = ((int (*)(void))addr)() - CHK_BYTE;
> + out_close:
> + close_jitdump(f);
> + return ret;
> + }
> + _end_of_file_
> + fi
> +
> + if ! $have_jitdump_workload ; then
> + echo "SKIP: No jitdump workload"
> + return 2
> + fi
> +
> + # Change to temp_dir so jitdump collateral files go there
> + cd "${temp_dir}"
> + perf_record_no_bpf -o "${tmpfile}" -e intel_pt//u "${jitdump_workload}"
> + perf inject -i "${tmpfile}" -o "${perfdatafile}" --jit
> + decode_br_cnt=$(perf script -i "${perfdatafile}" --itrace=b | wc -l)
> + # Note that overflow and lost errors are suppressed for the error count
> + decode_err_cnt=$(perf script -i "${perfdatafile}" --itrace=e-o-l | grep -ci error)
> + cd -
> + # Should be thousands of branches
> + if [ "${decode_br_cnt}" -lt 1000 ] ; then
> + echo "Decode failed, only ${decode_br_cnt} branches"
> + return 1
> + fi
> + # Should be no errors
> + if [ "${decode_err_cnt}" -ne 0 ] ; then
> + echo "Decode failed, ${decode_err_cnt} errors"
> + perf script -i "${perfdatafile}" --itrace=e-o-l
> + return 1
> + fi
> +
> + echo OK
> + return 0
> +}
> +
> count_result()
> {
> if [ "$1" -eq 2 ] ; then
> @@ -286,6 +447,7 @@ ret=0
> test_system_wide_side_band || ret=$? ; count_result $ret ; ret=0
> test_per_thread "" "" || ret=$? ; count_result $ret ; ret=0
> test_per_thread "k" "(incl. kernel) " || ret=$? ; count_result $ret ; ret=0
> +test_jitdump || ret=$? ; count_result $ret ; ret=0
>
> cleanup
>
> --
> 2.25.1

--

- Arnaldo