From c790c3d2b0ec5979d83451d0688d1cd07e23d8ba Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Mon, 20 May 2019 20:55:20 +1000 Subject: selftests/powerpc: Add a test of spectre_v2 mitigations This test uses the PMU to count branch prediction hits/misses for a known loop, and compare the result to the reported spectre v2 mitigation. This gives us a way of sanity checking that the reported mitigation is actually in effect. Sample output for some cases, eg: Power9: sysfs reports: 'Vulnerable' PM_BR_PRED_CCACHE: result 368 running/enabled 5792777124 PM_BR_MPRED_CCACHE: result 319 running/enabled 5792775546 PM_BR_PRED_PCACHE: result 2147483281 running/enabled 5792773128 PM_BR_MPRED_PCACHE: result 213604201 running/enabled 5792771640 Miss percent 9 % OK - Measured branch prediction rates match reported spectre v2 mitigation. sysfs reports: 'Mitigation: Indirect branch serialisation (kernel only)' PM_BR_PRED_CCACHE: result 895 running/enabled 5780320920 PM_BR_MPRED_CCACHE: result 822 running/enabled 5780312414 PM_BR_PRED_PCACHE: result 2147482754 running/enabled 5780308836 PM_BR_MPRED_PCACHE: result 213639731 running/enabled 5780307912 Miss percent 9 % OK - Measured branch prediction rates match reported spectre v2 mitigation. sysfs reports: 'Mitigation: Indirect branch cache disabled' PM_BR_PRED_CCACHE: result 2147483649 running/enabled 20540186160 PM_BR_MPRED_CCACHE: result 2147483649 running/enabled 20540180056 PM_BR_PRED_PCACHE: result 0 running/enabled 20540176090 PM_BR_MPRED_PCACHE: result 0 running/enabled 20540174182 Miss percent 100 % OK - Measured branch prediction rates match reported spectre v2 mitigation. Power8: sysfs reports: 'Vulnerable' PM_BR_PRED_CCACHE: result 2147483649 running/enabled 3505888142 PM_BR_MPRED_CCACHE: result 9 running/enabled 3505882788 Miss percent 0 % OK - Measured branch prediction rates match reported spectre v2 mitigation. sysfs reports: 'Mitigation: Indirect branch cache disabled' PM_BR_PRED_CCACHE: result 2147483649 running/enabled 16931421988 PM_BR_MPRED_CCACHE: result 2147483649 running/enabled 16931416478 Miss percent 100 % OK - Measured branch prediction rates match reported spectre v2 mitigation. success: spectre_v2 Signed-off-by: Michael Ellerman Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190520105520.22274-1-mpe@ellerman.id.au --- tools/testing/selftests/powerpc/utils.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'tools/testing/selftests/powerpc/utils.c') diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c index c02d24835db4..5ee0e98c4896 100644 --- a/tools/testing/selftests/powerpc/utils.c +++ b/tools/testing/selftests/powerpc/utils.c @@ -127,6 +127,26 @@ bool is_ppc64le(void) return strcmp(uts.machine, "ppc64le") == 0; } +int read_sysfs_file(char *fpath, char *result, size_t result_size) +{ + char path[PATH_MAX] = "/sys/"; + int rc = -1, fd; + + strncat(path, fpath, PATH_MAX - strlen(path) - 1); + + if ((fd = open(path, O_RDONLY)) < 0) + return rc; + + rc = read(fd, result, result_size); + + close(fd); + + if (rc < 0) + return rc; + + return 0; +} + int read_debugfs_file(char *debugfs_file, int *result) { int rc = -1, fd; -- cgit