| From foo@baz Fri Nov 20 07:57:18 AM CET 2020 |
| From: Daniel Axtens <dja@axtens.net> |
| Date: Fri, 20 Nov 2020 10:22:46 +1100 |
| Subject: selftests/powerpc: rfi_flush: disable entry flush if present |
| To: stable@vger.kernel.org |
| Cc: dja@axtens.net |
| Message-ID: <20201119232250.365304-2-dja@axtens.net> |
| |
| From: Russell Currey <ruscur@russell.cc> |
| |
| commit fcb48454c23c5679d1a2e252f127642e91b05cbe upstream. |
| |
| We are about to add an entry flush. The rfi (exit) flush test measures |
| the number of L1D flushes over a syscall with the RFI flush enabled and |
| disabled. But if the entry flush is also enabled, the effect of enabling |
| and disabling the RFI flush is masked. |
| |
| If there is a debugfs entry for the entry flush, disable it during the RFI |
| flush and restore it later. |
| |
| Reported-by: Spoorthy S <spoorts2@in.ibm.com> |
| Signed-off-by: Russell Currey <ruscur@russell.cc> |
| Signed-off-by: Daniel Axtens <dja@axtens.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| tools/testing/selftests/powerpc/security/rfi_flush.c | 35 +++++++++++++++---- |
| 1 file changed, 29 insertions(+), 6 deletions(-) |
| |
| --- a/tools/testing/selftests/powerpc/security/rfi_flush.c |
| +++ b/tools/testing/selftests/powerpc/security/rfi_flush.c |
| @@ -50,16 +50,30 @@ int rfi_flush_test(void) |
| __u64 l1d_misses_total = 0; |
| unsigned long iterations = 100000, zero_size = 24 * 1024; |
| unsigned long l1d_misses_expected; |
| - int rfi_flush_org, rfi_flush; |
| + int rfi_flush_orig, rfi_flush; |
| + int have_entry_flush, entry_flush_orig; |
| |
| SKIP_IF(geteuid() != 0); |
| |
| - if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_org)) { |
| + if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) { |
| perror("Unable to read powerpc/rfi_flush debugfs file"); |
| SKIP_IF(1); |
| } |
| |
| - rfi_flush = rfi_flush_org; |
| + if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) { |
| + have_entry_flush = 0; |
| + } else { |
| + have_entry_flush = 1; |
| + |
| + if (entry_flush_orig != 0) { |
| + if (write_debugfs_file("powerpc/entry_flush", 0) < 0) { |
| + perror("error writing to powerpc/entry_flush debugfs file"); |
| + return 1; |
| + } |
| + } |
| + } |
| + |
| + rfi_flush = rfi_flush_orig; |
| |
| fd = perf_event_open_counter(PERF_TYPE_RAW, /* L1d miss */ 0x400f0, -1); |
| FAIL_IF(fd < 0); |
| @@ -68,6 +82,7 @@ int rfi_flush_test(void) |
| |
| FAIL_IF(perf_event_enable(fd)); |
| |
| + // disable L1 prefetching |
| set_dscr(1); |
| |
| iter = repetitions; |
| @@ -109,8 +124,8 @@ again: |
| repetitions * l1d_misses_expected / 2, |
| passes, repetitions); |
| |
| - if (rfi_flush == rfi_flush_org) { |
| - rfi_flush = !rfi_flush_org; |
| + if (rfi_flush == rfi_flush_orig) { |
| + rfi_flush = !rfi_flush_orig; |
| if (write_debugfs_file("powerpc/rfi_flush", rfi_flush) < 0) { |
| perror("error writing to powerpc/rfi_flush debugfs file"); |
| return 1; |
| @@ -126,11 +141,19 @@ again: |
| |
| set_dscr(0); |
| |
| - if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_org) < 0) { |
| + if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_orig) < 0) { |
| perror("unable to restore original value of powerpc/rfi_flush debugfs file"); |
| return 1; |
| } |
| |
| + if (have_entry_flush) { |
| + if (write_debugfs_file("powerpc/entry_flush", entry_flush_orig) < 0) { |
| + perror("unable to restore original value of powerpc/entry_flush " |
| + "debugfs file"); |
| + return 1; |
| + } |
| + } |
| + |
| return rc; |
| } |
| |