This is a note to let you know that I've just added the patch titled selftests/powerpc: rfi_flush: disable entry flush if present to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: selftests-powerpc-rfi_flush-disable-entry-flush-if-present.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Fri Nov 20 08:16:31 AM CET 2020 From: Daniel Axtens <dja@xxxxxxxxxx> Date: Fri, 20 Nov 2020 10:35:12 +1100 Subject: selftests/powerpc: rfi_flush: disable entry flush if present To: stable@xxxxxxxxxxxxxxx Cc: dja@xxxxxxxxxx Message-ID: <20201119233516.368194-2-dja@xxxxxxxxxx> From: Russell Currey <ruscur@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Russell Currey <ruscur@xxxxxxxxxx> Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; } Patches currently in stable-queue which might be from dja@xxxxxxxxxx are queue-5.4/selftests-powerpc-rfi_flush-disable-entry-flush-if-present.patch queue-5.4/powerpc-64s-flush-l1d-after-user-accesses.patch queue-5.4/selftests-powerpc-entry-flush-test.patch queue-5.4/powerpc-64s-flush-l1d-on-kernel-entry.patch queue-5.4/powerpc-only-include-kup-radix.h-for-64-bit-book3s.patch