From: Daniel Axtens dja@axtens.net
commit 89a83a0c69c81a25ce91002b90ca27ed86132a0a upstream.
Add a test modelled on the RFI flush test which counts the number of L1D misses doing a simple syscall with the entry flush on and off.
For simplicity of backporting, this test duplicates a lot of code from the upstream rfi_flush. This is cleaned up upstream, but we don't clean it up here because it would involve bringing in even more commits.
Signed-off-by: Daniel Axtens dja@axtens.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kernel/setup_64.c | 2 arch/powerpc/platforms/powernv/setup.c | 6 tools/testing/selftests/powerpc/security/.gitignore | 1 tools/testing/selftests/powerpc/security/Makefile | 2 tools/testing/selftests/powerpc/security/entry_flush.c | 163 +++++++++++++++++ 5 files changed, 170 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/powerpc/security/entry_flush.c
--- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -1025,7 +1025,7 @@ void setup_uaccess_flush(bool enable) return;
if (!no_uaccess_flush) - uaccess_flush_enable(true); + uaccess_flush_enable(enable); }
#ifdef CONFIG_DEBUG_FS --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -124,10 +124,12 @@ static void pnv_setup_rfi_flush(void)
/* * If we are non-Power9 bare metal, we don't need to flush on kernel - * entry: it fixes a P9 specific vulnerability. + * entry or after user access: they fix a P9 specific vulnerability. */ - if (!pvr_version_is(PVR_POWER9)) + if (!pvr_version_is(PVR_POWER9)) { security_ftr_clear(SEC_FTR_L1D_FLUSH_ENTRY); + security_ftr_clear(SEC_FTR_L1D_FLUSH_UACCESS); + }
enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) && \ (security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) || \ --- a/tools/testing/selftests/powerpc/security/.gitignore +++ b/tools/testing/selftests/powerpc/security/.gitignore @@ -1 +1,2 @@ rfi_flush +entry_flush --- a/tools/testing/selftests/powerpc/security/Makefile +++ b/tools/testing/selftests/powerpc/security/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0+
-TEST_GEN_PROGS := rfi_flush +TEST_GEN_PROGS := rfi_flush entry_flush top_srcdir = ../../../../..
CFLAGS += -I../../../../../usr/include --- /dev/null +++ b/tools/testing/selftests/powerpc/security/entry_flush.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0+ + +/* + * Copyright 2018 IBM Corporation. + */ + +#define __SANE_USERSPACE_TYPES__ + +#include <sys/types.h> +#include <stdint.h> +#include <malloc.h> +#include <unistd.h> +#include <signal.h> +#include <stdlib.h> +#include <string.h> +#include <stdio.h> +#include "utils.h" + +#define CACHELINE_SIZE 128 + +struct perf_event_read { + __u64 nr; + __u64 l1d_misses; +}; + +static inline __u64 load(void *addr) +{ + __u64 tmp; + + asm volatile("ld %0,0(%1)" : "=r"(tmp) : "b"(addr)); + + return tmp; +} + +static void syscall_loop(char *p, unsigned long iterations, + unsigned long zero_size) +{ + for (unsigned long i = 0; i < iterations; i++) { + for (unsigned long j = 0; j < zero_size; j += CACHELINE_SIZE) + load(p + j); + getppid(); + } +} + +int entry_flush_test(void) +{ + char *p; + int repetitions = 10; + int fd, passes = 0, iter, rc = 0; + struct perf_event_read v; + __u64 l1d_misses_total = 0; + unsigned long iterations = 100000, zero_size = 24 * 1024; + unsigned long l1d_misses_expected; + int rfi_flush_orig; + int entry_flush, entry_flush_orig; + + SKIP_IF(geteuid() != 0); + + // The PMU event we use only works on Power7 or later + SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06)); + + if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) { + perror("Unable to read powerpc/rfi_flush debugfs file"); + SKIP_IF(1); + } + + if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) { + perror("Unable to read powerpc/entry_flush debugfs file"); + SKIP_IF(1); + } + + if (rfi_flush_orig != 0) { + if (write_debugfs_file("powerpc/rfi_flush", 0) < 0) { + perror("error writing to powerpc/rfi_flush debugfs file"); + FAIL_IF(1); + } + } + + entry_flush = entry_flush_orig; + + fd = perf_event_open_counter(PERF_TYPE_RAW, /* L1d miss */ 0x400f0, -1); + FAIL_IF(fd < 0); + + p = (char *)memalign(zero_size, CACHELINE_SIZE); + + FAIL_IF(perf_event_enable(fd)); + + // disable L1 prefetching + set_dscr(1); + + iter = repetitions; + + /* + * We expect to see l1d miss for each cacheline access when entry_flush + * is set. Allow a small variation on this. + */ + l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2); + +again: + FAIL_IF(perf_event_reset(fd)); + + syscall_loop(p, iterations, zero_size); + + FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v)); + + if (entry_flush && v.l1d_misses >= l1d_misses_expected) + passes++; + else if (!entry_flush && v.l1d_misses < (l1d_misses_expected / 2)) + passes++; + + l1d_misses_total += v.l1d_misses; + + while (--iter) + goto again; + + if (passes < repetitions) { + printf("FAIL (L1D misses with entry_flush=%d: %llu %c %lu) [%d/%d failures]\n", + entry_flush, l1d_misses_total, entry_flush ? '<' : '>', + entry_flush ? repetitions * l1d_misses_expected : + repetitions * l1d_misses_expected / 2, + repetitions - passes, repetitions); + rc = 1; + } else + printf("PASS (L1D misses with entry_flush=%d: %llu %c %lu) [%d/%d pass]\n", + entry_flush, l1d_misses_total, entry_flush ? '>' : '<', + entry_flush ? repetitions * l1d_misses_expected : + repetitions * l1d_misses_expected / 2, + passes, repetitions); + + if (entry_flush == entry_flush_orig) { + entry_flush = !entry_flush_orig; + if (write_debugfs_file("powerpc/entry_flush", entry_flush) < 0) { + perror("error writing to powerpc/entry_flush debugfs file"); + return 1; + } + iter = repetitions; + l1d_misses_total = 0; + passes = 0; + goto again; + } + + perf_event_disable(fd); + close(fd); + + set_dscr(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 (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; +} + +int main(int argc, char *argv[]) +{ + return test_harness(entry_flush_test, "entry_flush_test"); +}