diff options
author | Michael Ellerman <mpe@ellerman.id.au> | 2021-05-07 09:42:25 +0300 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-05-17 08:27:47 +0300 |
commit | 34f7f79827ec4db30cff9001dfba19f496473e8d (patch) | |
tree | 413b5e683c44bffdf055f3078b2d7f00ddfd811b /tools/testing/selftests/powerpc | |
parent | ca8cc36901e9bdd01d371f6236faf9f61d1325d1 (diff) | |
download | linux-34f7f79827ec4db30cff9001dfba19f496473e8d.tar.xz |
selftests/powerpc: Add test of mitigation patching
We recently discovered some of our mitigation patching was not safe
against other CPUs running concurrently.
Add a test which enable/disables all mitigations in a tight loop while
also running some stress load. On an unpatched system this almost always
leads to an oops and panic/reboot, but we also check if the kernel
becomes tainted in case we have a non-fatal oops.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210507064225.1556312-1-mpe@ellerman.id.au
Diffstat (limited to 'tools/testing/selftests/powerpc')
-rw-r--r-- | tools/testing/selftests/powerpc/security/Makefile | 2 | ||||
-rwxr-xr-x | tools/testing/selftests/powerpc/security/mitigation-patching.sh | 75 |
2 files changed, 77 insertions, 0 deletions
diff --git a/tools/testing/selftests/powerpc/security/Makefile b/tools/testing/selftests/powerpc/security/Makefile index 844d18cd5f93..7488315fd847 100644 --- a/tools/testing/selftests/powerpc/security/Makefile +++ b/tools/testing/selftests/powerpc/security/Makefile @@ -1,6 +1,8 @@ # SPDX-License-Identifier: GPL-2.0+ TEST_GEN_PROGS := rfi_flush entry_flush uaccess_flush spectre_v2 +TEST_PROGS := mitigation-patching.sh + top_srcdir = ../../../../.. CFLAGS += -I../../../../../usr/include diff --git a/tools/testing/selftests/powerpc/security/mitigation-patching.sh b/tools/testing/selftests/powerpc/security/mitigation-patching.sh new file mode 100755 index 000000000000..00197acb7ff1 --- /dev/null +++ b/tools/testing/selftests/powerpc/security/mitigation-patching.sh @@ -0,0 +1,75 @@ +#!/usr/bin/env bash + +set -euo pipefail + +TIMEOUT=10 + +function do_one +{ + local mitigation="$1" + local orig + local start + local now + + orig=$(cat "$mitigation") + + start=$EPOCHSECONDS + now=$start + + while [[ $((now-start)) -lt "$TIMEOUT" ]] + do + echo 0 > "$mitigation" + echo 1 > "$mitigation" + + now=$EPOCHSECONDS + done + + echo "$orig" > "$mitigation" +} + +rc=0 +cd /sys/kernel/debug/powerpc || rc=1 +if [[ "$rc" -ne 0 ]]; then + echo "Error: couldn't cd to /sys/kernel/debug/powerpc" >&2 + exit 1 +fi + +tainted=$(cat /proc/sys/kernel/tainted) +if [[ "$tainted" -ne 0 ]]; then + echo "Error: kernel already tainted!" >&2 + exit 1 +fi + +mitigations="barrier_nospec stf_barrier count_cache_flush rfi_flush entry_flush uaccess_flush" + +for m in $mitigations +do + do_one "$m" & +done + +echo "Spawned threads enabling/disabling mitigations ..." + +if stress-ng > /dev/null 2>&1; then + stress="stress-ng" +elif stress > /dev/null 2>&1; then + stress="stress" +else + stress="" +fi + +if [[ -n "$stress" ]]; then + "$stress" -m "$(nproc)" -t "$TIMEOUT" & + echo "Spawned VM stressors ..." +fi + +echo "Waiting for timeout ..." +wait + +tainted=$(cat /proc/sys/kernel/tainted) +if [[ "$tainted" -ne 0 ]]; then + echo "Error: kernel became tainted!" >&2 + exit 1 +fi + +echo "OK" +exit 0 |