From: Daniel Axtens <dja@axtens.net>
To: stable@vger.kernel.org
Cc: dja@axtens.net
Subject: [PATCH 5.4 1/5] selftests/powerpc: rfi_flush: disable entry flush if present
Date: Fri, 20 Nov 2020 10:35:12 +1100 [thread overview]
Message-ID: <20201119233516.368194-2-dja@axtens.net> (raw)
In-Reply-To: <20201119233516.368194-1-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>
---
.../selftests/powerpc/security/rfi_flush.c | 35 +++++++++++++++----
1 file changed, 29 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/powerpc/security/rfi_flush.c b/tools/testing/selftests/powerpc/security/rfi_flush.c
index 0a7d0afb26b8..533315e68133 100644
--- 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 @@ int rfi_flush_test(void)
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 @@ int rfi_flush_test(void)
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;
}
--
2.25.1
next prev parent reply other threads:[~2020-11-19 23:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 23:35 [PATCH 5.4 0/5] CVE-2020-4788: Speculation on incompletely validated data on IBM Power9 Daniel Axtens
2020-11-19 23:35 ` Daniel Axtens [this message]
2020-11-19 23:35 ` [PATCH 5.4 2/5] powerpc/64s: flush L1D on kernel entry Daniel Axtens
2020-11-19 23:35 ` [PATCH 5.4 3/5] powerpc/64s: flush L1D after user accesses Daniel Axtens
2020-11-19 23:35 ` [PATCH 5.4 4/5] powerpc: Only include kup-radix.h for 64-bit Book3S Daniel Axtens
2020-11-19 23:35 ` [PATCH 5.4 5/5] selftests/powerpc: entry flush test Daniel Axtens
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201119233516.368194-2-dja@axtens.net \
--to=dja@axtens.net \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).