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selftests/powerpc: rfi_flush: disable entry flush if present

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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: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Russell Currey 2020-11-17 16:59:11 +11:00 committed by Michael Ellerman
parent 3cea11cd5e
commit fcb48454c2
1 changed files with 29 additions and 6 deletions
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35
tools/testing/selftests/powerpc/security/rfi_flush.c
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@ -85,19 +85,33 @@ 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);
// 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_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);
@ -106,6 +120,7 @@ int rfi_flush_test(void)
FAIL_IF(perf_event_enable(fd));
// disable L1 prefetching
set_dscr(1);
iter = repetitions;
@ -147,8 +162,8 @@ 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;
@ -164,11 +179,19 @@ 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;
}