Re: [PATCH v2 2/2] selftests/powerpc: Add test to verify rfi flush across a system call

Michael Ellerman wrote:

"Naveen N. Rao" [off-list ref] writes:

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Michael Ellerman wrote:

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"Naveen N. Rao" [off-list ref] writes:

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diff --git a/tools/testing/selftests/powerpc/security/rfi_flush.c b/to=

ols/testing/selftests/powerpc/security/rfi_flush.c

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new file mode 100644
index 000000000000..a20fe8eca161

--- /dev/null
+++ b/tools/testing/selftests/powerpc/security/rfi_flush.c

@@ -0,0 +1,132 @@

...

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+
+int rfi_flush_test(void)
+{
+	char *p;
+	int repetitions =3D 10;
+	int fd, passes =3D 0, iter, rc =3D 0;
+	struct perf_event_read v;
+	uint64_t l1d_misses_total =3D 0;
+	unsigned long iterations =3D 100000, zero_size =3D 24*1024;
+	int rfi_flush_org, rfi_flush;
+
+	SKIP_IF(geteuid() !=3D 0);
+
+	if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_org)) {
+		perror("error reading powerpc/rfi_flush debugfs file");
+	        printf("unable to determine current rfi_flush setting");
+		return 1;
+	}

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This leads to a hard error on old kernels, which I don't want (breaks m=

y CI).

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Hmm... didn't realize new tests would be run on older kernels. Are those=

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older stable/distro releases, or actually just earlier kernel versions?

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All of the above :)
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Obviously keeping all the tests working across all kernel versions ever
is impossible, but when it's relatively easy like in this case, it's
nice to do.
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So that was mostly just an FYI, I don't expect test writers to get their
tests running across all kernel versions.

Good to know, thanks!
- Naveen

=