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selftests/powerpc: Add test to verify rfi flush across a system call

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This adds a test to verify proper functioning of the rfi flush
capability implemented to mitigate meltdown. The test works by
measuring the number of L1d cache misses encountered while loading
data from memory. Across a system call, since the L1d cache is flushed
when rfi_flush is enabled, the number of cache misses is expected to
be relative to the number of cachelines corresponding to the data
being loaded.

The current system setting is reflected via powerpc/rfi_flush under
debugfs (assumed to be /sys/kernel/debug/). This test verifies the
expected result with rfi_flush enabled as well as when it is disabled.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
[mpe: Add SPDX tags, clang format, skip if the debugfs is missing, use
 __u64 and SANE_USERSPACE_TYPES to avoid printf() build errors.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Naveen N. Rao
2018-05-21 20:43:57 +05:30
committed by Michael Ellerman
parent db3848515a
commit d2bf793237
5 changed files with 305 additions and 1 deletions
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10
tools/testing/selftests/powerpc/include/utils.h
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@@ -11,6 +11,7 @@
#include <stdint.h>
#include <stdbool.h>
#include <linux/auxvec.h>
#include <linux/perf_event.h>
#include "reg.h"
/* Avoid headaches with PRI?64 - just use %ll? always */
@@ -31,6 +32,15 @@ void *get_auxv_entry(int type);
int pick_online_cpu(void);
int read_debugfs_file(char *debugfs_file, int *result);
int write_debugfs_file(char *debugfs_file, int result);
void set_dscr(unsigned long val);
int perf_event_open_counter(unsigned int type,
unsigned long config, int group_fd);
int perf_event_enable(int fd);
int perf_event_disable(int fd);
int perf_event_reset(int fd);
static inline bool have_hwcap(unsigned long ftr)
{
return ((unsigned long)get_auxv_entry(AT_HWCAP) & ftr) == ftr;