[ Upstream commit 463538a383a27337cb83ae195e432a839a52d639 ]
Commit 5aa98879efe7 ("s390/cpum_sf: prohibit callchain data collection")
prohibits call graph sampling for hardware events on s390. The
information recorded is out of context and does not match.
On s390 this commit now breaks test case 68 Zstd perf.data
compression/decompression.
Therefore omit call graph sampling on s390 in this test.
Output before:
[root@t35lp46 perf]# ./perf test -Fv 68
68: Zstd perf.data compression/decompression :
--- start ---
Collecting compressed record file:
Error:
cycles: PMU Hardware doesn't support sampling/overflow-interrupts.
Try 'perf stat'
---- end ----
Zstd perf.data compression/decompression: FAILED!
[root@t35lp46 perf]#
Output after:
[root@t35lp46 perf]# ./perf test -Fv 68
68: Zstd perf.data compression/decompression :
--- start ---
Collecting compressed record file:
500+0 records in
500+0 records out
256000 bytes (256 kB, 250 KiB) copied, 0.00615638 s, 41.6 MB/s
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.004 MB /tmp/perf.data.X3M,
compressed (original 0.002 MB, ratio is 3.609) ]
Checking compressed events stats:
# compressed : Zstd, level = 1, ratio = 4
COMPRESSED events: 1
2ELIFREPh---- end ----
Zstd perf.data compression/decompression: Ok
[root@t35lp46 perf]#
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200729135314.91281-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2bbc83537614517730e9f2811195004b712de207 ]
This test places a kprobe to function getname_flags() in the kernel
which has the following prototype:
struct filename *getname_flags(const char __user *filename, int flags, int *empty)
The 'filename' argument points to a filename located in user space memory.
Looking at commit 88903c464321c ("tracing/probe: Add ustring type for
user-space string") the kprobe should indicate that user space memory is
accessed.
Output before:
[root@m35lp76 perf]# ./perf test 66 67
66: Use vfs_getname probe to get syscall args filenames : FAILED!
67: Check open filename arg using perf trace + vfs_getname: FAILED!
[root@m35lp76 perf]#
Output after:
[root@m35lp76 perf]# ./perf test 66 67
66: Use vfs_getname probe to get syscall args filenames : Ok
67: Check open filename arg using perf trace + vfs_getname: Ok
[root@m35lp76 perf]#
Comments from Masami Hiramatsu:
This bug doesn't happen on x86 or other archs on which user address
space and kernel address space is the same. On some arches (ppc64 in
this case?) user address space is partially or completely the same as
kernel address space.
(Yes, they switch the world when running into the kernel) In this case,
we need to use different data access functions for each space.
That is why I introduced the "ustring" type for kprobe events.
As far as I can see, Thomas's patch is sane. Thomas, could you show us
your result on your test environment?
Comments from Thomas Richter:
Test results for s/390 included above.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200217102111.61137-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Thomas Richter