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The function prologue prepares stack and registers before executing
function logic.
When target program is compiled without optimization, function parameter
information is only valid after the prologue.
When we probe entrypc of the function, and try to record a function
parameter, it contains a garbage value.
For example:
$ vim test.c
#include <stdio.h>
void foo(int i)
{
printf("i: %d\n", i);
}
int main()
{
foo(42);
return 0;
}
$ gcc -g test.c -o test
$ objdump -dl test | less
foo():
/home/ravi/test.c:4
400536: 55 push %rbp
400537: 48 89 e5 mov %rsp,%rbp
40053a: 48 83 ec 10 sub -bashx10,%rsp
40053e: 89 7d fc mov %edi,-0x4(%rbp)
/home/ravi/test.c:5
400541: 8b 45 fc mov -0x4(%rbp),%eax
...
...
main():
/home/ravi/test.c:9
400558: 55 push %rbp
400559: 48 89 e5 mov %rsp,%rbp
/home/ravi/test.c:10
40055c: bf 2a 00 00 00 mov -bashx2a,%edi
400561: e8 d0 ff ff ff callq 400536 <foo>
$ perf probe -x ./test 'foo i'
$ cat /sys/kernel/debug/tracing/uprobe_events
p:probe_test/foo /home/ravi/test:0x0000000000000536 i=-12(%sp):s32
$ perf record -e probe_test:foo ./test
$ perf script
test 5778 [001] 4918.562027: probe_test:foo: (400536) i=0
Here variable 'i' is passed via stack which is pushed on stack at
0x40053e. But we are probing at 0x400536.
To resolve this issues, we need to probe on next instruction after
prologue. gdb and systemtap also does same thing. I've implemented this
patch based on approach systemtap has used.
After applying patch:
$ perf probe -x ./test 'foo i'
$ cat /sys/kernel/debug/tracing/uprobe_events
p:probe_test/foo /home/ravi/test:0x0000000000000541 i=-4(%bp):s32
$ perf record -e probe_test:foo ./test
$ perf script
test 6300 [001] 5877.879327: probe_test:foo: (400541) i=42
No need to skip prologue for optimized case since debug info is correct
for each instructions for -O2 -g. For more details please visit:
https://bugzilla.redhat.com/show_bug.cgi?id=612253#c6
Changes in v2:
- Skipping prologue only when any ARG is either C variable, $params or
$vars.
- Probe on line(:1) may not be always possible. Recommend only address
to force probe on function entry.
Committer notes:
Testing it with 'perf trace':
# perf probe -x ./test foo i
Added new event:
probe_test:foo (on foo in /home/acme/c/test with i)
You can now use it in all perf tools, such as:
perf record -e probe_test:foo -aR sleep 1
# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_test/foo /home/acme/c/test:0x0000000000000526 i=-12(%sp):s32
# trace --no-sys --event probe_*:* ./test
i: 42
0.000 probe_test:foo:(400526) i=0)
#
After the patch:
# perf probe -d *:*
Removed event: probe_test:foo
# perf probe -x ./test foo i
Target program is compiled without optimization. Skipping prologue.
Probe on address 0x400526 to force probing at the function entry.
Added new event:
probe_test:foo (on foo in /home/acme/c/test with i)
You can now use it in all perf tools, such as:
perf record -e probe_test:foo -aR sleep 1
# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_test/foo /home/acme/c/test:0x0000000000000531 i=-4(%bp):s32
# trace --no-sys --event probe_*:* ./test
i: 42
0.000 probe_test:foo:(400531) i=42)
#
Reported-by: Michael Petlan <mpetlan@redhat.com>
Report-Link: https://www.mail-archive.com/linux-perf-users@vger.kernel.org/msg02348.html
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1299021
Link: http://lkml.kernel.org/r/1470214725-5023-2-git-send-email-ravi.bangoria@linux.vnet.ibm.com
[ Rename 'die' to 'cu_die' to avoid shadowing a die() definition on at least centos 5, Debian 7 and ubuntu:12.04.5]
[ Use PRIx64 instead of lx to format a Dwarf_Addr, aka long long unsigned int, fixing the build on 32-bit systems ]
[ dwarf_getsrclines() expects a size_t * argument ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When we call symbol__fixup_duplicate() we use algorithms to pick the
"best" symbols for cases where there are various functions/aliases to an
address, and those check zero size symbols, which, before calling
symbol__fixup_end() are _all_ symbols in a just parsed kallsyms file.
So first fixup the end, then fixup the duplicates.
Found while trying to figure out why 'perf test vmlinux' failed, see the
output of 'perf test -v vmlinux' to see cases where the symbols picked
as best for vmlinux don't match the ones picked for kallsyms.
Cc: Anton Blanchard <anton@samba.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 694bf407b0 ("perf symbols: Add some heuristics for choosing the best duplicate symbol")
Link: http://lkml.kernel.org/n/tip-rxqvdgr0mqjdxee0kf8i2ufn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The algorithms used to prune aliases in symbols__fixup_duplicate() uses
information available on ELF symtabs that are not present on
/proc/kallsyms, so it picks different aliases as "best" for vmlinux and
kallsyms.
We could probably improve a bit this by having a list of aliases for the
"best" symbols picked, instead of throwing this info, but that is left
for when we find a real need.
With this, 'perf test vmlinux' passes:
# perf test -F 1
1: vmlinux symtab matches kallsyms: Ok
#
When we ask for verbose mode, we can see those warning:
# perf test -F -v 1
1: vmlinux symtab matches kallsyms:
--- start ---
Looking at the vmlinux_path (8 entries long)
Using /lib/modules/4.8.0-rc4+/build/vmlinux for symbols
WARN: 0xffffffffb7001000: diff name v: xen_hypercall_set_trap_table k: hypercall_page
WARN: 0xffffffffb7077970: diff end addr for aesni_gcm_dec v: 0xffffffffb707a2f2 k: 0xffffffffb7077a02
WARN: 0xffffffffb707a300: diff end addr for aesni_gcm_enc v: 0xffffffffb707cc03 k: 0xffffffffb707a392
WARN: 0xffffffffb707f950: diff end addr for aesni_gcm_enc_avx_gen2 v: 0xffffffffb7084ef6 k: 0xffffffffb707f9c3
WARN: 0xffffffffb7084f00: diff end addr for aesni_gcm_dec_avx_gen2 v: 0xffffffffb708a691 k: 0xffffffffb7084f73
WARN: 0xffffffffb708aa10: diff end addr for aesni_gcm_enc_avx_gen4 v: 0xffffffffb708f844 k: 0xffffffffb708aa83
WARN: 0xffffffffb708f850: diff end addr for aesni_gcm_dec_avx_gen4 v: 0xffffffffb709486f k: 0xffffffffb708f8c3
WARN: 0xffffffffb71a6e50: diff name v: perf_pmu_commit_txn.part.98 k: perf_pmu_cancel_txn.part.97
WARN: 0xffffffffb752e480: diff name v: wakeup_expire_count_show.part.5 k: wakeup_active_count_show.part.7
WARN: 0xffffffffb76e8d00: diff name v: phys_switch_id_show.part.11 k: phys_port_name_show.part.12
WARN: Maps only in vmlinux:
ffffffffb7d7d000-ffffffffb7eeaac8 117d000 [kernel].init.text
ffffffffb7eeaac8-ffffffffc03ad000 12eaac8 [kernel].exit.text
---- end ----
vmlinux symtab matches kallsyms: Ok
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-6v5w1k8rpx4ggczlkw730vt0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Before:
# perf test -F -v 1
1: vmlinux symtab matches kallsyms:
--- start ---
<SNIP>
WARN: Maps only in vmlinux:
ffffffffb7d7d000-ffffffffb7eeaac8 117d000 [kernel].init.text
ffffffffb7eeaac8-ffffffffc03ad000 12eaac8 [kernel].exit.text
WARN: Maps in vmlinux with a different name in kallsyms:
WARN: Maps only in kallsyms:
---- end ----
vmlinux symtab matches kallsyms: Ok
#
The two last WARN lines are now suppressed, since there are no such
cases detected.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-9ww8uvzl682ykaw8ht1tozlr@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When the 'perf test -v vmlinux' test fails, it is not clear which of the
lines are errors or warnings, clarify that adding ERR/WARN prefixes:
# perf test -F -v 1
1: vmlinux symtab matches kallsyms :
--- start ---
Looking at the vmlinux_path (8 entries long)
Using /lib/modules/4.8.0-rc4+/build/vmlinux for symbols
ERR : 0xffffffffb7001000: diff name v: xen_hypercall_set_trap_table k: hypercall_page
WARN: 0xffffffffb7077970: diff end addr for aesni_gcm_dec v: 0xffffffffb707a2f2 k: 0xffffffffb7077a02
WARN: 0xffffffffb707a300: diff end addr for aesni_gcm_enc v: 0xffffffffb707cc03 k: 0xffffffffb707a392
WARN: 0xffffffffb707f950: diff end addr for aesni_gcm_enc_avx_gen2 v: 0xffffffffb7084ef6 k: 0xffffffffb707f9c3
WARN: 0xffffffffb7084f00: diff end addr for aesni_gcm_dec_avx_gen2 v: 0xffffffffb708a691 k: 0xffffffffb7084f73
WARN: 0xffffffffb708aa10: diff end addr for aesni_gcm_enc_avx_gen4 v: 0xffffffffb708f844 k: 0xffffffffb708aa83
WARN: 0xffffffffb708f850: diff end addr for aesni_gcm_dec_avx_gen4 v: 0xffffffffb709486f k: 0xffffffffb708f8c3
ERR : 0xffffffffb71a6e50: diff name v: perf_pmu_commit_txn.part.98 k: perf_pmu_cancel_txn.part.97
ERR : 0xffffffffb752e480: diff name v: wakeup_expire_count_show.part.5 k: wakeup_active_count_show.part.7
ERR : 0xffffffffb76e8d00: diff name v: phys_switch_id_show.part.11 k: phys_port_name_show.part.12
WARN: Maps only in vmlinux:
ffffffffb7d7d000-ffffffffb7eeaac8 117d000 [kernel].init.text
ffffffffb7eeaac8-ffffffffc03ad000 12eaac8 [kernel].exit.text
WARN: Maps in vmlinux with a different name in kallsyms:
WARN: Maps only in kallsyms:
---- end ----
vmlinux symtab matches kallsyms: FAILED!
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-n5ml8m7y9x8kzvxt09ipku88@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Ignore vmlinux build-id when user gives offline vmlinux if the command
does not affect running kernel.
perf-probe has several actions some of them does not change the running
kernel, like --lines, --vars, and --funcs.
e.g.
-----
$ ./perf probe -k ./vmlinux-arm -V do_sys_open:14
Available variables at do_sys_open:14
@<do_sys_open+202>
char* filename
int dfd
int fd
int flags
struct filename* tmp
struct open_flags op
umode_t mode
-----
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147222347320.5088.2582658035296667520.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Support probing on offline cross-architecture binary by adding getting
the target machine arch from ELF and choose correct register string for
the machine.
Here is an example:
-----
$ perf probe --vmlinux=./vmlinux-arm --definition 'do_sys_open $params'
p:probe/do_sys_open do_sys_open+0 dfd=%r5:s32 filename=%r1:u32 flags=%r6:s32 mode=%r3:u16
-----
Here, we can get probe/do_sys_open from above and append it to to the target
machine's tracing/kprobe_events file in the tracefs mountput, usually
/sys/kernel/debug/tracing/kprobe_events (or /sys/kernel/tracing/kprobe_events).
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147214229717.23638.6440579792548044658.stgit@devbox
[ Add definition for EM_AARCH64 to fix the build on at least centos 6, debian 7 & ubuntu 12.04.5 ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Ignore the buildid of running kernel when both of --definition and
--vmlinux is given because that kernel should be off-line.
This also skips post-processing of kprobe event for relocating symbol
and checking blacklist, because it can not be done on off-line kernel.
E.g. without this fix perf shows an error as below
----
$ perf probe --vmlinux=./vmlinux-arm --definition do_sys_open
./vmlinux-arm with build id 7a1f76dd56e9c4da707cd3d6333f50748141434b not found, continuing without symbols
Failed to find symbol do_sys_open in kernel
Error: Failed to add events.
----
with this fix, we can get the definition
----
$ perf probe --vmlinux=./vmlinux-arm --definition do_sys_open
p:probe/do_sys_open do_sys_open+0
----
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147214228193.23638.12581984840822162131.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The symbols in the synthesized @plt entries where not demangled before,
i.e. we could end up with entries such as:
$ perf report
Samples: 7K of event 'cycles:ppp', Event count (approx.): 6223833141
Children Self Command Shared Object Symbol
- 93.63% 28.89% lab_mandelbrot lab_mandelbrot [.] main
- 73.81% main
- 33.57% hypot
27.76% __hypot_finite
15.97% __muldc3
2.90% __muldc3@plt
2.40% _ZNK6QImage6heightEv@plt
+ 2.14% QColor::rgb
1.94% _ZNK6QImage5widthEv@plt
1.92% cabs@plt
This patch remedies this issue by also applying demangling to the
synthesized symbols. The output for the above is now:
$ perf report
Samples: 7K of event 'cycles:ppp', Event count (approx.): 6223833141
Children Self Command Shared Object Symbol
- 93.63% 28.89% lab_mandelbrot lab_mandelbrot [.] main
- 73.81% main
- 33.57% hypot
27.76% __hypot_finite
15.97% __muldc3
2.90% __muldc3@plt
2.40% QImage::height() const@plt
+ 2.14% QColor::rgb
1.94% QImage::width() const@plt
1.92% cabs@plt
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
LPU-Reference: 20160830114102.30863-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
It is simpler to just do the loop, no need for globals and the last user
of such facility disappears.
Testing:
# perf probe -F [a-z]*recvmsg
aead_recvmsg
compat_SyS_recvmsg
compat_sys_recvmsg
hash_recvmsg
inet_recvmsg
kernel_recvmsg
netlink_recvmsg
packet_recvmsg
ping_recvmsg
raw_recvmsg
rawv6_recvmsg
rng_recvmsg
security_socket_recvmsg
selinux_socket_recvmsg
skcipher_recvmsg
sock_common_recvmsg
sock_no_recvmsg
sock_recvmsg
sys_recvmsg
tcp_recvmsg
udp_recvmsg
udpv6_recvmsg
unix_dgram_recvmsg
unix_seqpacket_recvmsg
unix_stream_recvmsg
#
Without filters:
# perf probe -F | tail -5
zswap_pool_create
zswap_pool_current
zswap_update_total_size
zswap_writeback_entry
zswap_zpool_param_set
#
# perf probe -F | wc -l
33311
#
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20160831130427.GA13095@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
It is a requirement from the perf TODO list[1]:
''The feature tests should be performed only when a file that needs those
tests, or at least only when some .c or .h file will be rebuilt. An
initial step would be for 'make install-doc' not to run the feature
tests, there it is not needed at all.''
By adding 'install-doc' to the NON_CONFIG_TARGETS, it will skip running
the feature tests for such target. The Auto-detecting system features
list will not be displayed:
$ make install-doc
BUILD: Doing 'make -j2' parallel build
SUBDIR Documentation
make[2]: Nothing to be done for 'install'.
[1] https://perf.wiki.kernel.org/index.php/Todo
Signed-off-by: Rui Teng <rui.teng@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1470818948-17784-1-git-send-email-rui.teng@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
