When synthesizing FORK events, we are trying to create thread objects
for the already running tasks on the machine.
Normally, for a kernel FORK event, we want to clone the parent's maps
because that is what the kernel just did.
But when synthesizing, this should not be done. If we do, we end up
with overlapping maps as we process the sythesized MMAP2 events that
get delivered shortly thereafter.
Use the FORK event misc flags in an internal way to signal this
situation, so we can elide the map clone when appropriate.
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/20181030.222404.2085088822877051075.davem@davemloft.net
[ Added comment about flag use in machine__process_fork_event(),
use ternary op in thread__clone_map_groups() as suggested by Jiri ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When processing using 'perf report -g caller', which is the default, we
ended up reverting the callchain entries received from the kernel, but
simply reverting throws away the information that tells that from a
point onwards the addresses are for userspace, kernel, guest kernel,
guest user, hypervisor.
The idea is that if we are walking backwards, for each cluster of
non-cpumode entries we have to first scan backwards for the next one and
use that for the cluster.
This seems silly and more expensive than it needs to be but it is enough
for a initial fix.
The code here is really complicated because it is intimately intertwined
with the lbr and branch handling, as well as this callchain order,
further fixes will be needed to properly take into account the cpumode
in those cases.
Another problem with ORDER_CALLER is that the NULL "0" IP that is at the
end of most callchains shows up at the top of the histogram because
every callchain contains it and with ORDER_CALLER it is the first entry.
Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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: Souvik Banerjee <souvik1997@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: stable@vger.kernel.org # 4.19
Link: https://lkml.kernel.org/n/tip-2wt3ayp6j2y2f2xowixa8y6y@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Fixes a crash when the report encounters an address that could not be
associated with an mmaped region:
#0 0x00005555557bdc4a in callchain_srcline (ip=<error reading variable: Cannot access memory at address 0x38>, sym=0x0, map=0x0) at util/machine.c:2329
#1 unwind_entry (entry=entry@entry=0x7fffffff9180, arg=arg@entry=0x7ffff5642498) at util/machine.c:2329
#2 0x00005555558370af in entry (arg=0x7ffff5642498, cb=0x5555557bdb50 <unwind_entry>, thread=<optimized out>, ip=18446744073709551615) at util/unwind-libunwind-local.c:586
#3 get_entries (ui=ui@entry=0x7fffffff9620, cb=0x5555557bdb50 <unwind_entry>, arg=0x7ffff5642498, max_stack=<optimized out>) at util/unwind-libunwind-local.c:703
#4 0x0000555555837192 in _unwind__get_entries (cb=<optimized out>, arg=<optimized out>, thread=<optimized out>, data=<optimized out>, max_stack=<optimized out>) at util/unwind-libunwind-local.c:725
#5 0x00005555557c310f in thread__resolve_callchain_unwind (max_stack=127, sample=0x7fffffff9830, evsel=0x555555c7b3b0, cursor=0x7ffff5642498, thread=0x555555c7f6f0) at util/machine.c:2351
#6 thread__resolve_callchain (thread=0x555555c7f6f0, cursor=0x7ffff5642498, evsel=0x555555c7b3b0, sample=0x7fffffff9830, parent=0x7fffffff97b8, root_al=0x7fffffff9750, max_stack=127) at util/machine.c:2378
#7 0x00005555557ba4ee in sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fffffff97b8, evsel=<optimized out>, al=al@entry=0x7fffffff9750,
max_stack=<optimized out>) at util/callchain.c:1085
Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Tested-by: Sandipan Das <sandipan@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Fixes: 2a9d5050dc ("perf script: Show correct offsets for DWARF-based unwinding")
Link: http://lkml.kernel.org/r/20180926135207.30263-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
There's an issue with using threads::last_match in multithread mode
which is enabled during the perf top synthesize. It might crash with
following assertion:
perf: ...include/linux/refcount.h:109: refcount_inc:
Assertion `!(!refcount_inc_not_zero(r))' failed.
The gdb backtrace looks like this:
0x00007ffff50839fb in raise () from /lib64/libc.so.6
(gdb)
#0 0x00007ffff50839fb in raise () from /lib64/libc.so.6
#1 0x00007ffff5085800 in abort () from /lib64/libc.so.6
#2 0x00007ffff507c0da in __assert_fail_base () from /lib64/libc.so.6
#3 0x00007ffff507c152 in __assert_fail () from /lib64/libc.so.6
#4 0x0000000000535ff9 in refcount_inc (r=0x7fffe8009a70)
at ...include/linux/refcount.h:109
#5 0x0000000000536771 in thread__get (thread=0x7fffe8009a40)
at util/thread.c:115
#6 0x0000000000523cd0 in ____machine__findnew_thread (machine=0xbfde38,
threads=0xbfdf28, pid=2, tid=2, create=true) at util/machine.c:432
#7 0x0000000000523eb4 in __machine__findnew_thread (machine=0xbfde38,
pid=2, tid=2) at util/machine.c:489
#8 0x0000000000523f24 in machine__findnew_thread (machine=0xbfde38,
pid=2, tid=2) at util/machine.c:499
#9 0x0000000000526fbe in machine__process_fork_event (machine=0xbfde38,
...
The failing assertion is this one:
REFCOUNT_WARN(!refcount_inc_not_zero(r), ...
the problem is that we don't serialize access to threads::last_match.
We serialize the access to the threads tree, but we don't care how's
threads::last_match being accessed. Both locked/unlocked paths use
that data and can set it. In multithreaded mode we can end up with
invalid object in thread__get call, like in following paths race:
thread 1
...
machine__findnew_thread
down_write(&threads->lock);
__machine__findnew_thread
____machine__findnew_thread
th = threads->last_match;
if (th->tid == tid) {
thread__get
thread 2
...
machine__find_thread
down_read(&threads->lock);
__machine__findnew_thread
____machine__findnew_thread
th = threads->last_match;
if (th->tid == tid) {
thread__get
thread 3
...
machine__process_fork_event
machine__remove_thread
__machine__remove_thread
threads->last_match = NULL
thread__put
thread__put
Thread 1 and 2 might got stale last_match, before thread 3 clears
it. Thread 1 and 2 then race with thread 3's thread__put and they
might trigger the refcnt == 0 assertion above.
The patch is disabling the last_match cache for multiple thread
mode. It was originally meant for single thread scenarios, where
it's common to have multiple sequential searches of the same
thread.
In multithread mode this does not make sense, because top's threads
processes different /proc entries and so the 'struct threads' object
is queried for various threads. Moreover we'd need to add more locks
to make it work.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Lukasz Odzioba <lukasz.odzioba@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20180719143345.12963-4-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When perf/data is recorded with the dwarf call-graph option, the
callchain shown by 'perf script' still shows the binary offsets of the
userspace symbols instead of their virtual addresses. Since the symbol
offset calculation is based on using virtual address as the ip, we see
incorrect offsets as well.
The use of virtual addresses affects the ability to find out the
line number in the corresponding source file to which an address
maps to as described in commit 6754075915 ("perf unwind: Use
addr_location::addr instead of ip for entries").
This has also been addressed by temporarily converting the virtual
address to the correponding binary offset so that it can be mapped
to the source line number correctly.
This is a follow-up for commit 1961018469 ("perf script: Show
virtual addresses instead of offsets").
This can be verified on a powerpc64le system running Fedora 27 as
shown below:
# perf probe -x /usr/lib64/libc-2.26.so -a inet_pton
# perf record -e probe_libc:inet_pton --call-graph=dwarf ping -6 -c 1 ::1
Before:
# perf report --stdio --no-children -s sym,srcline -g address
# Samples: 1 of event 'probe_libc:inet_pton'
# Event count (approx.): 1
#
# Overhead Symbol Source:Line
# ........ .................... ...........
#
100.00% [.] __GI___inet_pton inet_pton.c
|
---gaih_inet getaddrinfo.c:537 (inlined)
__GI_getaddrinfo getaddrinfo.c:2304 (inlined)
main ping.c:519
generic_start_main libc-start.c:308 (inlined)
__libc_start_main libc-start.c:102
...
# perf script -F comm,ip,sym,symoff,srcline,dso
ping
15af28 __GI___inet_pton+0xffff000099160008 (/usr/lib64/libc-2.26.so)
libc-2.26.so[ffff80004ca0af28]
10fa53 gaih_inet+0xffff000099160f43
libc-2.26.so[ffff80004c9bfa53] (inlined)
1105b3 __GI_getaddrinfo+0xffff000099160163
libc-2.26.so[ffff80004c9c05b3] (inlined)
2d6f main+0xfffffffd9f1003df (/usr/bin/ping)
ping[fffffffecf882d6f]
2369f generic_start_main+0xffff00009916013f
libc-2.26.so[ffff80004c8d369f] (inlined)
23897 __libc_start_main+0xffff0000991600b7 (/usr/lib64/libc-2.26.so)
libc-2.26.so[ffff80004c8d3897]
After:
# perf report --stdio --no-children -s sym,srcline -g address
# Samples: 1 of event 'probe_libc:inet_pton'
# Event count (approx.): 1
#
# Overhead Symbol Source:Line
# ........ .................... ...........
#
100.00% [.] __GI___inet_pton inet_pton.c
|
---gaih_inet.constprop.7 getaddrinfo.c:537
getaddrinfo getaddrinfo.c:2304
main ping.c:519
generic_start_main.isra.0 libc-start.c:308
__libc_start_main libc-start.c:102
...
# perf script -F comm,ip,sym,symoff,srcline,dso
ping
7fffb38aaf28 __GI___inet_pton+0x8 (/usr/lib64/libc-2.26.so)
inet_pton.c:68
7fffb385fa53 gaih_inet.constprop.7+0xf43 (/usr/lib64/libc-2.26.so)
getaddrinfo.c:537
7fffb38605b3 getaddrinfo+0x163 (/usr/lib64/libc-2.26.so)
getaddrinfo.c:2304
130782d6f main+0x3df (/usr/bin/ping)
ping.c:519
7fffb377369f generic_start_main.isra.0+0x13f (/usr/lib64/libc-2.26.so)
libc-start.c:308
7fffb3773897 __libc_start_main+0xb7 (/usr/lib64/libc-2.26.so)
libc-start.c:102
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Fixes: 6754075915 ("perf unwind: Use addr_location::addr instead of ip for entries")
Link: http://lkml.kernel.org/r/20180703120555.32971-1-sandipan@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When perf data is recorded with the call-graph option enabled, the
callchain shown by perf script shows the binary offsets of the symbols
as the ip. This is incorrect for kernel symbols as the ip values are
always off by a fixed offset depending on the architecture. If the
offsets from the start of the symbols are printed, they are also
incorrect for both kernel and userspace symbols.
Without the call-graph option, the callchain shows the virtual addresses
of the symbols rather than their binary offsets. The offsets printed in
this case are also correct.
This fixes the inconsistency in perf script's output.
This can be verified on a powerpc64le system running Fedora 27 as
follows:
# cat /proc/kallsyms | grep sys_write
...
c0000000004025a0 T sys_write
c0000000004025a0 T __se_sys_write
...
# perf probe -a sys_write
Before applying this patch:
# perf record -e probe:sys_write -g ~/test
# perf script -F ip,sym,symoff
4125b0 sys_write+0x8000000000008010
1b9e0 system_call+0x8000000000008058
118234 __GI___libc_write+0xffff0000f52c0024
92c74 _IO_file_write@@GLIBC_2.17+0xffff0000f52c0044
5afbfd8a [unknown]
91a60 new_do_write+0xffff0000f52c0090
94638 _IO_do_write@@GLIBC_2.17+0xffff0000f52c0038
94bbc _IO_file_overflow@@GLIBC_2.17+0xffff0000f52c014c
95a24 __overflow+0xffff0000f52c0064
84548 _IO_puts+0xffff0000f52c0218
440 main+0xffffffffe0000020
236a0 generic_start_main.isra.0+0xffff0000f52c0140
23898 __libc_start_main+0xffff0000f52c00b8
0 [unknown]
...
# perf record -e probe:sys_write ~/test
# perf script -F ip,sym,symoff
c0000000004025b0 sys_write+0x10
...
After applying this patch:
# perf record -e probe:sys_write -g ~/test
# perf script -F ip,sym,symoff
c0000000004025b0 sys_write+0x10
c00000000000b9e0 system_call+0x58
7fffb70d8234 __GI___libc_write+0x24
7fffb7052c74 _IO_file_write@@GLIBC_2.17+0x44
5afc1818 [unknown]
7fffb7051a60 new_do_write+0x90
7fffb7054638 _IO_do_write@@GLIBC_2.17+0x38
7fffb7054bbc _IO_file_overflow@@GLIBC_2.17+0x14c
7fffb7055a24 __overflow+0x64
7fffb7044548 _IO_puts+0x218
10000440 main+0x20
7fffb6fe36a0 generic_start_main.isra.0+0x140
7fffb6fe3898 __libc_start_main+0xb8
0 [unknown]
...
# perf record -e probe:sys_write ~/test
# perf script -F ip,sym,symoff
c0000000004025b0 sys_write+0x10
...
Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: http://lkml.kernel.org/r/20180517063326.6319-1-sandipan@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Remove the split of symbol tables for data (MAP__VARIABLE) and for
functions (MAP__FUNCTION), its unneeded and there were various places
doing two lookups to find a symbol, so simplify this.
We still will consider only the symbols that matched the filters in
place, i.e. see the (elf_(sec,sym)|symbol_type)__filter() routines in
the patch, just so that we consider only the same symbols as before,
to reduce the possibility of regressions.
All the tests on 50-something build environments, in varios versions
of lots of distros and cross build environments were performed without
build regressions, as usual with all pull requests the other tests were
also performed: 'perf test' and 'make -C tools/perf build-test'.
Also this was done at a great granularity so that regressions can be
bisected more easily.
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: https://lkml.kernel.org/n/tip-hiq0fy2rsleupnqqwuojo1ne@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
David Miller
Milian Wolff
Jiri Olsa
Sandipan Das
Adrian Hunter
Sandipan Das
Arnaldo Carvalho de Melo