9 Commits
Author | SHA1 | Message | Date | |
---|---|---|---|---|
Sandipan Das
|
9068533e4f |
perf powerpc: Fix callchain ip filtering when return address is in a register
For powerpc64, perf will filter out the second entry in the callchain, i.e. the LR value, if the return address of the function corresponding to the probed location has already been saved on its caller's stack. The state of the return address is determined using debug information. At any point within a function, if the return address is already saved somewhere, a DWARF expression can tell us about its location. If the return address in still in LR only, no DWARF expression would exist. Typically, the instructions in a function's prologue first copy the LR value to R0 and then pushes R0 on to the stack. If LR has already been copied to R0 but R0 is yet to be pushed to the stack, we can still get a DWARF expression that says that the return address is in R0. This is indicating that getting a DWARF expression for the return address does not guarantee the fact that it has already been saved on the stack. This can be observed on a powerpc64le system running Fedora 27 as shown below. # objdump -d /usr/lib64/libc-2.26.so | less ... 000000000015af20 <inet_pton>: 15af20: 0b 00 4c 3c addis r2,r12,11 15af24: e0 c1 42 38 addi r2,r2,-15904 15af28: a6 02 08 7c mflr r0 15af2c: f0 ff c1 fb std r30,-16(r1) 15af30: f8 ff e1 fb std r31,-8(r1) 15af34: 78 1b 7f 7c mr r31,r3 15af38: 78 23 83 7c mr r3,r4 15af3c: 78 2b be 7c mr r30,r5 15af40: 10 00 01 f8 std r0,16(r1) 15af44: c1 ff 21 f8 stdu r1,-64(r1) 15af48: 28 00 81 f8 std r4,40(r1) ... # readelf --debug-dump=frames-interp /usr/lib64/libc-2.26.so | less ... 00027024 0000000000000024 00027028 FDE cie=00000000 pc=000000000015af20..000000000015af88 LOC CFA r30 r31 ra 000000000015af20 r1+0 u u u 000000000015af34 r1+0 c-16 c-8 r0 000000000015af48 r1+64 c-16 c-8 c+16 000000000015af5c r1+0 c-16 c-8 c+16 000000000015af78 r1+0 u u ... # perf probe -x /usr/lib64/libc-2.26.so -a inet_pton+0x18 # perf record -e probe_libc:inet_pton -g ping -6 -c 1 ::1 # perf script Before: ping 2829 [005] 512917.460174: probe_libc:inet_pton: (7fff7e2baf38) 7fff7e2baf38 __GI___inet_pton+0x18 (/usr/lib64/libc-2.26.so) 7fff7e2705b4 getaddrinfo+0x164 (/usr/lib64/libc-2.26.so) 12f152d70 _init+0xbfc (/usr/bin/ping) 7fff7e1836a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so) 7fff7e183898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so) 0 [unknown] ([unknown]) After: ping 2829 [005] 512917.460174: probe_libc:inet_pton: (7fff7e2baf38) 7fff7e2baf38 __GI___inet_pton+0x18 (/usr/lib64/libc-2.26.so) 7fff7e26fa54 gaih_inet.constprop.7+0xf44 (/usr/lib64/libc-2.26.so) 7fff7e2705b4 getaddrinfo+0x164 (/usr/lib64/libc-2.26.so) 12f152d70 _init+0xbfc (/usr/bin/ping) 7fff7e1836a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so) 7fff7e183898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so) 0 [unknown] ([unknown]) Reported-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Sandipan Das <sandipan@linux.ibm.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Maynard Johnson <maynard@us.ibm.com> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/66e848a7bdf2d43b39210a705ff6d828a0865661.1530724939.git.sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Sandipan Das
|
c715fcfda5 |
perf powerpc: Fix callchain ip filtering
For powerpc64, redundant entries in the callchain are filtered out by
determining the state of the return address and the stack frame using
DWARF debug information.
For making these filtering decisions we must analyze the debug
information for the location corresponding to the program counter value,
i.e. the first entry in the callchain, and not the LR value; otherwise,
perf may filter out either the second or the third entry in the
callchain incorrectly.
This can be observed on a powerpc64le system running Fedora 27 as shown
below.
Case 1 - Attaching a probe at inet_pton+0x8 (binary offset 0x15af28).
Return address is still in LR and a new stack frame is not yet
allocated. The LR value, i.e. the second entry, should not be
filtered out.
# objdump -d /usr/lib64/libc-2.26.so | less
...
000000000010eb10 <gaih_inet.constprop.7>:
...
10fa48: 78 bb e4 7e mr r4,r23
10fa4c: 0a 00 60 38 li r3,10
10fa50: d9 b4 04 48 bl 15af28 <inet_pton+0x8>
10fa54: 00 00 00 60 nop
10fa58: ac f4 ff 4b b 10ef04 <gaih_inet.constprop.7+0x3f4>
...
0000000000110450 <getaddrinfo>:
...
1105a8: 54 00 ff 38 addi r7,r31,84
1105ac: 58 00 df 38 addi r6,r31,88
1105b0: 69 e5 ff 4b bl 10eb18 <gaih_inet.constprop.7+0x8>
1105b4: 78 1b 71 7c mr r17,r3
1105b8: 50 01 7f e8 ld r3,336(r31)
...
000000000015af20 <inet_pton>:
15af20: 0b 00 4c 3c addis r2,r12,11
15af24: e0 c1 42 38 addi r2,r2,-15904
15af28: a6 02 08 7c mflr r0
15af2c: f0 ff c1 fb std r30,-16(r1)
15af30: f8 ff e1 fb std r31,-8(r1)
...
# perf probe -x /usr/lib64/libc-2.26.so -a inet_pton+0x8
# perf record -e probe_libc:inet_pton -g ping -6 -c 1 ::1
# perf script
Before:
ping 4507 [002] 514985.546540: probe_libc:inet_pton: (7fffa7dbaf28)
7fffa7dbaf28 __GI___inet_pton+0x8 (/usr/lib64/libc-2.26.so)
7fffa7d705b4 getaddrinfo+0x164 (/usr/lib64/libc-2.26.so)
13fb52d70 _init+0xbfc (/usr/bin/ping)
7fffa7c836a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so)
7fffa7c83898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so)
0 [unknown] ([unknown])
After:
ping 4507 [002] 514985.546540: probe_libc:inet_pton: (7fffa7dbaf28)
7fffa7dbaf28 __GI___inet_pton+0x8 (/usr/lib64/libc-2.26.so)
7fffa7d6fa54 gaih_inet.constprop.7+0xf44 (/usr/lib64/libc-2.26.so)
7fffa7d705b4 getaddrinfo+0x164 (/usr/lib64/libc-2.26.so)
13fb52d70 _init+0xbfc (/usr/bin/ping)
7fffa7c836a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so)
7fffa7c83898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so)
0 [unknown] ([unknown])
Case 2 - Attaching a probe at _int_malloc+0x180 (binary offset 0x9cf10).
Return address in still in LR and a new stack frame has already
been allocated but not used. The caller's caller, i.e. the third
entry, is invalid and should be filtered out and not the second
one.
# objdump -d /usr/lib64/libc-2.26.so | less
...
000000000009cd90 <_int_malloc>:
9cd90: 17 00 4c 3c addis r2,r12,23
9cd94: 70 a3 42 38 addi r2,r2,-23696
9cd98: 26 00 80 7d mfcr r12
9cd9c: f8 ff e1 fb std r31,-8(r1)
9cda0: 17 00 e4 3b addi r31,r4,23
9cda4: d8 ff 61 fb std r27,-40(r1)
9cda8: 78 23 9b 7c mr r27,r4
9cdac: 1f 00 bf 2b cmpldi cr7,r31,31
9cdb0: f0 ff c1 fb std r30,-16(r1)
9cdb4: b0 ff c1 fa std r22,-80(r1)
9cdb8: 78 1b 7e 7c mr r30,r3
9cdbc: 08 00 81 91 stw r12,8(r1)
9cdc0: 11 ff 21 f8 stdu r1,-240(r1)
9cdc4: 4c 01 9d 41 bgt cr7,9cf10 <_int_malloc+0x180>
9cdc8: 20 00 a4 2b cmpldi cr7,r4,32
...
9cf08: 00 00 00 60 nop
9cf0c: 00 00 42 60 ori r2,r2,0
9cf10: e4 06 ff 7b rldicr r31,r31,0,59
9cf14: 40 f8 a4 7f cmpld cr7,r4,r31
9cf18: 68 05 9d 41 bgt cr7,9d480 <_int_malloc+0x6f0>
...
000000000009e3c0 <tcache_init.part.4>:
...
9e420: 40 02 80 38 li r4,576
9e424: 78 fb e3 7f mr r3,r31
9e428: 71 e9 ff 4b bl 9cd98 <_int_malloc+0x8>
9e42c: 00 00 a3 2f cmpdi cr7,r3,0
9e430: 78 1b 7e 7c mr r30,r3
...
000000000009f7a0 <__libc_malloc>:
...
9f8f8: 00 00 89 2f cmpwi cr7,r9,0
9f8fc: 1c ff 9e 40 bne cr7,9f818 <__libc_malloc+0x78>
9f900: c9 ea ff 4b bl 9e3c8 <tcache_init.part.4+0x8>
9f904: 00 00 00 60 nop
9f908: e8 90 22 e9 ld r9,-28440(r2)
...
# perf probe -x /usr/lib64/libc-2.26.so -a _int_malloc+0x180
# perf record -e probe_libc:_int_malloc -g ./test-malloc
# perf script
Before:
test-malloc 6554 [009] 515975.797403: probe_libc:_int_malloc: (7fffa6e6cf10)
7fffa6e6cf10 _int_malloc+0x180 (/usr/lib64/libc-2.26.so)
7fffa6dd0000 [unknown] (/usr/lib64/libc-2.26.so)
7fffa6e6f904 malloc+0x164 (/usr/lib64/libc-2.26.so)
7fffa6e6f9fc malloc+0x25c (/usr/lib64/libc-2.26.so)
100006b4 main+0x38 (/home/testuser/test-malloc)
7fffa6df36a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so)
7fffa6df3898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so)
0 [unknown] ([unknown])
After:
test-malloc 6554 [009] 515975.797403: probe_libc:_int_malloc: (7fffa6e6cf10)
7fffa6e6cf10 _int_malloc+0x180 (/usr/lib64/libc-2.26.so)
7fffa6e6e42c tcache_init.part.4+0x6c (/usr/lib64/libc-2.26.so)
7fffa6e6f904 malloc+0x164 (/usr/lib64/libc-2.26.so)
7fffa6e6f9fc malloc+0x25c (/usr/lib64/libc-2.26.so)
100006b4 main+0x38 (/home/sandipan/test-malloc)
7fffa6df36a0 generic_start_main.isra.0+0x140 (/usr/lib64/libc-2.26.so)
7fffa6df3898 __libc_start_main+0xb8 (/usr/lib64/libc-2.26.so)
0 [unknown] ([unknown])
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Maynard Johnson <maynard@us.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Fixes:
|
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Sandipan Das
|
143c99f6ac |
perf report powerpc: Fix crash if callchain is empty
For some cases, the callchain provided by the kernel may be empty. So, the callchain ip filtering code will cause a crash if we do not check whether the struct ip_callchain pointer is NULL before accessing any members. This can be observed on a powerpc64le system running Fedora 27 as shown below. # perf record -b -e cycles:u ls Before: # perf report --branch-history perf: Segmentation fault -------- backtrace -------- perf[0x1027615c] linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0)[0x7fff856304d8] perf(arch_skip_callchain_idx+0x44)[0x10257c58] perf[0x1017f2e4] perf(thread__resolve_callchain+0x124)[0x1017ff5c] perf(sample__resolve_callchain+0xf0)[0x10172788] ... After: # perf report --branch-history Samples: 25 of event 'cycles:u', Event count (approx.): 2306870 Overhead Source:Line Symbol Shared Object + 11.60% _init+35736 [.] _init ls + 9.84% strcoll_l.c:137 [.] __strcoll_l libc-2.26.so + 9.16% memcpy.S:175 [.] __memcpy_power7 libc-2.26.so + 9.01% gconv_charset.h:54 [.] _nl_find_locale libc-2.26.so + 8.87% dl-addr.c:52 [.] _dl_addr libc-2.26.so + 8.83% _init+236 [.] _init ls ... Reported-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20180611104049.11048-1-sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Arnaldo Carvalho de Melo
|
4546263d72 |
perf thread: Introduce thread__find_symbol()
Out of thread__find_addr_location(..., MAP__FUNCTION, ...), idea here is to continue removing references to MAP__{FUNCTION,VARIABLE} ahead of getting both types of symbols in the same rbtree, as various places do two lookups, looking first at MAP__FUNCTION, then at MAP__VARIABLE. So thread__find_symbol() will eventually do just that, and 'struct symbol' will have the symbol type, for code that cares about that. 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-n7528en9e08yd3flzmb26tth@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Sukadev Bhattiprolu
|
6bcf9c1ff3 |
perf tools powerpc: Use dwfl_report_elf() instead of offline.
dwfl_report_offline() works only when libraries are prelinked. Replace dwfl_report_offline() with dwfl_report_elf() so we correctly extract debug info even from libraries that are not prelinked. Reported-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Tested-by: Jiri Olsa <jolsa@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Link: http://lkml.kernel.org/r/20150114221045.GA17703@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Arnaldo Carvalho de Melo
|
bb871a9c8d |
perf tools: A thread's machine can be found via thread->mg->machine
So stop passing both machine and thread to several thread methods, reducing function signature length. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: David Ahern <dsahern@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jean Pihet <jean.pihet@linaro.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-ckcy19dcp1jfkmdihdjcqdn1@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Sukadev Bhattiprolu
|
7d073b335e |
perf tools powerpc: Cache the DWARF debug info
Cache the DWARF debug info for DSO so we don't have to rebuild it for each address in the DSO. Note that dso__new() uses calloc() so don't need to set dso->dwfl to NULL. $ /tmp/perf.orig --version perf version 3.18.rc1.gc2661b8 $ /tmp/perf.new --version perf version 3.18.rc1.g402d62 $ perf stat -e cycles,instructions /tmp/perf.orig report -g > orig Performance counter stats for '/tmp/perf.orig report -g': 6,428,177,183 cycles # 0.000 GHz 4,176,288,391 instructions # 0.65 insns per cycle 1.840666132 seconds time elapsed $ perf stat -e cycles,instructions /tmp/perf.new report -g > new Performance counter stats for '/tmp/perf.new report -g': 305,773,142 cycles # 0.000 GHz 276,048,272 instructions # 0.90 insns per cycle 0.087693543 seconds time elapsed $ diff orig new $ Changelog[v2]: [Arnaldo Carvalho] Cache in existing global objects rather than create new static/globals in functions. Reported-by: Anton Blanchard <anton@samba.org> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Cc: Anton Blanchard <anton@au1.ibm.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/20141022000958.GB2228@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Sukadev Bhattiprolu
|
ad7e767a72 |
perf tools powerpc: Explicitly include util/debug.h
Looks like util/debug.h was indirectly included before and is no longer included now. pr_debug is left undefined and the build of perf tool fails on Powerpc. Explicitly include util/debug.h. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Michael Ellerman <michaele@au1.ibm.com> Link: http://lkml.kernel.org/r/20140807072700.GA17623@us.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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Sukadev Bhattiprolu
|
a60335ba32 |
perf tools powerpc: Adjust callchain based on DWARF debug info
When saving the callchain on Power, the kernel conservatively saves excess entries in the callchain. A few of these entries are needed in some cases but not others. We should use the DWARF debug information to determine when the entries are needed. Eg: the value in the link register (LR) is needed only when it holds the return address of a function. At other times it must be ignored. If the unnecessary entries are not ignored, we end up with duplicate arcs in the call-graphs. Use the DWARF debug information to determine if any callchain entries should be ignored when building call-graphs. Callgraph before the patch: 14.67% 2234 sprintft libc-2.18.so [.] __random | --- __random | |--61.12%-- __random | | | |--97.15%-- rand | | do_my_sprintf | | main | | generic_start_main.isra.0 | | __libc_start_main | | 0x0 | | | --2.85%-- do_my_sprintf | main | generic_start_main.isra.0 | __libc_start_main | 0x0 | --38.88%-- rand | |--94.01%-- rand | do_my_sprintf | main | generic_start_main.isra.0 | __libc_start_main | 0x0 | --5.99%-- do_my_sprintf main generic_start_main.isra.0 __libc_start_main 0x0 Callgraph after the patch: 14.67% 2234 sprintft libc-2.18.so [.] __random | --- __random | |--95.93%-- rand | do_my_sprintf | main | generic_start_main.isra.0 | __libc_start_main | 0x0 | --4.07%-- do_my_sprintf main generic_start_main.isra.0 __libc_start_main 0x0 TODO: For split-debug info objects like glibc, we can only determine the call-frame-address only when both .eh_frame and .debug_info sections are available. We should be able to determin the CFA even without the .eh_frame section. Fix suggested by Anton Blanchard. Thanks to valuable input on DWARF debug information from Ulrich Weigand. Reported-by: Maynard Johnson <maynard@us.ibm.com> Tested-by: Maynard Johnson <maynard@us.ibm.com> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20140625154903.GA29607@us.ibm.com Signed-off-by: Jiri Olsa <jolsa@kernel.org> |