From e71975f0d7d5821d384af9fac2c06a67619a962f Mon Sep 17 00:00:00 2001 From: Sandipan Das Date: Tue, 10 Jul 2018 19:28:14 +0530 Subject: perf powerpc: Fix callchain ip filtering when return address is in a register [ Upstream commit 9068533e4f470daf2b0f29c71d865990acd8826e ] 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 : 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 Signed-off-by: Sandipan Das Cc: Jiri Olsa Cc: Maynard Johnson Cc: Naveen N. Rao Cc: Ravi Bangoria Cc: Sukadev Bhattiprolu Link: http://lkml.kernel.org/r/66e848a7bdf2d43b39210a705ff6d828a0865661.1530724939.git.sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- tools/perf/arch/powerpc/util/skip-callchain-idx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'tools/perf/arch/powerpc/util/skip-callchain-idx.c') diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c index bd630c222e65..9d1f6e976a5a 100644 --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c @@ -58,9 +58,13 @@ static int check_return_reg(int ra_regno, Dwarf_Frame *frame) } /* - * Check if return address is on the stack. + * Check if return address is on the stack. If return address + * is in a register (typically R0), it is yet to be saved on + * the stack. */ - if (nops != 0 || ops != NULL) + if ((nops != 0 || ops != NULL) && + !(nops == 1 && ops[0].atom == DW_OP_regx && + ops[0].number2 == 0 && ops[0].offset == 0)) return 0; /* -- cgit v1.2.3 From d4aa4e4f77646293ad74d35f28fe4c48bea3ec9e Mon Sep 17 00:00:00 2001 From: Sandipan Das Date: Tue, 10 Jul 2018 19:28:13 +0530 Subject: perf powerpc: Fix callchain ip filtering [ Upstream commit c715fcfda5a08edabaa15508742be926b7ee51db ] 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 : ... 10fa48: 78 bb e4 7e mr r4,r23 10fa4c: 0a 00 60 38 li r3,10 10fa50: d9 b4 04 48 bl 15af28 10fa54: 00 00 00 60 nop 10fa58: ac f4 ff 4b b 10ef04 ... 0000000000110450 : ... 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 1105b4: 78 1b 71 7c mr r17,r3 1105b8: 50 01 7f e8 ld r3,336(r31) ... 000000000015af20 : 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 : ... 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 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 Cc: Jiri Olsa Cc: Maynard Johnson Cc: Naveen N. Rao Cc: Ravi Bangoria Cc: Sukadev Bhattiprolu Fixes: a60335ba3298 ("perf tools powerpc: Adjust callchain based on DWARF debug info") Link: http://lkml.kernel.org/r/24bb726d91ed173aebc972ec3f41a2ef2249434e.1530724939.git.sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- tools/perf/arch/powerpc/util/skip-callchain-idx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/perf/arch/powerpc/util/skip-callchain-idx.c') diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c index 9d1f6e976a5a..9a53f6e9ef43 100644 --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c @@ -250,7 +250,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain) if (!chain || chain->nr < 3) return skip_slot; - ip = chain->ips[2]; + ip = chain->ips[1]; thread__find_addr_location(thread, PERF_RECORD_MISC_USER, MAP__FUNCTION, ip, &al); -- cgit v1.2.3