4.18-stable review patch. If anyone has any objections, please let me know.
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From: Sandipan Das sandipan@linux.ibm.com
[ Upstream commit 2a9d5050dc84fa2060f08a52f632976923e0fa7e ]
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 67540759151a ("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 19610184693c ("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: 67540759151a ("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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/perf/util/machine.c | 9 ++++++++- tools/perf/util/unwind-libdw.c | 2 +- tools/perf/util/unwind-libunwind-local.c | 2 +- 3 files changed, 10 insertions(+), 3 deletions(-)
--- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2272,6 +2272,7 @@ static int unwind_entry(struct unwind_en { struct callchain_cursor *cursor = arg; const char *srcline = NULL; + u64 addr;
if (symbol_conf.hide_unresolved && entry->sym == NULL) return 0; @@ -2279,7 +2280,13 @@ static int unwind_entry(struct unwind_en if (append_inlines(cursor, entry->map, entry->sym, entry->ip) == 0) return 0;
- srcline = callchain_srcline(entry->map, entry->sym, entry->ip); + /* + * Convert entry->ip from a virtual address to an offset in + * its corresponding binary. + */ + addr = map__map_ip(entry->map, entry->ip); + + srcline = callchain_srcline(entry->map, entry->sym, addr); return callchain_cursor_append(cursor, entry->ip, entry->map, entry->sym, false, NULL, 0, 0, 0, srcline); --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -77,7 +77,7 @@ static int entry(u64 ip, struct unwind_i if (__report_module(&al, ip, ui)) return -1;
- e->ip = al.addr; + e->ip = ip; e->map = al.map; e->sym = al.sym;
--- a/tools/perf/util/unwind-libunwind-local.c +++ b/tools/perf/util/unwind-libunwind-local.c @@ -575,7 +575,7 @@ static int entry(u64 ip, struct thread * struct addr_location al;
e.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al); - e.ip = al.addr; + e.ip = ip; e.map = al.map;
pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",