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author | Masami Hiramatsu <mhiramat@kernel.org> | 2019-11-18 17:11:50 +0900 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-11-18 18:56:27 -0300 |
commit | 57f95bf5f88295612871c36cb0de5069e50570f8 (patch) | |
tree | ae37b486255f032c410ea18089998612252d37eb /tools/perf | |
parent | b980be189c9badba50634671e2303e92bf28e35a (diff) | |
download | linux-57f95bf5f88295612871c36cb0de5069e50570f8.tar.bz2 |
perf probe: Show correct statement line number by perf probe -l
The dwarf_getsrc_die() can return the line which is not a statement nor
the least line number among the lines which shares same address.
This can lead perf probe --list shows incorrect line number for probed
address.
To fix this, this introduces cu_getsrc_die() which returns only a
statement line and which is the least line number (we call it the
representive line for an address), and use it in cu_find_lineinfo().
Also, if the given address is the entry address of a real function,
cu_find_lineinfo() returns the function declared line number instead of
the start line number of the function body.
For example, without this change perf probe -l shows incorrect line as
below.
# perf probe -a kernel_read:2
Added new event:
probe:kernel_read (on kernel_read:2)
You can now use it in all perf tools, such as:
perf record -e probe:kernel_read -aR sleep 1
# perf probe -l
probe:kernel_read (on kernel_read:1@linux-5.0.0/fs/read_write.c)
With this fix, it shows correct line number as below;
# perf probe -l
probe:kernel_read (on kernel_read:2@linux-5.0.0/fs/read_write.c)
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: http://lore.kernel.org/lkml/157406471067.24476.17463149618465494448.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r-- | tools/perf/util/dwarf-aux.c | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 5544bfbd0f6c..aa898014ad12 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -59,6 +59,51 @@ const char *cu_get_comp_dir(Dwarf_Die *cu_die) return dwarf_formstring(&attr); } +/* Unlike dwarf_getsrc_die(), cu_getsrc_die() only returns statement line */ +static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr) +{ + Dwarf_Addr laddr; + Dwarf_Lines *lines; + Dwarf_Line *line; + size_t nlines, l, u, n; + bool flag; + + if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0 || + nlines == 0) + return NULL; + + /* Lines are sorted by address, use binary search */ + l = 0; u = nlines - 1; + while (l < u) { + n = u - (u - l) / 2; + line = dwarf_onesrcline(lines, n); + if (!line || dwarf_lineaddr(line, &laddr) != 0) + return NULL; + if (addr < laddr) + u = n - 1; + else + l = n; + } + /* Going backward to find the lowest line */ + do { + line = dwarf_onesrcline(lines, --l); + if (!line || dwarf_lineaddr(line, &laddr) != 0) + return NULL; + } while (laddr == addr); + l++; + /* Going foward to find the statement line */ + do { + line = dwarf_onesrcline(lines, l++); + if (!line || dwarf_lineaddr(line, &laddr) != 0 || + dwarf_linebeginstatement(line, &flag) != 0) + return NULL; + if (laddr > addr) + return NULL; + } while (!flag); + + return line; +} + /** * cu_find_lineinfo - Get a line number and file name for given address * @cu_die: a CU DIE @@ -72,17 +117,26 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr, const char **fname, int *lineno) { Dwarf_Line *line; - Dwarf_Addr laddr; + Dwarf_Die die_mem; + Dwarf_Addr faddr; - line = dwarf_getsrc_die(cu_die, (Dwarf_Addr)addr); - if (line && dwarf_lineaddr(line, &laddr) == 0 && - addr == (unsigned long)laddr && dwarf_lineno(line, lineno) == 0) { + if (die_find_realfunc(cu_die, (Dwarf_Addr)addr, &die_mem) + && die_entrypc(&die_mem, &faddr) == 0 && + faddr == addr) { + *fname = dwarf_decl_file(&die_mem); + dwarf_decl_line(&die_mem, lineno); + goto out; + } + + line = cu_getsrc_die(cu_die, (Dwarf_Addr)addr); + if (line && dwarf_lineno(line, lineno) == 0) { *fname = dwarf_linesrc(line, NULL, NULL); if (!*fname) /* line number is useless without filename */ *lineno = 0; } +out: return *lineno ?: -ENOENT; } |