The following commit has been merged into the perf/core branch of tip:
Commit-ID: 57f95bf5f88295612871c36cb0de5069e50570f8
Gitweb: https://git.kernel.org/tip/57f95bf5f88295612871c36cb0de5069e50570f8
Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Mon, 18 Nov 2019 17:11:50 +09:00
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Mon, 18 Nov 2019 18:56:27 -03:00
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@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/157406471067.24476.17463149618465494448.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/dwarf-aux.c | 62 +++++++++++++++++++++++++++++++++---
1 file changed, 58 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 5544bfb..aa89801 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;
}
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