Re: [PATCH] perf probe: Fix add event failed when 32-bit perf running in 64-bit kernel
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2021-07-14 08:36:00
Also in:
lkml
Subsystem:
performance events subsystem, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
Hi Yang, On Wed, 14 Jul 2021 14:54:32 +0800 Yang Jihong [off-list ref] wrote:
The "address" member of "struct probe_trace_point" uses long data type. If kernel is 64-bit and perf program is 32-bit, size of "address" variable is 32 bits. As a result, upper 32 bits of address read from kernel are truncated, An error occurs during address comparison in kprobe_warn_out_range function.
Good catch! I didn't imagine that such a use case. But that is important because perf probe can be used for cross-arch probe definition too.
Before:
# perf probe -a schedule
schedule is out of .text, skip it.
Error: Failed to add events.
Solution:
Change data type of "address" variable to u64 and change corresponding
address printing and value assignment.OK, as far as I can see, the other parts of the perf also uses u64 for "address" storing variables. (e.g. symbols, maps etc.)
After:
# perf.new.new probe -a schedule
Added new event:
probe:schedule (on schedule)
You can now use it in all perf tools, such as:
perf record -e probe:schedule -aR sleep 1
# perf probe -l
probe:schedule (on schedule)I think you missed one thing here. Usually, this shows the filename and line number of schedule(). Could you try below diff?
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 7d2ba8419b0c..609ca1671501 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c@@ -113,14 +113,14 @@ static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr) * * Find a line number and file name for @addr in @cu_die. */ -int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr, - const char **fname, int *lineno) +int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr, + const char **fname, int *lineno) { Dwarf_Line *line; Dwarf_Die die_mem; Dwarf_Addr faddr; - if (die_find_realfunc(cu_die, (Dwarf_Addr)addr, &die_mem) + if (die_find_realfunc(cu_die, addr, &die_mem) && die_entrypc(&die_mem, &faddr) == 0 && faddr == addr) { *fname = dwarf_decl_file(&die_mem);
@@ -128,7 +128,7 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr, goto out; } - line = cu_getsrc_die(cu_die, (Dwarf_Addr)addr); + line = cu_getsrc_die(cu_die, addr); if (line && dwarf_lineno(line, lineno) == 0) { *fname = dwarf_linesrc(line, NULL, NULL); if (!*fname)
diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index cb99646843a9..7ee0fa19b5c4 100644
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h@@ -19,7 +19,7 @@ const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname); const char *cu_get_comp_dir(Dwarf_Die *cu_die); /* Get a line number and file name for given address */ -int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr, +int cu_find_lineinfo(Dwarf_Die *cudie, Dwarf_Addr addr, const char **fname, int *lineno); /* Walk on functions at given address */
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 8ba01bbdf05c..50d861a80f57 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c@@ -1727,7 +1727,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr, } /* Find a corresponding line (filename and lineno) */ - cu_find_lineinfo(&cudie, addr, &fname, &lineno); + cu_find_lineinfo(&cudie, (Dwarf_Addr)addr, &fname, &lineno); /* Don't care whether it failed or not */ /* Find a corresponding function (name, baseline and baseaddr) */
@@ -1828,8 +1828,7 @@ static int line_range_add_line(const char *src, unsigned int lineno, } static int line_range_walk_cb(const char *fname, int lineno, - Dwarf_Addr addr __maybe_unused, - void *data) + Dwarf_Addr addr, void *data) { struct line_finder *lf = data; const char *__fname;
--
Masami Hiramatsu <mhiramat@kernel.org>