lkml.org 
[lkml]   [2021]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] perf probe: Fix add event failed when 32-bit perf running in 64-bit kernel
From
Date
Hello Hiramatsu,

On 2021/7/14 16:35, Masami Hiramatsu wrote:
> Hi Yang,
>
> On Wed, 14 Jul 2021 14:54:32 +0800
> Yang Jihong <yangjihong1@huawei.com> 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().
Yes, I tried the following diff and now it can show the filename (as is
function entry, relative line number is 0), thank you very much :)

The test result in my environment is as follows:

# perf 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 schedule -k vmlinux.debug
probe:schedule (on schedule@kernel/sched/core.c)


Can I put the following diff together and submit a v2 patch?
>
> 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;
>
>

\
 
 \ /
  Last update: 2021-07-15 03:21    [W:0.063 / U:0.668 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site