linux.git/tools/perf/util/map.c, branch v2.6.34

perf symbols: Improve debugging information about symtab origins

2010-02-25T11:27:17+00:00

Be more clear about DSO long names and tell from which file
kernel symbols were obtained, all in --verbose mode:

    [root@mica ~]# perf report -v > /dev/null
    Looking at the vmlinux_path (5 entries long)
    Using /lib/modules/2.6.33-rc8-tip-00777-g0918527-dirty/build/vmlinux for symbols
    [root@mica ~]# mv /lib/modules/2.6.33-rc8-tip-00777-g0918527-dirty/build/vmlinux /tmp/dd
    [root@mica ~]# perf report -v > /dev/null
    Looking at the vmlinux_path (5 entries long)
    Using /proc/kallsyms for symbols
    [root@mica ~]#

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1266866139-6361-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf top: Fix annotate for userspace

2010-02-07T16:30:20+00:00

First, for programs and prelinked libraries, annotate code was
fooled by objdump output IPs (src->eip in the code) being
wrongly converted to absolute IPs. In such case there were no
conversion needed, but in

   src->eip = strtoull(src->line, NULL, 16);
   src->eip = map->unmap_ip(map, src->eip); // = eip + map->start - map->pgoff

we were reading absolute address from objdump (e.g. 8048604) and
then almost doubling it, because eip & map->start are
approximately close for small programs.

Needless to say, that later, in record_precise_ip() there was no
matching with real runtime IPs.

And second, like with `perf annotate` the problem with
non-prelinked *.so was that we were doing rip -> objdump address
conversion wrong.

Also, because unlike `perf annotate`, `perf top` code does
annotation based on absolute IPs for performance reasons(*), new
helper for mapping objdump addresse to IP is introduced.

(*) we get samples info in absolute IPs, and since we do lots of
    hit-testing on absolute IPs at runtime in record_precise_ip(), it's
    better to convert objdump addresses to IPs once and do no conversion
    at runtime.

I also had to fix how objdump output is parsed (with hardcoded
8/16 characters format, which was inappropriate for ET_DYN dsos
with small addresses like '4ac')

Also note, that not all objdump output lines has associtated
IPs, e.g. look at source lines here:

    000004ac :
    extern "C"
    int my_strlen(const char *s)
     4ac:   55                      push   %ebp
     4ad:   89 e5                   mov    %esp,%ebp
     4af:   83 ec 10                sub    $0x10,%esp
    {
        int len = 0;
     4b2:   c7 45 fc 00 00 00 00    movl   $0x0,-0x4(%ebp)
     4b9:   eb 08                   jmp    4c3 

        while (*s) {
            ++len;
     4bb:   83 45 fc 01             addl   $0x1,-0x4(%ebp)
            ++s;
     4bf:   83 45 08 01             addl   $0x1,0x8(%ebp)

So we mark them with eip=0, and ignore such lines in annotate
lookup code.

Signed-off-by: Kirill Smelkov 
[ Note: one hunk of this patch was applied by Mike in 57d8188 ]
Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Mike Galbraith 
LKML-Reference: <1265550376-12665-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf annotate: Fix it for non-prelinked *.so

2010-02-04T08:33:27+00:00

The problem was we were incorrectly calculating objdump
addresses for sym->start and sym->end, look:

For simple ET_DYN type DSO (*.so) with one function, objdump -dS
output is something like this:

    000004ac :
    int my_strlen(const char *s)
     4ac:   55                      push   %ebp
     4ad:   89 e5                   mov    %esp,%ebp
     4af:   83 ec 10                sub    $0x10,%esp
    {

i.e. we have relative-to-dso-mapping IPs (=RIP) there.

For ET_EXEC type and probably for prelinked libs as well (sorry
can't test - I don't use prelink) objdump outputs absolute IPs,
e.g.

    08048604 :
    extern "C"
    int zz_strlen(const char *s)
     8048604:       55                      push   %ebp
     8048605:       89 e5                   mov    %esp,%ebp
     8048607:       83 ec 10                sub    $0x10,%esp
    {

So, if sym->start is always relative to dso mapping(*), we'll
have to unmap it for ET_EXEC like cases, and leave as is for
ET_DYN cases.

(*) and it is - we've explicitely made it relative. Look for
    adjust_symbols handling in dso__load_sym()

Previously we were always unmapping sym->start and for ET_DYN
dsos resulting addresses were wrong, and so objdump output was
empty.

The end result was that perf annotate output for symbols from
non-prelinked *.so had always 0.00% percents only, which is
wrong.

To fix it, let's introduce a helper for converting rip to
objdump address, and also let's document what map_ip() and
unmap_ip() do -- I had to study sources for several hours to
understand it.

Signed-off-by: Kirill Smelkov 
Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Mike Galbraith 
LKML-Reference: <1265223128-11786-8-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf symbols: Ditch vdso global variable

2010-02-04T08:33:26+00:00

We can check using strcmp, most DSOs don't start with '[' so the
test is cheap enough and we had to test it there anyway since
when reading perf.data files we weren't calling the routine that
created this global variable and thus weren't setting it as
"loaded", which was causing a bogus:

  Failed to open [vdso], continuing without symbols

Message as the first line of 'perf report'.

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1265223128-11786-3-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf symbols: Remove perf_session usage in symbols layer

2010-02-04T08:33:24+00:00

I noticed while writing the first test in 'perf regtest' that to
just test the symbol handling routines one needs to create a
perf session, that is a layer centered on a perf.data file,
events, etc, so I untied these layers.

This reduces the complexity for the users as the number of
parameters to most of the symbols and session APIs now was
reduced while not adding more state to all the map instances by
only having data that is needed to split the kernel (kallsyms
and ELF symtab sections) maps and do vmlinux relocation on the
main kernel map.

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1265223128-11786-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf probe: Check build-id of vmlinux

2009-12-15T19:22:04+00:00

Check build-id of vmlinux by using functions in symbol.c.
This also exposes map__load() for getting vmlinux path,
and removes vmlinux path list in builtin-probe.c,
because symbol.c already has that. Checking build-id
prevents users to open old or different debuginfo from
current running kernel.

Signed-off-by: Masami Hiramatsu 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Cc: Steven Rostedt 
Cc: Jim Keniston 
Cc: Ananth N Mavinakayanahalli 
Cc: Christoph Hellwig 
Cc: Frank Ch. Eigler 
Cc: Jason Baron 
Cc: K.Prasad 
Cc: Peter Zijlstra 
Cc: Srikar Dronamraju 
Cc: systemtap 
Cc: DLE 
Cc: Frederic Weisbecker 
LKML-Reference: <20091215153232.17436.45539.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar

perf session: Move kmaps to perf_session

2009-12-14T15:57:17+00:00

There is still some more work to do to disentangle map creation
from DSO loading, but this happens only for the kernel, and for
the early adopters of perf diff, where this disentanglement
matters most, we'll be testing different kernels, so no problem
here.

Further clarification: right now we create the kernel maps for
the various modules and discontiguous kernel text maps when
loading the DSO, we should do it as a two step process, first
creating the maps, for multiple mappings with the same DSO
store, then doing the dso load just once, for the first hit on
one of the maps sharing this DSO backing store.

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1260741029-4430-6-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf symbols: Ditch dso->find_symbol

2009-12-12T06:42:11+00:00

It is always wired to dso__find_symbol.

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1260564999-13371-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf symbols: Allow lookups by symbol name too

2009-12-12T06:42:11+00:00

Configurable via symbol_conf.sort_by_name, so that the cost of an
extra rb_node on all 'struct symbol' instances is not paid by tools
that only want to decode addresses.

How to use it:

	symbol_conf.sort_by_name = true;
	symbol_init(&symbol_conf);

	struct map *map = map_groups__find_by_name(kmaps, MAP__VARIABLE, "[kernel.kallsyms]");

	if (map == NULL) {
		pr_err("couldn't find map!\n");
		kernel_maps__fprintf(stdout);
	} else {
		struct symbol *sym = map__find_symbol_by_name(map, sym_filter, NULL);
		if (sym == NULL)
			pr_err("couldn't find symbol %s!\n", sym_filter);
		else
			pr_info("symbol %s: %#Lx-%#Lx \n", sym_filter, sym->start, sym->end);
	}

Looking over the vmlinux/kallsyms is common enough that I'll add a
variable to the upcoming struct perf_session to avoid the need to
use map_groups__find_by_name to get the main vmlinux/kallsyms map.

The above example looks on the 'variable' symtab, but it is just
like that for the functions one.

Also the sort operation is done when we first use
map__find_symbol_by_name, in a lazy way.

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Masami Hiramatsu 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1260564622-12392-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar

perf symbols: Better support for multiple symbol tables per dso

2009-11-27T19:21:59+00:00

By using an array of rb_roots in struct dso we can, from a
struct map instance to get the right symbol rb_tree more easily.
This way we can have just one symbol lookup method for struct
map instances, map__find_symbol, instead of one per symtab type
(functions, variables).

Signed-off-by: Arnaldo Carvalho de Melo 
Cc: Frédéric Weisbecker 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
LKML-Reference: <1259346563-12568-6-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar