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8d06367fa7
With this change 'perf record' will intercept PERF_RECORD_MMAP
calls, creating a linked list of DSOs, then when the session
finishes, it will traverse this list and read the buildids,
stashing them at the end of the file and will set up a new
feature bit in the header bitmask.
'perf report' will then notice this feature and populate the
'dsos' list and set the build ids.
When reading the symtabs it will refuse to load from a file that
doesn't have the same build id. This improves the
reliability of the profiler output, as symbols and profiling
data is more guaranteed to match.
Example:
[root@doppio ~]# perf report | head
/home/acme/bin/perf with build id b1ea544ac3746e7538972548a09aadecc5753868 not found, continuing without symbols
# Samples: 2621434559
#
# Overhead Command Shared Object Symbol
# ........ ............... ............................. ......
#
7.91% init [kernel] [k] read_hpet
7.64% init [kernel] [k] mwait_idle_with_hints
7.60% swapper [kernel] [k] read_hpet
7.60% swapper [kernel] [k] mwait_idle_with_hints
3.65% init [kernel] [k] 0xffffffffa02339d9
[root@doppio ~]#
In this case the 'perf' binary was an older one, vanished,
so its symbols probably wouldn't match or would cause subtly
different (and misleading) output.
Next patches will support the kernel as well, reading the build
id notes for it and the modules from /sys.
Another patch should also introduce a new plumbing command:
'perf list-buildids'
that will then be used in porcelain that is distro specific to
fetch -debuginfo packages where such buildids are present. This
will in turn allow for one to run 'perf record' in one machine
and 'perf report' in another.
Future work on having the buildid sent directly from the kernel
in the PERF_RECORD_MMAP event is needed to close races, as the
DSO can be changed during a 'perf record' session, but this
patch at least helps with non-corner cases and current/older
kernels.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K. Prasad <prasad@linux.vnet.ibm.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1257367843-26224-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
#ifndef __PERF_SYMBOL
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#define __PERF_SYMBOL 1
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#include <linux/types.h>
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#include <stdbool.h>
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#include "types.h"
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#include <linux/list.h>
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#include <linux/rbtree.h>
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#include "event.h"
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#ifdef HAVE_CPLUS_DEMANGLE
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extern char *cplus_demangle(const char *, int);
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static inline char *bfd_demangle(void __used *v, const char *c, int i)
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{
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return cplus_demangle(c, i);
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}
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#else
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#ifdef NO_DEMANGLE
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static inline char *bfd_demangle(void __used *v, const char __used *c,
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int __used i)
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{
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return NULL;
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}
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#else
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#include <bfd.h>
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#endif
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#endif
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/*
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* libelf 0.8.x and earlier do not support ELF_C_READ_MMAP;
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* for newer versions we can use mmap to reduce memory usage:
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*/
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#ifdef LIBELF_NO_MMAP
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# define PERF_ELF_C_READ_MMAP ELF_C_READ
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#else
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# define PERF_ELF_C_READ_MMAP ELF_C_READ_MMAP
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#endif
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#ifndef DMGL_PARAMS
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#define DMGL_PARAMS (1 << 0) /* Include function args */
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#define DMGL_ANSI (1 << 1) /* Include const, volatile, etc */
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#endif
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struct symbol {
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struct rb_node rb_node;
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u64 start;
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u64 end;
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char name[0];
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};
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extern unsigned int symbol__priv_size;
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static inline void *symbol__priv(struct symbol *self)
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{
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return ((void *)self) - symbol__priv_size;
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}
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struct dso {
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struct list_head node;
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struct rb_root syms;
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struct symbol *(*find_symbol)(struct dso *, u64 ip);
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u8 adjust_symbols:1;
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u8 slen_calculated:1;
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u8 loaded:1;
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u8 has_build_id:1;
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unsigned char origin;
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u8 build_id[BUILD_ID_SIZE];
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const char *short_name;
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char *long_name;
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char name[0];
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};
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struct dso *dso__new(const char *name);
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void dso__delete(struct dso *self);
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struct symbol *dso__find_symbol(struct dso *self, u64 ip);
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int dsos__load_kernel(const char *vmlinux, symbol_filter_t filter, int modules);
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struct dso *dsos__findnew(const char *name);
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int dso__load(struct dso *self, struct map *map, symbol_filter_t filter);
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void dsos__fprintf(FILE *fp);
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size_t dso__fprintf(struct dso *self, FILE *fp);
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char dso__symtab_origin(const struct dso *self);
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void dso__set_build_id(struct dso *self, void *build_id);
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int filename__read_build_id(const char *filename, void *bf, size_t size);
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int build_id__sprintf(u8 *self, int len, char *bf);
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int load_kernel(symbol_filter_t filter);
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void symbol__init(unsigned int priv_size);
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extern struct list_head dsos;
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extern struct map *kernel_map;
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extern struct dso *vdso;
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extern const char *vmlinux_name;
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extern int modules;
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#endif /* __PERF_SYMBOL */
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