linux/tools/perf/util/probe-finder.h
Masami Hiramatsu cb40273085 perf probe: Trace a magic number if variable is not found
Trace a magic number as immediate value if the target variable is not
found at some probe points which is based on one probe event.

This feature is good for the case if you trace a source code line with
some local variables, which is compiled into several instructions and
some of the variables are optimized out on some instructions.

Even if so, with this feature, perf probe trace a magic number instead
of such disappeared variables and fold those probes on one event.

E.g. without this patch:

  # perf probe -D "pud_page_vaddr pud"
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  Failed to find 'pud' in this function.
  p:probe/pud_page_vaddr _text+23480787 pud=%ax:x64
  p:probe/pud_page_vaddr _text+23808453 pud=%bp:x64
  p:probe/pud_page_vaddr _text+23558082 pud=%ax:x64
  p:probe/pud_page_vaddr _text+328373 pud=%r8:x64
  p:probe/pud_page_vaddr _text+348448 pud=%bx:x64
  p:probe/pud_page_vaddr _text+23816818 pud=%bx:x64

With this patch:

  # perf probe -D "pud_page_vaddr pud" | head
  spurious_kernel_fault is blacklisted function, skip it.
  vmalloc_fault is blacklisted function, skip it.
  p:probe/pud_page_vaddr _text+23480787 pud=%ax:x64
  p:probe/pud_page_vaddr _text+149051 pud=\deade12d:x64
  p:probe/pud_page_vaddr _text+23808453 pud=%bp:x64
  p:probe/pud_page_vaddr _text+315926 pud=\deade12d:x64
  p:probe/pud_page_vaddr _text+23807209 pud=\deade12d:x64
  p:probe/pud_page_vaddr _text+23557365 pud=%ax:x64
  p:probe/pud_page_vaddr _text+314097 pud=%di:x64
  p:probe/pud_page_vaddr _text+314015 pud=\deade12d:x64
  p:probe/pud_page_vaddr _text+313893 pud=\deade12d:x64
  p:probe/pud_page_vaddr _text+324083 pud=\deade12d:x64

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: http://lore.kernel.org/lkml/157406476931.24476.6261475888681844285.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-11-18 19:09:23 -03:00

124 lines
3.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _PROBE_FINDER_H
#define _PROBE_FINDER_H
#include <stdbool.h>
#include "intlist.h"
#include "probe-event.h"
#include <linux/ctype.h>
#define MAX_PROBE_BUFFER 1024
#define MAX_PROBES 128
#define MAX_PROBE_ARGS 128
#define PROBE_ARG_VARS "$vars"
#define PROBE_ARG_PARAMS "$params"
static inline int is_c_varname(const char *name)
{
/* TODO */
return isalpha(name[0]) || name[0] == '_';
}
#ifdef HAVE_DWARF_SUPPORT
#include "dwarf-aux.h"
/* TODO: export debuginfo data structure even if no dwarf support */
/* debug information structure */
struct debuginfo {
Dwarf *dbg;
Dwfl_Module *mod;
Dwfl *dwfl;
Dwarf_Addr bias;
};
/* This also tries to open distro debuginfo */
struct debuginfo *debuginfo__new(const char *path);
void debuginfo__delete(struct debuginfo *dbg);
/* Find probe_trace_events specified by perf_probe_event from debuginfo */
int debuginfo__find_trace_events(struct debuginfo *dbg,
struct perf_probe_event *pev,
struct probe_trace_event **tevs);
/* Find a perf_probe_point from debuginfo */
int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
struct perf_probe_point *ppt);
int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
bool adjust_offset);
/* Find a line range */
int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr);
/* Find available variables */
int debuginfo__find_available_vars_at(struct debuginfo *dbg,
struct perf_probe_event *pev,
struct variable_list **vls);
/* Find a src file from a DWARF tag path */
int get_real_path(const char *raw_path, const char *comp_dir,
char **new_path);
struct probe_finder {
struct perf_probe_event *pev; /* Target probe event */
/* Callback when a probe point is found */
int (*callback)(Dwarf_Die *sc_die, struct probe_finder *pf);
/* For function searching */
int lno; /* Line number */
Dwarf_Addr addr; /* Address */
const char *fname; /* Real file name */
Dwarf_Die cu_die; /* Current CU */
Dwarf_Die sp_die;
struct intlist *lcache; /* Line cache for lazy match */
/* For variable searching */
#if _ELFUTILS_PREREQ(0, 142)
/* Call Frame Information from .eh_frame */
Dwarf_CFI *cfi_eh;
/* Call Frame Information from .debug_frame */
Dwarf_CFI *cfi_dbg;
#endif
Dwarf_Op *fb_ops; /* Frame base attribute */
unsigned int machine; /* Target machine arch */
struct perf_probe_arg *pvar; /* Current target variable */
struct probe_trace_arg *tvar; /* Current result variable */
bool skip_empty_arg; /* Skip non-exist args */
};
struct trace_event_finder {
struct probe_finder pf;
Dwfl_Module *mod; /* For solving symbols */
struct probe_trace_event *tevs; /* Found trace events */
int ntevs; /* Number of trace events */
int max_tevs; /* Max number of trace events */
};
struct available_var_finder {
struct probe_finder pf;
Dwfl_Module *mod; /* For solving symbols */
struct variable_list *vls; /* Found variable lists */
int nvls; /* Number of variable lists */
int max_vls; /* Max no. of variable lists */
bool child; /* Search child scopes */
};
struct line_finder {
struct line_range *lr; /* Target line range */
const char *fname; /* File name */
int lno_s; /* Start line number */
int lno_e; /* End line number */
Dwarf_Die cu_die; /* Current CU */
Dwarf_Die sp_die;
int found;
};
#endif /* HAVE_DWARF_SUPPORT */
#endif /*_PROBE_FINDER_H */