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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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576b523721
Fix perf probe to probe on some symbols which have some optimzation
suffixes, e.g. ".part", ".isra", and ".constprop".
To fix this issue, instead of using the DIE name, perf probe uses the
symbol name found by dwfl_module_addrsym().
This also involves a perf probe --vars operation update which now shows
the symbol name instead of the DIE name.
Without this patch, putting a probe on an inlined function which was
compiled with a suffixed symbol will fail like this:
$ perf probe -v getname_flags
probe-definition(0): getname_flags
symbol:getname_flags file:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
Looking at the vmlinux_path (6 entries long)
Using /lib/modules/3.11.0+/build/vmlinux for symbols
found inline addr: 0xffffffff8119bb70
Probe point found: getname_flags+0
found inline addr: 0xffffffff8119bcb6
Probe point found: getname+6
found inline addr: 0xffffffff811a06a6
Probe point found: user_path_at_empty+6
find 3 probe_trace_events.
Opening /sys/kernel/debug//tracing/kprobe_events write=1
Added new events:
Writing event: p:probe/getname_flags getname_flags+0
Failed to write event: No such file or directory
Error: Failed to add events. (-1)
Because the debuginfo knows only the original (non suffix) symbol name,
it uses the original symbol for probe address but the kernel (kallsyms)
knows only suffixed symbol. Then, the kernel rejects that original
symbol.
This patch uses dwfl_module_addrsym() to get the correct (suffixed)
symbol from symtab when a probe point is found.
Reported-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20130925131616.31632.46658.stgit@udc4-manage.rcp.hitachi.co.jp
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
#ifndef _PROBE_FINDER_H
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#define _PROBE_FINDER_H
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#include <stdbool.h>
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#include "util.h"
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#include "probe-event.h"
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#define MAX_PROBE_BUFFER 1024
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#define MAX_PROBES 128
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static inline int is_c_varname(const char *name)
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{
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/* TODO */
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return isalpha(name[0]) || name[0] == '_';
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}
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#ifdef DWARF_SUPPORT
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#include "dwarf-aux.h"
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/* TODO: export debuginfo data structure even if no dwarf support */
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/* debug information structure */
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struct debuginfo {
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Dwarf *dbg;
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Dwfl_Module *mod;
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Dwfl *dwfl;
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Dwarf_Addr bias;
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};
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extern struct debuginfo *debuginfo__new(const char *path);
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extern struct debuginfo *debuginfo__new_online_kernel(unsigned long addr);
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extern void debuginfo__delete(struct debuginfo *self);
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/* Find probe_trace_events specified by perf_probe_event from debuginfo */
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extern int debuginfo__find_trace_events(struct debuginfo *self,
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struct perf_probe_event *pev,
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struct probe_trace_event **tevs,
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int max_tevs);
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/* Find a perf_probe_point from debuginfo */
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extern int debuginfo__find_probe_point(struct debuginfo *self,
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unsigned long addr,
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struct perf_probe_point *ppt);
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/* Find a line range */
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extern int debuginfo__find_line_range(struct debuginfo *self,
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struct line_range *lr);
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/* Find available variables */
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extern int debuginfo__find_available_vars_at(struct debuginfo *self,
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struct perf_probe_event *pev,
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struct variable_list **vls,
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int max_points, bool externs);
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struct probe_finder {
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struct perf_probe_event *pev; /* Target probe event */
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/* Callback when a probe point is found */
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int (*callback)(Dwarf_Die *sc_die, struct probe_finder *pf);
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/* For function searching */
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int lno; /* Line number */
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Dwarf_Addr addr; /* Address */
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const char *fname; /* Real file name */
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Dwarf_Die cu_die; /* Current CU */
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Dwarf_Die sp_die;
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struct list_head lcache; /* Line cache for lazy match */
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/* For variable searching */
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#if _ELFUTILS_PREREQ(0, 142)
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Dwarf_CFI *cfi; /* Call Frame Information */
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#endif
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Dwarf_Op *fb_ops; /* Frame base attribute */
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struct perf_probe_arg *pvar; /* Current target variable */
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struct probe_trace_arg *tvar; /* Current result variable */
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};
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struct trace_event_finder {
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struct probe_finder pf;
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Dwfl_Module *mod; /* For solving symbols */
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struct probe_trace_event *tevs; /* Found trace events */
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int ntevs; /* Number of trace events */
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int max_tevs; /* Max number of trace events */
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};
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struct available_var_finder {
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struct probe_finder pf;
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Dwfl_Module *mod; /* For solving symbols */
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struct variable_list *vls; /* Found variable lists */
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int nvls; /* Number of variable lists */
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int max_vls; /* Max no. of variable lists */
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bool externs; /* Find external vars too */
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bool child; /* Search child scopes */
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};
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struct line_finder {
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struct line_range *lr; /* Target line range */
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const char *fname; /* File name */
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int lno_s; /* Start line number */
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int lno_e; /* End line number */
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Dwarf_Die cu_die; /* Current CU */
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Dwarf_Die sp_die;
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int found;
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};
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#endif /* DWARF_SUPPORT */
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#endif /*_PROBE_FINDER_H */
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