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Commit d2332098 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Arnaldo Carvalho de Melo
Browse files

perf probe ppc: Fix symbol fixup issues due to ELF type 



If using the symbol table, symbol addresses are not being fixed up
properly, resulting in probes being placed at wrong addresses:

  # perf probe do_fork
  Added new event:
    probe:do_fork        (on do_fork)

  You can now use it in all perf tools, such as:

	  perf record -e probe:do_fork -aR sleep 1

  # cat /sys/kernel/debug/tracing/kprobe_events
  p:probe/do_fork _text+635952
  # printf "%x" 635952
  9b430
  # grep do_fork /boot/System.map
  c0000000000ab430 T .do_fork

Fix by checking for ELF type ET_DYN used by ppc64 kernels.

Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/41392bb856ef62d929995e0b61967689b7915207.1430217967.git.naveen.n.rao@linux.vnet.ibm.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent b64aa553

tools/perf/arch/powerpc/util/Build

+1 −0
Original line number Diff line number Diff line 
libperf-y += header.o

libperf-y += sym-handling.o



libperf-$(CONFIG_DWARF) += dwarf-regs.o

libperf-$(CONFIG_DWARF) += skip-callchain-idx.o

tools/perf/arch/powerpc/util/sym-handling.c

0 → 100644
+19 −0
Original line number Diff line number Diff line 
/*

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License, version 2, as

 * published by the Free Software Foundation.

 *

 * Copyright (C) 2015 Naveen N. Rao, IBM Corporation

 */



#include "debug.h"

#include "symbol.h"



#ifdef HAVE_LIBELF_SUPPORT

bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)

{

	return ehdr.e_type == ET_EXEC ||

	       ehdr.e_type == ET_REL ||

	       ehdr.e_type == ET_DYN;

}

#endif

tools/perf/util/symbol-elf.c

+6 −2
Original line number Diff line number Diff line
@@ -630,6 +630,11 @@ void symsrc__destroy(struct symsrc *ss) 
	close(ss->fd);

}



bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr)

{

	return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;

}



int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,

		 enum dso_binary_type type)

{
@@ -711,8 +716,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, 
						     ".gnu.prelink_undo",

						     NULL) != NULL);

	} else {

		ss->adjust_symbols = ehdr.e_type == ET_EXEC ||

				     ehdr.e_type == ET_REL;

		ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);

	}



	ss->name   = strdup(name);

tools/perf/util/symbol.h

+4 −0
Original line number Diff line number Diff line
@@ -303,4 +303,8 @@ int setup_list(struct strlist **list, const char *list_str, 
int setup_intlist(struct intlist **list, const char *list_str,

		  const char *list_name);



#ifdef HAVE_LIBELF_SUPPORT

bool elf__needs_adjust_symbols(GElf_Ehdr ehdr);

#endif



#endif /* __PERF_SYMBOL */