code.ossystems Code Review - openembedded-core.git/blob

   1 Upstream-Status: Backport
   2
   3 From ca6d916a6f8f0f8abbb4c9b6a97dd1a1615bb124 Mon Sep 17 00:00:00 2001
   4 From: Maynard Johnson <maynardj@us.ibm.com>
   5 Date: Wed, 5 Dec 2012 10:16:35 -0600
   6 Subject: [PATCH] Fix up configure to handle architectures that do not
   7  implement perf_event_open
   8
   9 This patch fixes the following problems:
  10
  11 1) The configure script allows the user to pass a location to kernel
  12 headers (via --with-kernel option) such that, even if the running
  13 kernel does not have perf_events support, it may be possible to
  14 build operf (e.g., in cross-compile environments).  But the message
  15 'This kernel does not have perf_events support; falling back to legacy
  16 oprofile' was being displayed inappropriately in such cases.  This
  17 patch changes the configure script so that the "falling back to
  18 legacy oprofile" message will only be displayed if we're running
  19 on a kernel that does not have perf_events support AND the user
  20 did not pass specify the "--with-kernel" option.
  21
  22 2) Some architectures don't even implement the perf_event_open syscall, so the
  23 configure script must do more than checking kernel version and whether or not
  24 perf_event.h is present in order to decide if perf_events is supported.
  25 This patch provides that extra capability.
  26
  27 These problems were reported by Tony Jones <tonyj@suse.com>.
  28
  29 Signed-off-by:  Maynard Johnson <maynardj@us.ibm.com>
  30 ---
  31  configure.ac                   |   74 +++++++++++++++++++++++++++++-----------
  32  utils/op_perf_events_checker.c |    6 ++--
  33  2 files changed, 58 insertions(+), 22 deletions(-)
  34
  35 diff --git a/configure.ac b/configure.ac
  36 index 5c3d13d..89336ee 100644
  37 --- a/configure.ac
  38 +++ b/configure.ac
  39 @@ -70,34 +70,66 @@ KERNELDIR=$withval)
  40
  41
  42  dnl Check kernel version for perf_events supported
  43 -AC_MSG_CHECKING([kernel version supports perf_events])
  44  if test "$KERNELDIR" != ""; then
  45         KINC="$KERNELDIR/include"
  46 -fi
  47 -AX_KERNEL_VERSION(2, 6, 31, <=, kernel_has_perf_events_support="yes",
  48 -kernel_has_perf_events_support="no")
  49 -
  50 -if test "$kernel_has_perf_events_support" = "no"; then
  51 -       AC_MSG_RESULT([This kernel does not have perf_events support; falling back to legacy oprofile])
  52 +       PERF_EVENT_FLAGS=" -I$KERNELDIR/include"
  53 +       AC_SUBST(PERF_EVENT_FLAGS)
  54 +       PERF_EVENT_H="$KERNELDIR/include/linux/perf_event.h"
  55  else
  56 -       AC_MSG_RESULT([This kernel has perf_events support])
  57 +       PERF_EVENT_H="/usr/include/linux/perf_event.h"
  58  fi
  59
  60 -if test "$KERNELDIR" == ""; then
  61 -       PERF_EVENT_H="/usr/include/linux/perf_event.h"
  62 +PERF_EVENT_H_EXISTS="no"
  63 +kernel_may_have_perf_events_support="no"
  64 +AX_KERNEL_VERSION(2, 6, 31, <=, kernel_may_have_perf_events_support="yes",
  65 +kernel_has_perf_events_support="no")
  66 +
  67 +dnl The AX_KERNEL_VERSION macro may return kernel_may_have_perf_events_support="yes",
  68 +dnl indicating a partial answer.  Some architectures do not implement the Performance
  69 +dnl Events Kernel Subsystem even with kernel versions > 2.6.31 -- i.e., not even
  70 +dnl implementing the perf_event_open syscall to return ENOSYS.  So the check below
  71 +dnl will identify and handle such situations.
  72 +
  73 +if test "$kernel_may_have_perf_events_support" = "yes"; then
  74 +       AC_CHECK_HEADER($PERF_EVENT_H,PERF_EVENT_H_EXISTS="yes")
  75 +       AC_MSG_CHECKING([kernel supports perf_events])
  76 +       if test "$PERF_EVENT_H_EXISTS" = "yes"; then
  77 +               rm -f test-for-PERF_EVENT_OPEN
  78 +               AC_LANG_CONFTEST(
  79 +                       [AC_LANG_PROGRAM([[#include <linux/perf_event.h>
  80 +                               #include <asm/unistd.h>
  81 +                               #include <sys/types.h>
  82 +                               #include <string.h>
  83 +                       ]],
  84 +                       [[struct perf_event_attr attr;
  85 +                               pid_t pid;
  86 +                               memset(&attr, 0, sizeof(attr));
  87 +                               attr.size = sizeof(attr);
  88 +                               attr.sample_type = PERF_SAMPLE_IP;
  89 +                               pid = getpid();
  90 +                               syscall(__NR_perf_event_open, &attr, pid, 0, -1, 0);
  91 +                               ]])
  92 +               ])
  93 +               $CC conftest.$ac_ext $CFLAGS $LDFLAGS $LIBS $PERF_EVENT_FLAGS -o test-for-PERF_EVENT_OPEN  > /dev/null 2>&1
  94 +               if test -f test-for-PERF_EVENT_OPEN; then
  95 +                       kernel_has_perf_events_support="yes"
  96 +                       AC_MSG_RESULT(yes)
  97 +               else
  98 +                       AC_MSG_RESULT(no)
  99 +                       kernel_has_perf_events_support="no"
 100 +               fi
 101 +       else
 102 +               AC_MSG_RESULT(unknown -- perf_event.h not found)
 103 +       fi
 104  else
 105 -       PERF_EVENT_H="$KERNELDIR/include/linux/perf_event.h"
 106 +       AC_MSG_RESULT(kernel supports perf_events... no)
 107 +       kernel_has_perf_events_support="no"
 108  fi
 109 -AC_CHECK_HEADER($PERF_EVENT_H,PERF_EVENT_H_EXISTS="yes")
 110 -AM_CONDITIONAL(BUILD_FOR_PERF_EVENT, test -n "$PERF_EVENT_H_EXISTS")
 111 -if test "$PERF_EVENT_H_EXISTS" = "yes"; then
 112 -       HAVE_PERF_EVENTS='1'
 113
 114 -       if test "$KERNELDIR" != ""; then
 115 -               PERF_EVENT_FLAGS=" -I$KERNELDIR/include"
 116 -               AC_SUBST(PERF_EVENT_FLAGS)
 117 -       fi
 118 +AM_CONDITIONAL(BUILD_FOR_PERF_EVENT, test "$kernel_has_perf_events_support" = "yes")
 119
 120 +if test "$kernel_has_perf_events_support" = "yes"; then
 121 +       HAVE_PERF_EVENTS='1'
 122         AC_MSG_CHECKING([whether PERF_RECORD_MISC_GUEST_KERNEL is defined in perf_event.h])
 123         rm -f test-for-PERF_GUEST
 124         AC_LANG_CONFTEST(
 125 @@ -117,7 +149,9 @@ if test "$PERF_EVENT_H_EXISTS" = "yes"; then
 126         rm -f test-for-PERF_GUEST*
 127  else
 128         HAVE_PERF_EVENTS='0'
 129 +       AC_MSG_RESULT([No perf_events support available; falling back to legacy oprofile])
 130  fi
 131 +
 132  AC_DEFINE_UNQUOTED(HAVE_PERF_EVENTS, $HAVE_PERF_EVENTS, [Kernel support for perf_events exists])
 133
 134  if test "$HAVE_PERF_EVENTS" = "1"; then
 135 @@ -433,7 +467,7 @@ elif test "`getent passwd oprofile 2>/dev/null`" == "" || \
 136         fi
 137  fi
 138
 139 -if  test "$PERF_EVENT_H_EXISTS" != "yes" && test "$kernel_has_perf_events_support" = "yes"; then
 140 +if  test "$PERF_EVENT_H_EXISTS" != "yes" && test "$kernel_may_have_perf_events_support" = "yes"; then
 141         echo "Warning: perf_event.h not found.  Either install the kernel headers package or"
 142         echo "use the --with-kernel option if you want the non-root, single application"
 143         echo "profiling support provided by operf."
 144 diff --git a/utils/op_perf_events_checker.c b/utils/op_perf_events_checker.c
 145 index 519cafa..74a410e 100644
 146 --- a/utils/op_perf_events_checker.c
 147 +++ b/utils/op_perf_events_checker.c
 148 @@ -49,8 +49,10 @@ int main(int argc, char **argv)
 149         }
 150
 151  #if HAVE_PERF_EVENTS
 152 -       /* If perf_events syscall is not implemented, the syscall below will fail
 153 -        * with ENOSYS (38).  If implemented, but the processor type on which this
 154 +       /* Even if the perf_event_open syscall is implemented, the architecture may still
 155 +        * not provide a full implementation of the perf_events subsystem, in which case,
 156 +        * the syscall below will fail with ENOSYS (38).  If the perf_events subsystem is
 157 +        * implemented for the architecture, but the processor type on which this
 158          * program is running is not supported by perf_events, the syscall returns
 159          * ENOENT (2).
 160          */
 161 --
 162 1.7.9.7
 163