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  1. 14 Aug, 2018 2 commits
    • Jiri Olsa's avatar
      perf tools: Move syscall_64.tbl check into check-headers.sh · c9b51a01
      Jiri Olsa authored 
      Probably leftover from the time we introducd the check-headers.sh script.

Committer testing:

Remove the 'rseq' syscall from tools/perf/arch/x86/entry/syscalls/syscall_64.tbl
to fake a diff:

make: Entering directory '/home/acme/git/perf/tools/perf'
  BUILD:   Doing 'make -j4' parallel build
Warning: Kernel ABI header at 'tools/perf/arch/x86/entry/syscalls/syscall_64.tbl' differs from latest version at 'arch/x86/entry/syscalls/syscall_64.tbl'
diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
  CC       /tmp/build/perf/util/syscalltbl.o
  INSTALL  trace_plugins
<SNIP>
  $ diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
  --- tools/perf/arch/x86/entry/syscalls/syscall_64.tbl	2018-08-13 15:49:50.896585176 -0300
  +++ arch/x86/entry/syscalls/syscall_64.tbl	2018-07-20 12:04:04.536858304 -0300
  @@ -342,6 +342,7 @@
   331	common	pkey_free		__x64_sys_pkey_free
   332	common	statx			__x64_sys_statx
   333	common	io_pgetevents		__x64_sys_io_pgetevents
  +334	common	rseq			__x64_sys_rseq

  #
  # x32-specific system call numbers start at 512 to avoid cache impact
  $
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180813111504.3568-2-jolsa@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      c9b51a01
    • Jiri Olsa's avatar
      perf tools: Make check-headers.sh check based on kernel dir · 7ea6e983
      Jiri Olsa authored 
      Changing the logic to compare files with paths relative to kernel source
base dir. This way we can keep the output message for 2 unrelated files,
which is coming in following patch.

Committer testing:

Remove a line from tools/arch/x86/lib/memcpy_64.S to have it detected:

make: Entering directory '/home/acme/git/perf/tools/perf'
  BUILD:   Doing 'make -j4' parallel build
Warning: Kernel ABI header at 'tools/arch/x86/lib/memcpy_64.S' differs from latest version at 'arch/x86/lib/memcpy_64.S'
diff -u tools/arch/x86/lib/memcpy_64.S arch/x86/lib/memcpy_64.S
  INSTALL  GTK UI
  INSTALL  binaries
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180813111504.3568-1-jolsa@kernel.org
Link: http://lkml.kernel.org/r/20180814072726.GA13931@krava
[ Do not use pushd/popd, its a bashism, reported by Michael Ellerman, fixed by Jiri Olsa ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      7ea6e983
  3. 13 Aug, 2018 25 commits
  5. 10 Aug, 2018 1 commit
  7. 09 Aug, 2018 1 commit
    • Sandipan Das's avatar
      perf probe powerpc: Fix trace event post-processing · 354b064b
      Sandipan Das authored 
      In some cases, a symbol may have multiple aliases. Attempting to add an
entry probe for such symbols results in a probe being added at an
incorrect location while it fails altogether for return probes. This is
only applicable for binaries with debug information.

During the arch-dependent post-processing, the offset from the start of
the symbol at which the probe is to be attached is determined and added
to the start address of the symbol to get the probe's location.  In case
there are multiple aliases, this offset gets added multiple times for
each alias of the symbol and we end up with an incorrect probe location.

This can be verified on a powerpc64le system as shown below.

  $ nm /lib/modules/$(uname -r)/build/vmlinux | grep "sys_open$"
  ...
  c000000000414290 T __se_sys_open
  c000000000414290 T sys_open

  $ objdump -d /lib/modules/$(uname -r)/build/vmlinux | grep -A 10 "<__se_sys_open>:"

  c000000000414290 <__se_sys_open>:
  c000000000414290:       19 01 4c 3c     addis   r2,r12,281
  c000000000414294:       70 c4 42 38     addi    r2,r2,-15248
  c000000000414298:       a6 02 08 7c     mflr    r0
  c00000000041429c:       e8 ff a1 fb     std     r29,-24(r1)
  c0000000004142a0:       f0 ff c1 fb     std     r30,-16(r1)
  c0000000004142a4:       f8 ff e1 fb     std     r31,-8(r1)
  c0000000004142a8:       10 00 01 f8     std     r0,16(r1)
  c0000000004142ac:       c1 ff 21 f8     stdu    r1,-64(r1)
  c0000000004142b0:       78 23 9f 7c     mr      r31,r4
  c0000000004142b4:       78 1b 7e 7c     mr      r30,r3

  For both the entry probe and the return probe, the probe location
  should be _text+4276888 (0xc000000000414298). Since another alias
  exists for 'sys_open', the post-processing code will end up adding
  the offset (8 for powerpc64le) twice and perf will attempt to add
  the probe at _text+4276896 (0xc0000000004142a0) instead.

Before:

  # perf probe -v -a sys_open

  probe-definition(0): sys_open
  symbol:sys_open file:(null) line:0 offset:0 return:0 lazy:(null)
  0 arguments
  Looking at the vmlinux_path (8 entries long)
  Using /lib/modules/4.18.0-rc8+/build/vmlinux for symbols
  Open Debuginfo file: /lib/modules/4.18.0-rc8+/build/vmlinux
  Try to find probe point from debuginfo.
  Symbol sys_open address found : c000000000414290
  Matched function: __se_sys_open [2ad03a0]
  Probe point found: __se_sys_open+0
  Found 1 probe_trace_events.
  Opening /sys/kernel/debug/tracing/kprobe_events write=1
  Writing event: p:probe/sys_open _text+4276896
  Added new event:
    probe:sys_open       (on sys_open)
  ...

  # perf probe -v -a sys_open%return $retval

  probe-definition(0): sys_open%return
  symbol:sys_open file:(null) line:0 offset:0 return:1 lazy:(null)
  0 arguments
  Looking at the vmlinux_path (8 entries long)
  Using /lib/modules/4.18.0-rc8+/build/vmlinux for symbols
  Open Debuginfo file: /lib/modules/4.18.0-rc8+/build/vmlinux
  Try to find probe point from debuginfo.
  Symbol sys_open address found : c000000000414290
  Matched function: __se_sys_open [2ad03a0]
  Probe point found: __se_sys_open+0
  Found 1 probe_trace_events.
  Opening /sys/kernel/debug/tracing/README write=0
  Opening /sys/kernel/debug/tracing/kprobe_events write=1
  Parsing probe_events: p:probe/sys_open _text+4276896
  Group:probe Event:sys_open probe:p
  Writing event: r:probe/sys_open__return _text+4276896
  Failed to write event: Invalid argument
    Error: Failed to add events. Reason: Invalid argument (Code: -22)

After:

  # perf probe -v -a sys_open

  probe-definition(0): sys_open
  symbol:sys_open file:(null) line:0 offset:0 return:0 lazy:(null)
  0 arguments
  Looking at the vmlinux_path (8 entries long)
  Using /lib/modules/4.18.0-rc8+/build/vmlinux for symbols
  Open Debuginfo file: /lib/modules/4.18.0-rc8+/build/vmlinux
  Try to find probe point from debuginfo.
  Symbol sys_open address found : c000000000414290
  Matched function: __se_sys_open [2ad03a0]
  Probe point found: __se_sys_open+0
  Found 1 probe_trace_events.
  Opening /sys/kernel/debug/tracing/kprobe_events write=1
  Writing event: p:probe/sys_open _text+4276888
  Added new event:
    probe:sys_open       (on sys_open)
  ...

  # perf probe -v -a sys_open%return $retval

  probe-definition(0): sys_open%return
  symbol:sys_open file:(null) line:0 offset:0 return:1 lazy:(null)
  0 arguments
  Looking at the vmlinux_path (8 entries long)
  Using /lib/modules/4.18.0-rc8+/build/vmlinux for symbols
  Open Debuginfo file: /lib/modules/4.18.0-rc8+/build/vmlinux
  Try to find probe point from debuginfo.
  Symbol sys_open address found : c000000000414290
  Matched function: __se_sys_open [2ad03a0]
  Probe point found: __se_sys_open+0
  Found 1 probe_trace_events.
  Opening /sys/kernel/debug/tracing/README write=0
  Opening /sys/kernel/debug/tracing/kprobe_events write=1
  Parsing probe_events: p:probe/sys_open _text+4276888
  Group:probe Event:sys_open probe:p
  Writing event: r:probe/sys_open__return _text+4276888
  Added new event:
    probe:sys_open__return (on sys_open%return)
  ...
Reported-by: default avatarAneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarSandipan Das <sandipan@linux.ibm.com>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Fixes: 99e608b5 ("perf probe ppc64le: Fix probe location when using DWARF")
Link: http://lkml.kernel.org/r/20180809161929.35058-1-sandipan@linux.ibm.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      354b064b
  9. 08 Aug, 2018 11 commits
    • Konstantin Khlebnikov's avatar
      perf map: Optimize maps__fixup_overlappings() · 6a9405b5
      Konstantin Khlebnikov authored 
      This function splits and removes overlapping areas.

Maps in tree are ordered by start address thus we could find first
overlap and stop if next map does not overlap.
Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/153365189407.435244.7234821822450484712.stgit@buzzSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      6a9405b5
    • Konstantin Khlebnikov's avatar
      perf map: Synthesize maps only for thread group leader · e5adfc3e
      Konstantin Khlebnikov authored 
      Threads share map_groups, all map events are merged into it.

Thus we could send mmaps only for thread group leader.  Otherwise it
took ages to attach and record something from processes with many vmas
and threads.

Thread group leader could be already dead, but it seems perf cannot
handle this case anyway.

Testing dummy:

  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/mman.h>
  #include <pthread.h>
  #include <unistd.h>

  void *thread(void *arg) {
          pause();
  }

  int main(int argc, char **argv) {
        int threads = 10000;
        int vmas = 50000;
        pthread_t th;
        for (int i = 0; i < threads; i++)
                pthread_create(&th, NULL, thread, NULL);
        for (int i = 0; i < vmas; i++)
                mmap(NULL, 4096, (i & 1) ? PROT_READ : PROT_WRITE,
                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
        sleep(60);
        return 0;
  }

Comment by Jiri Olsa:

We actualy synthesize the group leader (if we found one) for the thread
even if it's not present in the thread_map, so the process maps are
always in data.
Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/153363294102.396323.6277944760215058174.stgit@buzzSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      e5adfc3e
    • Arnaldo Carvalho de Melo's avatar
      perf trace: Wire up the augmented syscalls with the syscalls:sys_enter_FOO beautifier · 88cf7084
      Arnaldo Carvalho de Melo authored 
      We just check that the evsel is the one we associated with the
bpf-output event associated with the "__augmented_syscalls__" eBPF map,
to show that the formatting is done properly:

  # perf trace -e perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null
     0.000 (         ): __augmented_syscalls__:dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC
     0.006 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC
     0.007 ( 0.004 ms): cat/11486 openat(dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC                 ) = 3
     0.029 (         ): __augmented_syscalls__:dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC
     0.030 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC
     0.031 ( 0.004 ms): cat/11486 openat(dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC                 ) = 3
     0.249 (         ): __augmented_syscalls__:dfd: CWD, filename: 0xc3700d6
     0.250 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0xc3700d6
     0.252 ( 0.003 ms): cat/11486 openat(dfd: CWD, filename: 0xc3700d6                                  ) = 3
  #

Now we just need to get the full blown enter/exit handlers to check if the
evsel being processed is the augmented_syscalls one to go pick the pointer
payloads from the end of the payload.

We also need to state somehow what is the layout for multi pointer arg syscalls.

Also handy would be to have a BTF file with the struct definitions used in
syscalls, compact, generated at kernel built time and available for use in eBPF
programs.

Till we get there we can go on doing some manual coupling of the most relevant
syscalls with some hand built beautifiers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-r6ba5izrml82nwfmwcp7jpkm@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      88cf7084
    • Arnaldo Carvalho de Melo's avatar
      perf trace: Setup the augmented syscalls bpf-output event fields · d3d1c4bd
      Arnaldo Carvalho de Melo authored 
      The payload that is put in place by the eBPF script attached to
syscalls:sys_enter_openat (and other syscalls with pointers, in the
future) can be consumed by the existing sys_enter beautifiers if
evsel->priv is setup with a struct syscall_tp with struct tp_fields for
the 'syscall_id' and 'args' fields expected by the beautifiers, this
patch does just that.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-xfjyog8oveg2fjys9r1yy1es@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      d3d1c4bd
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Make bpf__setup_output_event() return the bpf-output event · 78e890ea
      Arnaldo Carvalho de Melo authored 
      We're calling it to setup that event, and we'll need it later to decide
if the bpf-output event we're handling is the one setup for a specific
purpose, return it using ERR_PTR, etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-zhachv7il2n1lopt9aonwhu7@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      78e890ea
    • Arnaldo Carvalho de Melo's avatar
      perf trace: Handle "bpf-output" events associated with "__augmented_syscalls__" BPF map · e0b6d2ef
      Arnaldo Carvalho de Melo authored 
      Add an example BPF script that writes syscalls:sys_enter_openat raw
tracepoint payloads augmented with the first 64 bytes of the "filename"
syscall pointer arg.

Then catch it and print it just like with things written to the
"__bpf_stdout__" map associated with a PERF_COUNT_SW_BPF_OUTPUT software
event, by just letting the default tracepoint handler in 'perf trace',
trace__event_handler(), to use bpf_output__fprintf(trace, sample), just
like it does with all other PERF_COUNT_SW_BPF_OUTPUT events, i.e. just
do a dump on the payload, so that we can check if what is being printed
has at least the first 64 bytes of the "filename" arg:

The augmented_syscalls.c eBPF script:

  # cat tools/perf/examples/bpf/augmented_syscalls.c
  // SPDX-License-Identifier: GPL-2.0

  #include <stdio.h>

  struct bpf_map SEC("maps") __augmented_syscalls__ = {
       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
       .key_size = sizeof(int),
       .value_size = sizeof(u32),
       .max_entries = __NR_CPUS__,
  };

  struct syscall_enter_openat_args {
	unsigned long long common_tp_fields;
	long		   syscall_nr;
	long		   dfd;
	char		   *filename_ptr;
	long		   flags;
	long		   mode;
  };

  struct augmented_enter_openat_args {
	struct syscall_enter_openat_args args;
	char				 filename[64];
  };

  int syscall_enter(openat)(struct syscall_enter_openat_args *args)
  {
	struct augmented_enter_openat_args augmented_args;

	probe_read(&augmented_args.args, sizeof(augmented_args.args), args);
	probe_read_str(&augmented_args.filename, sizeof(augmented_args.filename), args->filename_ptr);
	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU,
			  &augmented_args, sizeof(augmented_args));
	return 1;
  }

  license(GPL);
  #

So it will just prepare a raw_syscalls:sys_enter payload for the
"openat" syscall.

This will eventually be done for all syscalls with pointer args,
globally or just when the user asks, using some spec, which args of
which syscalls it wants "expanded" this way, we'll probably start with
just all the syscalls that have char * pointers with familiar names, the
ones we already handle with the probe:vfs_getname kprobe if it is in
place hooking the kernel getname_flags() function used to copy from user
the paths.

Running it we get:

  # perf trace -e perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null
     0.000 (         ): __augmented_syscalls__:X?.C......................`\..................../etc/ld.so.cache..#......,....ao.k...............k......1.".........
     0.006 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x5c600da8, flags: CLOEXEC
     0.008 ( 0.005 ms): cat/31292 openat(dfd: CWD, filename: 0x5c600da8, flags: CLOEXEC                 ) = 3
     0.036 (         ): __augmented_syscalls__:X?.C.......................\..................../lib64/libc.so.6......... .\....#........?.......=.C..../.".........
     0.037 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x5c808ce0, flags: CLOEXEC
     0.039 ( 0.007 ms): cat/31292 openat(dfd: CWD, filename: 0x5c808ce0, flags: CLOEXEC                 ) = 3
     0.323 (         ): __augmented_syscalls__:X?.C.....................P....................../etc/passwd......>.C....@................>.C.....,....ao.>.C........
     0.325 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0xe8be50d6
     0.327 ( 0.004 ms): cat/31292 openat(dfd: CWD, filename: 0xe8be50d6                                 ) = 3
  #

We need to go on optimizing this to avoid seding trash or zeroes in the
pointer content payload, using the return from bpf_probe_read_str(), but
to keep things simple at this stage and make incremental progress, lets
leave it at that for now.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-g360n1zbj6bkbk6q0qo11c28@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      e0b6d2ef
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Add wrappers to BPF_FUNC_probe_read(_str) functions · 8fa25f30
      Arnaldo Carvalho de Melo authored 
      Will be used shortly in the augmented syscalls work together with a
PERF_COUNT_SW_BPF_OUTPUT software event to insert syscalls + pointer
contents in the perf ring buffer, to be consumed by 'perf trace'
beautifiers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ajlkpz4cd688ulx1u30htkj3@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      8fa25f30
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Add bpf__setup_output_event() strerror() counterpart · aa31be3a
      Arnaldo Carvalho de Melo authored 
      That is just bpf__strerror_setup_stdout() renamed to the more general
"setup_output_event" method, keep the existing stdout() as a wrapper.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-nwnveo428qn0b48axj50vkc7@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      aa31be3a
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Generalize bpf__setup_stdout() · 92bbe8d8
      Arnaldo Carvalho de Melo authored 
      We will use it to set up other bpf-output events, for instance to
generate augmented syscall entry tracepoints with pointer contents.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4r7kw0nsyi4vyz6xm1tzx6a3@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      92bbe8d8
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Make bpf__for_each_stdout_map() generic · 5941d856
      Arnaldo Carvalho de Melo authored 
      By passing a 'name' arg, that will eventually be used to setup more
"bpf-output" events, e.g. to create a event where to create raw_syscalls
like events that in addition to the syscall arguments will also copy the
pointer contents being passed from/to userspace.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-talrnxps9p3qozk3aeh91fgv@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      5941d856
    • Arnaldo Carvalho de Melo's avatar
      perf bpf: Add bpf/stdio.h wrapper to bpf_perf_event_output function · 53a5d7b8
      Arnaldo Carvalho de Melo authored 
      That, together with the map __bpf_output__ that is already handled by
'perf trace' to print that event's contents as strings provides a
debugging facility, to show it in use, print a simple string everytime
the syscalls:sys_enter_openat() syscall tracepoint is hit:

  # cat tools/perf/examples/bpf/hello.c
  #include <stdio.h>

  int syscall_enter(openat)(void *args)
  {
	  puts("Hello, world\n");
	  return 0;
  }

  license(GPL);
  #
  # perf trace -e openat,tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
     0.016 (         ): __bpf_stdout__:Hello, world
     0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
     0.057 (         ): __bpf_stdout__:Hello, world
     0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
     0.417 (         ): __bpf_stdout__:Hello, world
     0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd) = 3
  #

This is part of an ongoing experimentation on making eBPF scripts as
consumed by perf to be as concise as possible and using familiar
concepts such as stdio.h functions, that end up just wrapping the
existing BPF functions, trying to hide as much boilerplate as possible
while using just conventions and C preprocessor tricks.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      53a5d7b8
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