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  1. 15 2月, 2018 19 次提交
  3. 10 2月, 2018 1 次提交
  5. 09 2月, 2018 5 次提交
    • J
      tools/libbpf: handle issues with bpf ELF objects containing .eh_frames · e3d91b0c
      由 Jesper Dangaard Brouer 提交于 
      V3: More generic skipping of relo-section (suggested by Daniel)

If clang >= 4.0.1 is missing the option '-target bpf', it will cause
llc/llvm to create two ELF sections for "Exception Frames", with
section names '.eh_frame' and '.rel.eh_frame'.

The BPF ELF loader library libbpf fails when loading files with these
sections.  The other in-kernel BPF ELF loader in samples/bpf/bpf_load.c,
handle this gracefully. And iproute2 loader also seems to work with these
"eh" sections.

The issue in libbpf is caused by bpf_object__elf_collect() skipping
some sections, and later when performing relocation it will be
pointing to a skipped section, as these sections cannot be found by
bpf_object__find_prog_by_idx() in bpf_object__collect_reloc().

This is a general issue that also occurs for other sections, like
debug sections which are also skipped and can have relo section.

As suggested by Daniel.  To avoid keeping state about all skipped
sections, instead perform a direct qlookup in the ELF object.  Lookup
the section that the relo-section points to and check if it contains
executable machine instructions (denoted by the sh_flags
SHF_EXECINSTR).  Use this check to also skip irrelevant relo-sections.

Note, for samples/bpf/ the '-target bpf' parameter to clang cannot be used
due to incompatibility with asm embedded headers, that some of the samples
include. This is explained in more details by Yonghong Song in bpf_devel_QA.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      e3d91b0c
    • J
      selftests/bpf: add selftest that use test_libbpf_open · f09b2e38
      由 Jesper Dangaard Brouer 提交于 
      This script test_libbpf.sh will be part of the 'make run_tests'
invocation, but can also be invoked manually in this directory,
and a verbose mode can be enabled via setting the environment
variable $VERBOSE like:

 $ VERBOSE=yes ./test_libbpf.sh

The script contains some tests that are commented out, as they
currently fail.  They are reminders about what we need to improve
for the libbpf loader library.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      f09b2e38
    • J
      selftests/bpf: add test program for loading BPF ELF files · 864db336
      由 Jesper Dangaard Brouer 提交于 
      V2: Moved program into selftests/bpf from tools/libbpf

This program can be used on its own for testing/debugging if a
BPF ELF-object file can be loaded with libbpf (from tools/lib/bpf).

If something is wrong with the ELF object, the program have
a --debug mode that will display the ELF sections and especially
the skipped sections.  This allows for quickly identifying the
problematic ELF section number, which can be corrolated with the
readelf tool.

The program signal error via return codes, and also have
a --quiet mode, which is practical for use in scripts like
selftests/bpf.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      864db336
    • J
      tools/libbpf: improve the pr_debug statements to contain section numbers · 077c066a
      由 Jesper Dangaard Brouer 提交于 
      While debugging a bpf ELF loading issue, I needed to correlate the
ELF section number with the failed relocation section reference.
Thus, add section numbers/index to the pr_debug.

In debug mode, also print section that were skipped.  This helped
me identify that a section (.eh_frame) was skipped, and this was
the reason the relocation section (.rel.eh_frame) could not find
that section number.

The section numbers corresponds to the readelf tools Section Headers [Nr].
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      077c066a
    • J
      bpf: Sync kernel ABI header with tooling header for bpf_common.h · 8c88181e
      由 Jesper Dangaard Brouer 提交于 
      I recently fixed up a lot of commits that forgot to keep the tooling
headers in sync.  And then I forgot to do the same thing in commit
cb5f7334 ("bpf: add comments to BPF ld/ldx sizes"). Let correct
that before people notice ;-).

Lawrence did partly fix/sync this for bpf.h in commit d6d4f60c
("bpf: add selftest for tcpbpf").

Fixes: cb5f7334 ("bpf: add comments to BPF ld/ldx sizes")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
      8c88181e
  7. 08 2月, 2018 10 次提交
  9. 07 2月, 2018 5 次提交
    • C
      lib: optimize cpumask_next_and() · 0ade34c3
      由 Clement Courbet 提交于 
      We've measured that we spend ~0.6% of sys cpu time in cpumask_next_and().
It's essentially a joined iteration in search for a non-zero bit, which is
currently implemented as a lookup join (find a nonzero bit on the lhs,
lookup the rhs to see if it's set there).

Implement a direct join (find a nonzero bit on the incrementally built
join).  Also add generic bitmap benchmarks in the new `test_find_bit`
module for new function (see `find_next_and_bit` in [2] and [3] below).

For cpumask_next_and, direct benchmarking shows that it's 1.17x to 14x
faster with a geometric mean of 2.1 on 32 CPUs [1].  No impact on memory
usage.  Note that on Arm, the new pure-C implementation still outperforms
the old one that uses a mix of C and asm (`find_next_bit`) [3].

[1] Approximate benchmark code:

```
  unsigned long src1p[nr_cpumask_longs] = {pattern1};
  unsigned long src2p[nr_cpumask_longs] = {pattern2};
  for (/*a bunch of repetitions*/) {
    for (int n = -1; n <= nr_cpu_ids; ++n) {
      asm volatile("" : "+rm"(src1p)); // prevent any optimization
      asm volatile("" : "+rm"(src2p));
      unsigned long result = cpumask_next_and(n, src1p, src2p);
      asm volatile("" : "+rm"(result));
    }
  }
```

Results:
pattern1    pattern2     time_before/time_after
0x0000ffff  0x0000ffff   1.65
0x0000ffff  0x00005555   2.24
0x0000ffff  0x00001111   2.94
0x0000ffff  0x00000000   14.0
0x00005555  0x0000ffff   1.67
0x00005555  0x00005555   1.71
0x00005555  0x00001111   1.90
0x00005555  0x00000000   6.58
0x00001111  0x0000ffff   1.46
0x00001111  0x00005555   1.49
0x00001111  0x00001111   1.45
0x00001111  0x00000000   3.10
0x00000000  0x0000ffff   1.18
0x00000000  0x00005555   1.18
0x00000000  0x00001111   1.17
0x00000000  0x00000000   1.25
-----------------------------
               geo.mean  2.06

[2] test_find_next_bit, X86 (skylake)

 [ 3913.477422] Start testing find_bit() with random-filled bitmap
 [ 3913.477847] find_next_bit: 160868 cycles, 16484 iterations
 [ 3913.477933] find_next_zero_bit: 169542 cycles, 16285 iterations
 [ 3913.478036] find_last_bit: 201638 cycles, 16483 iterations
 [ 3913.480214] find_first_bit: 4353244 cycles, 16484 iterations
 [ 3913.480216] Start testing find_next_and_bit() with random-filled
 bitmap
 [ 3913.481074] find_next_and_bit: 89604 cycles, 8216 iterations
 [ 3913.481075] Start testing find_bit() with sparse bitmap
 [ 3913.481078] find_next_bit: 2536 cycles, 66 iterations
 [ 3913.481252] find_next_zero_bit: 344404 cycles, 32703 iterations
 [ 3913.481255] find_last_bit: 2006 cycles, 66 iterations
 [ 3913.481265] find_first_bit: 17488 cycles, 66 iterations
 [ 3913.481266] Start testing find_next_and_bit() with sparse bitmap
 [ 3913.481272] find_next_and_bit: 764 cycles, 1 iterations

[3] test_find_next_bit, arm (v7 odroid XU3).

[  267.206928] Start testing find_bit() with random-filled bitmap
[  267.214752] find_next_bit: 4474 cycles, 16419 iterations
[  267.221850] find_next_zero_bit: 5976 cycles, 16350 iterations
[  267.229294] find_last_bit: 4209 cycles, 16419 iterations
[  267.279131] find_first_bit: 1032991 cycles, 16420 iterations
[  267.286265] Start testing find_next_and_bit() with random-filled
bitmap
[  267.302386] find_next_and_bit: 2290 cycles, 8140 iterations
[  267.309422] Start testing find_bit() with sparse bitmap
[  267.316054] find_next_bit: 191 cycles, 66 iterations
[  267.322726] find_next_zero_bit: 8758 cycles, 32703 iterations
[  267.329803] find_last_bit: 84 cycles, 66 iterations
[  267.336169] find_first_bit: 4118 cycles, 66 iterations
[  267.342627] Start testing find_next_and_bit() with sparse bitmap
[  267.356919] find_next_and_bit: 91 cycles, 1 iterations

[courbet@google.com: v6]
  Link: http://lkml.kernel.org/r/20171129095715.23430-1-courbet@google.com
[geert@linux-m68k.org: m68k/bitops: always include <asm-generic/bitops/find.h>]
  Link: http://lkml.kernel.org/r/1512556816-28627-1-git-send-email-geert@linux-m68k.org
Link: http://lkml.kernel.org/r/20171128131334.23491-1-courbet@google.comSigned-off-by: NClement Courbet <courbet@google.com>
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0ade34c3
    • S
      tools/lib/subcmd/pager.c: do not alias select() params · ad343a98
      由 Sergey Senozhatsky 提交于 
      Use a separate fd set for select()-s exception fds param to fix the
following gcc warning:

  pager.c:36:12: error: passing argument 2 to restrict-qualified parameter aliases with argument 4 [-Werror=restrict]
    select(1, &in, NULL, &in, NULL);
              ^~~        ~~~

Link: http://lkml.kernel.org/r/20180101105626.7168-1-sergey.senozhatsky@gmail.comSigned-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ad343a98
    • M
      idr: Make 1-based IDRs more efficient · 6ce711f2
      由 Matthew Wilcox 提交于 
      About 20% of the IDR users in the kernel want the allocated IDs to start
at 1.  The implementation currently searches all the way down the left
hand side of the tree, finds no free ID other than ID 0, walks all the
way back up, and then all the way down again.  This patch 'rebases' the
ID so we fill the entire radix tree, rather than leave a gap at 0.

Chris Wilson says: "I did the quick hack of allocating index 0 of the
idr and that eradicated idr_get_free() from being at the top of the
profiles for the many-object stress tests. This improvement will be
much appreciated."
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
      6ce711f2
    • M
      idr: Remove idr_alloc_ext · 460488c5
      由 Matthew Wilcox 提交于 
      It has no more users, so remove it.  Move idr_alloc() back into idr.c,
move the guts of idr_alloc_cmn() into idr_alloc_u32(), remove the
wrappers around idr_get_free_cmn() and rename it to idr_get_free().
While there is now no interface to allocate IDs larger than a u32,
the IDR internals remain ready to handle a larger ID should a need arise.

These changes make it possible to provide the guarantee that, if the
nextid pointer points into the object, the object's ID will be initialised
before a concurrent lookup can find the object.
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
      460488c5
    • M
      IDR test suite: Check handling negative end correctly · 6e6d3014
      由 Matthew Wilcox 提交于 
      One of the charming quirks of the idr_alloc() interface is that you
can pass a negative end and it will be interpreted as "maximum".  Ensure
we don't break that.
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
      6e6d3014