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Namhyung Kim 4d7a8a44e0 perf tools: Handle old data in PERF_RECORD_ATTR 
commit 9bf63282ea upstream.

The PERF_RECORD_ATTR is used for a pipe mode to describe an event with
attribute and IDs.  The ID table comes after the attr and it calculate
size of the table using the total record size and the attr size.

  n_ids = (total_record_size - end_of_the_attr_field) / sizeof(u64)

This is fine for most use cases, but sometimes it saves the pipe output
in a file and then process it later.  And it becomes a problem if there
is a change in attr size between the record and report.

  $ perf record -o- > perf-pipe.data  # old version
  $ perf report -i- < perf-pipe.data  # new version

For example, if the attr size is 128 and it has 4 IDs, then it would
save them in 168 byte like below:

   8 byte: perf event header { .type = PERF_RECORD_ATTR, .size = 168 },
 128 byte: perf event attr { .size = 128, ... },
  32 byte: event IDs [] = { 1234, 1235, 1236, 1237 },

But when report later, it thinks the attr size is 136 then it only read
the last 3 entries as ID.

   8 byte: perf event header { .type = PERF_RECORD_ATTR, .size = 168 },
 136 byte: perf event attr { .size = 136, ... },
  24 byte: event IDs [] = { 1235, 1236, 1237 },  // 1234 is missing

So it should use the recorded version of the attr.  The attr has the
size field already then it should honor the size when reading data.

Fixes: 2c46dbb517 ("perf: Convert perf header attrs into attr events")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230825152552.112913-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-09-19 12:23:02 +02:00
arch MIPS: Fix CONFIG_CPU_DADDI_WORKAROUNDS `modules_install' regression 2023-09-19 12:23:02 +02:00
block block/partition: fix signedness issue for Amiga partitions 2023-07-23 13:47:37 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto X.509: if signature is unsupported skip validation 2023-09-19 12:22:52 +02:00
Documentation dt-bindings: clock: xlnx,versal-clk: drop select:false 2023-09-19 12:22:56 +02:00
drivers drm/amd/display: prevent potential division by zero errors 2023-09-19 12:23:02 +02:00
fs btrfs: use the correct superblock to compare fsid in btrfs_validate_super 2023-09-19 12:23:01 +02:00
include ip_tunnels: use DEV_STATS_INC() 2023-09-19 12:22:59 +02:00
init x86/mm: Initialize text poking earlier 2023-08-08 19:58:33 +02:00
io_uring io_uring: break iopolling on signal 2023-09-19 12:22:54 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel tracing: Zero the pipe cpumask on alloc to avoid spurious -EBUSY 2023-09-19 12:22:53 +02:00
lib lib: test_scanf: Add explicit type cast to result initialization in test_number_prefix() 2023-09-19 12:23:01 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/vmalloc: add a safer version of find_vm_area() for debug 2023-09-19 12:22:50 +02:00
net netfilter: nfnetlink_osf: avoid OOB read 2023-09-19 12:23:00 +02:00
samples samples/bpf: fix broken map lookup probe 2023-09-19 12:22:34 +02:00
scripts kconfig: fix possible buffer overflow 2023-09-19 12:22:56 +02:00
security smackfs: Prevent underflow in smk_set_cipso() 2023-09-19 12:22:39 +02:00
sound ALSA: pcm: Fix missing fixup call in compat hw_refine ioctl 2023-09-19 12:22:50 +02:00
tools perf tools: Handle old data in PERF_RECORD_ATTR 2023-09-19 12:23:02 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:22:40 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-26 14:23:27 +02:00
Makefile kbuild: do not run depmod for 'make modules_sign' 2023-09-19 12:22:56 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.