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Adrian Hunter ad67f97b8b perf/core: Fix address filter match with backing files 
commit ebfc8542ad upstream.

It was reported that Intel PT address filters do not work in Docker
containers.  That relates to the use of overlayfs.

overlayfs records the backing file in struct vm_area_struct vm_file,
instead of the user file that the user mmapped.  In order for an address
filter to match, it must compare to the user file inode.  There is an
existing helper file_user_inode() for that situation.

Use file_user_inode() instead of file_inode() to get the inode for address
filter matching.

Example:

  Setup:

    # cd /root
    # mkdir test ; cd test ; mkdir lower upper work merged
    # cp `which cat` lower
    # mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merged
    # perf record --buildid-mmap -e intel_pt//u --filter 'filter * @ /root/test/merged/cat' -- /root/test/merged/cat /proc/self/maps
    ...
    55d61d246000-55d61d2e1000 r-xp 00018000 00:1a 3418                       /root/test/merged/cat
    ...
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.015 MB perf.data ]
    # perf buildid-cache --add /root/test/merged/cat

  Before:

    Address filter does not match so there are no control flow packets

    # perf script --itrace=e
    # perf script --itrace=b | wc -l
    0
    # perf script -D | grep 'TIP.PGE' | wc -l
    0
    #

  After:

    Address filter does match so there are control flow packets

    # perf script --itrace=e
    # perf script --itrace=b | wc -l
    235
    # perf script -D | grep 'TIP.PGE' | wc -l
    57
    #

With respect to stable kernels, overlayfs mmap function ovl_mmap() was
added in v4.19 but file_user_inode() was not added until v6.8 and never
back-ported to stable kernels.  FMODE_BACKING that it depends on was added
in v6.5.  This issue has gone largely unnoticed, so back-porting before
v6.8 is probably not worth it, so put 6.8 as the stable kernel prerequisite
version, although in practice the next long term kernel is 6.12.

Closes: https://lore.kernel.org/linux-perf-users/aBCwoq7w8ohBRQCh@fremen.lan
Reported-by: Edd Barrett <edd@theunixzoo.co.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Cc: stable@vger.kernel.org # 6.8
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-10-23 16:24:25 +02:00
arch KVM: arm64: Prevent access to vCPU events before init 2025-10-23 16:24:22 +02:00
block blk-crypto: fix missing blktrace bio split events 2025-10-19 16:37:23 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: essiv - Check ssize for decryption and in-place encryption 2025-10-19 16:37:14 +02:00
Documentation docs: kdoc: handle the obsolescensce of docutils.ErrorString() 2025-10-23 16:24:19 +02:00
drivers drm/xe: Increase global invalidation timeout to 1000us 2025-10-23 16:24:25 +02:00
fs cifs: parse_dfs_referrals: prevent oob on malformed input 2025-10-23 16:24:24 +02:00
include ata: libata-core: relax checks in ata_read_log_directory() 2025-10-23 16:24:20 +02:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:37:27 +02:00
io_uring io_uring: protect mem region deregistration 2025-10-23 16:24:22 +02:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel perf/core: Fix address filter match with backing files 2025-10-23 16:24:25 +02:00
lib lib/genalloc: fix device leak in of_gen_pool_get() 2025-10-19 16:37:28 +02:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm slab: reset slab->obj_ext when freeing and it is OBJEXTS_ALLOC_FAIL 2025-10-23 16:24:21 +02:00
net mptcp: reset blackhole on success with non-loopback ifaces 2025-10-19 16:37:36 +02:00
rust cpufreq: Make drivers using CPUFREQ_ETERNAL specify transition latency 2025-10-19 16:37:00 +02:00
samples 15 hotfixes. 11 are cc:stable and the remainder address post-6.16 issues 2025-09-17 21:34:26 -07:00
scripts kbuild: Add '.rel.*' strip pattern for vmlinux 2025-10-19 16:37:15 +02:00
security KEYS: trusted_tpm1: Compare HMAC values in constant time 2025-10-19 16:37:28 +02:00
sound ALSA: hda: Fix missing pointer check in hda_component_manager_init function 2025-10-23 16:24:25 +02:00
tools selftests: mptcp: join: validate C-flag + def limit 2025-10-19 16:37:36 +02:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore gitignore: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: retire Boris from TLS maintainers 2025-08-26 17:36:01 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
Makefile Linux 6.17.4 2025-10-19 16:37:45 +02:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.