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Eduard Zingerman 6fcd4977c0 selftests/bpf: Fix backtrace printing for selftests crashes 
[ Upstream commit 5bf1557e3d ]

test_progs uses glibc specific functions backtrace() and
backtrace_symbols_fd() to print backtrace in case of SIGSEGV.

Recent commit (see fixes) updated test_progs.c to define stub versions
of the same functions with attriubte "weak" in order to allow linking
test_progs against musl libc. Unfortunately this broke the backtrace
handling for glibc builds.

As it turns out, glibc defines backtrace() and backtrace_symbols_fd()
as weak:

  $ llvm-readelf --symbols /lib64/libc.so.6 \
     | grep -P '( backtrace_symbols_fd| backtrace)$'
  4910: 0000000000126b40   161 FUNC    WEAK   DEFAULT    16 backtrace
  6843: 0000000000126f90   852 FUNC    WEAK   DEFAULT    16 backtrace_symbols_fd

So does test_progs:

 $ llvm-readelf --symbols test_progs \
    | grep -P '( backtrace_symbols_fd| backtrace)$'
  2891: 00000000006ad190    15 FUNC    WEAK   DEFAULT    13 backtrace
 11215: 00000000006ad1a0    41 FUNC    WEAK   DEFAULT    13 backtrace_symbols_fd

In such situation dynamic linker is not obliged to favour glibc
implementation over the one defined in test_progs.

Compiling with the following simple modification to test_progs.c
demonstrates the issue:

  $ git diff
  ...
  \--- a/tools/testing/selftests/bpf/test_progs.c
  \+++ b/tools/testing/selftests/bpf/test_progs.c
  \@@ -1817,6 +1817,7 @@ int main(int argc, char **argv)
          if (err)
                  return err;

  +       *(int *)0xdeadbeef  = 42;
          err = cd_flavor_subdir(argv[0]);
          if (err)
                  return err;

  $ ./test_progs
  [0]: Caught signal #11!
  Stack trace:
  <backtrace not supported>
  Segmentation fault (core dumped)

Resolve this by hiding stub definitions behind __GLIBC__ macro check
instead of using "weak" attribute.

Fixes: c9a83e76b5 ("selftests/bpf: Fix compile if backtrace support missing in libc")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Tony Ambardar <tony.ambardar@gmail.com>
Reviewed-by: Tony Ambardar <tony.ambardar@gmail.com>
Acked-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/bpf/20241003210307.3847907-1-eddyz87@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-12-05 14:01:42 +01:00
arch arm64: dts: rockchip: correct analog audio name on Indiedroid Nova 2024-12-05 14:01:35 +01:00
block block: fix bio_split_rw_at to take zone_write_granularity into account 2024-12-05 14:01:14 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-05 14:01:18 +01:00
Documentation ASoC: dt-bindings: mt6359: Update generic node name and dmic-mode 2024-12-05 14:01:39 +01:00
drivers wifi: ath12k: fix one more memcpy size error 2024-12-05 14:01:42 +01:00
fs dlm: fix swapped args sb_flags vs sb_status 2024-12-05 14:01:41 +01:00
include platform/x86/intel/pmt: allow user offset for PMT callbacks 2024-12-05 14:01:35 +01:00
init initramfs: avoid filename buffer overrun 2024-12-05 14:01:12 +01:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel sched_ext: scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context 2024-12-05 14:01:35 +01:00
lib objpool: fix to make percpu slot allocation more robust 2024-11-07 14:14:58 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/mmap: fix __mmap_region() error handling in rare merge failure case 2024-11-22 15:30:26 +01:00
net hv_sock: Initializing vsk->trans to NULL to prevent a dangling pointer 2024-11-22 15:30:25 +01:00
rust rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT 2024-12-05 14:01:23 +01:00
samples bpf: Fix the xdp_adjust_tail sample prog issue 2024-12-05 14:01:42 +01:00
scripts kernel-doc: allow object-like macros in ReST output 2024-12-05 14:01:28 +01:00
security integrity-v6.12 2024-11-12 13:06:31 -08:00
sound ASoC: amd: acp: fix for cpu dai index logic 2024-12-05 14:01:41 +01:00
tools selftests/bpf: Fix backtrace printing for selftests crashes 2024-12-05 14:01:42 +01:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +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 Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.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: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: appoint myself the XFS maintainer for 6.12 LTS 2024-12-05 14:01:10 +01:00
Makefile Linux 6.12.1 2024-11-22 15:30:26 +01:00
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.