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Ard Biesheuvel 73cfc53cc3 objtool: Fix C jump table annotations for Clang
A C jump table (such as the one used by the BPF interpreter) is a const
global array of absolute code addresses, and this means that the actual
values in the table may not be known until the kernel is booted (e.g.,
when using KASLR or when the kernel VA space is sized dynamically).

When using PIE codegen, the compiler will default to placing such const
global objects in .data.rel.ro (which is annotated as writable), rather
than .rodata (which is annotated as read-only). As C jump tables are
explicitly emitted into .rodata, this used to result in warnings for
LoongArch builds (which uses PIE codegen for the entire kernel) like

  Warning: setting incorrect section attributes for .rodata..c_jump_table

due to the fact that the explicitly specified .rodata section inherited
the read-write annotation that the compiler uses for such objects when
using PIE codegen.

This warning was suppressed by explicitly adding the read-only
annotation to the __attribute__((section(""))) string, by commit

  c5b1184dec ("compiler.h: specify correct attribute for .rodata..c_jump_table")

Unfortunately, this hack does not work on Clang's integrated assembler,
which happily interprets the appended section type and permission
specifiers as part of the section name, which therefore no longer
matches the hard-coded pattern '.rodata..c_jump_table' that objtool
expects, causing it to emit a warning

  kernel/bpf/core.o: warning: objtool: ___bpf_prog_run+0x20: sibling call from callable instruction with modified stack frame

Work around this, by emitting C jump tables into .data.rel.ro instead,
which is treated as .rodata by the linker script for all builds, not
just PIE based ones.

Fixes: c5b1184dec ("compiler.h: specify correct attribute for .rodata..c_jump_table")
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn> # on LoongArch
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250221135704.431269-6-ardb+git@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-25 09:46:16 -08:00
arch sh updates for v6.14 2025-02-02 10:40:27 -08:00
block block-6.14-20250131 2025-01-31 11:49:30 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
Documentation 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
drivers 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
fs assorted stuff for this merge window 2025-02-01 15:07:56 -08:00
include objtool: Fix C jump table annotations for Clang 2025-02-25 09:46:16 -08:00
init Kbuild updates for v6.14 2025-01-31 12:07:07 -08:00
io_uring io_uring-6.14-20250131 2025-01-31 11:29:23 -08:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
lib 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm assorted stuff for this merge window 2025-02-01 15:07:56 -08:00
net assorted stuff for this merge window 2025-02-01 15:07:56 -08:00
rust Kbuild updates for v6.14 2025-01-31 12:07:07 -08:00
samples AT_EXECVE_CHECK update for v6.14-rc1 (fix1) 2025-01-31 17:12:31 -08:00
scripts 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
security treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
sound sound fixes for 6.14-rc1 2025-01-31 09:17:02 -08:00
tools objtool: Fix C jump table annotations for Clang 2025-02-25 09:46:16 -08:00
usr kbuild: Drop support for include/asm-<arch> in headers_check.pl 2024-12-21 11:43:17 +09:00
virt Merge branch 'kvm-mirror-page-tables' into HEAD 2025-01-20 07:15:58 -05:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.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: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: use host dylib naming convention to support macOS 2025-01-10 01:01:24 +01:00
.mailmap 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -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 Mainly individually changelogged singleton patches. The patch series in 2025-01-26 17:50:53 -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 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -08:00
Makefile Linux 6.14-rc1 2025-02-02 15:39:26 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.