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  • Ermine Ermine
1 author
  1. Nov 01, 2023
  3. Oct 30, 2023
  5. Oct 28, 2023
  7. Oct 27, 2023
  9. Oct 25, 2023
  11. Oct 23, 2023
    • Will Deacon's avatar
      scripts/faddr2line: Skip over mapping symbols in output from readelf · 60fd39af
      Will Deacon authored 
      
Mapping symbols emitted in the readelf output can confuse the
'faddr2line' symbol size calculation, resulting in the erroneous
rejection of valid offsets. This is especially prevalent when building
an arm64 kernel with CONFIG_CFI_CLANG=y, where most functions are
prefixed with a 32-bit data value in a '$d.n' section. For example:

447538: ffff800080014b80   548 FUNC    GLOBAL DEFAULT    2 do_one_initcall
   104: ffff800080014c74     0 NOTYPE  LOCAL  DEFAULT    2 $x.73
   106: ffff800080014d30     0 NOTYPE  LOCAL  DEFAULT    2 $x.75
   111: ffff800080014da4     0 NOTYPE  LOCAL  DEFAULT    2 $d.78
   112: ffff800080014da8     0 NOTYPE  LOCAL  DEFAULT    2 $x.79
    36: ffff800080014de0   200 FUNC    LOCAL  DEFAULT    2 run_init_process

Adding a warning to do_one_initcall() results in:

  | WARNING: CPU: 0 PID: 1 at init/main.c:1236 do_one_initcall+0xf4/0x260

Which 'faddr2line' refuses to accept:

$ ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260
skipping do_one_initcall address at 0xffff800080014c74 due to size mismatch (0x260 != 0x224)
no match for do_one_initcall+0xf4/0x260

Filter out these entries from readelf using a shell reimplementation of
is_mapping_symbol(), so that the size of a symbol is calculated as a
delta to the next symbol present in ksymtab.

Suggested-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20231002165750.1661-4-will@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
      60fd39af
    • Will Deacon's avatar
      scripts/faddr2line: Use LLVM addr2line and readelf if LLVM=1 · 86bf86e1
      Will Deacon authored 
      
GNU utilities cannot necessarily parse objects built by LLVM, which can
result in confusing errors when using 'faddr2line':

$ CROSS_COMPILE=aarch64-linux-gnu- ./scripts/faddr2line vmlinux do_one_initcall+0xf4/0x260
aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn'
aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25
do_one_initcall+0xf4/0x260:
aarch64-linux-gnu-addr2line: vmlinux: unknown type [0x13] section `.relr.dyn'
aarch64-linux-gnu-addr2line: DWARF error: invalid or unhandled FORM value: 0x25
$x.73 at main.c:?

Although this can be worked around by setting CROSS_COMPILE to "llvm=-",
it's cleaner to follow the same syntax as the top-level Makefile and
accept LLVM= as an indication to use the llvm- tools, optionally
specifying their location or specific version number.

Suggested-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20231002165750.1661-3-will@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
      86bf86e1
    • Will Deacon's avatar
      scripts/faddr2line: Don't filter out non-function symbols from readelf · 180af1a5
      Will Deacon authored 
      
As Josh points out in 20230724234734.zy67gm674vl3p3wv@treble:

> Problem is, I think the kernel's symbol printing code prints the
> nearest kallsyms symbol, and there are some valid non-FUNC code
> symbols.  For example, syscall_return_via_sysret.

so we shouldn't be considering only 'FUNC'-type symbols in the output
from readelf.

Drop the function symbol type filtering from the faddr2line outer loop.

Suggested-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230724234734.zy67gm674vl3p3wv@treble


Signed-off-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20231002165750.1661-2-will@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
      180af1a5
    • Yujie Liu's avatar
      scripts/kernel-doc: match -Werror flag strictly · 91f950e8
      Yujie Liu authored 
      
In our CI testing, we use some commands as below to only turn a specific
type of warnings into errors, but we notice that kernel-doc warnings
are also turned into errors unexpectedly.

$ make KCFLAGS="-Werror=return-type" W=1 kernel/fork.o

kernel/fork.c:1406: warning: Function parameter or member 'mm' not described in 'set_mm_exe_file'
kernel/fork.c:1406: warning: Function parameter or member 'new_exe_file' not described in 'set_mm_exe_file'
kernel/fork.c:1441: warning: Function parameter or member 'mm' not described in 'replace_mm_exe_file'
kernel/fork.c:1441: warning: Function parameter or member 'new_exe_file' not described in 'replace_mm_exe_file'
kernel/fork.c:1491: warning: Function parameter or member 'mm' not described in 'get_mm_exe_file'
kernel/fork.c:1510: warning: Function parameter or member 'task' not described in 'get_task_exe_file'
kernel/fork.c:1534: warning: Function parameter or member 'task' not described in 'get_task_mm'
kernel/fork.c:2109: warning: bad line:
kernel/fork.c:2130: warning: Function parameter or member 'ret' not described in '__pidfd_prepare'
kernel/fork.c:2130: warning: Excess function parameter 'pidfd' description in '__pidfd_prepare'
kernel/fork.c:2179: warning: Function parameter or member 'ret' not described in 'pidfd_prepare'
kernel/fork.c:2179: warning: Excess function parameter 'pidfd' description in 'pidfd_prepare'
kernel/fork.c:3195: warning: expecting prototype for clone3(). Prototype was for sys_clone3() instead
13 warnings as Errors
make[3]: *** [scripts/Makefile.build:243: kernel/fork.o] Error 13
make[3]: *** Deleting file 'kernel/fork.o'
make[2]: *** [scripts/Makefile.build:480: kernel] Error 2
make[1]: *** [/root/linux/Makefile:1913: .] Error 2
make: *** [Makefile:234: __sub-make] Error 2

>From the git history, commit 2c12c810 ("scripts/kernel-doc:
optionally treat warnings as errors") introduces a new command-line
option to make kernel-doc warnings into errors. It can also read the
KCFLAGS environment variable to decide whether to turn this option on,
but the regex used for matching may not be accurate enough. It can match
both "-Werror" and "-Werror=<diagnostic-type>", so the option is turned
on by mistake in the latter case.

Fix this by strictly matching the flag "-Werror": there must be a space
or start of string in the front, and a space or end of string at the
end. This can handle all the following cases correctly:

KCFLAGS="-Werror" make W=1 [MATCH]
KCFLAGS="-Werror=return-type" make W=1 [NO MATCH]
KCFLAGS="-Wcomment -Werror -Wundef" make W=1 [MATCH]
KCFLAGS="-Wcomment -Werror=return-type -Wundef" make W=1 [NO MATCH]

Fixes: 2c12c810 ("scripts/kernel-doc: optionally treat warnings as errors")
Signed-off-by: default avatarYujie Liu <yujie.liu@intel.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
Message-ID: <20231019095637.2471840-1-yujie.liu@intel.com>
      91f950e8
  13. Oct 21, 2023
  15. Oct 20, 2023
  17. Oct 18, 2023
  19. Oct 15, 2023
    • Miguel Ojeda's avatar
      rust: upgrade to Rust 1.73.0 · e08ff622
      Miguel Ojeda authored 
      This is the next upgrade to the Rust toolchain, from 1.72.1 to 1.73.0
(i.e. the latest) [1].

See the upgrade policy [2] and the comments on the first upgrade in
commit 3ed03f4d ("rust: upgrade to Rust 1.68.2").

# Unstable features

No unstable features (that we use) were stabilized.

Therefore, the only unstable feature allowed to be used outside
the `kernel` crate is still `new_uninit`, though other code to be
upstreamed may increase the list.

Please see [3] for details.

# Required changes

For the upgrade, the following changes are required:

  - Allow `internal_features` for `feature(compiler_builtins)` since
    now Rust warns about using internal compiler and standard library
    features (similar to how it also warns about incomplete ones) [4].

  - A cleanup for a documentation link thanks to a new `rustdoc` lint.
    See previous commits for details.

  - A need to make an intra-doc link to a macro explicit, due to a
    change in behavior in `rustdoc`. See previous commits for details.

# `alloc` upgrade and reviewing

The vast majority of changes are due to our `alloc` fork being upgraded
at once.

There are two kinds of changes to be aware of: the ones coming from
upstream, which we should follow as closely as possible, and the updates
needed in our added fallible APIs to keep them matching the newer
infallible APIs coming from upstream.

Instead of taking a look at the diff of this patch, an alternative
approach is reviewing a diff of the changes between upstream `alloc` and
the kernel's. This allows to easily inspect the kernel additions only,
especially to check if the fallible methods we already have still match
the infallible ones in the new version coming from upstream.

Another approach is reviewing the changes introduced in the additions in
the kernel fork between the two versions. This is useful to spot
potentially unintended changes to our additions.

To apply these approaches, one may follow steps similar to the following
to generate a pair of patches that show the differences between upstream
Rust and the kernel (for the subset of `alloc` we use) before and after
applying this patch:

    # Get the difference with respect to the old version.
    git -C rust checkout $(linux/scripts/min-tool-version.sh rustc)
    git -C linux ls-tree -r --name-only HEAD -- rust/alloc |
        cut -d/ -f3- |
        grep -Fv README.md |
        xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH
    git -C linux diff --patch-with-stat --summary -R > old.patch
    git -C linux restore rust/alloc

    # Apply this patch.
    git -C linux am rust-upgrade.patch

    # Get the difference with respect to the new version.
    git -C rust checkout $(linux/scripts/min-tool-version.sh rustc)
    git -C linux ls-tree -r --name-only HEAD -- rust/alloc |
        cut -d/ -f3- |
        grep -Fv README.md |
        xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH
    git -C linux diff --patch-with-stat --summary -R > new.patch
    git -C linux restore rust/alloc

Now one may check the `new.patch` to take a look at the additions (first
approach) or at the difference between those two patches (second
approach). For the latter, a side-by-side tool is recommended.

Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1730-2023-10-05 [1]
Link: https://rust-for-linux.com/rust-version-policy [2]
Link: https://github.com/Rust-for-Linux/linux/issues/2 [3]
Link: https://github.com/rust-lang/compiler-team/issues/596

 [4]
Reviewed-by: default avatarMartin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: default avatarVincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231005210556.466856-4-ojeda@kernel.org


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
      e08ff622
  21. Oct 14, 2023