linux-stable.git/tools/objtool, branch v6.18.26

x86-64: rename misleadingly named '__copy_user_nocache()' function

2026-04-22T11:22:31+00:00

commit d187a86de793f84766ea40b9ade7ac60aabbb4fe upstream.

This function was a masterclass in bad naming, for various historical
reasons.

It claimed to be a non-cached user copy.  It is literally _neither_ of
those things.  It's a specialty memory copy routine that uses
non-temporal stores for the destination (but not the source), and that
does exception handling for both source and destination accesses.

Also note that while it works for unaligned targets, any unaligned parts
(whether at beginning or end) will not use non-temporal stores, since
only words and quadwords can be non-temporal on x86.

The exception handling means that it _can_ be used for user space
accesses, but not on its own - it needs all the normal "start user space
access" logic around it.

But typically the user space access would be the source, not the
non-temporal destination.  That was the original intention of this,
where the destination was some fragile persistent memory target that
needed non-temporal stores in order to catch machine check exceptions
synchronously and deal with them gracefully.

Thus that non-descriptive name: one use case was to copy from user space
into a non-cached kernel buffer.  However, the existing users are a mix
of that intended use-case, and a couple of random drivers that just did
this as a performance tweak.

Some of those random drivers then actively misused the user copying
version (with STAC/CLAC and all) to do kernel copies without ever even
caring about the exception handling, _just_ for the non-temporal
destination.

Rename it as a first small step to actually make it halfway sane, and
change the prototype to be more normal: it doesn't take a user pointer
unless the caller has done the proper conversion, and the argument size
is the full size_t (it still won't actually copy more than 4GB in one
go, but there's also no reason to silently truncate the size argument in
the caller).

Finally, use this now sanely named function in the NTB code, which
mis-used a user copy version (with STAC/CLAC and all) of this interface
despite it not actually being a user copy at all.

Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix Clang jump table detection

2026-04-11T12:26:17+00:00

[ Upstream commit 4e5019216402ad0b4a84cff457b662d26803f103 ]

With Clang, there can be a conditional forward jump between the load of
the jump table address and the indirect branch.

Fixes the following warning:

  vmlinux.o: warning: objtool: ___bpf_prog_run+0x1c5: sibling call from callable instruction with modified stack frame

Reported-by: Arnd Bergmann 
Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.fastmail.com
Link: https://patch.msgid.link/7d8600caed08901b6679767488acd639f6df9688.1773071992.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

objtool: Handle Clang RSP musical chairs

2026-04-02T11:23:01+00:00

[ Upstream commit 7fdaa640c810cb42090a182c33f905bcc47a616a ]

For no apparent reason (possibly related to CONFIG_KMSAN), Clang can
randomly pass the value of RSP to other registers and then back again to
RSP.  Handle that accordingly.

Fixes the following warnings:

  drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: undefined stack state
  drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: unknown CFA base reg -1

Reported-by: Arnd Bergmann 
Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com
Link: https://patch.msgid.link/240e6a172cc73292499334a3724d02ccb3247fc7.1772818491.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

kbuild: Leave objtool binary around with 'make clean'

2026-03-19T15:08:50+00:00

[ Upstream commit fdb12c8a24a453bdd6759979b6ef1e04ebd4beb4 ]

The difference between 'make clean' and 'make mrproper' is documented in
'make help' as:

  clean     - Remove most generated files but keep the config and
              enough build support to build external modules
  mrproper  - Remove all generated files + config + various backup files

After commit 68b4fe32d737 ("kbuild: Add objtool to top-level clean
target"), running 'make clean' then attempting to build an external
module with the resulting build directory fails with

  $ make ARCH=x86_64 O=build clean

  $ make -C build M=... MO=...
  ...
  /bin/sh: line 1: .../build/tools/objtool/objtool: No such file or directory

as 'make clean' removes the objtool binary.

Split the objtool clean target into mrproper and clean like Kbuild does
and remove all generated artifacts with 'make clean' except for the
objtool binary, which is removed with 'make mrproper'. To avoid a small
race when running the objtool clean target through both objtool_mrproper
and objtool_clean when running 'make mrproper', modify objtool's clean
up find command to avoid using find's '-delete' command by piping the
files into 'xargs rm -f' like the rest of Kbuild does.

Cc: stable@vger.kernel.org
Fixes: 68b4fe32d737 ("kbuild: Add objtool to top-level clean target")
Reported-by: Michal Suchanek 
Closes: https://lore.kernel.org/20260225112633.6123-1-msuchanek@suse.de/
Reported-by: Rainer Fiebig 
Closes: https://lore.kernel.org/62d12399-76e5-3d40-126a-7490b4795b17@mailbox.org/
Acked-by: Josh Poimboeuf 
Acked-by: Peter Zijlstra (Intel) 
Reviewed-by: Nicolas Schier 
Tested-by: Nicolas Schier 
Link: https://patch.msgid.link/20260227-avoid-objtool-binary-removal-clean-v1-1-122f3e55eae9@kernel.org
Signed-off-by: Nathan Chancellor 
[ Context ]
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

kbuild: Add objtool to top-level clean target

2026-02-26T22:59:36+00:00

[ Upstream commit 68b4fe32d73789dea23e356f468de67c8367ef8f ]

Objtool is an integral part of the build, make sure it gets cleaned by
"make clean" and "make mrproper".

Fixes: 442f04c34a1a ("objtool: Add tool to perform compile-time stack metadata validation")
Reported-by: Jens Remus 
Closes: https://lore.kernel.org/15f2af3b-be33-46fc-b972-6b8e7e0aa52e@linux.ibm.com
Signed-off-by: Josh Poimboeuf 
Tested-by: Jens Remus 
Link: https://patch.msgid.link/968faf2ed30fa8b3519f79f01a1ecfe7929553e5.1770759919.git.jpoimboe@kernel.org
[nathan: use Closes: instead of Link: per checkpatch.pl]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Sasha Levin

objtool: Fix weak symbol detection

2025-12-18T13:02:28+00:00

[ Upstream commit 72567c630d32bc31f671977f78228c80937ed80e ]

find_symbol_hole_containing() fails to find a symbol hole (aka stripped
weak symbol) if its section has no symbols before the hole.  This breaks
weak symbol detection if -ffunction-sections is enabled.

Fix that by allowing the interval tree to contain section symbols, which
are always at offset zero for a given section.

Fixes a bunch of (-ffunction-sections) warnings like:

  vmlinux.o: warning: objtool: .text.__x64_sys_io_setup+0x10: unreachable instruction

Fixes: 4adb23686795 ("objtool: Ignore extra-symbol code")
Acked-by: Petr Mladek 
Tested-by: Joe Lawrence 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

objtool: Fix standalone --hacks=jump_label

2025-12-18T13:02:28+00:00

[ Upstream commit be8374a5ba7cbab6b97df94b4ffe0b92f5c8a6d2 ]

The objtool command line 'objtool --hacks=jump_label foo.o' on its own
should be expected to rewrite jump labels to NOPs. This means the
add_special_section_alts() code path needs to run when only this option
is provided.

This is mainly relevant in certain debugging situations, but could
potentially also fix kernel builds in which objtool is run with
--hacks=jump_label but without --orc, --stackval, --uaccess, or
--hacks=noinstr.

Fixes: de6fbcedf5ab ("objtool: Read special sections with alts only when specific options are selected")
Signed-off-by: Dylan Hatch 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

objtool: Fix skip_alt_group() for non-alternative STAC/CLAC

2025-11-01T06:43:20+00:00

If an insn->alt points to a STAC/CLAC instruction, skip_alt_group()
assumes it's part of an alternative ("alt group") as opposed to some
other kind of "alt" such as an exception fixup.

While that assumption may hold true in the current code base, Linus has
an out-of-tree patch which breaks that assumption by replacing the
STAC/CLAC alternatives with raw STAC/CLAC instructions.

Make skip_alt_group() more robust by making sure it's actually an alt
group before continuing.

Reported-by: Linus Torvalds 
Fixes: 2d12c6fb7875 ("objtool: Remove ANNOTATE_IGNORE_ALTERNATIVE from CLAC/STAC")
Closes: https://lore.kernel.org/CAHk-=wi6goUT36sR8GE47_P-aVrd5g38=VTRHpktWARbyE-0ow@mail.gmail.com
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Tested-by: Linus Torvalds 
Link: https://patch.msgid.link/3d22415f7b8e06a64e0873b21f48389290eeaa49.1761767616.git.jpoimboe@kernel.org

objtool: Fix failure when being compiled on x32 system

2025-10-22T13:21:55+00:00

Fix compilation failure when compiling the kernel with the x32 toolchain.

In file included from check.c:16:
check.c: In function ¡check_abs_references¢:
/usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:47:17: error: format ¡%lx¢ expects argument of type ¡long unsigned int¢, but argument 7 has type ¡u64¢ {aka ¡long
long unsigned int¢} [-Werror=format=]
   47 |                 "%s%s%s: objtool" extra ": " format "\n",               \
      |                 ^~~~~~~~~~~~~~~~~
/usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:54:9: note: in expansion of macro ¡___WARN¢
   54 |         ___WARN(severity, "", format, ##__VA_ARGS__)
      |         ^~~~~~~
/usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:74:27: note: in expansion of macro ¡__WARN¢
   74 | #define WARN(format, ...) __WARN(WARN_STR, format, ##__VA_ARGS__)
      |                           ^~~~~~
check.c:4713:33: note: in expansion of macro ¡WARN¢
 4713 |                                 WARN("section %s has absolute relocation at offset 0x%lx",
      |                                 ^~~~

Fixes: 0d6e4563fc03 ("objtool: Add action to check for absence of absolute relocations")
Signed-off-by: Mikulas Patocka 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Ard Biesheuvel 
Link: https://patch.msgid.link/1ac32fff-2e67-5155-f570-69aad5bf5412@redhat.com

objtool/rust: add one more `noreturn` Rust function

2025-10-22T13:21:54+00:00

Between Rust 1.79 and 1.86, under `CONFIG_RUST_KERNEL_DOCTESTS=y`,
`objtool` may report:

    rust/doctests_kernel_generated.o: warning: objtool:
    rust_doctest_kernel_alloc_kbox_rs_13() falls through to next
    function rust_doctest_kernel_alloc_kvec_rs_0()

(as well as in rust_doctest_kernel_alloc_kvec_rs_0) due to calls to the
`noreturn` symbol:

    core::option::expect_failed

from code added in commits 779db37373a3 ("rust: alloc: kvec: implement
AsPageIter for VVec") and 671618432f46 ("rust: alloc: kbox: implement
AsPageIter for VBox").

Thus add the mangled one to the list so that `objtool` knows it is
actually `noreturn`.

This can be reproduced as well in other versions by tweaking the code,
such as the latest stable Rust (1.90.0).

Stable does not have code that triggers this, but it could have it in
the future. Downstream forks could too. Thus tag it for backport.

See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions")
for more details.

Signed-off-by: Miguel Ojeda 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Alice Ryhl 
Cc: stable@vger.kernel.org # Needed in 6.12.y and later.
Link: https://patch.msgid.link/20251020020714.2511718-1-ojeda@kernel.org