- Introduce and start using TRAILING_OVERLAP() helper for fixing
embedded flex array instances (Gustavo A. R. Silva)
- mux: Convert mux_control_ops to a flex array member in mux_chip
(Thorsten Blum)
- string: Group str_has_prefix() and strstarts() (Andy Shevchenko)
- Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
Kees Cook)
- Refactor and rename stackleak feature to support Clang
- Add KUnit test for seq_buf API
- Fix KUnit fortify test under LTO
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Merge tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:
- Introduce and start using TRAILING_OVERLAP() helper for fixing
embedded flex array instances (Gustavo A. R. Silva)
- mux: Convert mux_control_ops to a flex array member in mux_chip
(Thorsten Blum)
- string: Group str_has_prefix() and strstarts() (Andy Shevchenko)
- Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
Kees Cook)
- Refactor and rename stackleak feature to support Clang
- Add KUnit test for seq_buf API
- Fix KUnit fortify test under LTO
* tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits)
sched/task_stack: Add missing const qualifier to end_of_stack()
kstack_erase: Support Clang stack depth tracking
kstack_erase: Add -mgeneral-regs-only to silence Clang warnings
init.h: Disable sanitizer coverage for __init and __head
kstack_erase: Disable kstack_erase for all of arm compressed boot code
x86: Handle KCOV __init vs inline mismatches
arm64: Handle KCOV __init vs inline mismatches
s390: Handle KCOV __init vs inline mismatches
arm: Handle KCOV __init vs inline mismatches
mips: Handle KCOV __init vs inline mismatch
powerpc/mm/book3s64: Move kfence and debug_pagealloc related calls to __init section
configs/hardening: Enable CONFIG_INIT_ON_FREE_DEFAULT_ON
configs/hardening: Enable CONFIG_KSTACK_ERASE
stackleak: Split KSTACK_ERASE_CFLAGS from GCC_PLUGINS_CFLAGS
stackleak: Rename stackleak_track_stack to __sanitizer_cov_stack_depth
stackleak: Rename STACKLEAK to KSTACK_ERASE
seq_buf: Introduce KUnit tests
string: Group str_has_prefix() and strstarts()
kunit/fortify: Add back "volatile" for sizeof() constants
acpi: nfit: intel: avoid multiple -Wflex-array-member-not-at-end warnings
...
The Clang stack depth tracking implementation has a fixed name for
the stack depth tracking callback, "__sanitizer_cov_stack_depth", so
rename the GCC plugin function to match since the plugin has no external
dependencies on naming.
Link: https://lore.kernel.org/r/20250717232519.2984886-2-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:
- Add the new top-level CONFIG_KSTACK_ERASE option which will be
implemented either with the stackleak GCC plugin, or with the Clang
stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
for what it does rather than what it protects against), but leave as
many of the internals alone as possible to avoid even more churn.
While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Toolchain and infrastructure:
- Fix build and modpost confusion for the upcoming Rust 1.89.0 release.
- Clean objtool warning for the upcoming Rust 1.89.0 release by adding
one more noreturn function.
'kernel' crate:
- Fix build error when using generics in the 'try_{,pin_}init!' macros.
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Merge tag 'rust-fixes-6.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Fix build and modpost confusion for the upcoming Rust 1.89.0
release
- Clean objtool warning for the upcoming Rust 1.89.0 release by
adding one more noreturn function
'kernel' crate:
- Fix build error when using generics in the 'try_{,pin_}init!'
macros"
* tag 'rust-fixes-6.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0
objtool/rust: add one more `noreturn` Rust function for Rust 1.89.0
rust: init: Fix generics in *_init! macros
Starting with Rust 1.89.0 (expected 2025-08-07), under
`CONFIG_RUST_DEBUG_ASSERTIONS=y`, `objtool` may report:
rust/kernel.o: warning: objtool: _R..._6kernel4pageNtB5_4Page8read_raw()
falls through to next function _R..._6kernel4pageNtB5_4Page9write_raw()
(and many others) due to calls to the `noreturn` symbol:
core::panicking::panic_nounwind_fmt
Thus add the mangled one to the list so that `objtool` knows it is
actually `noreturn`.
See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250712160103.1244945-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Trying to compile an x86 kernel on big endian results in this error:
net/ipv4/netfilter/iptable_nat.o: warning: objtool: iptable_nat_table_init+0x150: Unknown annotation type: 50331648
make[5]: *** [scripts/Makefile.build:287: net/ipv4/netfilter/iptable_nat.o] Error 255
Reason is a missing endian conversion in read_annotate().
Add the missing conversion to fix this.
Fixes: 2116b349e2 ("objtool: Generic annotation infrastructure")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250630131230.4130185-1-hca@linux.ibm.com
Developers are indeed hitting other of the `noreturn` slice symbols in
Nova [1], thus relax the last check in the list so that we catch all of
them, i.e.
*_4core5slice5index22slice_index_order_fail
*_4core5slice5index24slice_end_index_len_fail
*_4core5slice5index26slice_start_index_len_fail
*_4core5slice5index29slice_end_index_overflow_fail
*_4core5slice5index31slice_start_index_overflow_fail
These all exist since at least Rust 1.78.0, thus backport it too.
See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later.
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Timur Tabi <ttabi@nvidia.com>
Cc: Kane York <kanepyork@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reported-by: Joel Fernandes <joelagnelf@nvidia.com>
Fixes: 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
Closes: https://lore.kernel.org/rust-for-linux/20250513180757.GA1295002@joelnvbox/ [1]
Tested-by: Joel Fernandes <joelagnelf@nvidia.com>
Link: https://lore.kernel.org/r/20250520185555.825242-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Starting with Rust 1.87.0 (expected 2025-05-15), `objtool` may report:
rust/core.o: warning: objtool: _R..._4core9panicking9panic_fmt() falls
through to next function _R..._4core9panicking18panic_nounwind_fmt()
rust/core.o: warning: objtool: _R..._4core9panicking18panic_nounwind_fmt()
falls through to next function _R..._4core9panicking5panic()
The reason is that `rust_begin_unwind` is now mangled:
_R..._7___rustc17rust_begin_unwind
Thus add the mangled one to the list so that `objtool` knows it is
actually `noreturn`.
See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Alternatively, we could remove the fixed one in `noreturn.h` and relax
this test to cover both, but it seems best to be strict as long as we can.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250502140237.1659624-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Toolchain and infrastructure:
- Fix missing KASAN LLVM flags on first build (and fix spurious
rebuilds) by skipping '--target'.
- Fix Make < 4.3 build error by using '$(pound)'.
- Fix UML build error by removing 'volatile' qualifier from io helpers.
- Fix UML build error by adding 'dma_{alloc,free}_attrs()' helpers.
- Clean gendwarfksyms warnings by avoiding to export '__pfx' symbols.
- Clean objtool warning by adding a new 'noreturn' function for 1.86.0.
- Disable 'needless_continue' Clippy lint due to new 1.86.0 warnings.
- Add missing 'ffi' crate to 'generate_rust_analyzer.py'.
'pin-init' crate:
- Import a couple fixes from upstream.
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Merge tag 'rust-fixes-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Fix missing KASAN LLVM flags on first build (and fix spurious
rebuilds) by skipping '--target'
- Fix Make < 4.3 build error by using '$(pound)'
- Fix UML build error by removing 'volatile' qualifier from io
helpers
- Fix UML build error by adding 'dma_{alloc,free}_attrs()' helpers
- Clean gendwarfksyms warnings by avoiding to export '__pfx' symbols
- Clean objtool warning by adding a new 'noreturn' function for
1.86.0
- Disable 'needless_continue' Clippy lint due to new 1.86.0 warnings
- Add missing 'ffi' crate to 'generate_rust_analyzer.py'
'pin-init' crate:
- Import a couple fixes from upstream"
* tag 'rust-fixes-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: helpers: Add dma_alloc_attrs() and dma_free_attrs()
rust: helpers: Remove volatile qualifier from io helpers
rust: kbuild: use `pound` to support GNU Make < 4.3
objtool/rust: add one more `noreturn` Rust function for Rust 1.86.0
rust: kasan/kbuild: fix missing flags on first build
rust: disable `clippy::needless_continue`
rust: kbuild: Don't export __pfx symbols
rust: pin-init: use Markdown autolinks in Rust comments
rust: pin-init: alloc: restrict `impl ZeroableOption` for `Box` to `T: Sized`
scripts: generate_rust_analyzer: Add ffi crate
Starting with Rust 1.86.0 (see upstream commit b151b513ba2b ("Insert null
checks for pointer dereferences when debug assertions are enabled") [1]),
under some kernel configurations with `CONFIG_RUST_DEBUG_ASSERTIONS=y`,
one may trigger a new `objtool` warning:
rust/kernel.o: warning: objtool: _R..._6kernel9workqueue6system()
falls through to next function _R...9workqueue14system_highpri()
due to a call to the `noreturn` symbol:
core::panicking::panic_null_pointer_dereference
Thus add it to the list so that `objtool` knows it is actually `noreturn`.
See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Fixes: 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
Link: b151b513ba [1]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250413002338.1741593-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ANNOTATE_IGNORE_ALTERNATIVE adds additional noise to the code generated
by CLAC/STAC alternatives, hurting readability for those whose read
uaccess-related code generation on a regular basis.
Remove the annotation specifically for the "NOP patched with CLAC/STAC"
case in favor of a manual check.
Leave the other uses of that annotation in place as they're less common
and more difficult to detect.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/fc972ba4995d826fcfb8d02733a14be8d670900b.1744098446.git.jpoimboe@kernel.org
Objtool uses an arbitrary rule for INSN_SYSCALL and INSN_SYSRET that
almost works by accident: if it's in a function, control flow continues
after the instruction, otherwise it terminates.
That behavior should instead be based on the semantics of the underlying
instruction. Change INSN_SYSCALL to always preserve control flow and
INSN_SYSRET to always terminate it.
The changed semantic for INSN_SYSCALL requires a tweak to the
!CONFIG_IA32_EMULATION version of xen_entry_SYSCALL_compat(). In Xen,
SYSCALL is a hypercall which usually returns. But in this case it's a
hypercall to IRET which doesn't return. Add UD2 to tell objtool to
terminate control flow, and to prevent undefined behavior at runtime.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com> # for the Xen part
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/19453dfe9a0431b7f016e9dc16d031cad3812a50.1744095216.git.jpoimboe@kernel.org
INSN_CONTEXT_SWITCH is ambiguous. It can represent both call semantics
(SYSCALL, SYSENTER) and return semantics (SYSRET, IRET, RETS, RETU).
Those differ significantly: calls preserve control flow whereas returns
terminate it.
Objtool uses an arbitrary rule for INSN_CONTEXT_SWITCH that almost works
by accident: if in a function, keep going; otherwise stop. It should
instead be based on the semantics of the underlying instruction.
In preparation for improving that, split INSN_CONTEXT_SWITCH into
INSN_SYCALL and INSN_SYSRET.
No functional change.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/19a76c74d2c051d3bc9a775823cafc65ad267a7a.1744095216.git.jpoimboe@kernel.org
The !CONFIG_IA32_EMULATION version of xen_entry_SYSCALL_compat() ends
with a SYSCALL instruction which is classified by objtool as
INSN_CONTEXT_SWITCH.
Unlike validate_branch(), validate_unret() doesn't consider
INSN_CONTEXT_SWITCH in a non-function to be a dead end, so it keeps
going past the end of xen_entry_SYSCALL_compat(), resulting in the
following warning:
vmlinux.o: warning: objtool: xen_reschedule_interrupt+0x2a: RET before UNTRAIN
Fix that by adding INSN_CONTEXT_SWITCH handling to validate_unret() to
match what validate_branch() is already doing.
Fixes: a09a6e2399 ("objtool: Add entry UNRET validation")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/f5eda46fd09f15b1f5cde3d9ae3b92b958342add.1744095216.git.jpoimboe@kernel.org
In verbose mode, when printing the disassembly of affected functions, if
CROSS_COMPILE isn't set, the objdump command string gets prefixed with
"(null)".
Somehow this worked before. Maybe some versions of glibc return an
empty string instead of NULL. Fix it regardless.
[ jpoimboe: Rewrite commit log. ]
Fixes: ca653464dd ("objtool: Add verbose option for disassembling affected functions")
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250215142321.14081-1-david.laight.linux@gmail.com
Link: https://lore.kernel.org/r/b931a4786bc0127aa4c94e8b35ed617dcbd3d3da.1743481539.git.jpoimboe@kernel.org
Objtool writes several object annotations which are used to enable
critical kernel runtime functionalities like static calls and
retpoline/rethunk patching.
In the rare case where it fails to read or write an object, the
annotations don't get written, causing runtime code patching to fail and
code to become corrupted.
Due to the catastrophic nature of such warnings, convert them to errors
which fail the build regardless of CONFIG_OBJTOOL_WERROR.
Reported-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/7d35684ca61eac56eb2424f300ca43c5d257b170.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/SJ1PR11MB61295789E25C2F5197EFF2F6B9A72@SJ1PR11MB6129.namprd11.prod.outlook.com
This reverts commit 0a7fb6f07e.
The "skipping duplicate warnings" warning is technically not an actual
warning, which can cause confusion. This feature isn't all that useful
anyway. It's exceedingly rare for a function to have more than one
unrelated warning.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/e5abe5e858acf1a9207a5dfa0f37d17ac9dca872.1743481539.git.jpoimboe@kernel.org
When KCOV or GCOV is enabled, dead code can be left behind, in which
case objtool silences unreachable and undefined behavior (fallthrough)
warnings.
Fallthrough warnings, and their variant "end of section" warnings, were
silenced with the following commit:
6b023c7842 ("objtool: Silence more KCOV warnings")
Another variant of a fallthrough warning is a jump to the end of a
function. If that function happens to be at the end of a section, the
jump destination doesn't actually exist.
Normally that would be a fatal objtool error, but for KCOV/GCOV it's
just another undefined behavior fallthrough. Silence it like the
others.
Fixes the following warning:
drivers/iommu/dma-iommu.o: warning: objtool: iommu_dma_sw_msi+0x92: can't find jump dest instruction at .text+0x54d5
Fixes: 6b023c7842 ("objtool: Silence more KCOV warnings")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/08fbe7d7e1e20612206f1df253077b94f178d93e.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/314f8809-cd59-479b-97d7-49356bf1c8d1@infradead.org/
The recent STACK_FRAME_NON_STANDARD refactoring forgot about .cold
subfunctions. They must also be ignored.
Fixes the following warning:
drivers/gpu/drm/vmwgfx/vmwgfx_msg.o: warning: objtool: vmw_recv_msg.cold+0x0: unreachable instruction
Fixes: c84301d706 ("objtool: Ignore entire functions rather than instructions")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/70a09ec0b0704398b2bbfb3153ce3d7cb8a381be.1743136205.git.jpoimboe@kernel.org
__stack_chk_fail() can be called from uaccess-enabled code. Make sure
uaccess gets disabled before calling panic().
Fixes the following warning:
kernel/trace/trace_branch.o: error: objtool: ftrace_likely_update+0x1ea: call to __stack_chk_fail() with UACCESS enabled
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/a3e97e0119e1b04c725a8aa05f7bc83d98e657eb.1742852847.git.jpoimboe@kernel.org
Remove the following from CONFIG_OBJTOOL_WERROR:
* backtrace
* "upgraded warnings to errors" message
* cmdline args
This makes the default output less cluttered and makes it easier to spot
the actual warnings. Note the above options are still are available
with --verbose or OBJTOOL_VERBOSE=1.
Also, do the cmdline arg printing on all warnings, regardless of werror.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/d61df69f64b396fa6b2a1335588aad7a34ea9e71.1742852846.git.jpoimboe@kernel.org
Fix some error handling issues, improve error messages, properly
distinguish betwee errors and warnings, and generally try to make all
the error handling more consistent.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/3094bb4463dad29b6bd1bea03848d1571ace771c.1742852846.git.jpoimboe@kernel.org
If opts.uaccess isn't set, the uaccess validation is disabled, but only
partially: it doesn't read the uaccess_safe_builtin list but still tries
to do the validation. Disable it completely to prevent false warnings.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/0e95581c1d2107fb5f59418edf2b26bba38b0cbb.1742852846.git.jpoimboe@kernel.org
In the past there were issues with KCOV triggering unreachable
instruction warnings, which is why unreachable warnings are now disabled
with CONFIG_KCOV.
Now some new KCOV warnings are showing up with GCC 14:
vmlinux.o: warning: objtool: cpuset_write_resmask() falls through to next function cpuset_update_active_cpus.cold()
drivers/usb/core/driver.o: error: objtool: usb_deregister() falls through to next function usb_match_device()
sound/soc/codecs/snd-soc-wcd934x.o: warning: objtool: .text.wcd934x_slim_irq_handler: unexpected end of section
All are caused by GCC KCOV not finishing an optimization, leaving behind
a never-taken conditional branch to a basic block which falls through to
the next function (or end of section).
At a high level this is similar to the unreachable warnings mentioned
above, in that KCOV isn't fully removing dead code. Treat it the same
way by adding these to the list of warnings to ignore with CONFIG_KCOV.
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/66a61a0b65d74e072d3dc02384e395edb2adc3c5.1742852846.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/Z9iTsI09AEBlxlHC@gmail.com
Closes: https://lore.kernel.org/oe-kbuild-all/202503180044.oH9gyPeg-lkp@intel.com/
If IBT is enabled and a module uses the deprecated init_module() magic
function name rather than module_init(fn), its ENDBR will get removed,
causing an IBT failure during module load.
Objtool does print an obscure warning, but then does nothing to either
correct it or return an error.
Improve the usefulness of the warning and return an error so it will at
least fail the build with CONFIG_OBJTOOL_WERROR.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/366bfdbe92736cde9fb01d5d3eb9b98e9070a1ec.1742852846.git.jpoimboe@kernel.org
For X86_FEATURE_SMAP alternatives which replace NOP with STAC or CLAC,
uaccess validation skips the NOP branch to avoid following impossible
code paths, e.g. where a STAC would be patched but a CLAC wouldn't.
However, it's not safe to assume an X86_FEATURE_SMAP alternative is
patching STAC/CLAC. There can be other alternatives, like
static_cpu_has(), where both branches need to be validated.
Fix that by repurposing ANNOTATE_IGNORE_ALTERNATIVE for skipping either
original instructions or new ones. This is a more generic approach
which enables the removal of the feature checking hacks and the
insn->ignore bit.
Fixes the following warnings:
arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8ec: __stack_chk_fail() missing __noreturn in .c/.h or NORETURN() in noreturns.h
arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8f1: unreachable instruction
[ mingo: Fix up conflicts with recent x86 changes. ]
Fixes: ea24213d80 ("objtool: Add UACCESS validation")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/de0621ca242130156a55d5d74fed86994dfa4c9c.1742852846.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503181736.zkZUBv4N-lkp@intel.com/
The jump table detection code assumes jump tables are in the same order
as their corresponding indirect branches. That's apparently not always
true with Clang 20.
Fix that by changing how multiple jump tables are detected. In the
first detection pass, mark the beginning of each jump table so the
second pass can tell where one ends and the next one begins.
Fixes the following warnings:
vmlinux.o: warning: objtool: SiS_GetCRT2Ptr+0x1ad: stack state mismatch: cfa1=4+8 cfa2=5+16
sound/core/seq/snd-seq.o: warning: objtool: cc_ev_to_ump_midi2+0x589: return with modified stack frame
Fixes: be2f0b1e12 ("objtool: Get rid of reloc->jump_table_start")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/141752fff614eab962dba6bdfaa54aa67ff03bba.1742852846.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503171547.LlCTJLQL-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202503200535.J3hAvcjw-lkp@intel.com/
two locking commits in the locking tree,
part of the locking-core-2025-03-22 pull request. ]
x86 CPU features support:
- Generate the <asm/cpufeaturemasks.h> header based on build config
(H. Peter Anvin, Xin Li)
- x86 CPUID parsing updates and fixes (Ahmed S. Darwish)
- Introduce the 'setcpuid=' boot parameter (Brendan Jackman)
- Enable modifying CPU bug flags with '{clear,set}puid='
(Brendan Jackman)
- Utilize CPU-type for CPU matching (Pawan Gupta)
- Warn about unmet CPU feature dependencies (Sohil Mehta)
- Prepare for new Intel Family numbers (Sohil Mehta)
Percpu code:
- Standardize & reorganize the x86 percpu layout and
related cleanups (Brian Gerst)
- Convert the stackprotector canary to a regular percpu
variable (Brian Gerst)
- Add a percpu subsection for cache hot data (Brian Gerst)
- Unify __pcpu_op{1,2}_N() macros to __pcpu_op_N() (Uros Bizjak)
- Construct __percpu_seg_override from __percpu_seg (Uros Bizjak)
MM:
- Add support for broadcast TLB invalidation using AMD's INVLPGB instruction
(Rik van Riel)
- Rework ROX cache to avoid writable copy (Mike Rapoport)
- PAT: restore large ROX pages after fragmentation
(Kirill A. Shutemov, Mike Rapoport)
- Make memremap(MEMREMAP_WB) map memory as encrypted by default
(Kirill A. Shutemov)
- Robustify page table initialization (Kirill A. Shutemov)
- Fix flush_tlb_range() when used for zapping normal PMDs (Jann Horn)
- Clear _PAGE_DIRTY for kernel mappings when we clear _PAGE_RW
(Matthew Wilcox)
KASLR:
- x86/kaslr: Reduce KASLR entropy on most x86 systems,
to support PCI BAR space beyond the 10TiB region
(CONFIG_PCI_P2PDMA=y) (Balbir Singh)
CPU bugs:
- Implement FineIBT-BHI mitigation (Peter Zijlstra)
- speculation: Simplify and make CALL_NOSPEC consistent (Pawan Gupta)
- speculation: Add a conditional CS prefix to CALL_NOSPEC (Pawan Gupta)
- RFDS: Exclude P-only parts from the RFDS affected list (Pawan Gupta)
System calls:
- Break up entry/common.c (Brian Gerst)
- Move sysctls into arch/x86 (Joel Granados)
Intel LAM support updates: (Maciej Wieczor-Retman)
- selftests/lam: Move cpu_has_la57() to use cpuinfo flag
- selftests/lam: Skip test if LAM is disabled
- selftests/lam: Test get_user() LAM pointer handling
AMD SMN access updates:
- Add SMN offsets to exclusive region access (Mario Limonciello)
- Add support for debugfs access to SMN registers (Mario Limonciello)
- Have HSMP use SMN through AMD_NODE (Yazen Ghannam)
Power management updates: (Patryk Wlazlyn)
- Allow calling mwait_play_dead with an arbitrary hint
- ACPI/processor_idle: Add FFH state handling
- intel_idle: Provide the default enter_dead() handler
- Eliminate mwait_play_dead_cpuid_hint()
Bootup:
Build system:
- Raise the minimum GCC version to 8.1 (Brian Gerst)
- Raise the minimum LLVM version to 15.0.0
(Nathan Chancellor)
Kconfig: (Arnd Bergmann)
- Add cmpxchg8b support back to Geode CPUs
- Drop 32-bit "bigsmp" machine support
- Rework CONFIG_GENERIC_CPU compiler flags
- Drop configuration options for early 64-bit CPUs
- Remove CONFIG_HIGHMEM64G support
- Drop CONFIG_SWIOTLB for PAE
- Drop support for CONFIG_HIGHPTE
- Document CONFIG_X86_INTEL_MID as 64-bit-only
- Remove old STA2x11 support
- Only allow CONFIG_EISA for 32-bit
Headers:
- Replace __ASSEMBLY__ with __ASSEMBLER__ in UAPI and non-UAPI headers
(Thomas Huth)
Assembly code & machine code patching:
- x86/alternatives: Simplify alternative_call() interface (Josh Poimboeuf)
- x86/alternatives: Simplify callthunk patching (Peter Zijlstra)
- KVM: VMX: Use named operands in inline asm (Josh Poimboeuf)
- x86/hyperv: Use named operands in inline asm (Josh Poimboeuf)
- x86/traps: Cleanup and robustify decode_bug() (Peter Zijlstra)
- x86/kexec: Merge x86_32 and x86_64 code using macros from <asm/asm.h>
(Uros Bizjak)
- Use named operands in inline asm (Uros Bizjak)
- Improve performance by using asm_inline() for atomic locking instructions
(Uros Bizjak)
Earlyprintk:
- Harden early_serial (Peter Zijlstra)
NMI handler:
- Add an emergency handler in nmi_desc & use it in nmi_shootdown_cpus()
(Waiman Long)
Miscellaneous fixes and cleanups:
- by Ahmed S. Darwish, Andy Shevchenko, Ard Biesheuvel,
Artem Bityutskiy, Borislav Petkov, Brendan Jackman, Brian Gerst,
Dan Carpenter, Dr. David Alan Gilbert, H. Peter Anvin,
Ingo Molnar, Josh Poimboeuf, Kevin Brodsky, Mike Rapoport,
Lukas Bulwahn, Maciej Wieczor-Retman, Max Grobecker,
Patryk Wlazlyn, Pawan Gupta, Peter Zijlstra,
Philip Redkin, Qasim Ijaz, Rik van Riel, Thomas Gleixner,
Thorsten Blum, Tom Lendacky, Tony Luck, Uros Bizjak,
Vitaly Kuznetsov, Xin Li, liuye.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core x86 updates from Ingo Molnar:
"x86 CPU features support:
- Generate the <asm/cpufeaturemasks.h> header based on build config
(H. Peter Anvin, Xin Li)
- x86 CPUID parsing updates and fixes (Ahmed S. Darwish)
- Introduce the 'setcpuid=' boot parameter (Brendan Jackman)
- Enable modifying CPU bug flags with '{clear,set}puid=' (Brendan
Jackman)
- Utilize CPU-type for CPU matching (Pawan Gupta)
- Warn about unmet CPU feature dependencies (Sohil Mehta)
- Prepare for new Intel Family numbers (Sohil Mehta)
Percpu code:
- Standardize & reorganize the x86 percpu layout and related cleanups
(Brian Gerst)
- Convert the stackprotector canary to a regular percpu variable
(Brian Gerst)
- Add a percpu subsection for cache hot data (Brian Gerst)
- Unify __pcpu_op{1,2}_N() macros to __pcpu_op_N() (Uros Bizjak)
- Construct __percpu_seg_override from __percpu_seg (Uros Bizjak)
MM:
- Add support for broadcast TLB invalidation using AMD's INVLPGB
instruction (Rik van Riel)
- Rework ROX cache to avoid writable copy (Mike Rapoport)
- PAT: restore large ROX pages after fragmentation (Kirill A.
Shutemov, Mike Rapoport)
- Make memremap(MEMREMAP_WB) map memory as encrypted by default
(Kirill A. Shutemov)
- Robustify page table initialization (Kirill A. Shutemov)
- Fix flush_tlb_range() when used for zapping normal PMDs (Jann Horn)
- Clear _PAGE_DIRTY for kernel mappings when we clear _PAGE_RW
(Matthew Wilcox)
KASLR:
- x86/kaslr: Reduce KASLR entropy on most x86 systems, to support PCI
BAR space beyond the 10TiB region (CONFIG_PCI_P2PDMA=y) (Balbir
Singh)
CPU bugs:
- Implement FineIBT-BHI mitigation (Peter Zijlstra)
- speculation: Simplify and make CALL_NOSPEC consistent (Pawan Gupta)
- speculation: Add a conditional CS prefix to CALL_NOSPEC (Pawan
Gupta)
- RFDS: Exclude P-only parts from the RFDS affected list (Pawan
Gupta)
System calls:
- Break up entry/common.c (Brian Gerst)
- Move sysctls into arch/x86 (Joel Granados)
Intel LAM support updates: (Maciej Wieczor-Retman)
- selftests/lam: Move cpu_has_la57() to use cpuinfo flag
- selftests/lam: Skip test if LAM is disabled
- selftests/lam: Test get_user() LAM pointer handling
AMD SMN access updates:
- Add SMN offsets to exclusive region access (Mario Limonciello)
- Add support for debugfs access to SMN registers (Mario Limonciello)
- Have HSMP use SMN through AMD_NODE (Yazen Ghannam)
Power management updates: (Patryk Wlazlyn)
- Allow calling mwait_play_dead with an arbitrary hint
- ACPI/processor_idle: Add FFH state handling
- intel_idle: Provide the default enter_dead() handler
- Eliminate mwait_play_dead_cpuid_hint()
Build system:
- Raise the minimum GCC version to 8.1 (Brian Gerst)
- Raise the minimum LLVM version to 15.0.0 (Nathan Chancellor)
Kconfig: (Arnd Bergmann)
- Add cmpxchg8b support back to Geode CPUs
- Drop 32-bit "bigsmp" machine support
- Rework CONFIG_GENERIC_CPU compiler flags
- Drop configuration options for early 64-bit CPUs
- Remove CONFIG_HIGHMEM64G support
- Drop CONFIG_SWIOTLB for PAE
- Drop support for CONFIG_HIGHPTE
- Document CONFIG_X86_INTEL_MID as 64-bit-only
- Remove old STA2x11 support
- Only allow CONFIG_EISA for 32-bit
Headers:
- Replace __ASSEMBLY__ with __ASSEMBLER__ in UAPI and non-UAPI
headers (Thomas Huth)
Assembly code & machine code patching:
- x86/alternatives: Simplify alternative_call() interface (Josh
Poimboeuf)
- x86/alternatives: Simplify callthunk patching (Peter Zijlstra)
- KVM: VMX: Use named operands in inline asm (Josh Poimboeuf)
- x86/hyperv: Use named operands in inline asm (Josh Poimboeuf)
- x86/traps: Cleanup and robustify decode_bug() (Peter Zijlstra)
- x86/kexec: Merge x86_32 and x86_64 code using macros from
<asm/asm.h> (Uros Bizjak)
- Use named operands in inline asm (Uros Bizjak)
- Improve performance by using asm_inline() for atomic locking
instructions (Uros Bizjak)
Earlyprintk:
- Harden early_serial (Peter Zijlstra)
NMI handler:
- Add an emergency handler in nmi_desc & use it in
nmi_shootdown_cpus() (Waiman Long)
Miscellaneous fixes and cleanups:
- by Ahmed S. Darwish, Andy Shevchenko, Ard Biesheuvel, Artem
Bityutskiy, Borislav Petkov, Brendan Jackman, Brian Gerst, Dan
Carpenter, Dr. David Alan Gilbert, H. Peter Anvin, Ingo Molnar,
Josh Poimboeuf, Kevin Brodsky, Mike Rapoport, Lukas Bulwahn, Maciej
Wieczor-Retman, Max Grobecker, Patryk Wlazlyn, Pawan Gupta, Peter
Zijlstra, Philip Redkin, Qasim Ijaz, Rik van Riel, Thomas Gleixner,
Thorsten Blum, Tom Lendacky, Tony Luck, Uros Bizjak, Vitaly
Kuznetsov, Xin Li, liuye"
* tag 'x86-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (211 commits)
zstd: Increase DYNAMIC_BMI2 GCC version cutoff from 4.8 to 11.0 to work around compiler segfault
x86/asm: Make asm export of __ref_stack_chk_guard unconditional
x86/mm: Only do broadcast flush from reclaim if pages were unmapped
perf/x86/intel, x86/cpu: Replace Pentium 4 model checks with VFM ones
perf/x86/intel, x86/cpu: Simplify Intel PMU initialization
x86/headers: Replace __ASSEMBLY__ with __ASSEMBLER__ in non-UAPI headers
x86/headers: Replace __ASSEMBLY__ with __ASSEMBLER__ in UAPI headers
x86/locking/atomic: Improve performance by using asm_inline() for atomic locking instructions
x86/asm: Use asm_inline() instead of asm() in clwb()
x86/asm: Use CLFLUSHOPT and CLWB mnemonics in <asm/special_insns.h>
x86/hweight: Use asm_inline() instead of asm()
x86/hweight: Use ASM_CALL_CONSTRAINT in inline asm()
x86/hweight: Use named operands in inline asm()
x86/stackprotector/64: Only export __ref_stack_chk_guard on CONFIG_SMP
x86/head/64: Avoid Clang < 17 stack protector in startup code
x86/kexec: Merge x86_32 and x86_64 code using macros from <asm/asm.h>
x86/runtime-const: Add the RUNTIME_CONST_PTR assembly macro
x86/cpu/intel: Limit the non-architectural constant_tsc model checks
x86/mm/pat: Replace Intel x86_model checks with VFM ones
x86/cpu/intel: Fix fast string initialization for extended Families
...
Any objtool warning has the potential of reflecting (or triggering) a
major bug in the kernel or compiler which could result in crashing the
kernel or breaking the livepatch consistency model.
In preparation for failing the build on objtool errors/warnings, add a
new --Werror option.
[ jpoimboe: commit log, comments, error out on fatal errors too ]
Co-developed-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/e423ea4ec297f510a108aa6c78b52b9fe30fa8c1.1741975349.git.jpoimboe@kernel.org
Increase the per-function WARN_FUNC() rate limit from 1 to 2. If the
number of warnings for a given function goes beyond 2, print "skipping
duplicate warning(s)". This helps root out additional warnings in a
function that might be hiding behind the first one.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/aec318d66c037a51c9f376d6fb0e8ff32812a037.1741975349.git.jpoimboe@kernel.org
The CONFIG_X86_ESPFIX64 version of exc_double_fault() can return to its
caller, but the !CONFIG_X86_ESPFIX64 version never does. In the latter
case the compiler and/or objtool may consider it to be implicitly
noreturn.
However, due to the currently inflexible way objtool detects noreturns,
a function's noreturn status needs to be consistent across configs.
The current workaround for this issue is to suppress unreachable
warnings for exc_double_fault()'s callers. Unfortunately that can
result in ORC coverage gaps and potentially worse issues like inert
static calls and silently disabled CPU mitigations.
Instead, prevent exc_double_fault() from ever being implicitly marked
noreturn by forcing a return behind a never-taken conditional.
Until a more integrated noreturn detection method exists, this is likely
the least objectionable workaround.
Fixes: 55eeab2a8a ("objtool: Ignore exc_double_fault() __noreturn warnings")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/d1f4026f8dc35d0de6cc61f2684e0cb6484009d1.1741975349.git.jpoimboe@kernel.org
For the most part, an absolute relocation type is used for rodata.
In the case of STT_SECTION, reloc->sym->offset is always zero, for
the other symbol types, reloc_addend(reloc) is always zero, thus it
can use a simple statement "reloc->sym->offset + reloc_addend(reloc)"
to obtain the symbol offset for various symbol types.
When compiling on LoongArch, there exist PC relative relocation types
for rodata, it needs to calculate the symbol offset with "S + A - PC"
according to the spec of "ELF for the LoongArch Architecture".
If there is only one jump table in the rodata, the "PC" is the entry
address which is equal with the value of reloc_offset(reloc), at this
time, reloc_offset(table) is 0.
If there are many jump tables in the rodata, the "PC" is the offset
of the jump table's base address which is equal with the value of
reloc_offset(reloc) - reloc_offset(table).
So for LoongArch, if the relocation type is PC relative, it can use a
statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC"
value when calculating the symbol offset with "S + A - PC" for one or
many jump tables in the rodata.
Add an arch-specific function arch_jump_table_sym_offset() to assign
the symbol offset, for the most part that is an absolute relocation,
the default value is "reloc->sym->offset + reloc_addend(reloc)" in
the weak definition, it can be overridden by each architecture that
has different requirements.
Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
In the most cases, the entry size of rodata is 8 bytes because the
relocation type is 64 bit. There are also 32 bit relocation types,
the entry size of rodata should be 4 bytes in this case.
Add an arch-specific function arch_reloc_size() to assign the entry
size of rodata for x86, powerpc and LoongArch.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-3-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
In the relocation section ".rela.rodata" of each .o file compiled with
LoongArch toolchain, there are various symbol types such as STT_NOTYPE,
STT_OBJECT, STT_FUNC in addition to the usual STT_SECTION, it needs to
use reloc symbol offset instead of reloc addend to find the destination
instruction in find_jump_table() and add_jump_table().
For the most part, an absolute relocation type is used for rodata. In the
case of STT_SECTION, reloc->sym->offset is always zero, and for the other
symbol types, reloc_addend(reloc) is always zero, thus it can use a simple
statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol
offset for various symbol types.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-2-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
build warnings that happens on PIE-enabled architectures
such as LoongArch.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Ingo Molnar:
"Fix an objtool false positive, and objtool related build warnings that
happens on PIE-enabled architectures such as LoongArch"
* tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns
objtool: Fix C jump table annotations for Clang
vmlinux.lds: Ensure that const vars with relocations are mapped R/O
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>
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Merge tag 'v6.14-rc3' into x86/core, to pick up fixes
Pick up upstream x86 fixes before applying new patches.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
breakage has been fixed in the meantime
- Teach objtool to ignore dangling jump table entries added by Clang
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Merge tag 'objtool_urgent_for_v6.14_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Borislav Petkov:
- Move a warning about a lld.ld breakage into the verbose setting as
said breakage has been fixed in the meantime
- Teach objtool to ignore dangling jump table entries added by Clang
* tag 'objtool_urgent_for_v6.14_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Move dodgy linker warn to verbose
objtool: Ignore dangling jump table entries
Now that paravirt call patching is implemented using alternatives, it
is possible to avoid having to patch the alternative sites by
including the altinstr_replacement calls in the call_sites list.
This means we're now stacking relative adjustments like so:
callthunks_patch_builtin_calls():
patches all function calls to target: func() -> func()-10
since the CALL accounting lives in the CALL_PADDING.
This explicitly includes .altinstr_replacement
alt_replace_call():
patches: x86_BUG() -> target()
this patching is done in a relative manner, and will preserve
the above adjustment, meaning that with calldepth patching it
will do: x86_BUG()-10 -> target()-10
apply_relocation():
does code relocation, and adjusts all RIP-relative instructions
to the new location, also in a relative manner.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20250207122546.617187089@infradead.org
Starting with Rust 1.85.0 (currently in beta, to be released 2025-02-20),
under some kernel configurations with `CONFIG_RUST_DEBUG_ASSERTIONS=y`,
one may trigger a new `objtool` warning:
rust/kernel.o: warning: objtool: _R...securityNtB2_11SecurityCtx8as_bytes()
falls through to next function _R...core3ops4drop4Drop4drop()
due to a call to the `noreturn` symbol:
core::panicking::assert_failed::<usize, usize>
Thus add it to the list so that `objtool` knows it is actually `noreturn`.
Do so matching with `strstr` since it is a generic.
See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Cc: stable@vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is pinned in older LTSs).
Fixes: 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20250112143951.751139-1-ojeda@kernel.org
[ Updated Cc: stable@ to include 6.13.y. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The lld.ld borkage is fixed in the latest llvm release (?) but will
not be backported, meaning we're stuck with broken linker for a fair
while.
Lets not spam all clang build logs and move warning to verbose.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
