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: 0d6e4563fc ("objtool: Add action to check for absence of absolute relocations")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://patch.msgid.link/1ac32fff-2e67-5155-f570-69aad5bf5412@redhat.com
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 779db37373 ("rust: alloc: kvec: implement
AsPageIter for VVec") and 671618432f ("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 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later.
Link: https://patch.msgid.link/20251020020714.2511718-1-ojeda@kernel.org
Pull more x86 updates from Borislav Petkov:
- Remove a bunch of asm implementing condition flags testing in KVM's
emulator in favor of int3_emulate_jcc() which is written in C
- Replace KVM fastops with C-based stubs which avoids problems with the
fastop infra related to latter not adhering to the C ABI due to their
special calling convention and, more importantly, bypassing compiler
control-flow integrity checking because they're written in asm
- Remove wrongly used static branches and other ugliness accumulated
over time in hyperv's hypercall implementation with a proper static
function call to the correct hypervisor call variant
- Add some fixes and modifications to allow running FRED-enabled
kernels in KVM even on non-FRED hardware
- Add kCFI improvements like validating indirect calls and prepare for
enabling kCFI with GCC. Add cmdline params documentation and other
code cleanups
- Use the single-byte 0xd6 insn as the official #UD single-byte
undefined opcode instruction as agreed upon by both x86 vendors
- Other smaller cleanups and touchups all over the place
* tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86,retpoline: Optimize patch_retpoline()
x86,ibt: Use UDB instead of 0xEA
x86/cfi: Remove __noinitretpoline and __noretpoline
x86/cfi: Add "debug" option to "cfi=" bootparam
x86/cfi: Standardize on common "CFI:" prefix for CFI reports
x86/cfi: Document the "cfi=" bootparam options
x86/traps: Clarify KCFI instruction layout
compiler_types.h: Move __nocfi out of compiler-specific header
objtool: Validate kCFI calls
x86/fred: KVM: VMX: Always use FRED for IRQs when CONFIG_X86_FRED=y
x86/fred: Play nice with invoking asm_fred_entry_from_kvm() on non-FRED hardware
x86/fred: Install system vector handlers even if FRED isn't fully enabled
x86/hyperv: Use direct call to hypercall-page
x86/hyperv: Clean up hv_do_hypercall()
KVM: x86: Remove fastops
KVM: x86: Convert em_salc() to C
KVM: x86: Introduce EM_ASM_3WCL
KVM: x86: Introduce EM_ASM_1SRC2
KVM: x86: Introduce EM_ASM_2CL
KVM: x86: Introduce EM_ASM_2W
...
Pull Kbuild updates from Nathan Chancellor:
- Extend modules.builtin.modinfo to include module aliases from
MODULE_DEVICE_TABLE for builtin modules so that userspace tools (such
as kmod) can verify that a particular module alias will be handled by
a builtin module
- Bump the minimum version of LLVM for building the kernel to 15.0.0
- Upgrade several userspace API checks in headers_check.pl to errors
- Unify and consolidate CONFIG_WERROR / W=e handling
- Turn assembler and linker warnings into errors with CONFIG_WERROR /
W=e
- Respect CONFIG_WERROR / W=e when building userspace programs
(userprogs)
- Enable -Werror unconditionally when building host programs
(hostprogs)
- Support copy_file_range() and data segment alignment in gen_init_cpio
to improve performance on filesystems that support reflinks such as
btrfs and XFS
- Miscellaneous small changes to scripts and configuration files
* tag 'kbuild-6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (47 commits)
modpost: Initialize builtin_modname to stop SIGSEGVs
Documentation: kbuild: note CONFIG_DEBUG_EFI in reproducible builds
kbuild: vmlinux.unstripped should always depend on .vmlinux.export.o
modpost: Create modalias for builtin modules
modpost: Add modname to mod_device_table alias
scsi: Always define blogic_pci_tbl structure
kbuild: extract modules.builtin.modinfo from vmlinux.unstripped
kbuild: keep .modinfo section in vmlinux.unstripped
kbuild: always create intermediate vmlinux.unstripped
s390: vmlinux.lds.S: Reorder sections
KMSAN: Remove tautological checks
objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY
lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
riscv: Unconditionally use linker relaxation
riscv: Remove version check for LTO_CLANG selects
powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()
mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER
arm64: Remove tautological LLVM Kconfig conditions
ARM: Clean up definition of ARM_HAS_GROUP_RELOCS
...
When building with CONFIG_CFI_CLANG=y after the recent series to
separate the x86 startup code, there are objtool warnings along the
lines of:
vmlinux.o: warning: objtool: __pi___cfi_startup_64_load_idt() falls through to next function __pi_startup_64_load_idt()
vmlinux.o: warning: objtool: __pi___cfi_startup_64_setup_gdt_idt() falls through to next function __pi_startup_64_setup_gdt_idt()
vmlinux.o: warning: objtool: __pi___cfi___startup_64() falls through to next function __pi___startup_64()
As the comment in validate_branch() states, this is expected, so ignore
these symbols in the same way that __cfi_ and __pfx_ symbols are already
ignored for the rest of the kernel.
Fixes: 7b38dec3c5 ("x86/boot: Create a confined code area for startup code")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
In order to be able to have tight control over which code may execute
from the early 1:1 mapping of memory, but still link vmlinux as a single
executable, prefix all symbol references in startup code with __pi_, and
invoke it from outside using the __pi_ prefix.
Use objtool to check that no absolute symbol references are present in
the startup code, as these cannot be used from code running from the 1:1
mapping.
Note that this also requires disabling the latent-entropy GCC plugin, as
the global symbol references that it injects would require explicit
exports, and given that the startup code rarely executes more than once,
it is not a useful source of entropy anyway.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250828102202.1849035-43-ardb+git@google.com
The x86 startup code must not use absolute references to code or data,
as it executes before the kernel virtual mapping is up.
Add an action to objtool to check all allocatable sections (with the
exception of __patchable_function_entries, which uses absolute
references for nebulous reasons) and raise an error if any absolute
references are found.
Note that debug sections typically contain lots of absolute references
too, but those are not allocatable so they will be ignored.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/20250828102202.1849035-39-ardb+git@google.com
Validate that all indirect calls adhere to kCFI rules. Notably doing
nocfi indirect call to a cfi function is broken.
Apparently some Rust 'core' code violates this and explodes when ran
with FineIBT.
All the ANNOTATE_NOCFI_SYM sites are prime targets for attackers.
- runtime EFI is especially henous because it also needs to disable
IBT. Basically calling unknown code without CFI protection at
runtime is a massice security issue.
- Kexec image handover; if you can exploit this, you get to keep it :-)
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lkml.kernel.org/r/20250714103441.496787279@infradead.org
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>
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
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>
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>
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
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/
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/
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
...
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>
