Kees Cook 6606c8c7e8 bitops: Add __attribute_const__ to generic ffs()-family implementations ... While tracking down a problem where constant expressions used by BUILD_BUG_ON() suddenly stopped working[1], we found that an added static initializer was convincing the compiler that it couldn't track the state of the prior statically initialized value. Tracing this down found that ffs() was used in the initializer macro, but since it wasn't marked with __attribute__const__, the compiler had to assume the function might change variable states as a side-effect (which is not true for ffs(), which provides deterministic math results). Add missing __attribute_const__ annotations to generic implementations of ffs(), __ffs(), fls(), and __fls() functions. These are pure mathematical functions that always return the same result for the same input with no side effects, making them eligible for compiler optimization. Build tested with x86_64 defconfig using GCC 14.2.0, which should validate the implementations when used by ARM, ARM64, LoongArch, Microblaze, NIOS2, and SPARC32 architectures. Link: https://github.com/KSPP/linux/issues/364 [1] Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20250804164417.1612371-2-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>		2025-09-08 14:58:50 -07:00
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bitops	bitops: Add __attribute_const__ to generic ffs()-family implementations	2025-09-08 14:58:50 -07:00
vdso	vdso/vsyscall: Split up __arch_update_vsyscall() into __arch_update_vdso_clock()	2025-07-09 11:52:34 +02:00
Kbuild	unwind_user: Add user space unwinding API with frame pointer support	2025-07-29 14:46:07 -04:00
access_ok.h	uaccess: remove CONFIG_SET_FS	2022-02-25 09:36:06 +01:00
agp.h	char/agp: introduce asm-generic/agp.h	2023-02-13 22:13:29 +01:00
archrandom.h	random: handle archrandom with multiple longs	2022-07-25 13:26:14 +02:00
asm-offsets.h	…
asm-prototypes.h	…
atomic.h	locking/atomic: make atomic*_{cmp,}xchg optional	2023-06-05 09:57:14 +02:00
atomic64.h	locking/atomic: delete !ARCH_ATOMIC remnants	2021-05-26 13:20:52 +02:00
audit_change_attr.h	fs/xattr: add *at family syscalls	2024-11-06 12:59:44 -05:00
audit_dir_write.h	…
audit_read.h	…
audit_signal.h	…
audit_write.h	…
barrier.h	sched: Add missing memory barrier in switch_mm_cid	2024-04-16 13:59:45 +02:00
bitops.h	include: move find.h from asm_generic to linux	2022-01-15 08:47:31 -08:00
bitsperlong.h	lib: extend the scope of small_const_nbits() macro	2021-05-06 19:24:11 -07:00
bug.h	bug: Improve comment	2024-05-07 14:20:48 +02:00
cache.h	…
cacheflush.h	mm: Introduce flush_cache_vmap_early()	2023-12-14 00:23:17 -08:00
cfi.h	cfi: Flip headers	2023-12-15 16:25:55 -08:00
checksum.h	asm-generic: Improve csum_fold	2024-01-17 17:52:29 -08:00
cmpxchg-local.h	asm-generic: Fix 32 bit __generic_cmpxchg_local	2024-01-05 23:19:14 +01:00
cmpxchg.h	asm-generic: avoid __generic_cmpxchg_local warnings	2023-04-04 17:58:11 +02:00
codetag.lds.h	codetag: avoid unused alloc_tags sections/symbols	2025-07-09 22:42:14 -07:00
compat.h	asm-generic: compat: fix compat_arg_u64() and compat_arg_u64_dual()	2022-11-01 10:20:11 +11:00
current.h	asm-generic: current: Don't include thread-info.h if building asm	2023-08-26 22:38:49 +02:00
delay.h	delay: Fix ndelay() spuriously treated as udelay()	2024-11-29 11:40:22 +01:00
device.h	…
div64.h	__arch_xprod64(): make __always_inline when optimizing for performance	2024-10-28 21:44:28 +00:00
dma-mapping.h	dma-mapping: no need to pass a bus_type into get_arch_dma_ops()	2023-02-15 12:35:20 +01:00
dma.h	…
early_ioremap.h	mm/early_ioremap: add null pointer checks to prevent NULL-pointer dereference	2025-01-13 22:40:59 -08:00
emergency-restart.h	…
error-injection.h	docs: fault-injection: add requirements of error injectable functions	2023-02-02 22:50:00 -08:00
exec.h	…
extable.h	…
fixmap.h	fixmap: Remove unused set_fixmap_offset_io()	2024-07-11 17:41:23 +02:00
flat.h	…
fprobe.h	fprobe: Add fprobe_header encoding feature	2024-12-26 10:50:05 -05:00
ftrace.h	…
futex.h	futex: Fix additional regressions	2021-12-11 23:31:51 +01:00
getorder.h	asm-generic: force inlining of get_order() to work around gcc10 poor decision	2020-12-15 22:46:15 -08:00
hardirq.h	irqstat: Move declaration into asm-generic/hardirq.h	2020-11-23 10:31:06 +01:00
hugetlb.h	mm: drop hugetlb_free_pgd_range()	2025-07-24 19:12:32 -07:00
hw_irq.h	…
int-ll64.h	…
io.h	- The 6 patch series "Enable strict percpu address space checks" from	2025-04-01 09:29:18 -07:00
ioctl.h	…
iomap.h	asm-generic/io.h: rework split ioread64/iowrite64 helpers	2025-03-01 21:00:22 +01:00
irq.h	…
irq_regs.h	…
irq_work.h	…
irqflags.h	…
kdebug.h	…
kmap_size.h	mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL	2020-11-24 14:42:08 +01:00
kprobes.h	treewide: Convert macro and uses of __section(foo) to __section("foo")	2020-10-25 14:51:49 -07:00
kvm_para.h	…
kvm_types.h	KVM: Move x86's version of struct kvm_mmu_memory_cache to common code	2020-07-09 13:29:42 -04:00
linkage.h	…
local.h	locking/generic: Wire up local{,64}_try_cmpxchg()	2023-04-29 09:09:09 +02:00
local64.h	locking/generic: Wire up local{,64}_try_cmpxchg()	2023-04-29 09:09:09 +02:00
logic_io.h	logic_io instance of iounmap() needs volatile on argument	2021-12-21 21:31:08 +01:00
mcs_spinlock.h	locking: Move MCS struct definition to public header	2025-03-18 10:28:21 -07:00
memory_model.h	mm: implement for_each_valid_pfn() for CONFIG_FLATMEM	2025-05-12 23:50:43 -07:00
mm_hooks.h	mm: remove arch_unmap()	2024-09-01 20:26:13 -07:00
mmiowb.h	asm-generic/mmiowb: Allow mmiowb_set_pending() when preemptible()	2020-07-17 10:02:03 +01:00
mmiowb_types.h	…
mmu.h	…
mmu_context.h	asm-generic: add generic MMU versions of mmu context functions	2020-10-26 16:45:03 +01:00
mmzone.h	arch, mm: move definition of node_data to generic code	2024-09-03 21:15:28 -07:00
module.h	asm-generic: Always define Elf_Rel and Elf_Rela	2025-03-26 15:56:43 -07:00
module.lds.h	kbuild: preprocess module linker script	2020-09-25 00:36:41 +09:00
mshyperv.h	Drivers: hv: Remove hv_alloc/free_* helpers	2025-05-23 16:30:56 +00:00
msi.h	irqchip/gic-v5: Add GICv5 IWB support	2025-07-08 18:35:52 +01:00
nommu_context.h	asm-generic: add generic MMU versions of mmu context functions	2020-10-26 16:45:03 +01:00
numa.h	arch_numa: switch over to numa_memblks	2024-09-03 21:15:32 -07:00
param.h	alpha: regularize the situation with asm/param.h	2025-06-24 22:02:05 -04:00
parport.h	…
pci.h	asm-generic: Add new pci.h and use it	2022-07-22 17:34:57 -05:00
pci_iomap.h	PCI: Stub __pci_ioport_map() for arches that don't support it at all	2022-07-29 12:01:00 -05:00
percpu.h	percpu: repurpose __percpu tag as a named address space qualifier	2025-03-16 22:05:53 -07:00
pgalloc.h	mm: call ctor/dtor for kernel PTEs	2025-05-11 17:48:21 -07:00
pgtable-nop4d.h	mm: rename p4d_page_vaddr to p4d_pgtable and make it return pud_t *	2021-07-08 11:48:22 -07:00
pgtable-nopmd.h	mm: recover pud_leaf() definitions in nopmd case	2024-03-13 12:12:21 -07:00
pgtable-nopud.h	mm: rename p4d_page_vaddr to p4d_pgtable and make it return pud_t *	2021-07-08 11:48:22 -07:00
pgtable_uffd.h	userfaultfd: wp: add pmd_swp_*uffd_wp() helpers	2020-04-07 10:43:39 -07:00
preempt.h	riscv: support PREEMPT_DYNAMIC with static keys	2023-08-31 00:18:34 -07:00
qrwlock.h	asm-generic changes for 5.19	2022-05-26 10:50:30 -07:00
qrwlock_types.h	locking/qrwlock: Change "queue rwlock" to "queued rwlock"	2022-05-11 16:27:04 +02:00
qspinlock.h	riscv: Add qspinlock support	2024-11-11 07:33:20 -08:00
qspinlock_types.h	locking/qspinlock: Do not include atomic.h from qspinlock_types.h	2020-07-29 16:14:19 +02:00
resource.h	…
rqspinlock.h	bpf: Introduce rqspinlock kfuncs	2025-03-19 08:03:06 -07:00
runtime-const.h	runtime constants: add default dummy infrastructure	2024-06-19 12:34:34 -07:00
rwonce.h	rwonce: fix crash by removing READ_ONCE() for unaligned read	2025-03-26 22:16:50 +01:00
seccomp.h	seccomp: Use -1 marker for end of mode 1 syscall list	2020-07-10 16:01:52 -07:00
sections.h	percpu: Remove __per_cpu_load	2025-02-18 10:16:00 +01:00
serial.h	…
set_memory.h	…
shmparam.h	…
signal.h	asm-generic: Remove empty #ifdef SA_RESTORER	2022-09-10 09:56:53 +02:00
simd.h	asm-generic: Add sched.h inclusion in simd.h	2025-05-30 20:56:48 +08:00
softirq_stack.h	asm-generic: Conditionally enable do_softirq_own_stack() via Kconfig.	2022-09-05 17:20:55 +02:00
spinlock.h	asm-generic: ticket-lock: Add separate ticket-lock.h	2024-11-11 07:33:17 -08:00
spinlock_types.h	asm-generic: ticket-lock: Reuse arch_spinlock_t of qspinlock	2024-11-11 07:33:16 -08:00
statfs.h	…
string.h	…
switch_to.h	…
syscall.h	syscall.h: introduce syscall_set_nr()	2025-05-11 17:48:15 -07:00
syscalls.h	syscalls: mmap(): use unsigned offset type consistently	2024-06-25 15:57:38 +02:00
text-patching.h	asm-generic: introduce text-patching.h	2024-11-07 14:25:15 -08:00
ticket_spinlock.h	riscv: Add qspinlock support	2024-11-11 07:33:20 -08:00
timex.h	…
tlb.h	mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables()	2025-05-31 22:46:12 -07:00
tlbflush.h	…
topology.h	mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA	2021-06-29 10:53:55 -07:00
trace_clock.h	…
uaccess.h	move asm/unaligned.h to linux/unaligned.h	2024-10-02 17:23:23 -04:00
unwind_user.h	unwind_user: Add user space unwinding API with frame pointer support	2025-07-29 14:46:07 -04:00
user.h	…
vermagic.h	arch: split MODULE_ARCH_VERMAGIC definitions out to <asm/vermagic.h>	2020-04-23 10:50:26 +09:00
vga.h	empty include/asm-generic/vga.h	2024-11-11 21:51:42 +01:00
video.h	arch: Rename fbdev header and source files	2024-05-03 17:07:50 +02:00
vmlinux.lds.h	tracing: Remove redundant config HAVE_FTRACE_MCOUNT_RECORD	2025-07-22 20:15:56 -04:00
word-at-a-time.h	kernel.h: removed REPEAT_BYTE from kernel.h	2024-02-01 09:47:59 -08:00
xor.h	lib/xor: make xor prototypes more friendly to compiler vectorization	2022-02-11 20:39:39 +11:00