Merge tag 'ffs-const-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull ffs const-attribute cleanups from Kees Cook:
 "While working on various hardening refactoring a while back we
  encountered inconsistencies in the application of __attribute_const__
  on the ffs() family of functions.

  This series fixes this across all archs and adds KUnit tests.

  Notably, this found a theoretical underflow in PCI (also fixed here)
  and uncovered an inefficiency in ARC (fixed in the ARC arch PR). I
  kept the series separate from the general hardening PR since it is a
  stand-alone "topic".

   - PCI: Fix theoretical underflow in use of ffs().

   - Universally apply __attribute_const__ to all architecture's
     ffs()-family of functions.

   - Add KUnit tests for ffs() behavior and const-ness"

* tag 'ffs-const-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  KUnit: ffs: Validate all the __attribute_const__ annotations
  sparc: Add __attribute_const__ to ffs()-family implementations
  xtensa: Add __attribute_const__ to ffs()-family implementations
  s390: Add __attribute_const__ to ffs()-family implementations
  parisc: Add __attribute_const__ to ffs()-family implementations
  mips: Add __attribute_const__ to ffs()-family implementations
  m68k: Add __attribute_const__ to ffs()-family implementations
  openrisc: Add __attribute_const__ to ffs()-family implementations
  riscv: Add __attribute_const__ to ffs()-family implementations
  hexagon: Add __attribute_const__ to ffs()-family implementations
  alpha: Add __attribute_const__ to ffs()-family implementations
  sh: Add __attribute_const__ to ffs()-family implementations
  powerpc: Add __attribute_const__ to ffs()-family implementations
  x86: Add __attribute_const__ to ffs()-family implementations
  csky: Add __attribute_const__ to ffs()-family implementations
  bitops: Add __attribute_const__ to generic ffs()-family implementations
  KUnit: Introduce ffs()-family tests
  PCI: Test for bit underflow in pcie_set_readrq()

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index eebbc8889e70..a835f891164d 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -246,7 +246,7 @@ arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
 					  variable_test_bit(nr, addr);
 }
 
-static __always_inline unsigned long variable__ffs(unsigned long word)
+static __always_inline __attribute_const__ unsigned long variable__ffs(unsigned long word)
 {
 	asm("tzcnt %1,%0"
 		: "=r" (word)
@@ -265,7 +265,7 @@ static __always_inline unsigned long variable__ffs(unsigned long word)
 	 (unsigned long)__builtin_ctzl(word) :	\
 	 variable__ffs(word))
 
-static __always_inline unsigned long variable_ffz(unsigned long word)
+static __always_inline __attribute_const__ unsigned long variable_ffz(unsigned long word)
 {
 	return variable__ffs(~word);
 }
@@ -287,7 +287,7 @@ static __always_inline unsigned long variable_ffz(unsigned long word)
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned long __fls(unsigned long word)
+static __always_inline __attribute_const__ unsigned long __fls(unsigned long word)
 {
 	if (__builtin_constant_p(word))
 		return BITS_PER_LONG - 1 - __builtin_clzl(word);
@@ -301,7 +301,7 @@ static __always_inline unsigned long __fls(unsigned long word)
 #undef ADDR
 
 #ifdef __KERNEL__
-static __always_inline int variable_ffs(int x)
+static __always_inline __attribute_const__ int variable_ffs(int x)
 {
 	int r;
 
@@ -355,7 +355,7 @@ static __always_inline int variable_ffs(int x)
  * set bit if value is nonzero. The last (most significant) bit is
  * at position 32.
  */
-static __always_inline int fls(unsigned int x)
+static __always_inline __attribute_const__ int fls(unsigned int x)
 {
 	int r;
 
@@ -400,7 +400,7 @@ static __always_inline int fls(unsigned int x)
  * at position 64.
  */
 #ifdef CONFIG_X86_64
-static __always_inline int fls64(__u64 x)
+static __always_inline __attribute_const__ int fls64(__u64 x)
 {
 	int bitpos = -1;