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, 5 insertions, 5 deletions

diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index a5ca0a947691..fbcc3e1cc776 100644
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -179,7 +179,7 @@ static inline unsigned char __flogr(unsigned long word)
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static inline unsigned long __ffs(unsigned long word)
+static inline __attribute_const__ unsigned long __ffs(unsigned long word)
 {
 	return __flogr(-word & word) ^ (BITS_PER_LONG - 1);
 }
@@ -191,7 +191,7 @@ static inline unsigned long __ffs(unsigned long word)
  * This is defined the same way as the libc and
  * compiler builtin ffs routines (man ffs).
  */
-static inline int ffs(int word)
+static inline __attribute_const__ int ffs(int word)
 {
 	unsigned long mask = 2 * BITS_PER_LONG - 1;
 	unsigned int val = (unsigned int)word;
@@ -205,7 +205,7 @@ static inline int ffs(int word)
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static inline unsigned long __fls(unsigned long word)
+static inline __attribute_const__ unsigned long __fls(unsigned long word)
 {
 	return __flogr(word) ^ (BITS_PER_LONG - 1);
 }
@@ -221,7 +221,7 @@ static inline unsigned long __fls(unsigned long word)
  * set bit if value is nonzero. The last (most significant) bit is
  * at position 64.
  */
-static inline int fls64(unsigned long word)
+static inline __attribute_const__ int fls64(unsigned long word)
 {
 	unsigned long mask = 2 * BITS_PER_LONG - 1;
 
@@ -235,7 +235,7 @@ static inline int fls64(unsigned long word)
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static inline int fls(unsigned int word)
+static inline __attribute_const__ int fls(unsigned int word)
 {
 	return fls64(word);
 }