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()

9 files changed, 10 insertions, 10 deletions

diff --git a/include/asm-generic/bitops/__ffs.h b/include/asm-generic/bitops/__ffs.h
index 2d08c750c8a7..3a899c626fdc 100644
--- a/include/asm-generic/bitops/__ffs.h
+++ b/include/asm-generic/bitops/__ffs.h
@@ -10,7 +10,7 @@
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned int generic___ffs(unsigned long word)
+static __always_inline __attribute_const__ unsigned int generic___ffs(unsigned long word)
 {
 	unsigned int num = 0;
 
diff --git a/include/asm-generic/bitops/__fls.h b/include/asm-generic/bitops/__fls.h
index e974ec932ec1..35f33780ca6c 100644
--- a/include/asm-generic/bitops/__fls.h
+++ b/include/asm-generic/bitops/__fls.h
@@ -10,7 +10,7 @@
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned int generic___fls(unsigned long word)
+static __always_inline __attribute_const__ unsigned int generic___fls(unsigned long word)
 {
 	unsigned int num = BITS_PER_LONG - 1;
 
diff --git a/include/asm-generic/bitops/builtin-__ffs.h b/include/asm-generic/bitops/builtin-__ffs.h
index cf4b3d33bf96..d3c3f567045d 100644
--- a/include/asm-generic/bitops/builtin-__ffs.h
+++ b/include/asm-generic/bitops/builtin-__ffs.h
@@ -8,7 +8,7 @@
  *
  * Undefined if no bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned int __ffs(unsigned long word)
+static __always_inline __attribute_const__ unsigned int __ffs(unsigned long word)
 {
 	return __builtin_ctzl(word);
 }
diff --git a/include/asm-generic/bitops/builtin-__fls.h b/include/asm-generic/bitops/builtin-__fls.h
index 6d72fc8a5259..7770c4f1bfcd 100644
--- a/include/asm-generic/bitops/builtin-__fls.h
+++ b/include/asm-generic/bitops/builtin-__fls.h
@@ -8,7 +8,7 @@
  *
  * Undefined if no set bit exists, so code should check against 0 first.
  */
-static __always_inline unsigned int __fls(unsigned long word)
+static __always_inline __attribute_const__ unsigned int __fls(unsigned long word)
 {
 	return (sizeof(word) * 8) - 1 - __builtin_clzl(word);
 }
diff --git a/include/asm-generic/bitops/builtin-fls.h b/include/asm-generic/bitops/builtin-fls.h
index c8455cc28841..be707da8c7cd 100644
--- a/include/asm-generic/bitops/builtin-fls.h
+++ b/include/asm-generic/bitops/builtin-fls.h
@@ -9,7 +9,7 @@
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static __always_inline int fls(unsigned int x)
+static __always_inline __attribute_const__ int fls(unsigned int x)
 {
 	return x ? sizeof(x) * 8 - __builtin_clz(x) : 0;
 }
diff --git a/include/asm-generic/bitops/ffs.h b/include/asm-generic/bitops/ffs.h
index 4c43f242daeb..5ff2b7fbda6d 100644
--- a/include/asm-generic/bitops/ffs.h
+++ b/include/asm-generic/bitops/ffs.h
@@ -10,7 +10,7 @@
  * the libc and compiler builtin ffs routines, therefore
  * differs in spirit from ffz (man ffs).
  */
-static inline int generic_ffs(int x)
+static inline __attribute_const__ int generic_ffs(int x)
 {
 	int r = 1;
 
diff --git a/include/asm-generic/bitops/fls.h b/include/asm-generic/bitops/fls.h
index 26f3ce1dd6e4..8eed3437edb9 100644
--- a/include/asm-generic/bitops/fls.h
+++ b/include/asm-generic/bitops/fls.h
@@ -10,7 +10,7 @@
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
 
-static __always_inline int generic_fls(unsigned int x)
+static __always_inline __attribute_const__ int generic_fls(unsigned int x)
 {
 	int r = 32;
 
diff --git a/include/asm-generic/bitops/fls64.h b/include/asm-generic/bitops/fls64.h
index 866f2b2304ff..b5f58dd261a3 100644
--- a/include/asm-generic/bitops/fls64.h
+++ b/include/asm-generic/bitops/fls64.h
@@ -16,7 +16,7 @@
  * at position 64.
  */
 #if BITS_PER_LONG == 32
-static __always_inline int fls64(__u64 x)
+static __always_inline __attribute_const__ int fls64(__u64 x)
 {
 	__u32 h = x >> 32;
 	if (h)
@@ -24,7 +24,7 @@ static __always_inline int fls64(__u64 x)
 	return fls(x);
 }
 #elif BITS_PER_LONG == 64
-static __always_inline int fls64(__u64 x)
+static __always_inline __attribute_const__ int fls64(__u64 x)
 {
 	if (x == 0)
 		return 0;
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 9be2d50da09a..ea7898cc5903 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -267,7 +267,7 @@ static inline int parity8(u8 val)
  * The result is not defined if no bits are set, so check that @word
  * is non-zero before calling this.
  */
-static inline unsigned int __ffs64(u64 word)
+static inline __attribute_const__ unsigned int __ffs64(u64 word)
 {
 #if BITS_PER_LONG == 32
 	if (((u32)word) == 0UL)