Message-Id: <20241123-riscv-always-inline-bitops-v1-1-00e8262ab1cf@kernel.org>
Date: Sat, 23 Nov 2024 19:30:19 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Palmer Dabbelt <palmer@...belt.com>, Yury Norov <yury.norov@...il.com>, 
 Rasmus Villemoes <linux@...musvillemoes.dk>, 
 Paul Walmsley <paul.walmsley@...ive.com>, Albert Ou <aou@...s.berkeley.edu>
Cc: Conor Dooley <conor@...nel.org>, linux-riscv@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
 Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] riscv: Always inline bitops

When building allmodconfig + ThinLTO with certain versions of clang,
arch_set_bit() may not be inlined, resulting in a modpost warning:

  WARNING: modpost: vmlinux: section mismatch in reference: arch_set_bit+0x58 (section: .text.arch_set_bit) -> numa_nodes_parsed (section: .init.data)

acpi_numa_rintc_affinity_init() calls arch_set_bit() via __node_set()
with numa_nodes_parsed, which is marked as __initdata. If arch_set_bit()
is not inlined, modpost will flag that it is being called with data that
will be freed after init.

As acpi_numa_rintc_affinity_init() is marked as __init, there is not
actually a functional issue here. However, the bitop functions should be
marked as __always_inline, so that they work consistently for init and
non-init code, which the comment in include/linux/nodemask.h alludes to.
This matches s390 and x86's implementations.

Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 arch/riscv/include/asm/bitops.h | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/include/asm/bitops.h b/arch/riscv/include/asm/bitops.h
index fae152ea0508d2e1ea490fffd645eab99cf387bf..c6bd3d8354a96b4e7bbef0e98a201da412301b57 100644
--- a/arch/riscv/include/asm/bitops.h
+++ b/arch/riscv/include/asm/bitops.h
@@ -228,7 +228,7 @@ static __always_inline int variable_fls(unsigned int x)
  *
  * This operation may be reordered on other architectures than x86.
  */
-static inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(or, __NOP, nr, addr);
 }
@@ -240,7 +240,7 @@ static inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
  *
  * This operation can be reordered on other architectures other than x86.
  */
-static inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(and, __NOT, nr, addr);
 }
@@ -253,7 +253,7 @@ static inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
  * This operation is atomic and cannot be reordered.
  * It also implies a memory barrier.
  */
-static inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(xor, __NOP, nr, addr);
 }
@@ -270,7 +270,7 @@ static inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
  * Note that @nr may be almost arbitrarily large; this function is not
  * restricted to acting on a single-word quantity.
  */
-static inline void arch_set_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_set_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(or, __NOP, nr, addr);
 }
@@ -284,7 +284,7 @@ static inline void arch_set_bit(int nr, volatile unsigned long *addr)
  * on non x86 architectures, so if you are writing portable code,
  * make sure not to rely on its reordering guarantees.
  */
-static inline void arch_clear_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_clear_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(and, __NOT, nr, addr);
 }
@@ -298,7 +298,7 @@ static inline void arch_clear_bit(int nr, volatile unsigned long *addr)
  * Note that @nr may be almost arbitrarily large; this function is not
  * restricted to acting on a single-word quantity.
  */
-static inline void arch_change_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_change_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(xor, __NOP, nr, addr);
 }
@@ -311,7 +311,7 @@ static inline void arch_change_bit(int nr, volatile unsigned long *addr)
  * This operation is atomic and provides acquire barrier semantics.
  * It can be used to implement bit locks.
  */
-static inline int arch_test_and_set_bit_lock(
+static __always_inline int arch_test_and_set_bit_lock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit_ord(or, __NOP, nr, addr, .aq);
@@ -324,7 +324,7 @@ static inline int arch_test_and_set_bit_lock(
  *
  * This operation is atomic and provides release barrier semantics.
  */
-static inline void arch_clear_bit_unlock(
+static __always_inline void arch_clear_bit_unlock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	__op_bit_ord(and, __NOT, nr, addr, .rl);
@@ -345,13 +345,13 @@ static inline void arch_clear_bit_unlock(
  * non-atomic property here: it's a lot more instructions and we still have to
  * provide release semantics anyway.
  */
-static inline void arch___clear_bit_unlock(
+static __always_inline void arch___clear_bit_unlock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	arch_clear_bit_unlock(nr, addr);
 }
 
-static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
+static __always_inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
 		volatile unsigned long *addr)
 {
 	unsigned long res;

---
base-commit: 0eb512779d642b21ced83778287a0f7a3ca8f2a1
change-id: 20241123-riscv-always-inline-bitops-0021c4dae36b

Best regards,
-- 
Nathan Chancellor <nathan@...nel.org>

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