linux-kernel - [PATCH] sparc: mark __arch_xchg() as __always

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Date:   Wed, 28 Jun 2023 11:49:18 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Kees Cook <keescook@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Guenter Roeck <linux@...ck-us.net>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andi Shyti <andi.shyti@...ux.intel.com>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] sparc: mark __arch_xchg() as __always_inline

From: Arnd Bergmann <arnd@...db.de>

An otherwise correct change to the atomic operations uncovered an
existing bug in the sparc __arch_xchg() function, which is calls
__xchg_called_with_bad_pointer() when its arguments are unknown at
compile time:

ERROR: modpost: "__xchg_called_with_bad_pointer" [lib/atomic64_test.ko] undefined!

This now happens because gcc determines that it's better to not inline the
function. Avoid this by just marking the function as __always_inline
to force the compiler to do the right thing here.

Reported-by: Guenter Roeck <linux@...ck-us.net>
Link: https://lore.kernel.org/all/c525adc9-6623-4660-8718-e0c9311563b8@roeck-us.net/
Fixes: d12157efc8e08 ("locking/atomic: make atomic*_{cmp,}xchg optional")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/sparc/include/asm/cmpxchg_32.h | 2 +-
 arch/sparc/include/asm/cmpxchg_64.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/include/asm/cmpxchg_32.h b/arch/sparc/include/asm/cmpxchg_32.h
index 7a1339533d1d7..d0af82c240b73 100644
--- a/arch/sparc/include/asm/cmpxchg_32.h
+++ b/arch/sparc/include/asm/cmpxchg_32.h
@@ -15,7 +15,7 @@
 unsigned long __xchg_u32(volatile u32 *m, u32 new);
 void __xchg_called_with_bad_pointer(void);
 
-static inline unsigned long __arch_xchg(unsigned long x, __volatile__ void * ptr, int size)
+static __always_inline unsigned long __arch_xchg(unsigned long x, __volatile__ void * ptr, int size)
 {
 	switch (size) {
 	case 4:
diff --git a/arch/sparc/include/asm/cmpxchg_64.h b/arch/sparc/include/asm/cmpxchg_64.h
index 66cd61dde9ec1..3de25262c4118 100644
--- a/arch/sparc/include/asm/cmpxchg_64.h
+++ b/arch/sparc/include/asm/cmpxchg_64.h
@@ -87,7 +87,7 @@ xchg16(__volatile__ unsigned short *m, unsigned short val)
 	return (load32 & mask) >> bit_shift;
 }
 
-static inline unsigned long
+static __always_inline unsigned long
 __arch_xchg(unsigned long x, __volatile__ void * ptr, int size)
 {
 	switch (size) {
-- 
2.39.2