linux-kernel - Re: [PATCH v1 1/3] powerpc: Fix eh field when calling lwarx on PPC32

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Message-ID: <20220802191002.h5pzq5goo34owqfv@pali>
Date:   Tue, 2 Aug 2022 21:10:02 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v1 1/3] powerpc: Fix eh field when calling lwarx on PPC32

On Tuesday 02 August 2022 11:02:36 Christophe Leroy wrote:
> Commit 9401f4e46cf6 ("powerpc: Use lwarx/ldarx directly instead of
> PPC_LWARX/LDARX macros") properly handled the eh field of lwarx
> in asm/bitops.h but failed to clear it for PPC32 in
> asm/simple_spinlock.h
> 
> So, do as in arch_atomic_try_cmpxchg_lock(), set it to 1 if PPC64
> but set it to 0 if PPC32. For that use IS_ENABLED(CONFIG_PPC64) which
> returns 1 when CONFIG_PPC64 is set and 0 otherwise.
> 
> Reported-by: Pali Rohár <pali@...nel.org>
> Fixes: 9401f4e46cf6 ("powerpc: Use lwarx/ldarx directly instead of PPC_LWARX/LDARX macros")
> Cc: stable@...r.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>

This fix works perfectly. Thanks!

Tested-by: Pali Rohár <pali@...nel.org>

> ---
>  arch/powerpc/include/asm/simple_spinlock.h | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/simple_spinlock.h b/arch/powerpc/include/asm/simple_spinlock.h
> index 7ae6aeef8464..5095c636a680 100644
> --- a/arch/powerpc/include/asm/simple_spinlock.h
> +++ b/arch/powerpc/include/asm/simple_spinlock.h
> @@ -48,10 +48,11 @@ static inline int arch_spin_is_locked(arch_spinlock_t *lock)
>  static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock)
>  {
>  	unsigned long tmp, token;
> +	unsigned int eh = IS_ENABLED(CONFIG_PPC64);
>  
>  	token = LOCK_TOKEN;
>  	__asm__ __volatile__(
> -"1:	lwarx		%0,0,%2,1\n\
> +"1:	lwarx		%0,0,%2,%3\n\
>  	cmpwi		0,%0,0\n\
>  	bne-		2f\n\
>  	stwcx.		%1,0,%2\n\
> @@ -59,7 +60,7 @@ static inline unsigned long __arch_spin_trylock(arch_spinlock_t *lock)
>  	PPC_ACQUIRE_BARRIER
>  "2:"
>  	: "=&r" (tmp)
> -	: "r" (token), "r" (&lock->slock)
> +	: "r" (token), "r" (&lock->slock), "i" (eh)
>  	: "cr0", "memory");
>  
>  	return tmp;
> @@ -156,9 +157,10 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
>  static inline long __arch_read_trylock(arch_rwlock_t *rw)
>  {
>  	long tmp;
> +	unsigned int eh = IS_ENABLED(CONFIG_PPC64);
>  
>  	__asm__ __volatile__(
> -"1:	lwarx		%0,0,%1,1\n"
> +"1:	lwarx		%0,0,%1,%2\n"
>  	__DO_SIGN_EXTEND
>  "	addic.		%0,%0,1\n\
>  	ble-		2f\n"
> @@ -166,7 +168,7 @@ static inline long __arch_read_trylock(arch_rwlock_t *rw)
>  	bne-		1b\n"
>  	PPC_ACQUIRE_BARRIER
>  "2:"	: "=&r" (tmp)
> -	: "r" (&rw->lock)
> +	: "r" (&rw->lock), "i" (eh)
>  	: "cr0", "xer", "memory");
>  
>  	return tmp;
> @@ -179,17 +181,18 @@ static inline long __arch_read_trylock(arch_rwlock_t *rw)
>  static inline long __arch_write_trylock(arch_rwlock_t *rw)
>  {
>  	long tmp, token;
> +	unsigned int eh = IS_ENABLED(CONFIG_PPC64);
>  
>  	token = WRLOCK_TOKEN;
>  	__asm__ __volatile__(
> -"1:	lwarx		%0,0,%2,1\n\
> +"1:	lwarx		%0,0,%2,%3\n\
>  	cmpwi		0,%0,0\n\
>  	bne-		2f\n"
>  "	stwcx.		%1,0,%2\n\
>  	bne-		1b\n"
>  	PPC_ACQUIRE_BARRIER
>  "2:"	: "=&r" (tmp)
> -	: "r" (token), "r" (&rw->lock)
> +	: "r" (token), "r" (&rw->lock), "i" (eh)
>  	: "cr0", "memory");
>  
>  	return tmp;
> -- 
> 2.36.1
>