[PATCH 2/6] ARM: smp_on_up: move inline asm ALT_SMP patching macro out of spinlock.h

[Nicolas Pitre]

On Tue, 23 Jul 2013, Will Deacon wrote:

> Patching UP/SMP alternatives inside inline assembly blocks is useful
> outside of the spinlock implementation, where it is used for sev and wfe.
> 
> This patch lifts the macro into processor.h and gives it a scarier name
> to (a) avoid conflicts in the global namespace and (b) to try and deter
> its usage unless you "know what you're doing". The W macro for generating
> wide instructions when targetting Thumb-2 is also made available under
> the name WASM, to reduce the potential for conflicts with other headers.
> 
> Signed-off-by: Will Deacon <will.deacon at arm.com>

Acked-by: Nicolas Pitre <nico at linaro.org>

> ---
>  arch/arm/include/asm/processor.h | 12 ++++++++++++
>  arch/arm/include/asm/spinlock.h  | 15 ++++-----------
>  arch/arm/include/asm/unified.h   |  4 ++++
>  3 files changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
> index 91cfe08..cbdb130 100644
> --- a/arch/arm/include/asm/processor.h
> +++ b/arch/arm/include/asm/processor.h
> @@ -22,6 +22,7 @@
>  #include <asm/hw_breakpoint.h>
>  #include <asm/ptrace.h>
>  #include <asm/types.h>
> +#include <asm/unified.h>
>  
>  #ifdef __KERNEL__
>  #define STACK_TOP	((current->personality & ADDR_LIMIT_32BIT) ? \
> @@ -91,6 +92,17 @@ unsigned long get_wchan(struct task_struct *p);
>  #define KSTK_EIP(tsk)	task_pt_regs(tsk)->ARM_pc
>  #define KSTK_ESP(tsk)	task_pt_regs(tsk)->ARM_sp
>  
> +#ifdef CONFIG_SMP
> +#define __ALT_SMP_ASM(smp, up)						\
> +	"9998:	" smp "\n"						\
> +	"	.pushsection \".alt.smp.init\", \"a\"\n"		\
> +	"	.long	9998b\n"					\
> +	"	" up "\n"						\
> +	"	.popsection\n"
> +#else
> +#define __ALT_SMP_ASM(smp, up)	up
> +#endif
> +
>  /*
>   * Prefetching support - only ARMv5.
>   */
> diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
> index f8b8965..0de7bec 100644
> --- a/arch/arm/include/asm/spinlock.h
> +++ b/arch/arm/include/asm/spinlock.h
> @@ -11,15 +11,7 @@
>   * sev and wfe are ARMv6K extensions.  Uniprocessor ARMv6 may not have the K
>   * extensions, so when running on UP, we have to patch these instructions away.
>   */
> -#define ALT_SMP(smp, up)					\
> -	"9998:	" smp "\n"					\
> -	"	.pushsection \".alt.smp.init\", \"a\"\n"	\
> -	"	.long	9998b\n"				\
> -	"	" up "\n"					\
> -	"	.popsection\n"
> -
>  #ifdef CONFIG_THUMB2_KERNEL
> -#define SEV		ALT_SMP("sev.w", "nop.w")
>  /*
>   * For Thumb-2, special care is needed to ensure that the conditional WFE
>   * instruction really does assemble to exactly 4 bytes (as required by
> @@ -31,17 +23,18 @@
>   * the assembler won't change IT instructions which are explicitly present
>   * in the input.
>   */
> -#define WFE(cond)	ALT_SMP(		\
> +#define WFE(cond)	__ALT_SMP_ASM(		\
>  	"it " cond "\n\t"			\
>  	"wfe" cond ".n",			\
>  						\
>  	"nop.w"					\
>  )
>  #else
> -#define SEV		ALT_SMP("sev", "nop")
> -#define WFE(cond)	ALT_SMP("wfe" cond, "nop")
> +#define WFE(cond)	__ALT_SMP_ASM("wfe" cond, "nop")
>  #endif
>  
> +#define SEV		__ALT_SMP_ASM(WASM(sev), WASM(nop))
> +
>  static inline void dsb_sev(void)
>  {
>  #if __LINUX_ARM_ARCH__ >= 7
> diff --git a/arch/arm/include/asm/unified.h b/arch/arm/include/asm/unified.h
> index f5989f4..b88beab 100644
> --- a/arch/arm/include/asm/unified.h
> +++ b/arch/arm/include/asm/unified.h
> @@ -38,6 +38,8 @@
>  #ifdef __ASSEMBLY__
>  #define W(instr)	instr.w
>  #define BSYM(sym)	sym + 1
> +#else
> +#define WASM(instr)	#instr ".w"
>  #endif
>  
>  #else	/* !CONFIG_THUMB2_KERNEL */
> @@ -50,6 +52,8 @@
>  #ifdef __ASSEMBLY__
>  #define W(instr)	instr
>  #define BSYM(sym)	sym
> +#else
> +#define WASM(instr)	#instr
>  #endif
>  
>  #endif	/* CONFIG_THUMB2_KERNEL */
> -- 
> 1.8.2.2
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>