Commit 539615de authored by Uros Bizjak's avatar Uros Bizjak Committed by Ingo Molnar
Browse files

x86/percpu: Introduce the __raw_cpu_read_const() macro 



Introduce the __raw_cpu_read_const() macro to further reduce ifdeffery
and differences between configs w/ and w/o USE_X86_SEG_SUPPORT.

No functional change intended.

Signed-off-by: default avatarUros Bizjak <ubizjak@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240430091833.196482-4-ubizjak@gmail.com
parent a50ea641

arch/x86/include/asm/percpu.h

+9 −10
Original line number Diff line number Diff line
@@ -156,6 +156,8 @@ do { \ 
	*(qual __my_cpu_type(pcp) *)__my_cpu_ptr(&(pcp)) = (val);	\

} while (0)



#define __raw_cpu_read_const(pcp)	__raw_cpu_read(, , pcp)



#else /* CONFIG_USE_X86_SEG_SUPPORT */



#define __raw_cpu_read(size, qual, _var)				\
@@ -180,6 +182,12 @@ do { \ 
	    : [val] __pcpu_reg_imm_##size(pto_val__));			\

} while (0)



/*

 * The generic per-cpu infrastrucutre is not suitable for

 * reading const-qualified variables.

 */

#define __raw_cpu_read_const(pcp)	({ BUILD_BUG(); (typeof(pcp))0; })



#endif /* CONFIG_USE_X86_SEG_SUPPORT */



#define percpu_stable_op(size, op, _var)				\
@@ -470,16 +478,7 @@ do { \ 
#define this_cpu_write_8(pcp, val)	__raw_cpu_write(8, volatile, pcp, val)

#endif



#ifdef CONFIG_USE_X86_SEG_SUPPORT

#define this_cpu_read_const(pcp)	__raw_cpu_read(, , pcp)

#else /* CONFIG_USE_X86_SEG_SUPPORT */



/*

 * The generic per-cpu infrastrucutre is not suitable for

 * reading const-qualified variables.

 */

#define this_cpu_read_const(pcp)	({ BUILD_BUG(); (typeof(pcp))0; })

#endif /* CONFIG_USE_X86_SEG_SUPPORT */

#define this_cpu_read_const(pcp)	__raw_cpu_read_const(pcp)



#define this_cpu_read_stable_1(pcp)	percpu_stable_op(1, "mov", pcp)

#define this_cpu_read_stable_2(pcp)	percpu_stable_op(2, "mov", pcp)