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sh: add AT_HWCAP flag for J-Core cas.l instruction 

The J-Core cpu has, as an ISA extension, an atomic compare-and-swap
instruction cas.l which applications need to use (instead the imask or
gusa atomic models, which are fundamentally limited to UP) for
synchronization in order to be compatible with SMP systems. Provide a
hwcap flag so that it's possible to do runtime selection and support
both.

Signed-off-by: Rich Felker <dalias@libc.org>
This commit is contained in:
Rich Felker 2016-04-22 23:29:13 +00:00
parent 5a846abad0
commit 834da19705
2 changed files with 3 additions and 0 deletions
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1
arch/sh/include/uapi/asm/cpu-features.h
View File

@ -22,5 +22,6 @@
#define CPU_HAS_L2_CACHE 0x0080 /* Secondary cache / URAM */
#define CPU_HAS_OP32 0x0100 /* 32-bit instruction support */
#define CPU_HAS_PTEAEX 0x0200 /* PTE ASID Extension support */
#define CPU_HAS_CAS_L 0x0400 /* cas.l atomic compare-and-swap */
#endif /* __ASM_SH_CPU_FEATURES_H */

2
arch/sh/kernel/cpu/sh2/probe.c
View File

@ -57,6 +57,8 @@ void __ref cpu_probe(void)
boot_cpu_data.dcache.entry_shift = 5;
boot_cpu_data.dcache.linesz = 32;
boot_cpu_data.dcache.flags = 0;
boot_cpu_data.flags |= CPU_HAS_CAS_L;
#else
/*
* SH-2 doesn't have separate caches