diff options
| author | David S. Miller <davem@davemloft.net> | 2012-10-27 23:00:41 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-10-27 23:00:41 -0700 |
| commit | e9b9eb59ffcdee09ec96b040f85c919618f4043e (patch) | |
| tree | 30f93cc20aa577ec5b12f609641fdf84d0bd5124 /arch/sparc/kernel | |
| parent | 270c10e00a1e557e068803a22e0556281ceb1830 (diff) | |
sparc64: Use pause instruction when available.
In atomic backoff and cpu_relax(), use the pause instruction
found on SPARC-T4 and later.
It makes the cpu strand unselectable for the given number of
cycles, unless an intervening disrupting trap occurs.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/kernel')
| -rw-r--r-- | arch/sparc/kernel/entry.h | 7 | ||||
| -rw-r--r-- | arch/sparc/kernel/setup_64.c | 21 | ||||
| -rw-r--r-- | arch/sparc/kernel/vmlinux.lds.S | 5 |
3 files changed, 33 insertions, 0 deletions
diff --git a/arch/sparc/kernel/entry.h b/arch/sparc/kernel/entry.h index 0c218e4c0881..51742df63c75 100644 --- a/arch/sparc/kernel/entry.h +++ b/arch/sparc/kernel/entry.h @@ -59,6 +59,13 @@ struct popc_6insn_patch_entry { extern struct popc_6insn_patch_entry __popc_6insn_patch, __popc_6insn_patch_end; +struct pause_patch_entry { + unsigned int addr; + unsigned int insns[3]; +}; +extern struct pause_patch_entry __pause_patch, + __pause_patch_end; + extern void __init per_cpu_patch(void); extern void sun4v_patch_1insn_range(struct sun4v_1insn_patch_entry *, struct sun4v_1insn_patch_entry *); diff --git a/arch/sparc/kernel/setup_64.c b/arch/sparc/kernel/setup_64.c index 0800e71d8a88..b45cff408de3 100644 --- a/arch/sparc/kernel/setup_64.c +++ b/arch/sparc/kernel/setup_64.c @@ -316,6 +316,25 @@ static void __init popc_patch(void) } } +static void __init pause_patch(void) +{ + struct pause_patch_entry *p; + + p = &__pause_patch; + while (p < &__pause_patch_end) { + unsigned long i, addr = p->addr; + + for (i = 0; i < 3; i++) { + *(unsigned int *) (addr + (i * 4)) = p->insns[i]; + wmb(); + __asm__ __volatile__("flush %0" + : : "r" (addr + (i * 4))); + } + + p++; + } +} + #ifdef CONFIG_SMP void __init boot_cpu_id_too_large(int cpu) { @@ -528,6 +547,8 @@ static void __init init_sparc64_elf_hwcap(void) if (sparc64_elf_hwcap & AV_SPARC_POPC) popc_patch(); + if (sparc64_elf_hwcap & AV_SPARC_PAUSE) + pause_patch(); } void __init setup_arch(char **cmdline_p) diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S index 89c2c29f154b..847f9f793618 100644 --- a/arch/sparc/kernel/vmlinux.lds.S +++ b/arch/sparc/kernel/vmlinux.lds.S @@ -132,6 +132,11 @@ SECTIONS *(.popc_6insn_patch) __popc_6insn_patch_end = .; } + .pause_patch : { + __pause_patch = .; + *(.pause_patch) + __pause_patch_end = .; + } PERCPU_SECTION(SMP_CACHE_BYTES) . = ALIGN(PAGE_SIZE); |