[tip:x86/asm] x86-64: Reduce SMP locks table size
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From: tip-bot for Jan Beulich on 28 Apr 2010 21:00 Commit-ID: 5967ed87ade85a421ef814296c3c7f182b08c225 Gitweb: http://git.kernel.org/tip/5967ed87ade85a421ef814296c3c7f182b08c225 Author: Jan Beulich <JBeulich(a)novell.com> AuthorDate: Wed, 21 Apr 2010 16:08:14 +0100 Committer: H. Peter Anvin <hpa(a)zytor.com> CommitDate: Wed, 28 Apr 2010 17:15:47 -0700 x86-64: Reduce SMP locks table size Reduce the SMP locks table size by using relative pointers instead of absolute ones, thus cutting the table size by half. Signed-off-by: Jan Beulich <jbeulich(a)novell.com> LKML-Reference: <4BCF30FE020000780003B3B6(a)vpn.id2.novell.com> Signed-off-by: H. Peter Anvin <hpa(a)zytor.com> --- arch/x86/include/asm/alternative-asm.h | 4 +- arch/x86/include/asm/alternative.h | 4 +- arch/x86/kernel/alternative.c | 45 +++++++++++++++++-------------- 3 files changed, 29 insertions(+), 24 deletions(-) diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h index b97f786..a63a68b 100644 --- a/arch/x86/include/asm/alternative-asm.h +++ b/arch/x86/include/asm/alternative-asm.h @@ -6,8 +6,8 @@ .macro LOCK_PREFIX 1: lock .section .smp_locks,"a" - _ASM_ALIGN - _ASM_PTR 1b + .balign 4 + .long 1b - . .previous .endm #else diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index b09ec55..714bf24 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -30,8 +30,8 @@ #ifdef CONFIG_SMP #define LOCK_PREFIX \ ".section .smp_locks,\"a\"\n" \ - _ASM_ALIGN "\n" \ - _ASM_PTR "661f\n" /* address */ \ + ".balign 4\n" \ + ".long 661f - .\n" /* offset */ \ ".previous\n" \ "661:\n\tlock; " diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 1a160d5..9367384 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -194,7 +194,7 @@ static void __init_or_module add_nops(void *insns, unsigned int len) } extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; -extern u8 *__smp_locks[], *__smp_locks_end[]; +extern s32 __smp_locks[], __smp_locks_end[]; static void *text_poke_early(void *addr, const void *opcode, size_t len); /* Replace instructions with better alternatives for this CPU type. @@ -235,37 +235,39 @@ void __init_or_module apply_alternatives(struct alt_instr *start, #ifdef CONFIG_SMP -static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end) +static void alternatives_smp_lock(const s32 *start, const s32 *end, + u8 *text, u8 *text_end) { - u8 **ptr; + const s32 *poff; mutex_lock(&text_mutex); - for (ptr = start; ptr < end; ptr++) { - if (*ptr < text) - continue; - if (*ptr > text_end) + for (poff = start; poff < end; poff++) { + u8 *ptr = (u8 *)poff + *poff; + + if (!*poff || ptr < text || ptr >= text_end) continue; /* turn DS segment override prefix into lock prefix */ - text_poke(*ptr, ((unsigned char []){0xf0}), 1); + text_poke(ptr, ((unsigned char []){0xf0}), 1); }; mutex_unlock(&text_mutex); } -static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end) +static void alternatives_smp_unlock(const s32 *start, const s32 *end, + u8 *text, u8 *text_end) { - u8 **ptr; + const s32 *poff; if (noreplace_smp) return; mutex_lock(&text_mutex); - for (ptr = start; ptr < end; ptr++) { - if (*ptr < text) - continue; - if (*ptr > text_end) + for (poff = start; poff < end; poff++) { + u8 *ptr = (u8 *)poff + *poff; + + if (!*poff || ptr < text || ptr >= text_end) continue; /* turn lock prefix into DS segment override prefix */ - text_poke(*ptr, ((unsigned char []){0x3E}), 1); + text_poke(ptr, ((unsigned char []){0x3E}), 1); }; mutex_unlock(&text_mutex); } @@ -276,8 +278,8 @@ struct smp_alt_module { char *name; /* ptrs to lock prefixes */ - u8 **locks; - u8 **locks_end; + const s32 *locks; + const s32 *locks_end; /* .text segment, needed to avoid patching init code ;) */ u8 *text; @@ -398,16 +400,19 @@ void alternatives_smp_switch(int smp) int alternatives_text_reserved(void *start, void *end) { struct smp_alt_module *mod; - u8 **ptr; + const s32 *poff; u8 *text_start = start; u8 *text_end = end; list_for_each_entry(mod, &smp_alt_modules, next) { if (mod->text > text_end || mod->text_end < text_start) continue; - for (ptr = mod->locks; ptr < mod->locks_end; ptr++) - if (text_start <= *ptr && text_end >= *ptr) + for (poff = mod->locks; poff < mod->locks_end; poff++) { + const u8 *ptr = (const u8 *)poff + *poff; + + if (text_start <= ptr && text_end > ptr) return 1; + } } return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |