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@novell.com>
LKML-Reference: <4BCF30FE020000780003B3B6@vpn.id2.novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index b97f786a48d597ce4c718667a19c0d8c2b45c9c7..a63a68be1cce2258daf9cadf0d465b291296c930 100644 (file)
--- 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 b09ec55650b3806f91f4909558a61688a39404ee..714bf24172845313b62f08519d1c2ce49d9dc5da 100644 (file)
--- 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 1a160d5d44d0bd0f47b0b88b9e6a98f4b9b7f2b3..936738427223e40e9a48ba254aee7b7e5a71a143 100644 (file)
--- 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;