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/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 @@
}
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 @@
#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 @@
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 @@
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;