summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/alternative.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/alternative.c')
-rw-r--r--arch/x86/kernel/alternative.c115
1 files changed, 30 insertions, 85 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 931280ff829..ef5ccca79a6 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -23,19 +23,6 @@
#define MAX_PATCH_LEN (255-1)
-#ifdef CONFIG_HOTPLUG_CPU
-static int smp_alt_once;
-
-static int __init bootonly(char *str)
-{
- smp_alt_once = 1;
- return 1;
-}
-__setup("smp-alt-boot", bootonly);
-#else
-#define smp_alt_once 1
-#endif
-
static int __initdata_or_module debug_alternative;
static int __init debug_alt(char *str)
@@ -165,7 +152,7 @@ static const unsigned char * const k7_nops[ASM_NOP_MAX+2] =
#endif
#ifdef P6_NOP1
-static const unsigned char __initconst_or_module p6nops[] =
+static const unsigned char p6nops[] =
{
P6_NOP1,
P6_NOP2,
@@ -224,7 +211,7 @@ void __init arch_init_ideal_nops(void)
ideal_nops = intel_nops;
#endif
}
-
+ break;
default:
#ifdef CONFIG_X86_64
ideal_nops = k8_nops;
@@ -317,7 +304,7 @@ static void alternatives_smp_lock(const s32 *start, const s32 *end,
/* turn DS segment override prefix into lock prefix */
if (*ptr == 0x3e)
text_poke(ptr, ((unsigned char []){0xf0}), 1);
- };
+ }
mutex_unlock(&text_mutex);
}
@@ -326,9 +313,6 @@ static void alternatives_smp_unlock(const s32 *start, const s32 *end,
{
const s32 *poff;
- if (noreplace_smp)
- return;
-
mutex_lock(&text_mutex);
for (poff = start; poff < end; poff++) {
u8 *ptr = (u8 *)poff + *poff;
@@ -338,7 +322,7 @@ static void alternatives_smp_unlock(const s32 *start, const s32 *end,
/* turn lock prefix into DS segment override prefix */
if (*ptr == 0xf0)
text_poke(ptr, ((unsigned char []){0x3E}), 1);
- };
+ }
mutex_unlock(&text_mutex);
}
@@ -359,7 +343,7 @@ struct smp_alt_module {
};
static LIST_HEAD(smp_alt_modules);
static DEFINE_MUTEX(smp_alt);
-static int smp_mode = 1; /* protected by smp_alt */
+static bool uniproc_patched = false; /* protected by smp_alt */
void __init_or_module alternatives_smp_module_add(struct module *mod,
char *name,
@@ -368,19 +352,18 @@ void __init_or_module alternatives_smp_module_add(struct module *mod,
{
struct smp_alt_module *smp;
- if (noreplace_smp)
- return;
+ mutex_lock(&smp_alt);
+ if (!uniproc_patched)
+ goto unlock;
- if (smp_alt_once) {
- if (boot_cpu_has(X86_FEATURE_UP))
- alternatives_smp_unlock(locks, locks_end,
- text, text_end);
- return;
- }
+ if (num_possible_cpus() == 1)
+ /* Don't bother remembering, we'll never have to undo it. */
+ goto smp_unlock;
smp = kzalloc(sizeof(*smp), GFP_KERNEL);
if (NULL == smp)
- return; /* we'll run the (safe but slow) SMP code then ... */
+ /* we'll run the (safe but slow) SMP code then ... */
+ goto unlock;
smp->mod = mod;
smp->name = name;
@@ -392,11 +375,10 @@ void __init_or_module alternatives_smp_module_add(struct module *mod,
__func__, smp->locks, smp->locks_end,
smp->text, smp->text_end, smp->name);
- mutex_lock(&smp_alt);
list_add_tail(&smp->next, &smp_alt_modules);
- if (boot_cpu_has(X86_FEATURE_UP))
- alternatives_smp_unlock(smp->locks, smp->locks_end,
- smp->text, smp->text_end);
+smp_unlock:
+ alternatives_smp_unlock(locks, locks_end, text, text_end);
+unlock:
mutex_unlock(&smp_alt);
}
@@ -404,24 +386,18 @@ void __init_or_module alternatives_smp_module_del(struct module *mod)
{
struct smp_alt_module *item;
- if (smp_alt_once || noreplace_smp)
- return;
-
mutex_lock(&smp_alt);
list_for_each_entry(item, &smp_alt_modules, next) {
if (mod != item->mod)
continue;
list_del(&item->next);
- mutex_unlock(&smp_alt);
- DPRINTK("%s: %s\n", __func__, item->name);
kfree(item);
- return;
+ break;
}
mutex_unlock(&smp_alt);
}
-bool skip_smp_alternatives;
-void alternatives_smp_switch(int smp)
+void alternatives_enable_smp(void)
{
struct smp_alt_module *mod;
@@ -436,34 +412,21 @@ void alternatives_smp_switch(int smp)
pr_info("lockdep: fixing up alternatives\n");
#endif
- if (noreplace_smp || smp_alt_once || skip_smp_alternatives)
- return;
- BUG_ON(!smp && (num_online_cpus() > 1));
+ /* Why bother if there are no other CPUs? */
+ BUG_ON(num_possible_cpus() == 1);
mutex_lock(&smp_alt);
- /*
- * Avoid unnecessary switches because it forces JIT based VMs to
- * throw away all cached translations, which can be quite costly.
- */
- if (smp == smp_mode) {
- /* nothing */
- } else if (smp) {
+ if (uniproc_patched) {
pr_info("switching to SMP code\n");
+ BUG_ON(num_online_cpus() != 1);
clear_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
clear_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
list_for_each_entry(mod, &smp_alt_modules, next)
alternatives_smp_lock(mod->locks, mod->locks_end,
mod->text, mod->text_end);
- } else {
- pr_info("switching to UP code\n");
- set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
- set_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
- list_for_each_entry(mod, &smp_alt_modules, next)
- alternatives_smp_unlock(mod->locks, mod->locks_end,
- mod->text, mod->text_end);
+ uniproc_patched = false;
}
- smp_mode = smp;
mutex_unlock(&smp_alt);
}
@@ -540,40 +503,22 @@ void __init alternative_instructions(void)
apply_alternatives(__alt_instructions, __alt_instructions_end);
- /* switch to patch-once-at-boottime-only mode and free the
- * tables in case we know the number of CPUs will never ever
- * change */
-#ifdef CONFIG_HOTPLUG_CPU
- if (num_possible_cpus() < 2)
- smp_alt_once = 1;
-#endif
-
#ifdef CONFIG_SMP
- if (smp_alt_once) {
- if (1 == num_possible_cpus()) {
- pr_info("switching to UP code\n");
- set_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
- set_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
-
- alternatives_smp_unlock(__smp_locks, __smp_locks_end,
- _text, _etext);
- }
- } else {
+ /* Patch to UP if other cpus not imminent. */
+ if (!noreplace_smp && (num_present_cpus() == 1 || setup_max_cpus <= 1)) {
+ uniproc_patched = true;
alternatives_smp_module_add(NULL, "core kernel",
__smp_locks, __smp_locks_end,
_text, _etext);
-
- /* Only switch to UP mode if we don't immediately boot others */
- if (num_present_cpus() == 1 || setup_max_cpus <= 1)
- alternatives_smp_switch(0);
}
-#endif
- apply_paravirt(__parainstructions, __parainstructions_end);
- if (smp_alt_once)
+ if (!uniproc_patched || num_possible_cpus() == 1)
free_init_pages("SMP alternatives",
(unsigned long)__smp_locks,
(unsigned long)__smp_locks_end);
+#endif
+
+ apply_paravirt(__parainstructions, __parainstructions_end);
restart_nmi();
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-30 17:24:30 +0000