[PATCH] x86: Remove noreplacement option
noreplacement is dangerous on modern systems because it will not replace the
context switch FNSAVE with SSE aware FXSAVE. But other places in the kernel still assume
SSE and do FXSAVE and the CPU will then access FXSAVE information with
FNSAVE and cause corruption.
Easiest way to avoid this is to remove the option. It was mostly for paranoia
reasons anyways and alternative()s have been stable for some time.
Thanks to Jeremy F. for reporting and helping debug it.
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 625a21d..85f51e5 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -293,7 +293,3 @@
stuck (default)
Miscellaneous
-
- noreplacement Don't replace instructions with more appropriate ones
- for the CPU. This may be useful on asymmetric MP systems
- where some CPUs have less capabilities than others.
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 9eca21b..426f59b 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -5,15 +5,9 @@
#include <asm/alternative.h>
#include <asm/sections.h>
-static int no_replacement = 0;
static int smp_alt_once = 0;
static int debug_alternative = 0;
-static int __init noreplacement_setup(char *s)
-{
- no_replacement = 1;
- return 1;
-}
static int __init bootonly(char *str)
{
smp_alt_once = 1;
@@ -25,7 +19,6 @@
return 1;
}
-__setup("noreplacement", noreplacement_setup);
__setup("smp-alt-boot", bootonly);
__setup("debug-alternative", debug_alt);
@@ -252,9 +245,6 @@
struct smp_alt_module *smp;
unsigned long flags;
- if (no_replacement)
- return;
-
if (smp_alt_once) {
if (boot_cpu_has(X86_FEATURE_UP))
alternatives_smp_unlock(locks, locks_end,
@@ -289,7 +279,7 @@
struct smp_alt_module *item;
unsigned long flags;
- if (no_replacement || smp_alt_once)
+ if (smp_alt_once)
return;
spin_lock_irqsave(&smp_alt, flags);
@@ -320,7 +310,7 @@
return;
#endif
- if (no_replacement || smp_alt_once)
+ if (smp_alt_once)
return;
BUG_ON(!smp && (num_online_cpus() > 1));
@@ -386,13 +376,6 @@
void __init alternative_instructions(void)
{
unsigned long flags;
- if (no_replacement) {
- printk(KERN_INFO "(SMP-)alternatives turned off\n");
- free_init_pages("SMP alternatives",
- (unsigned long)__smp_alt_begin,
- (unsigned long)__smp_alt_end);
- return;
- }
local_irq_save(flags);
apply_alternatives(__alt_instructions, __alt_instructions_end);