The patch titled
Remove noreplacement option
has been added to the -mm tree. Its filename is
remove-noreplacement-option.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Remove noreplacement option
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
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@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/x86_64/boot-options.txt | 4 ----
arch/i386/kernel/alternative.c | 21 ++-------------------
2 files changed, 2 insertions(+), 23 deletions(-)
diff -puN Documentation/x86_64/boot-options.txt~remove-noreplacement-option Documentation/x86_64/boot-options.txt
--- a/Documentation/x86_64/boot-options.txt~remove-noreplacement-option
+++ a/Documentation/x86_64/boot-options.txt
@@ -305,7 +305,3 @@ Debugging
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 -puN arch/i386/kernel/alternative.c~remove-noreplacement-option arch/i386/kernel/alternative.c
--- a/arch/i386/kernel/alternative.c~remove-noreplacement-option
+++ a/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 @@ static int __init debug_alt(char *str)
return 1;
}
-__setup("noreplacement", noreplacement_setup);
__setup("smp-alt-boot", bootonly);
__setup("debug-alternative", debug_alt);
@@ -252,9 +245,6 @@ void alternatives_smp_module_add(struct
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 @@ void alternatives_smp_module_del(struct
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 @@ void alternatives_smp_switch(int smp)
return;
#endif
- if (no_replacement || smp_alt_once)
+ if (smp_alt_once)
return;
BUG_ON(!smp && (num_online_cpus() > 1));
@@ -386,13 +376,6 @@ extern struct paravirt_patch __start_par
void __init alternative_instructions(void)
{
unsigned long flags;
- if (no_replacement) {
- printk(KERN_INFO "(SMP-)alternatives turned off\n");
- free_init_pages("SMP alternatives",
- __pa_symbol(&__smp_alt_begin),
- __pa_symbol(&__smp_alt_end));
- return;
- }
local_irq_save(flags);
apply_alternatives(__alt_instructions, __alt_instructions_end);
_
Patches currently in -mm which might be from jeremy@xxxxxxxx are
re-enable-vdso-by-default-with-paravirt.patch
remove-noreplacement-option.patch
remove-smp_alt_instructions.patch
rename-the-parainstructions-symbols-to-be-consistent-with-the-others.patch
allow-boot-time-disable-of-smp-altinstructions.patch
allow-boot-time-disable-of-paravirt_ops-patching.patch
fixes-and-cleanups-for-earlyprintk-aka-boot-console.patch
ignore-stolen-time-in-the-softlockup-watchdog.patch
add-touch_all_softlockup_watchdogs.patch
clean-up-elf-note-generation.patch
-
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