Messages in this thread Patch in this message | | | Date | Fri, 27 Feb 2015 23:07:00 -0800 | From | tip-bot for Steven Rostedt <> | Subject | [tip:x86/urgent] x86: Init per-cpu shadow copy of CR4 on 32-bit CPUs too |
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Commit-ID: 5b2bdbc84556774afbe11bcfd24c2f6411cfa92b Gitweb: http://git.kernel.org/tip/5b2bdbc84556774afbe11bcfd24c2f6411cfa92b Author: Steven Rostedt <rostedt@goodmis.org> AuthorDate: Fri, 27 Feb 2015 14:50:19 -0500 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Sat, 28 Feb 2015 08:04:20 +0100
x86: Init per-cpu shadow copy of CR4 on 32-bit CPUs too
Commit:
1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
added a shadow CR4 such that reads and writes that do not modify the CR4 execute much faster than always reading the register itself.
The change modified cpu_init() in common.c, so that the shadow CR4 gets initialized before anything uses it.
Unfortunately, there's two cpu_init()s in common.c. There's one for 64-bit and one for 32-bit. The commit only added the shadow init to the 64-bit path, but the 32-bit path needs the init too.
Link: http://lkml.kernel.org/r/20150227125208.71c36402@gandalf.local.home Fixes: 1e02ce4cccdc "x86: Store a per-cpu shadow copy of CR4" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20150227145019.2bdd4354@gandalf.local.home Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/kernel/cpu/common.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index b5c8ff5..2346c95 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1396,6 +1396,12 @@ void cpu_init(void) wait_for_master_cpu(cpu); + /* + * Initialize the CR4 shadow before doing anything that could + * try to read it. + */ + cr4_init_shadow(); + show_ucode_info_early(); printk(KERN_INFO "Initializing CPU#%d\n", cpu);
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