Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH 3/3] x86, FPU: Do not use static_cpu_has before alternatives | Date | Mon, 29 Apr 2013 16:04:22 +0200 |
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From: Borislav Petkov <bp@suse.de>
The call stack below shows how this happens: basically eager_fpu_init() calls __thread_fpu_begin(current) which then does if (!use_eager_fpu()), which, in turn, uses static_cpu_has.
And we're executing before alternatives so static_cpu_has doesn't work there yet.
However, I don't want to cause the penalty of not using static_cpu_has to all callers of use_eager_fpu() which are a bunch spread around the tree so let's add the change only to __thread_fpu_begin() - it is still on the context switch path but we can at least keep the static_cpu_has call in the rest of the use_eager_fpu() callsites.
WARNING: at arch/x86/kernel/cpu/common.c:1368 warn_pre_alternatives+0x1e/0x20() Hardware name: 2320CTO You're using static_cpu_has before alternatives have run! Modules linked in: Pid: 0, comm: swapper Not tainted 3.9.0-rc8+ #1 Call Trace: warn_slowpath_common warn_slowpath_fmt ? fpu_finit warn_pre_alternatives eager_fpu_init fpu_init cpu_init trap_init start_kernel ? repair_env_string x86_64_start_reservations x86_64_start_kernel
Signed-off-by: Borislav Petkov <bp@suse.de> --- arch/x86/include/asm/fpu-internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index fb808d71cd70..0e34793aafd4 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -343,7 +343,7 @@ static inline void __thread_fpu_end(struct task_struct *tsk) static inline void __thread_fpu_begin(struct task_struct *tsk) { - if (!use_eager_fpu()) + if (!cpu_has_eager_fpu) clts(); __thread_set_has_fpu(tsk); } -- 1.8.3.rc0
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