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x86/fpu: Generalize 'init_xstate_ctx'

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So the handling of init_xstate_ctx has a layering violation: both
'struct xsave_struct' and 'union thread_xstate' have a
'struct i387_fxsave_struct' member:

   xsave_struct::i387
   thread_xstate::fxsave

The handling of init_xstate_ctx is generic, it is used on all
CPUs, with or without XSAVE instruction. So it's confusing how
the generic code passes around and handles an XSAVE specific
format.

What we really want is for init_xstate_ctx to be a proper
fpstate and we use its ::fxsave and ::xsave members, as
appropriate.

Since the xsave_struct::i387 and thread_xstate::fxsave aliases
each other this is not a functional problem.

So implement this, and move init_xstate_ctx to the generic FPU
code in the process.

Also, since init_xstate_ctx is not XSAVE specific anymore,
rename it to init_fpstate, and mark it __read_mostly,
because it's only modified once during bootup, and used
as a reference fpstate later on.

There's no change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar
2015-04-30 11:07:06 +02:00
parent bf935b0b52
commit 6f57502310
5 changed files with 18 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/fpu/internal.h
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@@ -22,6 +22,8 @@
extern unsigned int mxcsr_feature_mask;
extern union thread_xstate init_fpstate;
extern void fpu__init_cpu(void);
extern void fpu__init_system_xstate(void);
extern void fpu__init_cpu_xstate(void);
@@ -342,9 +344,9 @@ static inline void fpregs_deactivate(struct fpu *fpu)
static inline void restore_init_xstate(void)
{
if (use_xsave())
xrstor_state(&init_xstate_ctx, -1);
xrstor_state(&init_fpstate.xsave, -1);
else
fxrstor_checking(&init_xstate_ctx.i387);
fxrstor_checking(&init_fpstate.fxsave);
}
/*