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Commit 5e907bb0 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/alternatives, x86/fpu: Add 'alternatives_patched' debug flag and use it in xsave_state() 



We'd like to use xsave_state() earlier, but its SYSTEM_BOOTING check
is too imprecise.

The real condition that xsave_state() would like to check is whether
alternative XSAVE instructions were patched into the kernel image
already.

Add such a (read-mostly) debug flag and use it in xsave_state().

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: default avatarIngo Molnar <mingo@kernel.org>
parent 2e85591a

arch/x86/include/asm/alternative.h

+6 −0
Original line number Diff line number Diff line
@@ -52,6 +52,12 @@ struct alt_instr { 
	u8  padlen;		/* length of build-time padding */

} __packed;



/*

 * Debug flag that can be tested to see whether alternative

 * instructions were patched in already:

 */

extern int alternatives_patched;



extern void alternative_instructions(void);

extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);

arch/x86/include/asm/fpu/xstate.h

+1 −1
Original line number Diff line number Diff line
@@ -119,7 +119,7 @@ static inline int xsave_state(struct xsave_struct *fx) 
	u32 hmask = mask >> 32;

	int err = 0;



	WARN_ON(system_state == SYSTEM_BOOTING);

	WARN_ON(!alternatives_patched);



	/*

	 * If xsaves is enabled, xsaves replaces xsaveopt because

arch/x86/kernel/alternative.c

+5 −0
Original line number Diff line number Diff line
@@ -21,6 +21,10 @@ 
#include <asm/io.h>

#include <asm/fixmap.h>



int __read_mostly alternatives_patched;



EXPORT_SYMBOL_GPL(alternatives_patched);



#define MAX_PATCH_LEN (255-1)



static int __initdata_or_module debug_alternative;
@@ -627,6 +631,7 @@ void __init alternative_instructions(void) 
	apply_paravirt(__parainstructions, __parainstructions_end);



	restart_nmi();

	alternatives_patched = 1;

}



/**