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Commit 84d88d5d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'sched-fixes-for-linus' of... 

Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched_clock: Fix atomicity/continuity bug by using cmpxchg64()
  x86: Provide an alternative() based cmpxchg64()
parents e399835c 152f9d07

arch/x86/include/asm/cmpxchg_32.h

+17 −13
Original line number Diff line number Diff line
@@ -315,16 +315,20 @@ extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64); 
#define cmpxchg64(ptr, o, n)					\

({								\

	__typeof__(*(ptr)) __ret;				\

	if (likely(boot_cpu_data.x86 > 4))				\

		__ret = (__typeof__(*(ptr)))__cmpxchg64((ptr),		\

				(unsigned long long)(o),		\

				(unsigned long long)(n));		\

	else								\

		__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr),	\

				(unsigned long long)(o),		\

				(unsigned long long)(n));		\

	__ret;								\

})

	__typeof__(*(ptr)) __old = (o);				\

	__typeof__(*(ptr)) __new = (n);				\

	alternative_io("call cmpxchg8b_emu",			\

			"lock; cmpxchg8b (%%esi)" ,		\

		       X86_FEATURE_CX8,				\

		       "=A" (__ret),				\

		       "S" ((ptr)), "0" (__old),		\

		       "b" ((unsigned int)__new),		\

		       "c" ((unsigned int)(__new>>32))		\

		       : "memory");				\

	__ret; })







#define cmpxchg64_local(ptr, o, n)					\

({									\

	__typeof__(*(ptr)) __ret;					\

arch/x86/kernel/i386_ksyms_32.c

+8 −0
Original line number Diff line number Diff line
@@ -10,6 +10,14 @@ 
EXPORT_SYMBOL(mcount);

#endif



/*

 * Note, this is a prototype to get at the symbol for

 * the export, but dont use it from C code, it is used

 * by assembly code and is not using C calling convention!

 */

extern void cmpxchg8b_emu(void);

EXPORT_SYMBOL(cmpxchg8b_emu);



/* Networking helper routines. */

EXPORT_SYMBOL(csum_partial_copy_generic);

arch/x86/lib/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ ifeq ($(CONFIG_X86_32),y) 
        obj-y += atomic64_32.o

        lib-y += checksum_32.o

        lib-y += strstr_32.o

        lib-y += semaphore_32.o string_32.o

        lib-y += semaphore_32.o string_32.o cmpxchg8b_emu.o



        lib-$(CONFIG_X86_USE_3DNOW) += mmx_32.o

else

arch/x86/lib/cmpxchg8b_emu.S

0 → 100644
+57 −0
Original line number Diff line number Diff line 
/*

 *	This program is free software; you can redistribute it and/or

 *	modify it under the terms of the GNU General Public License

 *	as published by the Free Software Foundation; version 2

 *	of the License.

 *

 */



#include <linux/linkage.h>

#include <asm/alternative-asm.h>

#include <asm/frame.h>

#include <asm/dwarf2.h>





.text



/*

 * Inputs:

 * %esi : memory location to compare

 * %eax : low 32 bits of old value

 * %edx : high 32 bits of old value

 * %ebx : low 32 bits of new value

 * %ecx : high 32 bits of new value

 */

ENTRY(cmpxchg8b_emu)

CFI_STARTPROC



#

# Emulate 'cmpxchg8b (%esi)' on UP except we don't

# set the whole ZF thing (caller will just compare

# eax:edx with the expected value)

#

cmpxchg8b_emu:

	pushfl

	cli



	cmpl  (%esi), %eax

	jne not_same

	cmpl 4(%esi), %edx

	jne half_same



	movl %ebx,  (%esi)

	movl %ecx, 4(%esi)



	popfl

	ret



 not_same:

	movl  (%esi), %eax

 half_same:

	movl 4(%esi), %edx



	popfl

	ret



CFI_ENDPROC

ENDPROC(cmpxchg8b_emu)

kernel/sched_clock.c

+2 −2
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ static u64 sched_clock_local(struct sched_clock_data *scd) 
	clock = wrap_max(clock, min_clock);

	clock = wrap_min(clock, max_clock);



	if (cmpxchg(&scd->clock, old_clock, clock) != old_clock)

	if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock)

		goto again;



	return clock;
@@ -163,7 +163,7 @@ static u64 sched_clock_remote(struct sched_clock_data *scd) 
		val = remote_clock;

	}



	if (cmpxchg(ptr, old_val, val) != old_val)

	if (cmpxchg64(ptr, old_val, val) != old_val)

		goto again;



	return val;