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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()
This commit is contained in:
commit
84d88d5d4e
5 changed files with 85 additions and 16 deletions
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@ -312,19 +312,23 @@ static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
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extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
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#define cmpxchg64(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) __ret; \
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if (likely(boot_cpu_data.x86 > 4)) \
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__ret = (__typeof__(*(ptr)))__cmpxchg64((ptr), \
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(unsigned long long)(o), \
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(unsigned long long)(n)); \
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else \
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__ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
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(unsigned long long)(o), \
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(unsigned long long)(n)); \
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__ret; \
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})
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#define cmpxchg64(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) __ret; \
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__typeof__(*(ptr)) __old = (o); \
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__typeof__(*(ptr)) __new = (n); \
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alternative_io("call cmpxchg8b_emu", \
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"lock; cmpxchg8b (%%esi)" , \
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X86_FEATURE_CX8, \
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"=A" (__ret), \
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"S" ((ptr)), "0" (__old), \
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"b" ((unsigned int)__new), \
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"c" ((unsigned int)(__new>>32)) \
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: "memory"); \
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__ret; })
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#define cmpxchg64_local(ptr, o, n) \
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({ \
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__typeof__(*(ptr)) __ret; \
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@ -10,6 +10,14 @@
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EXPORT_SYMBOL(mcount);
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#endif
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/*
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* Note, this is a prototype to get at the symbol for
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* the export, but dont use it from C code, it is used
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* by assembly code and is not using C calling convention!
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*/
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extern void cmpxchg8b_emu(void);
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EXPORT_SYMBOL(cmpxchg8b_emu);
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/* Networking helper routines. */
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EXPORT_SYMBOL(csum_partial_copy_generic);
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@ -15,7 +15,7 @@ ifeq ($(CONFIG_X86_32),y)
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obj-y += atomic64_32.o
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lib-y += checksum_32.o
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lib-y += strstr_32.o
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lib-y += semaphore_32.o string_32.o
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lib-y += semaphore_32.o string_32.o cmpxchg8b_emu.o
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lib-$(CONFIG_X86_USE_3DNOW) += mmx_32.o
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else
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57
arch/x86/lib/cmpxchg8b_emu.S
Normal file
57
arch/x86/lib/cmpxchg8b_emu.S
Normal file
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@ -0,0 +1,57 @@
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*
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*/
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#include <linux/linkage.h>
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#include <asm/alternative-asm.h>
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#include <asm/frame.h>
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#include <asm/dwarf2.h>
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.text
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/*
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* Inputs:
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* %esi : memory location to compare
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* %eax : low 32 bits of old value
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* %edx : high 32 bits of old value
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* %ebx : low 32 bits of new value
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* %ecx : high 32 bits of new value
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*/
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ENTRY(cmpxchg8b_emu)
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CFI_STARTPROC
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#
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# Emulate 'cmpxchg8b (%esi)' on UP except we don't
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# set the whole ZF thing (caller will just compare
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# eax:edx with the expected value)
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#
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cmpxchg8b_emu:
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pushfl
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cli
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cmpl (%esi), %eax
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jne not_same
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cmpl 4(%esi), %edx
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jne half_same
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movl %ebx, (%esi)
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movl %ecx, 4(%esi)
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popfl
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ret
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not_same:
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movl (%esi), %eax
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half_same:
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movl 4(%esi), %edx
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popfl
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ret
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CFI_ENDPROC
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ENDPROC(cmpxchg8b_emu)
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@ -127,7 +127,7 @@ static u64 sched_clock_local(struct sched_clock_data *scd)
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clock = wrap_max(clock, min_clock);
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clock = wrap_min(clock, max_clock);
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if (cmpxchg(&scd->clock, old_clock, clock) != old_clock)
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if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock)
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goto again;
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return clock;
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@ -163,7 +163,7 @@ static u64 sched_clock_remote(struct sched_clock_data *scd)
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val = remote_clock;
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}
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if (cmpxchg(ptr, old_val, val) != old_val)
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if (cmpxchg64(ptr, old_val, val) != old_val)
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goto again;
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return val;
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