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arm64: percpu: Make this_cpu accessors pre-empt safe

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this_cpu operations were implemented for arm64 in:
 5284e1b arm64: xchg: Implement cmpxchg_double
 f97fc81 arm64: percpu: Implement this_cpu operations

Unfortunately, it is possible for pre-emption to take place between
address generation and data access. This can lead to cases where data
is being manipulated by this_cpu for a different CPU than it was
called on. Which effectively breaks the spec.

This patch disables pre-emption for the this_cpu operations
guaranteeing that address generation and data manipulation take place
without a pre-emption in-between.

Fixes: 5284e1b4bc ("arm64: xchg: Implement cmpxchg_double")
Fixes: f97fc81079 ("arm64: percpu: Implement this_cpu operations")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steve Capper <steve.capper@linaro.org>
[catalin.marinas@arm.com: remove space after type cast]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Steve Capper 2015-03-22 14:51:51 +00:00 committed by Catalin Marinas
parent e53f21bce4
commit f3eab7184d
2 changed files with 57 additions and 19 deletions
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30
arch/arm64/include/asm/cmpxchg.h
View File

@ -246,14 +246,30 @@ static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
__ret; \
})
#define this_cpu_cmpxchg_1(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n)
#define this_cpu_cmpxchg_2(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n)
#define this_cpu_cmpxchg_4(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n)
#define this_cpu_cmpxchg_8(ptr, o, n) cmpxchg_local(raw_cpu_ptr(&(ptr)), o, n)
#define _protect_cmpxchg_local(pcp, o, n) \
({ \
typeof(*raw_cpu_ptr(&(pcp))) __ret; \
preempt_disable(); \
__ret = cmpxchg_local(raw_cpu_ptr(&(pcp)), o, n); \
preempt_enable(); \
__ret; \
})
#define this_cpu_cmpxchg_double_8(ptr1, ptr2, o1, o2, n1, n2) \
cmpxchg_double_local(raw_cpu_ptr(&(ptr1)), raw_cpu_ptr(&(ptr2)), \
o1, o2, n1, n2)
#define this_cpu_cmpxchg_1(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
#define this_cpu_cmpxchg_2(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
#define this_cpu_cmpxchg_4(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
#define this_cpu_cmpxchg_8(ptr, o, n) _protect_cmpxchg_local(ptr, o, n)
#define this_cpu_cmpxchg_double_8(ptr1, ptr2, o1, o2, n1, n2) \
({ \
int __ret; \
preempt_disable(); \
__ret = cmpxchg_double_local( raw_cpu_ptr(&(ptr1)), \
raw_cpu_ptr(&(ptr2)), \
o1, o2, n1, n2); \
preempt_enable(); \
__ret; \
})
#define cmpxchg64(ptr,o,n) cmpxchg((ptr),(o),(n))
#define cmpxchg64_local(ptr,o,n) cmpxchg_local((ptr),(o),(n))

46
arch/arm64/include/asm/percpu.h
View File

@ -204,25 +204,47 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val,
return ret;
}
#define _percpu_add(pcp, val) \
__percpu_add(raw_cpu_ptr(&(pcp)), val, sizeof(pcp))
#define _percpu_read(pcp) \
({ \
typeof(pcp) __retval; \
preempt_disable(); \
__retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \
sizeof(pcp)); \
preempt_enable(); \
__retval; \
})
#define _percpu_add_return(pcp, val) (typeof(pcp)) (_percpu_add(pcp, val))
#define _percpu_write(pcp, val) \
do { \
preempt_disable(); \
__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \
sizeof(pcp)); \
preempt_enable(); \
} while(0) \
#define _pcp_protect(operation, pcp, val) \
({ \
typeof(pcp) __retval; \
preempt_disable(); \
__retval = (typeof(pcp))operation(raw_cpu_ptr(&(pcp)), \
(val), sizeof(pcp)); \
preempt_enable(); \
__retval; \
})
#define _percpu_add(pcp, val) \
_pcp_protect(__percpu_add, pcp, val)
#define _percpu_add_return(pcp, val) _percpu_add(pcp, val)
#define _percpu_and(pcp, val) \
__percpu_and(raw_cpu_ptr(&(pcp)), val, sizeof(pcp))
_pcp_protect(__percpu_and, pcp, val)
#define _percpu_or(pcp, val) \
__percpu_or(raw_cpu_ptr(&(pcp)), val, sizeof(pcp))
#define _percpu_read(pcp) (typeof(pcp)) \
(__percpu_read(raw_cpu_ptr(&(pcp)), sizeof(pcp)))
#define _percpu_write(pcp, val) \
__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), sizeof(pcp))
_pcp_protect(__percpu_or, pcp, val)
#define _percpu_xchg(pcp, val) (typeof(pcp)) \
(__percpu_xchg(raw_cpu_ptr(&(pcp)), (unsigned long)(val), sizeof(pcp)))
_pcp_protect(__percpu_xchg, pcp, (unsigned long)(val))
#define this_cpu_add_1(pcp, val) _percpu_add(pcp, val)
#define this_cpu_add_2(pcp, val) _percpu_add(pcp, val)