diff options
| author | Will Deacon <will.deacon@arm.com> | 2013-02-28 16:47:36 (GMT) |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-03-03 22:54:14 (GMT) |
| commit | 8a4e3a9ead7e37ce1505602b564c15da09ac039f (patch) | |
| tree | 5cc8ad188810649ea0739c769977451b825e4325 /arch/arm/include | |
| parent | 37f47e3d62533c931b04cb409f2eb299e6342331 (diff) | |
| download | linux-8a4e3a9ead7e37ce1505602b564c15da09ac039f.tar.xz | |
ARM: 7659/1: mm: make mm->context.id an atomic64_t variable
mm->context.id is updated under asid_lock when a new ASID is allocated
to an mm_struct. However, it is also read without the lock when a task
is being scheduled and checking whether or not the current ASID
generation is up-to-date.
If two threads of the same process are being scheduled in parallel and
the bottom bits of the generation in their mm->context.id match the
current generation (that is, the mm_struct has not been used for ~2^24
rollovers) then the non-atomic, lockless access to mm->context.id may
yield the incorrect ASID.
This patch fixes this issue by making mm->context.id and atomic64_t,
ensuring that the generation is always read consistently. For code that
only requires access to the ASID bits (e.g. TLB flushing by mm), then
the value is accessed directly, which GCC converts to an ldrb.
Cc: <stable@vger.kernel.org> # 3.8
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/mmu.h | 8 | ||||
| -rw-r--r-- | arch/arm/include/asm/mmu_context.h | 2 |
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h index 9f77e78..e3d5554 100644 --- a/arch/arm/include/asm/mmu.h +++ b/arch/arm/include/asm/mmu.h @@ -5,15 +5,15 @@ typedef struct { #ifdef CONFIG_CPU_HAS_ASID - u64 id; + atomic64_t id; #endif - unsigned int vmalloc_seq; + unsigned int vmalloc_seq; } mm_context_t; #ifdef CONFIG_CPU_HAS_ASID #define ASID_BITS 8 #define ASID_MASK ((~0ULL) << ASID_BITS) -#define ASID(mm) ((mm)->context.id & ~ASID_MASK) +#define ASID(mm) ((mm)->context.id.counter & ~ASID_MASK) #else #define ASID(mm) (0) #endif @@ -26,7 +26,7 @@ typedef struct { * modified for 2.6 by Hyok S. Choi <hyok.choi@samsung.com> */ typedef struct { - unsigned long end_brk; + unsigned long end_brk; } mm_context_t; #endif diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h index e1f644b..863a661 100644 --- a/arch/arm/include/asm/mmu_context.h +++ b/arch/arm/include/asm/mmu_context.h @@ -25,7 +25,7 @@ void __check_vmalloc_seq(struct mm_struct *mm); #ifdef CONFIG_CPU_HAS_ASID void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk); -#define init_new_context(tsk,mm) ({ mm->context.id = 0; }) +#define init_new_context(tsk,mm) ({ atomic64_set(&mm->context.id, 0); 0; }) #else /* !CONFIG_CPU_HAS_ASID */ |