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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2007-05-08 23:03:09 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2007-05-08 23:03:09 +0400 |
| commit | 8678c1f04277daaa914abb107fb9fe71298d916d (patch) | |
| tree | c4916538ff592210363909099aad866e1ba67985 /arch/arm/mm/context.c | |
| parent | 08fdffd4cf4ddd4eb4b32e78f93f4ff53ccec78f (diff) | |
| download | linux-8678c1f04277daaa914abb107fb9fe71298d916d.tar.xz | |
[ARM] Fix ASID version switch
Close a hole in the ASID version switch, particularly the following
scenario:
CPU0 MM PID CPU1 MM PID
idle
A pid(A)
A idle(lazy tlb)
* new asid version triggered by B *
B pid(B)
A pid(A)
* MM A gets new asid version *
A idle(lazy tlb)
A pid(A)
* CPU1 doesn't see the new ASID *
The result is that CPU1 continues running with the hardware set
for the original (stale) ASID value, but mm->context.id contains
the new ASID value. The result is that the next MM fault on CPU1
updates the page table entries, but flush_tlb_page() fails due to
wrong ASID.
There is a related case with a threaded application is allocated
a new ASID on one CPU while another of its threads is running on
some different CPU. This scenario is not fixed by this commit.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/context.c')
| -rw-r--r-- | arch/arm/mm/context.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index 9da43a0fdcdf..930c04c4f53c 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -14,7 +14,8 @@ #include <asm/mmu_context.h> #include <asm/tlbflush.h> -unsigned int cpu_last_asid = { 1 << ASID_BITS }; +static DEFINE_SPINLOCK(cpu_asid_lock); +unsigned int cpu_last_asid = ASID_FIRST_VERSION; /* * We fork()ed a process, and we need a new context for the child @@ -31,15 +32,16 @@ void __new_context(struct mm_struct *mm) { unsigned int asid; + spin_lock(&cpu_asid_lock); asid = ++cpu_last_asid; if (asid == 0) - asid = cpu_last_asid = 1 << ASID_BITS; + asid = cpu_last_asid = ASID_FIRST_VERSION; /* * If we've used up all our ASIDs, we need * to start a new version and flush the TLB. */ - if ((asid & ~ASID_MASK) == 0) { + if (unlikely((asid & ~ASID_MASK) == 0)) { asid = ++cpu_last_asid; /* set the reserved ASID before flushing the TLB */ asm("mcr p15, 0, %0, c13, c0, 1 @ set reserved context ID\n" @@ -48,6 +50,8 @@ void __new_context(struct mm_struct *mm) isb(); flush_tlb_all(); } + spin_unlock(&cpu_asid_lock); + mm->cpu_vm_mask = cpumask_of_cpu(smp_processor_id()); mm->context.id = asid; } |