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ae120d9edf
When a CPU is running a process, the ASID for that process is
held in a per-CPU variable (the "active ASIDs" array). When
the ASID allocator handles a rollover, it copies the active
ASIDs into a "reserved ASIDs" array to ensure that a process
currently running on another CPU will continue to run unaffected.
The active array is zero-ed to indicate that a rollover occurred.
Because of this mechanism, a reserved ASID is only remembered for
a single rollover. A subsequent rollover will completely refill
the reserved ASIDs array.
In a severely oversubscribed environment where a CPU can be
prevented from running for extended periods of time (think virtual
machines), the above has a horrible side effect:
[P{a} denotes process P running with ASID a]
CPU-0 CPU-1
A{x} [active = <x 0>]
[suspended] runs B{y} [active = <x y>]
[rollover:
active = <0 0>
reserved = <x y>]
runs B{y} [active = <0 y>
reserved = <x y>]
[rollover:
active = <0 0>
reserved = <0 y>]
runs C{x} [active = <0 x>]
[resumes]
runs A{x}
At that stage, both A and C have the same ASID, with deadly
consequences.
The fix is to preserve reserved ASIDs across rollovers if
the CPU doesn't have an active ASID when the rollover occurs.
Cc: <stable@vger.kernel.org> # 3.9
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Carinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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| .. | ||
| abort-ev4.S | ||
| abort-ev4t.S | ||
| abort-ev5t.S | ||
| abort-ev5tj.S | ||
| abort-ev6.S | ||
| abort-ev7.S | ||
| abort-lv4t.S | ||
| abort-macro.S | ||
| abort-nommu.S | ||
| alignment.c | ||
| cache-aurora-l2.h | ||
| cache-fa.S | ||
| cache-feroceon-l2.c | ||
| cache-l2x0.c | ||
| cache-tauros2.c | ||
| cache-v4.S | ||
| cache-v4wb.S | ||
| cache-v4wt.S | ||
| cache-v6.S | ||
| cache-v7.S | ||
| cache-xsc3l2.c | ||
| context.c | ||
| copypage-fa.c | ||
| copypage-feroceon.c | ||
| copypage-v4mc.c | ||
| copypage-v4wb.c | ||
| copypage-v4wt.c | ||
| copypage-v6.c | ||
| copypage-xsc3.c | ||
| copypage-xscale.c | ||
| dma-mapping.c | ||
| extable.c | ||
| fault-armv.c | ||
| fault.c | ||
| fault.h | ||
| flush.c | ||
| fsr-2level.c | ||
| fsr-3level.c | ||
| highmem.c | ||
| idmap.c | ||
| init.c | ||
| iomap.c | ||
| ioremap.c | ||
| Kconfig | ||
| Makefile | ||
| mm.h | ||
| mmap.c | ||
| mmu.c | ||
| nommu.c | ||
| pabort-legacy.S | ||
| pabort-v6.S | ||
| pabort-v7.S | ||
| pgd.c | ||
| proc-arm7tdmi.S | ||
| proc-arm9tdmi.S | ||
| proc-arm720.S | ||
| proc-arm740.S | ||
| proc-arm920.S | ||
| proc-arm922.S | ||
| proc-arm925.S | ||
| proc-arm926.S | ||
| proc-arm940.S | ||
| proc-arm946.S | ||
| proc-arm1020.S | ||
| proc-arm1020e.S | ||
| proc-arm1022.S | ||
| proc-arm1026.S | ||
| proc-fa526.S | ||
| proc-feroceon.S | ||
| proc-macros.S | ||
| proc-mohawk.S | ||
| proc-sa110.S | ||
| proc-sa1100.S | ||
| proc-syms.c | ||
| proc-v6.S | ||
| proc-v7-2level.S | ||
| proc-v7-3level.S | ||
| proc-v7.S | ||
| proc-xsc3.S | ||
| proc-xscale.S | ||
| tcm.h | ||
| tlb-fa.S | ||
| tlb-v4.S | ||
| tlb-v4wb.S | ||
| tlb-v4wbi.S | ||
| tlb-v6.S | ||
| tlb-v7.S | ||