提交 e918a62a 编写于 作者: P Punit Agrawal 提交者: Russell King

ARM: 8135/1: Fix in-correct barrier usage in SWP{B} emulation

According to the ARM ARMv7, explicit barriers are necessary when using
synchronisation primitives such as SWP{B}. The use of these
instructions does not automatically imply a barrier and any ordering
requirements by the software must be explicitly expressed with the use
of suitable barriers.

Based on this, remove the barriers from SWP{B} emulation.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
上级 a040803a
无相关合并请求
......@@ -142,14 +142,6 @@ static int emulate_swpX(unsigned int address, unsigned int *data,
while (1) {
unsigned long temp;
/*
* Barrier required between accessing protected resource and
* releasing a lock for it. Legacy code might not have done
* this, and we cannot determine that this is not the case
* being emulated, so insert always.
*/
smp_mb();
if (type == TYPE_SWPB)
__user_swpb_asm(*data, address, res, temp);
else
......@@ -162,13 +154,6 @@ static int emulate_swpX(unsigned int address, unsigned int *data,
}
if (res == 0) {
/*
* Barrier also required between acquiring a lock for a
* protected resource and accessing the resource. Inserted for
* same reason as above.
*/
smp_mb();
if (type == TYPE_SWPB)
swpbcounter++;
else
......
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