]> git.karo-electronics.de Git - karo-tx-linux.git/commit
arm64: cpufeature: Schedule enable() calls instead of calling them via IPI
authorJames Morse <james.morse@arm.com>
Tue, 18 Oct 2016 10:27:46 +0000 (11:27 +0100)
committerWill Deacon <will.deacon@arm.com>
Thu, 20 Oct 2016 08:50:53 +0000 (09:50 +0100)
commit2a6dcb2b5f3e21592ca8dfa198dcce7bec09b020
tree48b4ba1964223e9c90a967752babd3ce24f2739b
parent87261d19046aeaeed8eb3d2793fde850ae1b5c9e
arm64: cpufeature: Schedule enable() calls instead of calling them via IPI

The enable() call for a cpufeature/errata is called using on_each_cpu().
This issues a cross-call IPI to get the work done. Implicitly, this
stashes the running PSTATE in SPSR when the CPU receives the IPI, and
restores it when we return. This means an enable() call can never modify
PSTATE.

To allow PAN to do this, change the on_each_cpu() call to use
stop_machine(). This schedules the work on each CPU which allows
us to modify PSTATE.

This involves changing the protype of all the enable() functions.

enable_cpu_capabilities() is called during boot and enables the feature
on all online CPUs. This path now uses stop_machine(). CPU features for
hotplug'd CPUs are enabled by verify_local_cpu_features() which only
acts on the local CPU, and can already modify the running PSTATE as it
is called from secondary_start_kernel().

Reported-by: Tony Thompson <anthony.thompson@arm.com>
Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm64/include/asm/cpufeature.h
arch/arm64/include/asm/processor.h
arch/arm64/kernel/cpu_errata.c
arch/arm64/kernel/cpufeature.c
arch/arm64/kernel/traps.c
arch/arm64/mm/fault.c