Re: [PATCH 1/2] arm64: entry: remove pointless SPSR mode check

[Catalin Marinas]

On Tue, Jan 05, 2016 at 05:33:34PM +0000, Mark Rutland wrote:
> In work_pending  we may skip work if the stacked SPSR value represents
> anything other than an EL0 context. We then immediately invoke the
> kernel_exit 0 macro as part of ret_to_user, assuming a return to EL0.
> This is somewhat confusing.
> 
> We use work_pending as part of the ret_to_user/ret_fast_syscall state
> machine. We only use ret_fast_syscall in the return from an SVC issued
> from EL0. We use ret_to_user for return from EL0 exception handlers and
> also for return from ret_from_fork in the case the task was not a kernel
> thread (i.e. it is a user task).
> 
> Thus in all cases the stacked SPSR value must represent an EL0 context,
> and the check is redundant. This patch removes it, along with the now
> unused no_work_pending label.
> 
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>

Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
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