From ee03353bc04f8e460cc4e3da80d9721d9ecb89f1 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 5 Jan 2016 17:33:34 +0000 Subject: [PATCH] arm64: entry: remove pointless SPSR mode check 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. Cc: Chris Metcalf Acked-by: Catalin Marinas Signed-off-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/kernel/entry.S | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index c0db321db7e1..1f7f5a2b61bf 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -676,10 +676,7 @@ ret_fast_syscall_trace: work_pending: tbnz x1, #TIF_NEED_RESCHED, work_resched /* TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_FOREIGN_FPSTATE case */ - ldr x2, [sp, #S_PSTATE] mov x0, sp // 'regs' - tst x2, #PSR_MODE_MASK // user mode regs? - b.ne no_work_pending // returning to kernel enable_irq // enable interrupts for do_notify_resume() bl do_notify_resume b ret_to_user @@ -698,7 +695,6 @@ ret_to_user: and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending enable_step_tsk x1, x2 -no_work_pending: kernel_exit 0 ENDPROC(ret_to_user) -- 2.20.1