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authorMark Rutland <mark.rutland@arm.com>2016-01-05 18:33:34 +0100
committerWill Deacon <will.deacon@arm.com>2016-01-06 16:40:38 +0100
commitee03353bc04f8e460cc4e3da80d9721d9ecb89f1 (patch)
tree7079b34f326357afdc3aff8af868f327684ac31f /arch/arm64/kernel/entry.S
parentarm64: mm: move pgd_cache initialisation to pgtable_cache_init (diff)
downloadlinux-ee03353bc04f8e460cc4e3da80d9721d9ecb89f1.tar.xz
linux-ee03353bc04f8e460cc4e3da80d9721d9ecb89f1.zip
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 <cmetcalf@ezchip.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
-rw-r--r--arch/arm64/kernel/entry.S4
1 files changed, 0 insertions, 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)