diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2020-01-16 18:35:48 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-01-17 13:22:14 +0000 |
| commit | 3e3934176a4f9d479dea5cdd2fe6dd560f0ca0cf (patch) | |
| tree | 226179cf9042e53587e0d324c374ed9cbadd7375 /arch/arm64/kernel/entry.S | |
| parent | 7a2c094464e39a54f5b9228cd78208cd43872bbd (diff) | |
arm64: entry: cleanup sp_el0 manipulation
The kernel stashes the current task struct in sp_el0 so that this can be
acquired consistently/cheaply when required. When we take an exception
from EL0 we have to:
1) stash the original sp_el0 value
2) find the current task
3) update sp_el0 with the current task pointer
Currently steps #1 and #2 occur in one place, and step #3 a while later.
As the value of sp_el0 is immaterial between these points, let's move
them together to make the code clearer and minimize ifdeffery. This
necessitates moving the comment for MDSCR_EL1.SS.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 7c6a0a41676f..3d7a9c0ab844 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -167,9 +167,13 @@ alternative_cb_end .if \el == 0 clear_gp_regs mrs x21, sp_el0 - ldr_this_cpu tsk, __entry_task, x20 // Ensure MDSCR_EL1.SS is clear, - ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug - disable_step_tsk x19, x20 // exceptions when scheduling. + ldr_this_cpu tsk, __entry_task, x20 + msr sp_el0, tsk + + // Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions + // when scheduling. + ldr x19, [tsk, #TSK_TI_FLAGS] + disable_step_tsk x19, x20 apply_ssbd 1, x22, x23 @@ -232,13 +236,6 @@ alternative_else_nop_endif str w21, [sp, #S_SYSCALLNO] .endif - /* - * Set sp_el0 to current thread_info. - */ - .if \el == 0 - msr sp_el0, tsk - .endif - /* Save pmr */ alternative_if ARM64_HAS_IRQ_PRIO_MASKING mrs_s x20, SYS_ICC_PMR_EL1 |