@@ -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
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> --- arch/arm64/kernel/entry.S | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)