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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
	will@kernel.org, james.morse@arm.com
Cc: mark.rutland@arm.com, keescook@chromium.org, maz@kernel.org,
	broonie@kernel.org, labbott@redhat.com, robin.murphy@arm.com,
	julien.thierry.kdev@gmail.com, alex.popov@linux.com
Subject: [PATCH 17/17] arm64: entry: cleanup sp_el0 manipulation
Date: Wed,  8 Jan 2020 18:56:34 +0000	[thread overview]
Message-ID: <20200108185634.1163-18-mark.rutland@arm.com> (raw)
In-Reply-To: <20200108185634.1163-1-mark.rutland@arm.com>

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.

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 | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 537b44c413df..40d1cd8fb4c6 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -152,6 +152,7 @@ alternative_cb_end
 	clear_gp_regs
 	mrs	x21, sp_el0
 	ldr_this_cpu	tsk, __entry_task, x20
+	msr	sp_el0, tsk
 
 	apply_ssbd 1, x22, x23
 
@@ -208,13 +209,6 @@ alternative_else_nop_endif
 
 	stp	x22, x23, [sp, #S_PC]
 
-	/*
-	 * 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
-- 
2.11.0


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      parent reply	other threads:[~2020-01-08 19:01 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08 18:56 [PATCH 00/17] arm64: entry deasmification and cleanup Mark Rutland
2020-01-08 18:56 ` [PATCH 01/17] arm64: entry: mark all entry code as notrace Mark Rutland
2020-01-09  5:21   ` Anshuman Khandual
2020-01-13 15:44     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 02/17] arm64: entry: cleanup el0 svc handler naming Mark Rutland
2020-01-09  5:33   ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 03/17] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2020-01-09  5:36   ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 04/17] arm64: entry: move preempt logic to C Mark Rutland
2020-01-09  6:43   ` Anshuman Khandual
2020-01-09 12:22     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 05/17] arm64: entry: add a call_on_stack helper Mark Rutland
2020-01-09  8:00   ` Anshuman Khandual
2020-01-14 18:24     ` Mark Rutland
2020-01-09 14:30   ` Laura Abbott
2020-01-09 14:46     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 06/17] arm64: entry: convert irq entry to C Mark Rutland
2020-01-08 18:56 ` [PATCH 07/17] arm64: entry: convert error " Mark Rutland
2020-01-09  9:12   ` Anshuman Khandual
2020-01-09 12:49     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 08/17] arm64: entry: Split el0_sync_compat from el0_sync Mark Rutland
2020-01-09  9:50   ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 09/17] arm64: entry: organise handler stubs consistently Mark Rutland
2020-01-09 10:01   ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 10/17] arm64: entry: consolidate EL1 return paths Mark Rutland
2020-01-10  3:39   ` Anshuman Khandual
2020-01-10 16:02     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 11/17] stackleak: allow C to call stackleak_erase() Mark Rutland
2020-01-10  3:45   ` Anshuman Khandual
2020-01-10 16:07     ` Mark Rutland
2020-01-27 23:00   ` Kees Cook
2020-01-08 18:56 ` [PATCH 12/17] arm64: debug-monitors: refactor MDSCR manipulation Mark Rutland
2020-01-10  4:35   ` Anshuman Khandual
2020-01-10 16:09     ` Mark Rutland
2020-01-08 18:56 ` [PATCH 13/17] arm64: entry: move common el0 entry/return work to C Mark Rutland
2020-01-09 15:19   ` Mark Rutland
2020-01-08 18:56 ` [PATCH 14/17] arm64: entry: move NO_SYSCALL setup " Mark Rutland
2020-01-10  5:37   ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 15/17] arm64: entry: move ARM64_ERRATUM_845719 workaround " Mark Rutland
2020-01-08 18:56 ` [PATCH 16/17] arm64: entry: move ARM64_ERRATUM_1418040 " Mark Rutland
2020-01-08 18:56 ` Mark Rutland [this message]

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