linux-kernel - [PATCH v3 03/21] arm64: Turn the MMU-on sequence into a macro

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Date:   Mon, 11 Jan 2021 13:27:53 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Brazdil <dbrazdil@...gle.com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Jing Zhang <jingzhangos@...gle.com>,
        Ajay Patil <pajay@....qualcomm.com>,
        Prasad Sodagudi <psodagud@...eaurora.org>,
        Srinivas Ramana <sramana@...eaurora.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kernel-team@...roid.com
Subject: [PATCH v3 03/21] arm64: Turn the MMU-on sequence into a macro

Turning the MMU on is a popular sport in the arm64 kernel, and
we do it more than once, or even twice. As we are about to add
even more, let's turn it into a macro.

No expected functional change.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 arch/arm64/include/asm/assembler.h | 17 +++++++++++++++++
 arch/arm64/kernel/head.S           | 19 ++++---------------
 arch/arm64/mm/proc.S               | 12 +-----------
 3 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index bf125c591116..8cded93f99c3 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -675,6 +675,23 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 	.endif
 	.endm
 
+/*
+ * Set SCTLR_EL1 to the passed value, and invalidate the local icache
+ * in the process. This is called when setting the MMU on.
+ */
+.macro set_sctlr_el1, reg
+	msr	sctlr_el1, \reg
+	isb
+	/*
+	 * Invalidate the local I-cache so that any instructions fetched
+	 * speculatively from the PoC are discarded, since they may have
+	 * been dynamically patched at the PoU.
+	 */
+	ic	iallu
+	dsb	nsh
+	isb
+.endm
+
 /*
  * Check whether to yield to another runnable task from kernel mode NEON code
  * (which runs with preemption disabled).
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a0dc987724ed..28e9735302df 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -703,16 +703,9 @@ SYM_FUNC_START(__enable_mmu)
 	offset_ttbr1 x1, x3
 	msr	ttbr1_el1, x1			// load TTBR1
 	isb
-	msr	sctlr_el1, x0
-	isb
-	/*
-	 * Invalidate the local I-cache so that any instructions fetched
-	 * speculatively from the PoC are discarded, since they may have
-	 * been dynamically patched at the PoU.
-	 */
-	ic	iallu
-	dsb	nsh
-	isb
+
+	set_sctlr_el1	x0
+
 	ret
 SYM_FUNC_END(__enable_mmu)
 
@@ -883,11 +876,7 @@ SYM_FUNC_START_LOCAL(__primary_switch)
 	tlbi	vmalle1				// Remove any stale TLB entries
 	dsb	nsh
 
-	msr	sctlr_el1, x19			// re-enable the MMU
-	isb
-	ic	iallu				// flush instructions fetched
-	dsb	nsh				// via old mapping
-	isb
+	set_sctlr_el1	x19			// re-enable the MMU
 
 	bl	__relocate_kernel
 #endif
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index ece785477bdc..c967bfd30d2b 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -291,17 +291,7 @@ skip_pgd:
 	/* We're done: fire up the MMU again */
 	mrs	x17, sctlr_el1
 	orr	x17, x17, #SCTLR_ELx_M
-	msr	sctlr_el1, x17
-	isb
-
-	/*
-	 * Invalidate the local I-cache so that any instructions fetched
-	 * speculatively from the PoC are discarded, since they may have
-	 * been dynamically patched at the PoU.
-	 */
-	ic	iallu
-	dsb	nsh
-	isb
+	set_sctlr_el1	x17
 
 	/* Set the flag to zero to indicate that we're all done */
 	str	wzr, [flag_ptr]
-- 
2.29.2