linux-kernel - [PATCH v1 31/46] powerpc/8xx: Add function to update pinned TLBs

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Date:   Mon, 16 Mar 2020 12:36:16 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v1 31/46] powerpc/8xx: Add function to update pinned TLBs

Pinned TLBs are not easy to modify when the MMU is enabled.

Create a small function to update a pinned TLB entry with MMU off.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/include/asm/nohash/32/mmu-8xx.h |  3 ++
 arch/powerpc/kernel/head_8xx.S               | 44 ++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
index a092e6434bda..794bce83c5b0 100644
--- a/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/mmu-8xx.h
@@ -193,6 +193,9 @@
 
 #include <linux/mmdebug.h>
 
+void mpc8xx_update_tlb(int data, int idx, unsigned long epn,
+		       unsigned long twc, unsigned long rpn);
+
 typedef struct {
 	unsigned int id;
 	unsigned int active;
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 423465b10c82..84b3c7692b37 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -866,6 +866,50 @@ initial_mmu:
 	mtspr	SPRN_DER, r8
 	blr
 
+/*
+ * void mpc8xx_update_tlb(int data, int idx, unsigned long epn,
+ *			  unsigned long twc, unsigned long rpn);
+ */
+_GLOBAL(mpc8xx_update_tlb)
+	lis	r9, (1f - PAGE_OFFSET)@h
+	ori	r9, r9, (1f - PAGE_OFFSET)@l
+	mfmsr	r10
+	mflr	r11
+	li	r12, MSR_KERNEL & ~(MSR_IR | MSR_DR)
+	rlwinm	r0, r10, 0, ~MSR_RI
+	rlwinm	r0, r0, 0, ~MSR_EE
+	mtmsr	r0
+	isync
+	.align	4
+	mtspr	SPRN_SRR0, r9
+	mtspr	SPRN_SRR1, r12
+	rfi
+
+1:	cmpwi	r3, 0
+	beq	2f
+
+	mfspr	r0, SPRN_MD_CTR
+	rlwimi	r0, r4, 8, 0x00001f00
+	mtspr	SPRN_MD_CTR, r0
+
+	mtspr	SPRN_MD_EPN, r5
+	mtspr	SPRN_MD_TWC, r6
+	mtspr	SPRN_MD_RPN, r7
+	b	3f
+
+2:	mfspr	r0, SPRN_MI_CTR
+	rlwimi	r0, r4, 8, 0x00001f00
+	mtspr	SPRN_MI_CTR, r0
+
+	mtspr	SPRN_MI_EPN, r5
+	mtspr	SPRN_MI_TWC, r6
+	mtspr	SPRN_MI_RPN, r7
+
+3:	li	r12, MSR_KERNEL & ~(MSR_IR | MSR_DR | MSR_RI)
+	mtmsr	r12
+	mtspr	SPRN_SRR1, r10
+	mtspr	SPRN_SRR0, r11
+	rfi
 
 /*
  * We put a few things here that have to be page-aligned.
-- 
2.25.0