linux-kernel - [PATCH] powerpc/e200: Skip tlb1 entries used for kernel mapping

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Date:   Tue, 24 Jul 2018 11:29:45 +0530
From:   Bharat Bhushan <Bharat.Bhushan@....com>
To:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     Bharat Bhushan <Bharat.Bhushan@....com>
Subject: [PATCH] powerpc/e200: Skip tlb1 entries used for kernel mapping

E200 have TLB1 only and it does not have TLB0.
So TLB1 are used for mapping kernel and user-space both.
TLB miss handler for E200 does not consider skipping TLBs
used for kernel mapping. This patch ensures that we skip
tlb1 entries used for kernel mapping (tlbcam_index).

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@....com>
---
 arch/powerpc/kernel/head_fsl_booke.S | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index bf4c602..951fb96 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -801,12 +801,28 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
 	/* Round robin TLB1 entries assignment */
 	mfspr	r12, SPRN_MAS0
 
+	/* Get first free tlbcam entry */
+	lis	r11, tlbcam_index@ha
+	lwz	r11, tlbcam_index@l(r11)
+
+	/* Extract MAS0(NV) */
+	andi.	r13, r12, 0xfff
+	cmpw	0, r13, r11
+	blt	0, 5f
+	b	6f
+5:
+	/* When NV is less than first free tlbcam entry, use first free
+	 * tlbcam entry for ESEL and set NV */
+	rlwimi	r12, r11, 16, 4, 15
+	addi	r11, r11, 1
+	rlwimi	r12, r11, 0, 20, 31
+	b	7f
+6:
 	/* Extract TLB1CFG(NENTRY) */
 	mfspr	r11, SPRN_TLB1CFG
 	andi.	r11, r11, 0xfff
 
-	/* Extract MAS0(NV) */
-	andi.	r13, r12, 0xfff
+	/* Set MAS0(NV) for next TLB miss exception */
 	addi	r13, r13, 1
 	cmpw	0, r13, r11
 	addi	r12, r12, 1
-- 
1.9.3