linux-kernel - [PATCH] powerpc/fsl_booke: avoid creating duplicate tlb1 entry

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Message-ID: <20200123111914.2565-1-laurentiu.tudor@nxp.com>
Date:   Thu, 23 Jan 2020 11:19:25 +0000
From:   Laurentiu Tudor <laurentiu.tudor@....com>
To:     "oss@...error.net" <oss@...error.net>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>
CC:     "christophe.leroy@....fr" <christophe.leroy@....fr>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Diana Madalina Craciun <diana.craciun@....com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: [PATCH] powerpc/fsl_booke: avoid creating duplicate tlb1 entry

In the current implementation, the call to loadcam_multi() is wrapped
between switch_to_as1() and restore_to_as0() calls so, when it tries
to create its own temporary AS=1 TLB1 entry, it ends up duplicating the
existing one created by switch_to_as1(). Add a check to skip creating
the temporary entry if already running in AS=1.

Fixes: d9e1831a4202 ("powerpc/85xx: Load all early TLB entries at once")
Signed-off-by: Laurentiu Tudor <laurentiu.tudor@....com>
Cc: stable@...r.kernel.org
---
 arch/powerpc/mm/nohash/tlb_low.S | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/tlb_low.S b/arch/powerpc/mm/nohash/tlb_low.S
index 2ca407cedbe7..eaeee402f96e 100644
--- a/arch/powerpc/mm/nohash/tlb_low.S
+++ b/arch/powerpc/mm/nohash/tlb_low.S
@@ -397,7 +397,7 @@ _GLOBAL(set_context)
  * extern void loadcam_entry(unsigned int index)
  *
  * Load TLBCAM[index] entry in to the L2 CAM MMU
- * Must preserve r7, r8, r9, and r10
+ * Must preserve r7, r8, r9, r10 and r11
  */
 _GLOBAL(loadcam_entry)
 	mflr	r5
@@ -433,6 +433,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
  */
 _GLOBAL(loadcam_multi)
 	mflr	r8
+	/* Don't switch to AS=1 if already there */
+	mfmsr	r11
+	andi.	r11,r11,MSR_IS
+	bne	10f
 
 	/*
 	 * Set up temporary TLB entry that is the same as what we're
@@ -458,6 +462,7 @@ _GLOBAL(loadcam_multi)
 	mtmsr	r6
 	isync
 
+10:
 	mr	r9,r3
 	add	r10,r3,r4
 2:	bl	loadcam_entry
@@ -466,6 +471,10 @@ _GLOBAL(loadcam_multi)
 	mr	r3,r9
 	blt	2b
 
+	/* Don't return to AS=0 if we were in AS=1 at function start */
+	andi.	r11,r11,MSR_IS
+	bne	3f
+
 	/* Return to AS=0 and clear the temporary entry */
 	mfmsr	r6
 	rlwinm.	r6,r6,0,~(MSR_IS|MSR_DS)
@@ -481,6 +490,7 @@ _GLOBAL(loadcam_multi)
 	tlbwe
 	isync
 
+3:
 	mtlr	r8
 	blr
 #endif
-- 
2.17.1