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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pei Huang <huangpei@loongson.cn>,
        Huacai Chen <chenhc@lemote.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Subject: [PATCH 5.4 114/232] MIPS/tlbex: Fix LDDIR usage in setup_pw() for Loongson-3
Date:   Thu, 16 Apr 2020 15:23:28 +0200
Message-Id: <20200416131329.401367116@linuxfoundation.org>
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From: Huacai Chen <chenhc@lemote.com>

commit d191aaffe3687d1e73e644c185f5f0550ec242b5 upstream.

LDDIR/LDPTE is Loongson-3's acceleration for Page Table Walking. If BD
(Base Directory, the 4th page directory) is not enabled, then GDOffset
is biased by BadVAddr[63:62]. So, if GDOffset (aka. BadVAddr[47:36] for
Loongson-3) is big enough, "0b11(BadVAddr[63:62])|BadVAddr[47:36]|...."
can far beyond pg_swapper_dir. This means the pg_swapper_dir may NOT be
accessed by LDDIR correctly, so fix it by set PWDirExt in CP0_PWCtl.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pei Huang <huangpei@loongson.cn>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/mm/tlbex.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -1480,6 +1480,7 @@ static void build_r4000_tlb_refill_handl
 
 static void setup_pw(void)
 {
+	unsigned int pwctl;
 	unsigned long pgd_i, pgd_w;
 #ifndef __PAGETABLE_PMD_FOLDED
 	unsigned long pmd_i, pmd_w;
@@ -1506,6 +1507,7 @@ static void setup_pw(void)
 
 	pte_i = ilog2(_PAGE_GLOBAL);
 	pte_w = 0;
+	pwctl = 1 << 30; /* Set PWDirExt */
 
 #ifndef __PAGETABLE_PMD_FOLDED
 	write_c0_pwfield(pgd_i << 24 | pmd_i << 12 | pt_i << 6 | pte_i);
@@ -1516,8 +1518,9 @@ static void setup_pw(void)
 #endif
 
 #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
-	write_c0_pwctl(1 << 6 | psn);
+	pwctl |= (1 << 6 | psn);
 #endif
+	write_c0_pwctl(pwctl);
 	write_c0_kpgd((long)swapper_pg_dir);
 	kscratch_used_mask |= (1 << 7); /* KScratch6 is used for KPGD */
 }