linux-kernel - [PATCH] microblaze: mm: Flush TLB to ensure correct mapping when higmem ON

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Message-Id: <434d075d3360ddfd5c40a16ad95af288a45cd7a9.1496125641.git.michal.simek@xilinx.com>
Date:   Tue, 30 May 2017 08:27:36 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     linux-kernel@...r.kernel.org, monstr@...str.eu
Subject: [PATCH] microblaze: mm: Flush TLB to ensure correct mapping when higmem ON

MMU contains invalid mapping which wasn't flushed and new mapping
is using the same addresses as previous one. That's why TLB miss is not
happening to get new correct TLB entry and MMU points to incorrect area.

This is replicatable when large files(256MB and more) are copied and
checked.

Signed-off-by: Michal Simek <michal.simek@...inx.com>
---

 arch/microblaze/mm/highmem.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/arch/microblaze/mm/highmem.c b/arch/microblaze/mm/highmem.c
index 2fcc5a52d84d..ed4454c5ce35 100644
--- a/arch/microblaze/mm/highmem.c
+++ b/arch/microblaze/mm/highmem.c
@@ -60,6 +60,7 @@ void __kunmap_atomic(void *kvaddr)
 {
 	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 	int type;
+	unsigned int idx;
 
 	if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
 		pagefault_enable();
@@ -68,21 +69,18 @@ void __kunmap_atomic(void *kvaddr)
 	}
 
 	type = kmap_atomic_idx();
-#ifdef CONFIG_DEBUG_HIGHMEM
-	{
-		unsigned int idx;
-
-		idx = type + KM_TYPE_NR * smp_processor_id();
-		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 
-		/*
-		 * force other mappings to Oops if they'll try to access
-		 * this pte without first remap it
-		 */
-		pte_clear(&init_mm, vaddr, kmap_pte-idx);
-		local_flush_tlb_page(NULL, vaddr);
-	}
+	idx = type + KM_TYPE_NR * smp_processor_id();
+#ifdef CONFIG_DEBUG_HIGHMEM
+	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 #endif
+	/*
+	 * force other mappings to Oops if they'll try to access
+	 * this pte without first remap it
+	 */
+	pte_clear(&init_mm, vaddr, kmap_pte-idx);
+	local_flush_tlb_page(NULL, vaddr);
+
 	kmap_atomic_idx_pop();
 	pagefault_enable();
 	preempt_enable();
-- 
1.9.1