linux-kernel - [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page

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Message-Id: <e31c57eb5308a5a73a5c8232454c0dd9f65f6175.1580485014.git.christophe.leroy@c-s.fr>
Date:   Fri, 31 Jan 2020 15:37:34 +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] powerpc/32s: Don't flush all TLBs when flushing one page

When flushing a range, the flushing function flushes all TLBs.

When the range is a single page, do a page flush instead.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/mm/book3s32/tlb.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c
index 2fcd321040ff..8e0089065a7e 100644
--- a/arch/powerpc/mm/book3s32/tlb.c
+++ b/arch/powerpc/mm/book3s32/tlb.c
@@ -79,14 +79,17 @@ static void flush_range(struct mm_struct *mm, unsigned long start,
 	int count;
 	unsigned int ctx = mm->context.id;
 
+	start &= PAGE_MASK;
+	end = (end - 1) | ~PAGE_MASK;
 	if (!Hash) {
-		_tlbia();
+		if (end - start == PAGE_SIZE)
+			_tlbie(start);
+		else
+			_tlbia();
 		return;
 	}
-	start &= PAGE_MASK;
 	if (start >= end)
 		return;
-	end = (end - 1) | ~PAGE_MASK;
 	pmd = pmd_offset(pud_offset(pgd_offset(mm, start), start), start);
 	for (;;) {
 		pmd_end = ((start + PGDIR_SIZE) & PGDIR_MASK) - 1;
-- 
2.25.0