linux-kernel - [PATCH v2 2/4] powerpc/mm: Leave a gap between early allocated IO areas

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Date:   Mon, 19 Apr 2021 10:47:26 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Steven Price <steven.price@....com>, akpm@...ux-foundation.org,
        dja@...ens.net
Cc:     Oliver O'Halloran <oohall@...il.com>, linux-arch@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH v2 2/4] powerpc/mm: Leave a gap between early allocated IO
 areas

Vmalloc system leaves a gap between allocated areas. It helps catching
overflows.

Do the same for IO areas which are allocated with early_ioremap_range()
until slab_is_available().

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/mm/ioremap_32.c | 4 ++--
 arch/powerpc/mm/ioremap_64.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/ioremap_32.c b/arch/powerpc/mm/ioremap_32.c
index 743e11384dea..9d13143b8be4 100644
--- a/arch/powerpc/mm/ioremap_32.c
+++ b/arch/powerpc/mm/ioremap_32.c
@@ -70,10 +70,10 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
 	 */
 	pr_warn("ioremap() called early from %pS. Use early_ioremap() instead\n", caller);
 
-	err = early_ioremap_range(ioremap_bot - size, p, size, prot);
+	err = early_ioremap_range(ioremap_bot - size - PAGE_SIZE, p, size, prot);
 	if (err)
 		return NULL;
-	ioremap_bot -= size;
+	ioremap_bot -= size + PAGE_SIZE;
 
 	return (void __iomem *)ioremap_bot + offset;
 }
diff --git a/arch/powerpc/mm/ioremap_64.c b/arch/powerpc/mm/ioremap_64.c
index ba5cbb0d66bd..3acece00b33e 100644
--- a/arch/powerpc/mm/ioremap_64.c
+++ b/arch/powerpc/mm/ioremap_64.c
@@ -38,7 +38,7 @@ void __iomem *__ioremap_caller(phys_addr_t addr, unsigned long size,
 		return NULL;
 
 	ret = (void __iomem *)ioremap_bot + offset;
-	ioremap_bot += size;
+	ioremap_bot += size + PAGE_SIZE;
 
 	return ret;
 }
-- 
2.25.0