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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
        "Russell King" <rmk+kernel@armlinux.org.uk>,
        "Nicolas Pitre" <nico@linaro.org>,
        "Thomas Petazzoni" <thomas.petazzoni@free-electrons.com>
Date:   Sun, 09 Dec 2018 21:50:33 +0000
Message-ID: <lsq.1544392233.151909631@decadent.org.uk>
Subject: [PATCH 3.16 248/328] ARM: 8799/1: mm: fix pci_ioremap_io() offset
 check
In-Reply-To: <lsq.1544392232.713909046@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

commit 3a58ac65e2d7969bcdf1b6acb70fa4d12a88e53e upstream.

IO_SPACE_LIMIT is the ending address of the PCI IO space, i.e
something like 0xfffff (and not 0x100000).

Therefore, when offset = 0xf0000 is passed as argument, this function
fails even though the offset + SZ_64K fits below the
IO_SPACE_LIMIT. This makes the last chunk of 64 KB of the I/O space
not usable as it cannot be mapped.

This patch fixes that by substracing 1 to offset + SZ_64K, so that we
compare the addrss of the last byte of the I/O space against
IO_SPACE_LIMIT instead of the address of the first byte of what is
after the I/O space.

Fixes: c2794437091a4 ("ARM: Add fixed PCI i/o mapping")
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/arm/mm/ioremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -447,7 +447,7 @@ void pci_ioremap_set_mem_type(int mem_ty
 
 int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr)
 {
-	BUG_ON(offset + SZ_64K > IO_SPACE_LIMIT);
+	BUG_ON(offset + SZ_64K - 1 > IO_SPACE_LIMIT);
 
 	return ioremap_page_range(PCI_IO_VIRT_BASE + offset,
 				  PCI_IO_VIRT_BASE + offset + SZ_64K,