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author | Miquel Raynal <miquel.raynal@bootlin.com> | 2019-10-22 17:58:59 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-17 22:34:42 +0300 |
commit | 37b8438a6f49ab4d06a088dd55e5b09afa0d59ab (patch) | |
tree | 0588a14fd1eb9b35537f3c1e0f09df149b9ada2a /drivers/virtio | |
parent | 2e0e2b4860ccef8dc8033648e79fdff0d6a93613 (diff) | |
download | linux-37b8438a6f49ab4d06a088dd55e5b09afa0d59ab.tar.xz |
mtd: spear_smi: Fix Write Burst mode
commit 69c7f4618c16b4678f8a4949b6bb5ace259c0033 upstream.
Any write with either dd or flashcp to a device driven by the
spear_smi.c driver will pass through the spear_smi_cpy_toio()
function. This function will get called for chunks of up to 256 bytes.
If the amount of data is smaller, we may have a problem if the data
length is not 4-byte aligned. In this situation, the kernel panics
during the memcpy:
# dd if=/dev/urandom bs=1001 count=1 of=/dev/mtd6
spear_smi_cpy_toio [620] dest c9070000, src c7be8800, len 256
spear_smi_cpy_toio [620] dest c9070100, src c7be8900, len 256
spear_smi_cpy_toio [620] dest c9070200, src c7be8a00, len 256
spear_smi_cpy_toio [620] dest c9070300, src c7be8b00, len 233
Unhandled fault: external abort on non-linefetch (0x808) at 0xc90703e8
[...]
PC is at memcpy+0xcc/0x330
The above error occurs because the implementation of memcpy_toio()
tries to optimize the number of I/O by writing 4 bytes at a time as
much as possible, until there are less than 4 bytes left and then
switches to word or byte writes.
Unfortunately, the specification states about the Write Burst mode:
"the next AHB Write request should point to the next
incremented address and should have the same size (byte,
half-word or word)"
This means ARM architecture implementation of memcpy_toio() cannot
reliably be used blindly here. Workaround this situation by update the
write path to stick to byte access when the burst length is not
multiple of 4.
Fixes: f18dbbb1bfe0 ("mtd: ST SPEAr: Add SMI driver for serial NOR flash")
Cc: Russell King <linux@armlinux.org.uk>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/virtio')
0 files changed, 0 insertions, 0 deletions