Re: [PATCH] crypto: ux500: make interrupt mode plausible

On Thu, Jun 26, 2014 at 01:43:02PM +0200, Arnd Bergmann wrote:

The interrupt handler in the ux500 crypto driver has an obviously
incorrect way to access the data buffer, which for a while has
caused this build warning:

../ux500/cryp/cryp_core.c: In function 'cryp_interrupt_handler':
../ux500/cryp/cryp_core.c:234:5: warning: passing argument 1 of '__fswab32' makes integer from pointer without a cast [enabled by default]
     writel_relaxed(ctx->indata,
     ^
In file included from ../include/linux/swab.h:4:0,
                 from ../include/uapi/linux/byteorder/big_endian.h:12,
                 from ../include/linux/byteorder/big_endian.h:4,
                 from ../arch/arm/include/uapi/asm/byteorder.h:19,
                 from ../include/asm-generic/bitops/le.h:5,
                 from ../arch/arm/include/asm/bitops.h:340,
                 from ../include/linux/bitops.h:33,
                 from ../include/linux/kernel.h:10,
                 from ../include/linux/clk.h:16,
                 from ../drivers/crypto/ux500/cryp/cryp_core.c:12:
../include/uapi/linux/swab.h:57:119: note: expected '__u32' but argument is of type 'const u8 *'
 static inline __attribute_const__ __u32 __fswab32(__u32 val)

There are at least two, possibly three problems here:
a) when writing into the FIFO, we copy the pointer rather than the
   actual data we want to give to the hardware
b) the data pointer is an array of 8-bit values, while the FIFO
   is 32-bit wide, so both the read and write access fail to do
   a proper type conversion
c) This seems incorrect for big-endian kernels, on which we need to
   byte-swap any register access, but not normally FIFO accesses,
   at least the DMA case doesn't do it either.

This converts the bogus loop to use the same readsl/writesl pair
that we use for the two other modes (DMA and polling). This is
more efficient and consistent, and probably correct for endianess.

The bug has existed since the driver was first merged, and was
probably never detected because nobody tried to use interrupt mode.
It might make sense to backport this fix to stable kernels, depending
on how the crypto maintainers feel about that.

Patch applied.  I'm not going to push this to stable though until
I see some more testing.  We can always push this later if needed.

Thanks,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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