From: Linus Torvalds torvalds@linux-foundation.org
[ Upstream commit 0a4c56c80f90797e9b9f8426c6aae4c0cf1c9785 ]
Commit ef91bb196b0d ("kernel.h: Silence sparse warning in lower_32_bits") caused new warnings to show in the fsldma driver, but that commit was not to blame: it only exposed some very incorrect code that tried to take the low 32 bits of an address.
That made no sense for multiple reasons, the most notable one being that that code was intentionally limited to only 32-bit ppc builds, so "only low 32 bits of an address" was completely nonsensical. There were no high bits to mask off to begin with.
But even more importantly fropm a correctness standpoint, turning the address into an integer then caused the subsequent address arithmetic to be completely wrong too, and the "+1" actually incremented the address by one, rather than by four.
Which again was incorrect, since the code was reading two 32-bit values and trying to make a 64-bit end result of it all. Surprisingly, the iowrite64() did not suffer from the same odd and incorrect model.
This code has never worked, but it's questionable whether anybody cared: of the two users that actually read the 64-bit value (by way of some C preprocessor hackery and eventually the 'get_cdar()' inline function), one of them explicitly ignored the value, and the other one might just happen to work despite the incorrect value being read.
This patch at least makes it not fail the build any more, and makes the logic superficially sane. Whether it makes any difference to the code _working_ or not shall remain a mystery.
Compile-tested-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/fsldma.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h index 56f18ae992332..308bed0a560ac 100644 --- a/drivers/dma/fsldma.h +++ b/drivers/dma/fsldma.h @@ -205,10 +205,10 @@ struct fsldma_chan { #else static u64 fsl_ioread64(const u64 __iomem *addr) { - u32 fsl_addr = lower_32_bits(addr); - u64 fsl_addr_hi = (u64)in_le32((u32 *)(fsl_addr + 1)) << 32; + u32 val_lo = in_le32((u32 __iomem *)addr); + u32 val_hi = in_le32((u32 __iomem *)addr + 1);
- return fsl_addr_hi | in_le32((u32 *)fsl_addr); + return ((u64)val_hi << 32) + val_lo; }
static void fsl_iowrite64(u64 val, u64 __iomem *addr) @@ -219,10 +219,10 @@ static void fsl_iowrite64(u64 val, u64 __iomem *addr)
static u64 fsl_ioread64be(const u64 __iomem *addr) { - u32 fsl_addr = lower_32_bits(addr); - u64 fsl_addr_hi = (u64)in_be32((u32 *)fsl_addr) << 32; + u32 val_hi = in_be32((u32 __iomem *)addr); + u32 val_lo = in_be32((u32 __iomem *)addr + 1);
- return fsl_addr_hi | in_be32((u32 *)(fsl_addr + 1)); + return ((u64)val_hi << 32) + val_lo; }
static void fsl_iowrite64be(u64 val, u64 __iomem *addr)