linux-kernel - [PATCH] dmaengine: fsldma: Do not pass pointers to lower_32

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Message-ID: <20200829124535.GA11751@gondor.apana.org.au>
Date:   Sat, 29 Aug 2020 22:45:35 +1000
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joerg.roedel@....com>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Wen He <wen.he_1@....com>, Peng Ma <peng.ma@....com>,
        Vinod Koul <vkoul@...nel.org>
Subject: [PATCH] dmaengine: fsldma: Do not pass pointers to lower_32_bits

On Sat, Aug 29, 2020 at 03:51:16AM -0700, Guenter Roeck wrote:
> 
> This patch results in the following compile error when compiling 
> ppc:mpc85xx_defconfig.
> 
> Error log:
> In file included from ./include/linux/list.h:9,
>                  from ./include/linux/module.h:12,
>                  from drivers/dma/fsldma.c:23:
> drivers/dma/fsldma.h: In function 'fsl_ioread64':
> ./include/linux/kernel.h:189:37: error: invalid operands to binary & (have 'const u64 *' {aka 'const long long unsigned int *'} and 'unsigned int')
>   189 | #define lower_32_bits(n) ((u32)((n) & 0xffffffff))
>       |                                     ^
> drivers/dma/fsldma.h:208:17: note: in expansion of macro 'lower_32_bits'
>   208 |  u32 fsl_addr = lower_32_bits(addr);
>       |                 ^~~~~~~~~~~~~
> drivers/dma/fsldma.h: In function 'fsl_ioread64be':
> ./include/linux/kernel.h:189:37: error: invalid operands to binary & (have 'const u64 *' {aka 'const long long unsigned int *'} and 'unsigned int')
>   189 | #define lower_32_bits(n) ((u32)((n) & 0xffffffff))
>       |                                     ^
> drivers/dma/fsldma.h:222:17: note: in expansion of macro 'lower_32_bits'
>   222 |  u32 fsl_addr = lower_32_bits(addr);
>       |                 ^~~~~~~~~~~~~
> make[2]: *** [drivers/dma/fsldma.o] Error 1

Thanks for the report.  Passing a pointer to lower_32_bits is just
bad.

---8<---
The functions fsl_ioread64* were passing a pointer to lower_32_bits
which just happened to work because it was a macro that simply did
a cast on the argument.

However, now that lower_32_bits does a mask on the argument it no
longer works.  Passing a pointer to lower_32_bits doesn't look
right anyway.

This patch adds explicit casts so that an integer is passed along
as the argument to lower_32_bits.

Reported-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
index 56f18ae99233..da5816b1706e 100644
--- a/drivers/dma/fsldma.h
+++ b/drivers/dma/fsldma.h
@@ -205,7 +205,7 @@ struct fsldma_chan {
 #else
 static u64 fsl_ioread64(const u64 __iomem *addr)
 {
-	u32 fsl_addr = lower_32_bits(addr);
+	u32 fsl_addr = lower_32_bits((unsigned long)addr);
 	u64 fsl_addr_hi = (u64)in_le32((u32 *)(fsl_addr + 1)) << 32;
 
 	return fsl_addr_hi | in_le32((u32 *)fsl_addr);
@@ -219,7 +219,7 @@ static void fsl_iowrite64(u64 val, u64 __iomem *addr)
 
 static u64 fsl_ioread64be(const u64 __iomem *addr)
 {
-	u32 fsl_addr = lower_32_bits(addr);
+	u32 fsl_addr = lower_32_bits((unsigned long)addr);
 	u64 fsl_addr_hi = (u64)in_be32((u32 *)fsl_addr) << 32;
 
 	return fsl_addr_hi | in_be32((u32 *)(fsl_addr + 1));
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt