As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") failed to follow this rule as buffers passed to ->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") Reported-by: Jarkko Nikula jarkko.nikula@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com --- Note that the ->{read,write}() path is still buggy since nothing guarantees that buffers passed by the MTD layer to the SPI NOR layer are DMA-able, but this is a long-standing issue which we'll have to address at the spi-nor level (this layer can choose the bounce buffer size based on nor->page_size). --- drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index cbfafc453274..3b7fafa4bbd6 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY, - SPI_MEM_OP_DATA_IN(len, val, 1)); + SPI_MEM_OP_DATA_IN(len, NULL, 1)); + void *scratchbuf; int ret;
+ scratchbuf = kmemdup(val, len, GFP_KERNEL); + if (!scratchbuf) + return -ENOMEM; + + op.data.buf.in = scratchbuf; ret = spi_mem_exec_op(flash->spimem, &op); if (ret < 0) dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret, code);
+ kfree(scratchbuf); + return ret; }
@@ -56,9 +64,19 @@ static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY, - SPI_MEM_OP_DATA_OUT(len, buf, 1)); + SPI_MEM_OP_DATA_OUT(len, NULL, 1)); + void *scratchbuf; + int ret;
- return spi_mem_exec_op(flash->spimem, &op); + scratchbuf = kmemdup(buf, len, GFP_KERNEL); + if (!scratchbuf) + return -ENOMEM; + + op.data.buf.out = scratchbuf; + ret = spi_mem_exec_op(flash->spimem, &op); + kfree(scratchbuf); + + return ret; }
static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
Oops. You should read "Make *sure* ...".
On Mon, 17 Sep 2018 15:36:52 +0200 Boris Brezillon boris.brezillon@bootlin.com wrote:
As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") failed to follow this rule as buffers passed to ->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") Reported-by: Jarkko Nikula jarkko.nikula@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com
Note that the ->{read,write}() path is still buggy since nothing guarantees that buffers passed by the MTD layer to the SPI NOR layer are DMA-able, but this is a long-standing issue which we'll have to address at the spi-nor level (this layer can choose the bounce buffer size based on nor->page_size).
drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index cbfafc453274..3b7fafa4bbd6 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY,
SPI_MEM_OP_DATA_IN(len, val, 1));
SPI_MEM_OP_DATA_IN(len, NULL, 1));- void *scratchbuf; int ret;
- scratchbuf = kmemdup(val, len, GFP_KERNEL);
- if (!scratchbuf)
return -ENOMEM;- op.data.buf.in = scratchbuf; ret = spi_mem_exec_op(flash->spimem, &op); if (ret < 0) dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret, code);
- kfree(scratchbuf);
- return ret;
} @@ -56,9 +64,19 @@ static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(opcode, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY,
SPI_MEM_OP_DATA_OUT(len, buf, 1));
SPI_MEM_OP_DATA_OUT(len, NULL, 1));- void *scratchbuf;
- int ret;
- return spi_mem_exec_op(flash->spimem, &op);
- scratchbuf = kmemdup(buf, len, GFP_KERNEL);
- if (!scratchbuf)
return -ENOMEM;- op.data.buf.out = scratchbuf;
- ret = spi_mem_exec_op(flash->spimem, &op);
- kfree(scratchbuf);
- return ret;
} static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
On 09/17/2018 04:36 PM, Boris Brezillon wrote:
As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") failed to follow this rule as buffers passed to ->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") Reported-by: Jarkko Nikula jarkko.nikula@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com
Note that the ->{read,write}() path is still buggy since nothing guarantees that buffers passed by the MTD layer to the SPI NOR layer are DMA-able, but this is a long-standing issue which we'll have to address at the spi-nor level (this layer can choose the bounce buffer size based on nor->page_size).
drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index cbfafc453274..3b7fafa4bbd6 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY,
SPI_MEM_OP_DATA_IN(len, val, 1));
SPI_MEM_OP_DATA_IN(len, NULL, 1));- void *scratchbuf; int ret;
- scratchbuf = kmemdup(val, len, GFP_KERNEL);
- if (!scratchbuf)
return -ENOMEM;- op.data.buf.in = scratchbuf; ret = spi_mem_exec_op(flash->spimem, &op); if (ret < 0) dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret, code);
- kfree(scratchbuf);
Actually this makes things even worse: "unrecognized JEDEC id bytes: b1, 74, 01" since we don't copy scratchbuf to original buffer and kmemdup before bus read is needless :-)
On Mon, 17 Sep 2018 17:13:32 +0300 Jarkko Nikula jarkko.nikula@linux.intel.com wrote:
On 09/17/2018 04:36 PM, Boris Brezillon wrote:
As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") failed to follow this rule as buffers passed to ->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API") Reported-by: Jarkko Nikula jarkko.nikula@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com
Note that the ->{read,write}() path is still buggy since nothing guarantees that buffers passed by the MTD layer to the SPI NOR layer are DMA-able, but this is a long-standing issue which we'll have to address at the spi-nor level (this layer can choose the bounce buffer size based on nor->page_size).
drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index cbfafc453274..3b7fafa4bbd6 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len) struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1), SPI_MEM_OP_NO_ADDR, SPI_MEM_OP_NO_DUMMY,
SPI_MEM_OP_DATA_IN(len, val, 1));
SPI_MEM_OP_DATA_IN(len, NULL, 1));- void *scratchbuf; int ret;
- scratchbuf = kmemdup(val, len, GFP_KERNEL);
- if (!scratchbuf)
return -ENOMEM;- op.data.buf.in = scratchbuf; ret = spi_mem_exec_op(flash->spimem, &op); if (ret < 0) dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret, code);
- kfree(scratchbuf);
Actually this makes things even worse: "unrecognized JEDEC id bytes: b1, 74, 01" since we don't copy scratchbuf to original buffer and kmemdup before bus read is needless :-)
True :-).
I'll fix that and send a v2.
linux-stable-mirror@lists.linaro.org
-
Boris Brezillon -
Jarkko Nikula