* [PATCH] dell_rbu: stop abusing the DMA API
@ 2019-01-29 7:34 Christoph Hellwig
2019-02-01 18:28 ` Stuart Hayes
2019-02-01 23:15 ` Darren Hart
0 siblings, 2 replies; 6+ messages in thread
From: Christoph Hellwig @ 2019-01-29 7:34 UTC (permalink / raw)
To: stuart.w.hayes, dvhart; +Cc: andy, platform-driver-x86, linux-kernel
For some odd reason dell_rbu actually seems to want the physical and
not a bus address for the allocated buffer. Lets assume that actually
is correct given that it is BIOS-related and that is a good source
of insanity. In that case we should not use dma_alloc_coherent with
a NULL device to allocate memory, but use GFP_DMA32 to stay under
the 32-bit BIOS limit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/platform/x86/dell_rbu.c | 52 ++++++++++-----------------------
1 file changed, 15 insertions(+), 37 deletions(-)
diff --git a/drivers/platform/x86/dell_rbu.c b/drivers/platform/x86/dell_rbu.c
index ccefa84f7305..fba7d96c1714 100644
--- a/drivers/platform/x86/dell_rbu.c
+++ b/drivers/platform/x86/dell_rbu.c
@@ -59,7 +59,6 @@ static struct _rbu_data {
unsigned long image_update_buffer_size;
unsigned long bios_image_size;
int image_update_ordernum;
- int dma_alloc;
spinlock_t lock;
unsigned long packet_read_count;
unsigned long num_packets;
@@ -89,7 +88,6 @@ static struct packet_data packet_data_head;
static struct platform_device *rbu_device;
static int context;
-static dma_addr_t dell_rbu_dmaaddr;
static void init_packet_head(void)
{
@@ -380,12 +378,8 @@ static void img_update_free(void)
*/
memset(rbu_data.image_update_buffer, 0,
rbu_data.image_update_buffer_size);
- if (rbu_data.dma_alloc == 1)
- dma_free_coherent(NULL, rbu_data.bios_image_size,
- rbu_data.image_update_buffer, dell_rbu_dmaaddr);
- else
- free_pages((unsigned long) rbu_data.image_update_buffer,
- rbu_data.image_update_ordernum);
+ free_pages((unsigned long) rbu_data.image_update_buffer,
+ rbu_data.image_update_ordernum);
/*
* Re-initialize the rbu_data variables after a free
@@ -394,7 +388,6 @@ static void img_update_free(void)
rbu_data.image_update_buffer = NULL;
rbu_data.image_update_buffer_size = 0;
rbu_data.bios_image_size = 0;
- rbu_data.dma_alloc = 0;
}
/*
@@ -410,10 +403,8 @@ static void img_update_free(void)
static int img_update_realloc(unsigned long size)
{
unsigned char *image_update_buffer = NULL;
- unsigned long rc;
unsigned long img_buf_phys_addr;
int ordernum;
- int dma_alloc = 0;
/*
* check if the buffer of sufficient size has been
@@ -444,36 +435,23 @@ static int img_update_realloc(unsigned long size)
ordernum = get_order(size);
image_update_buffer =
- (unsigned char *) __get_free_pages(GFP_KERNEL, ordernum);
-
- img_buf_phys_addr =
- (unsigned long) virt_to_phys(image_update_buffer);
-
- if (img_buf_phys_addr > BIOS_SCAN_LIMIT) {
- free_pages((unsigned long) image_update_buffer, ordernum);
- ordernum = -1;
- image_update_buffer = dma_alloc_coherent(NULL, size,
- &dell_rbu_dmaaddr, GFP_KERNEL);
- dma_alloc = 1;
- }
-
- spin_lock(&rbu_data.lock);
-
- if (image_update_buffer != NULL) {
- rbu_data.image_update_buffer = image_update_buffer;
- rbu_data.image_update_buffer_size = size;
- rbu_data.bios_image_size =
- rbu_data.image_update_buffer_size;
- rbu_data.image_update_ordernum = ordernum;
- rbu_data.dma_alloc = dma_alloc;
- rc = 0;
- } else {
+ (unsigned char *)__get_free_pages(GFP_DMA32, ordernum);
+ if (!image_update_buffer) {
pr_debug("Not enough memory for image update:"
"size = %ld\n", size);
- rc = -ENOMEM;
+ return -ENOMEM;
}
- return rc;
+ img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
+ if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
+ return -EINVAL; /* can't happen per defintion */
+
+ spin_lock(&rbu_data.lock);
+ rbu_data.image_update_buffer = image_update_buffer;
+ rbu_data.image_update_buffer_size = size;
+ rbu_data.bios_image_size = rbu_data.image_update_buffer_size;
+ rbu_data.image_update_ordernum = ordernum;
+ return 0;
}
static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] dell_rbu: stop abusing the DMA API
2019-01-29 7:34 [PATCH] dell_rbu: stop abusing the DMA API Christoph Hellwig
@ 2019-02-01 18:28 ` Stuart Hayes
2019-02-01 23:17 ` Darren Hart
2019-02-01 23:15 ` Darren Hart
1 sibling, 1 reply; 6+ messages in thread
From: Stuart Hayes @ 2019-02-01 18:28 UTC (permalink / raw)
To: Christoph Hellwig, dvhart; +Cc: andy, platform-driver-x86, linux-kernel
On 1/29/2019 1:34 AM, Christoph Hellwig wrote:
> For some odd reason dell_rbu actually seems to want the physical and
> not a bus address for the allocated buffer. Lets assume that actually
> is correct given that it is BIOS-related and that is a good source
> of insanity. In that case we should not use dma_alloc_coherent with
> a NULL device to allocate memory, but use GFP_DMA32 to stay under
> the 32-bit BIOS limit.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/platform/x86/dell_rbu.c | 52 ++++++++++-----------------------
> 1 file changed, 15 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/platform/x86/dell_rbu.c b/drivers/platform/x86/dell_rbu.c
> index ccefa84f7305..fba7d96c1714 100644
> --- a/drivers/platform/x86/dell_rbu.c
> +++ b/drivers/platform/x86/dell_rbu.c
> @@ -59,7 +59,6 @@ static struct _rbu_data {
> unsigned long image_update_buffer_size;
> unsigned long bios_image_size;
> int image_update_ordernum;
> - int dma_alloc;
> spinlock_t lock;
> unsigned long packet_read_count;
> unsigned long num_packets;
> @@ -89,7 +88,6 @@ static struct packet_data packet_data_head;
>
> static struct platform_device *rbu_device;
> static int context;
> -static dma_addr_t dell_rbu_dmaaddr;
>
> static void init_packet_head(void)
> {
> @@ -380,12 +378,8 @@ static void img_update_free(void)
> */
> memset(rbu_data.image_update_buffer, 0,
> rbu_data.image_update_buffer_size);
> - if (rbu_data.dma_alloc == 1)
> - dma_free_coherent(NULL, rbu_data.bios_image_size,
> - rbu_data.image_update_buffer, dell_rbu_dmaaddr);
> - else
> - free_pages((unsigned long) rbu_data.image_update_buffer,
> - rbu_data.image_update_ordernum);
> + free_pages((unsigned long) rbu_data.image_update_buffer,
> + rbu_data.image_update_ordernum);
>
> /*
> * Re-initialize the rbu_data variables after a free
> @@ -394,7 +388,6 @@ static void img_update_free(void)
> rbu_data.image_update_buffer = NULL;
> rbu_data.image_update_buffer_size = 0;
> rbu_data.bios_image_size = 0;
> - rbu_data.dma_alloc = 0;
> }
>
> /*
> @@ -410,10 +403,8 @@ static void img_update_free(void)
> static int img_update_realloc(unsigned long size)
> {
> unsigned char *image_update_buffer = NULL;
> - unsigned long rc;
> unsigned long img_buf_phys_addr;
> int ordernum;
> - int dma_alloc = 0;
>
> /*
> * check if the buffer of sufficient size has been
> @@ -444,36 +435,23 @@ static int img_update_realloc(unsigned long size)
>
> ordernum = get_order(size);
> image_update_buffer =
> - (unsigned char *) __get_free_pages(GFP_KERNEL, ordernum);
> -
> - img_buf_phys_addr =
> - (unsigned long) virt_to_phys(image_update_buffer);
> -
> - if (img_buf_phys_addr > BIOS_SCAN_LIMIT) {
> - free_pages((unsigned long) image_update_buffer, ordernum);
> - ordernum = -1;
> - image_update_buffer = dma_alloc_coherent(NULL, size,
> - &dell_rbu_dmaaddr, GFP_KERNEL);
> - dma_alloc = 1;
> - }
> -
> - spin_lock(&rbu_data.lock);
> -
> - if (image_update_buffer != NULL) {
> - rbu_data.image_update_buffer = image_update_buffer;
> - rbu_data.image_update_buffer_size = size;
> - rbu_data.bios_image_size =
> - rbu_data.image_update_buffer_size;
> - rbu_data.image_update_ordernum = ordernum;
> - rbu_data.dma_alloc = dma_alloc;
> - rc = 0;
> - } else {
> + (unsigned char *)__get_free_pages(GFP_DMA32, ordernum);
> + if (!image_update_buffer) {
> pr_debug("Not enough memory for image update:"
> "size = %ld\n", size);
> - rc = -ENOMEM;
> + return -ENOMEM;
> }
>
> - return rc;
> + img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
> + if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
> + return -EINVAL; /* can't happen per defintion */
> +
> + spin_lock(&rbu_data.lock);
> + rbu_data.image_update_buffer = image_update_buffer;
> + rbu_data.image_update_buffer_size = size;
> + rbu_data.bios_image_size = rbu_data.image_update_buffer_size;
> + rbu_data.image_update_ordernum = ordernum;
> + return 0;
> }
>
> static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
>
Acked-by: Stuart Hayes <stuart.w.hayes@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] dell_rbu: stop abusing the DMA API
2019-02-01 18:28 ` Stuart Hayes
@ 2019-02-01 23:17 ` Darren Hart
0 siblings, 0 replies; 6+ messages in thread
From: Darren Hart @ 2019-02-01 23:17 UTC (permalink / raw)
To: Stuart Hayes; +Cc: Christoph Hellwig, andy, platform-driver-x86, linux-kernel
On Fri, Feb 01, 2019 at 12:28:46PM -0600, Stuart Hayes wrote:
>
> On 1/29/2019 1:34 AM, Christoph Hellwig wrote:
> > For some odd reason dell_rbu actually seems to want the physical and
> > not a bus address for the allocated buffer. Lets assume that actually
> > is correct given that it is BIOS-related and that is a good source
> > of insanity. In that case we should not use dma_alloc_coherent with
> > a NULL device to allocate memory, but use GFP_DMA32 to stay under
> > the 32-bit BIOS limit.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
...
>
> Acked-by: Stuart Hayes <stuart.w.hayes@gmail.com>
>
Ah, prematurely pulled in Mario - thanks Stuart.
--
Darren Hart
VMware Open Source Technology Center
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dell_rbu: stop abusing the DMA API
2019-01-29 7:34 [PATCH] dell_rbu: stop abusing the DMA API Christoph Hellwig
2019-02-01 18:28 ` Stuart Hayes
@ 2019-02-01 23:15 ` Darren Hart
2019-02-02 17:16 ` Christoph Hellwig
1 sibling, 1 reply; 6+ messages in thread
From: Darren Hart @ 2019-02-01 23:15 UTC (permalink / raw)
To: Christoph Hellwig
Cc: stuart.w.hayes, andy, platform-driver-x86, linux-kernel,
Mario_Limonciello
On Tue, Jan 29, 2019 at 08:34:09AM +0100, Christoph Hellwig wrote:
> For some odd reason dell_rbu actually seems to want the physical and
> not a bus address for the allocated buffer. Lets assume that actually
> is correct given that it is BIOS-related and that is a good source
> of insanity. In that case we should not use dma_alloc_coherent with
> a NULL device to allocate memory, but use GFP_DMA32 to stay under
> the 32-bit BIOS limit.
+ Mario re bios related physical address - is Christoph's assumption
correct?
Christoph, did you observe a failure? If so, we should probably also
tag for stable.
--
Darren Hart
VMware Open Source Technology Center
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dell_rbu: stop abusing the DMA API
2019-02-01 23:15 ` Darren Hart
@ 2019-02-02 17:16 ` Christoph Hellwig
2019-02-07 20:47 ` Darren Hart
0 siblings, 1 reply; 6+ messages in thread
From: Christoph Hellwig @ 2019-02-02 17:16 UTC (permalink / raw)
To: Darren Hart
Cc: Christoph Hellwig, stuart.w.hayes, andy, platform-driver-x86,
linux-kernel, Mario_Limonciello
On Fri, Feb 01, 2019 at 03:15:59PM -0800, Darren Hart wrote:
> On Tue, Jan 29, 2019 at 08:34:09AM +0100, Christoph Hellwig wrote:
> > For some odd reason dell_rbu actually seems to want the physical and
> > not a bus address for the allocated buffer. Lets assume that actually
> > is correct given that it is BIOS-related and that is a good source
> > of insanity. In that case we should not use dma_alloc_coherent with
> > a NULL device to allocate memory, but use GFP_DMA32 to stay under
> > the 32-bit BIOS limit.
>
> + Mario re bios related physical address - is Christoph's assumption
> correct?
>
> Christoph, did you observe a failure? If so, we should probably also
> tag for stable.
No, I've been auditing for DMA API (ab-)users that don't pass a
struct device. Generally the fix was to just pass a struct device
that is easily available. But dell_rbu doesn't actually seem to
be a "device" in the traditional sense, and the way it uses the
DMA API is really, really odd - it first does a virt_to_phys on
memory allocated from the page allocator (so works with physical
addresses in that case) and the retries with a dma_alloc_coherent
with a NULL argument, which in no way is guaranteed to you give
you something else, although for the current x86 implementation
will give you the equivalent of a GFP_DMA32 page allocator allocation
plus virt_to_phys.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dell_rbu: stop abusing the DMA API
2019-02-02 17:16 ` Christoph Hellwig
@ 2019-02-07 20:47 ` Darren Hart
0 siblings, 0 replies; 6+ messages in thread
From: Darren Hart @ 2019-02-07 20:47 UTC (permalink / raw)
To: Christoph Hellwig
Cc: stuart.w.hayes, andy, platform-driver-x86, linux-kernel,
Mario_Limonciello
On Sat, Feb 02, 2019 at 06:16:59PM +0100, Christoph Hellwig wrote:
> On Fri, Feb 01, 2019 at 03:15:59PM -0800, Darren Hart wrote:
> > On Tue, Jan 29, 2019 at 08:34:09AM +0100, Christoph Hellwig wrote:
> > > For some odd reason dell_rbu actually seems to want the physical and
> > > not a bus address for the allocated buffer. Lets assume that actually
> > > is correct given that it is BIOS-related and that is a good source
> > > of insanity. In that case we should not use dma_alloc_coherent with
> > > a NULL device to allocate memory, but use GFP_DMA32 to stay under
> > > the 32-bit BIOS limit.
> >
> > + Mario re bios related physical address - is Christoph's assumption
> > correct?
> >
> > Christoph, did you observe a failure? If so, we should probably also
> > tag for stable.
>
> No, I've been auditing for DMA API (ab-)users that don't pass a
> struct device. Generally the fix was to just pass a struct device
> that is easily available. But dell_rbu doesn't actually seem to
> be a "device" in the traditional sense, and the way it uses the
> DMA API is really, really odd - it first does a virt_to_phys on
> memory allocated from the page allocator (so works with physical
> addresses in that case) and the retries with a dma_alloc_coherent
> with a NULL argument, which in no way is guaranteed to you give
> you something else, although for the current x86 implementation
> will give you the equivalent of a GFP_DMA32 page allocator allocation
> plus virt_to_phys.
>
Thanks Christoph, merged to for-next.
--
Darren Hart
VMware Open Source Technology Center
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-02-07 20:47 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2019-01-29 7:34 [PATCH] dell_rbu: stop abusing the DMA API Christoph Hellwig
2019-02-01 18:28 ` Stuart Hayes
2019-02-01 23:17 ` Darren Hart
2019-02-01 23:15 ` Darren Hart
2019-02-02 17:16 ` Christoph Hellwig
2019-02-07 20:47 ` Darren Hart
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