[PATCH v2 03/25] ALSA: core: Add memory copy helpers between iov_iter and iomem

From: Takashi Iwai
Date: Tue Aug 15 2023 - 15:03:28 EST


Add two more helpers for copying memory between iov_iter and iomem,
which will be used by the new PCM copy ops in a few drivers.
The existing helpers became wrappers of those now.

Note that copy_from/to_iter() returns the copied bytes, hence the
error condition is adjusted accordingly.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
include/sound/pcm.h | 5 ++++
sound/core/memory.c | 56 ++++++++++++++++++++++++++++++++++++++-------
2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index ff4a0c1c93a2..f75beead79e3 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -1559,6 +1559,11 @@ static inline u64 pcm_format_to_bits(snd_pcm_format_t pcm_format)
#define pcm_dbg(pcm, fmt, args...) \
dev_dbg((pcm)->card->dev, fmt, ##args)

+/* helpers for copying between iov_iter and iomem */
+int copy_to_iter_fromio(struct iov_iter *itert, const void __iomem *src,
+ size_t count);
+int copy_from_iter_toio(void __iomem *dst, struct iov_iter *iter, size_t count);
+
struct snd_pcm_status64 {
snd_pcm_state_t state; /* stream state */
u8 rsvd[4];
diff --git a/sound/core/memory.c b/sound/core/memory.c
index 5d894dc32f7d..2d2d0094c897 100644
--- a/sound/core/memory.c
+++ b/sound/core/memory.c
@@ -9,6 +9,7 @@
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sound/core.h>
+#include <sound/pcm.h>

/**
* copy_to_user_fromio - copy data from mmio-space to user-space
@@ -21,9 +22,30 @@
* Return: Zero if successful, or non-zero on failure.
*/
int copy_to_user_fromio(void __user *dst, const volatile void __iomem *src, size_t count)
+{
+ struct iov_iter iter;
+
+ if (import_ubuf(ITER_DEST, dst, count, &iter))
+ return -EFAULT;
+ return copy_to_iter_fromio(&iter, (const void __iomem *)src, count);
+}
+EXPORT_SYMBOL(copy_to_user_fromio);
+
+/**
+ * copy_to_iter_fromio - copy data from mmio-space to iov_iter
+ * @dst: the destination iov_iter
+ * @src: the source pointer on mmio
+ * @count: the data size to copy in bytes
+ *
+ * Copies the data from mmio-space to iov_iter.
+ *
+ * Return: Zero if successful, or non-zero on failure.
+ */
+int copy_to_iter_fromio(struct iov_iter *dst, const void __iomem *src,
+ size_t count)
{
#if defined(__i386__) || defined(CONFIG_SPARC32)
- return copy_to_user(dst, (const void __force*)src, count) ? -EFAULT : 0;
+ return copy_to_iter((const void __force *)src, count, dst) == count ? 0 : -EFAULT;
#else
char buf[256];
while (count) {
@@ -31,16 +53,15 @@ int copy_to_user_fromio(void __user *dst, const volatile void __iomem *src, size
if (c > sizeof(buf))
c = sizeof(buf);
memcpy_fromio(buf, (void __iomem *)src, c);
- if (copy_to_user(dst, buf, c))
+ if (copy_to_iter(buf, c, dst) != c)
return -EFAULT;
count -= c;
- dst += c;
src += c;
}
return 0;
#endif
}
-EXPORT_SYMBOL(copy_to_user_fromio);
+EXPORT_SYMBOL(copy_to_iter_fromio);

/**
* copy_from_user_toio - copy data from user-space to mmio-space
@@ -53,23 +74,42 @@ EXPORT_SYMBOL(copy_to_user_fromio);
* Return: Zero if successful, or non-zero on failure.
*/
int copy_from_user_toio(volatile void __iomem *dst, const void __user *src, size_t count)
+{
+ struct iov_iter iter;
+
+ if (import_ubuf(ITER_SOURCE, (void __user *)src, count, &iter))
+ return -EFAULT;
+ return copy_from_iter_toio((void __iomem *)dst, &iter, count);
+}
+EXPORT_SYMBOL(copy_from_user_toio);
+
+/**
+ * copy_from_iter_toio - copy data from iov_iter to mmio-space
+ * @dst: the destination pointer on mmio-space
+ * @src: the source iov_iter
+ * @count: the data size to copy in bytes
+ *
+ * Copies the data from iov_iter to mmio-space.
+ *
+ * Return: Zero if successful, or non-zero on failure.
+ */
+int copy_from_iter_toio(void __iomem *dst, struct iov_iter *src, size_t count)
{
#if defined(__i386__) || defined(CONFIG_SPARC32)
- return copy_from_user((void __force *)dst, src, count) ? -EFAULT : 0;
+ return copy_from_iter((void __force *)dst, count, src) == count ? 0 : -EFAULT;
#else
char buf[256];
while (count) {
size_t c = count;
if (c > sizeof(buf))
c = sizeof(buf);
- if (copy_from_user(buf, src, c))
+ if (copy_from_iter(buf, c, src) != c)
return -EFAULT;
memcpy_toio(dst, buf, c);
count -= c;
dst += c;
- src += c;
}
return 0;
#endif
}
-EXPORT_SYMBOL(copy_from_user_toio);
+EXPORT_SYMBOL(copy_from_iter_toio);
--
2.35.3