[Qemu-devel] [PATCH 0/6] Drop cpu_to_*w, *_to_cpup, document cpu_to_*, *_to_cpu

[Qemu-devel] [PATCH 0/6] Drop cpu_to_*w, *_to_cpup, document cpu_to_*, *_to_cpu

[Peter Maydell]

This patchset removes the final uses of the deprecated
cpu_to_*w() and *_to_cpup() conversion functions, and
then removes their implementations. We can then document
the remaining cpu_to_*() and *_to_cpu() conversion functions.

The block/qcow2 patch is in the qcow2 queue but not in master yet;
the hw/bt patch was posted a while back but not yet reviewed;
I've put them in this series so it's self-contained.
The 9p patch I thought I'd posted but apparently not.

Patches 4..6 are definitely new.

This is all pretty safe to go into 2.7, but the only justification
for doing so really is that it gets a pending item off my list
of things-in-flight :-)

thanks
-- PMM


Peter Maydell (6):
  fsdev/9p-iov-marshal.c: Don't use cpu_to_*w() functions
  block/qcow2: Don't use cpu_to_*w()
  hw/bt: Don't use cpu_to_*w() and *_to_cpup()
  bswap.h: Remove unused cpu_to_*w() and *_to_cpup()
  bswap.h: Fix comment typo
  bswap.h: Document cpu_to_* and *_to_cpu conversion functions

 block/qcow2-cluster.c  |  2 +-
 block/qcow2-refcount.c | 11 ++++----
 block/qcow2.c          |  6 ++---
 fsdev/9p-iov-marshal.c | 18 +++++--------
 hw/bt/hci.c            | 10 +++-----
 hw/bt/l2cap.c          | 12 ++++-----
 include/qemu/bswap.h   | 70 ++++++++++++++++++++++++++++++++++++++++++--------
 7 files changed, 83 insertions(+), 46 deletions(-)

-- 
1.9.1

[Qemu-devel] [PATCH 1/6] fsdev/9p-iov-marshal.c: Don't use cpu_to_*w() functions

[Peter Maydell]

Don't use the cpu_to_*w() functions, which we are trying to deprecate.
Instead just use cpu_to_*() to do the byteswap, which brings the
code in the marshal function in line with that in the unmarshal.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 fsdev/9p-iov-marshal.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/fsdev/9p-iov-marshal.c b/fsdev/9p-iov-marshal.c
index fce1ee9..c33fac6 100644
--- a/fsdev/9p-iov-marshal.c
+++ b/fsdev/9p-iov-marshal.c
@@ -208,31 +208,25 @@ ssize_t v9fs_iov_vmarshal(struct iovec *in_sg, int in_num, size_t offset,
             break;
         }
         case 'w': {
-            uint16_t val;
+            uint16_t val = va_arg(ap, int);
             if (bswap) {
-                cpu_to_le16w(&val, va_arg(ap, int));
-            } else {
-                val =  va_arg(ap, int);
+                val = cpu_to_le16(val);
             }
             copied = v9fs_pack(in_sg, in_num, offset, &val, sizeof(val));
             break;
         }
         case 'd': {
-            uint32_t val;
+            uint32_t val = va_arg(ap, uint32_t);
             if (bswap) {
-                cpu_to_le32w(&val, va_arg(ap, uint32_t));
-            } else {
-                val =  va_arg(ap, uint32_t);
+                val = cpu_to_le32(val);
             }
             copied = v9fs_pack(in_sg, in_num, offset, &val, sizeof(val));
             break;
         }
         case 'q': {
-            uint64_t val;
+            uint64_t val = va_arg(ap, uint64_t);;
             if (bswap) {
-                cpu_to_le64w(&val, va_arg(ap, uint64_t));
-            } else {
-                val =  va_arg(ap, uint64_t);
+                val = cpu_to_le64(val);
             }
             copied = v9fs_pack(in_sg, in_num, offset, &val, sizeof(val));
             break;
-- 
1.9.1

Re: [Qemu-devel] [PATCH 1/6] fsdev/9p-iov-marshal.c: Don't use cpu_to_*w() functions

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 729 bytes --]

On 06/28/2016 08:50 AM, Peter Maydell wrote:
> Don't use the cpu_to_*w() functions, which we are trying to deprecate.
> Instead just use cpu_to_*() to do the byteswap, which brings the
> code in the marshal function in line with that in the unmarshal.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  fsdev/9p-iov-marshal.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 

>          case 'q': {
> -            uint64_t val;
> +            uint64_t val = va_arg(ap, uint64_t);;

s/;;/;/

With that fix,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH 2/6] block/qcow2: Don't use cpu_to_*w()

[Peter Maydell]

Don't use the cpu_to_*w() functions, which we are trying to deprecate.
Instead either just use cpu_to_*() to do the byteswap, or use
st*_be_p() if we need to do the store somewhere other than to a
variable that's already the correct type.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 block/qcow2-cluster.c  |  2 +-
 block/qcow2-refcount.c | 11 +++++------
 block/qcow2.c          |  6 +++---
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 0fb4356..9c6be96 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -117,7 +117,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
 
     /* set new table */
     BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
-    cpu_to_be32w((uint32_t*)data, new_l1_size);
+    stl_be_p(data, new_l1_size);
     stq_be_p(data + 4, new_l1_table_offset);
     ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size),
                            data, sizeof(data));
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 3bef410..233763d 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -562,8 +562,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
         uint64_t d64;
         uint32_t d32;
     } data;
-    cpu_to_be64w(&data.d64, table_offset);
-    cpu_to_be32w(&data.d32, table_clusters);
+    data.d64 = cpu_to_be64(table_offset);
+    data.d32 = cpu_to_be32(table_clusters);
     BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE);
     ret = bdrv_pwrite_sync(bs->file->bs,
                            offsetof(QCowHeader, refcount_table_offset),
@@ -2155,10 +2155,9 @@ write_refblocks:
     }
 
     /* Enter new reftable into the image header */
-    cpu_to_be64w(&reftable_offset_and_clusters.reftable_offset,
-                 reftable_offset);
-    cpu_to_be32w(&reftable_offset_and_clusters.reftable_clusters,
-                 size_to_clusters(s, reftable_size * sizeof(uint64_t)));
+    reftable_offset_and_clusters.reftable_offset = cpu_to_be64(reftable_offset);
+    reftable_offset_and_clusters.reftable_clusters =
+        cpu_to_be32(size_to_clusters(s, reftable_size * sizeof(uint64_t)));
     ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader,
                                                   refcount_table_offset),
                            &reftable_offset_and_clusters,
diff --git a/block/qcow2.c b/block/qcow2.c
index 23f666d..cd0081e 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2693,9 +2693,9 @@ static int make_completely_empty(BlockDriverState *bs)
     /* "Create" an empty reftable (one cluster) directly after the image
      * header and an empty L1 table three clusters after the image header;
      * the cluster between those two will be used as the first refblock */
-    cpu_to_be64w(&l1_ofs_rt_ofs_cls.l1_offset, 3 * s->cluster_size);
-    cpu_to_be64w(&l1_ofs_rt_ofs_cls.reftable_offset, s->cluster_size);
-    cpu_to_be32w(&l1_ofs_rt_ofs_cls.reftable_clusters, 1);
+    l1_ofs_rt_ofs_cls.l1_offset = cpu_to_be64(3 * s->cluster_size);
+    l1_ofs_rt_ofs_cls.reftable_offset = cpu_to_be64(s->cluster_size);
+    l1_ofs_rt_ofs_cls.reftable_clusters = cpu_to_be32(1);
     ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_table_offset),
                            &l1_ofs_rt_ofs_cls, sizeof(l1_ofs_rt_ofs_cls));
     if (ret < 0) {
-- 
1.9.1

Re: [Qemu-devel] [PATCH 2/6] block/qcow2: Don't use cpu_to_*w()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 697 bytes --]

On 06/28/2016 08:50 AM, Peter Maydell wrote:
> Don't use the cpu_to_*w() functions, which we are trying to deprecate.
> Instead either just use cpu_to_*() to do the byteswap, or use
> st*_be_p() if we need to do the store somewhere other than to a
> variable that's already the correct type.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  block/qcow2-cluster.c  |  2 +-
>  block/qcow2-refcount.c | 11 +++++------
>  block/qcow2.c          |  6 +++---
>  3 files changed, 9 insertions(+), 10 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 2/6] block/qcow2: Don't use cpu_to_*w()

[Peter Maydell]

On 28 June 2016 at 15:50, Peter Maydell <peter.maydell@linaro.org> wrote:
> Don't use the cpu_to_*w() functions, which we are trying to deprecate.
> Instead either just use cpu_to_*() to do the byteswap, or use
> st*_be_p() if we need to do the store somewhere other than to a
> variable that's already the correct type.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Apologies for dropping the

Reviewed-by: Eric Blake <eblake@redhat.com>

that this should have; forgot to update before resend.

-- PMM

[Qemu-devel] [PATCH 3/6] hw/bt: Don't use cpu_to_*w() and *_to_cpup()

[Peter Maydell]

Don't use cpu_to_*w() and *_to_cpup() to do byte-swapped loads
and stores; instead use ld*_p() and st*_p() which correctly handle
misaligned accesses.

Bring the HNDL() macro into line with how we deal with
PARAMHANDLE(), by using cpu_to_le16() rather than an ifdef
HOST_WORDS_BIGENDIAN.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/bt/hci.c   | 10 +++-------
 hw/bt/l2cap.c | 12 ++++++------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/hw/bt/hci.c b/hw/bt/hci.c
index 7d52205..351123f 100644
--- a/hw/bt/hci.c
+++ b/hw/bt/hci.c
@@ -426,11 +426,7 @@ static void bt_submit_raw_acl(struct bt_piconet_s *net, int length, uint8_t *dat
  * be continuously allocated.  We do it though, to preserve similar
  * behaviour between hosts.  Some things, like the BD_ADDR cannot be
  * preserved though (for example if a real hci is used).  */
-#ifdef HOST_WORDS_BIGENDIAN
-# define HNDL(raw)	bswap16(raw)
-#else
-# define HNDL(raw)	(raw)
-#endif
+#define HNDL(raw) cpu_to_le16(raw)
 
 static const uint8_t bt_event_reserved_mask[8] = {
     0xff, 0x9f, 0xfb, 0xff, 0x07, 0x18, 0x00, 0x00,
@@ -1504,8 +1500,8 @@ static void bt_submit_hci(struct HCIInfo *info,
         return;
 
 #define PARAM(cmd, param)	(((cmd##_cp *) data)->param)
-#define PARAM16(cmd, param)	le16_to_cpup(&PARAM(cmd, param))
-#define PARAMHANDLE(cmd)	HNDL(PARAM(cmd, handle))
+#define PARAM16(cmd, param) lduw_le_p(&PARAM(cmd, param))
+#define PARAMHANDLE(cmd) PARAM16(cmd, handle)
 #define LENGTH_CHECK(cmd)	if (length < sizeof(cmd##_cp)) goto short_hci
     /* Note: the supported commands bitmask in bt_hci_read_local_commands_rp
      * needs to be updated every time a command is implemented here!  */
diff --git a/hw/bt/l2cap.c b/hw/bt/l2cap.c
index dfc95ed..e342045 100644
--- a/hw/bt/l2cap.c
+++ b/hw/bt/l2cap.c
@@ -526,9 +526,9 @@ static int l2cap_channel_config(struct l2cap_instance_s *l2cap,
             }
 
             /* MTU */
-            val = le16_to_cpup((void *) opt->val);
+            val = lduw_le_p(opt->val);
             if (val < ch->min_mtu) {
-                cpu_to_le16w((void *) opt->val, ch->min_mtu);
+                stw_le_p(opt->val, ch->min_mtu);
                 result = L2CAP_CONF_UNACCEPT;
                 break;
             }
@@ -543,7 +543,7 @@ static int l2cap_channel_config(struct l2cap_instance_s *l2cap,
             }
 
             /* Flush Timeout */
-            val = le16_to_cpup((void *) opt->val);
+            val = lduw_le_p(opt->val);
             if (val < 0x0001) {
                 opt->val[0] = 0xff;
                 opt->val[1] = 0xff;
@@ -987,7 +987,7 @@ static void l2cap_bframe_in(struct l2cap_chan_s *ch, uint16_t cid,
 static void l2cap_iframe_in(struct l2cap_chan_s *ch, uint16_t cid,
                 const l2cap_hdr *hdr, int len)
 {
-    uint16_t fcs = le16_to_cpup((void *) (hdr->data + len - 2));
+    uint16_t fcs = lduw_le_p(hdr->data + len - 2);
 
     if (len < 4)
         goto len_error;
@@ -1002,7 +1002,7 @@ static void l2cap_iframe_in(struct l2cap_chan_s *ch, uint16_t cid,
             /* TODO: Signal an error? */
             return;
         }
-        l2cap_sframe_in(ch, le16_to_cpup((void *) hdr->data));
+        l2cap_sframe_in(ch, lduw_le_p(hdr->data));
         return;
     }
 
@@ -1022,7 +1022,7 @@ static void l2cap_iframe_in(struct l2cap_chan_s *ch, uint16_t cid,
         if (len - 6 > ch->mps)
             goto len_error;
 
-        ch->len_total = le16_to_cpup((void *) (hdr->data + 2));
+        ch->len_total = lduw_le_p(hdr->data + 2);
         if (len >= 6 + ch->len_total)
             goto seg_error;
 
-- 
1.9.1

Re: [Qemu-devel] [PATCH 3/6] hw/bt: Don't use cpu_to_*w() and *_to_cpup()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 711 bytes --]

On 06/28/2016 08:50 AM, Peter Maydell wrote:
> Don't use cpu_to_*w() and *_to_cpup() to do byte-swapped loads
> and stores; instead use ld*_p() and st*_p() which correctly handle
> misaligned accesses.
> 
> Bring the HNDL() macro into line with how we deal with
> PARAMHANDLE(), by using cpu_to_le16() rather than an ifdef
> HOST_WORDS_BIGENDIAN.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/bt/hci.c   | 10 +++-------
>  hw/bt/l2cap.c | 12 ++++++------
>  2 files changed, 9 insertions(+), 13 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH 4/6] bswap.h: Remove unused cpu_to_*w() and *_to_cpup()

[Peter Maydell]

Now that all uses of cpu_to_*w() and *_to_cpup() have been replaced
with either ld*_p()/st*_p() or by doing direct dereferences and
using the cpu_to_*()/*_to_cpu() byteswap functions, we can remove
the unused implementations.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/qemu/bswap.h | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index ce3c42e..3b48cf4 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -99,16 +99,6 @@ static inline void endian ## size ## _to_cpus(type *p)\
 static inline void cpu_to_ ## endian ## size ## s(type *p)\
 {\
     glue(endian, _bswaps)(p, size);\
-}\
-\
-static inline type endian ## size ## _to_cpup(const type *p)\
-{\
-    return glue(glue(endian, size), _to_cpu)(*p);\
-}\
-\
-static inline void cpu_to_ ## endian ## size ## w(type *p, type v)\
-{\
-    *p = glue(glue(cpu_to_, endian), size)(v);\
 }
 
 CPU_CONVERT(be, 16, uint16_t)
-- 
1.9.1

Re: [Qemu-devel] [PATCH 4/6] bswap.h: Remove unused cpu_to_*w() and *_to_cpup()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 593 bytes --]

On 06/28/2016 08:50 AM, Peter Maydell wrote:
> Now that all uses of cpu_to_*w() and *_to_cpup() have been replaced
> with either ld*_p()/st*_p() or by doing direct dereferences and
> using the cpu_to_*()/*_to_cpu() byteswap functions, we can remove
> the unused implementations.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/qemu/bswap.h | 10 ----------
>  1 file changed, 10 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH 5/6] bswap.h: Fix comment typo

[Peter Maydell]

Fix a typo in a comment.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/qemu/bswap.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index 3b48cf4..a17d9aa 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -116,7 +116,7 @@ static inline uint32_t qemu_bswap_len(uint32_t value, int len)
 }
 
 /*
- * Same as cpu_to_le{16,23}, except that gcc will figure the result is
+ * Same as cpu_to_le{16,32}, except that gcc will figure the result is
  * a compile-time constant if you pass in a constant.  So this can be
  * used to initialize static variables.
  */
-- 
1.9.1

Re: [Qemu-devel] [PATCH 5/6] bswap.h: Fix comment typo

[Stefan Weil]

Am 28.06.2016 um 16:50 schrieb Peter Maydell:
> Fix a typo in a comment.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/qemu/bswap.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
> index 3b48cf4..a17d9aa 100644
> --- a/include/qemu/bswap.h
> +++ b/include/qemu/bswap.h
> @@ -116,7 +116,7 @@ static inline uint32_t qemu_bswap_len(uint32_t value, int len)
>  }
>  
>  /*
> - * Same as cpu_to_le{16,23}, except that gcc will figure the result is
> + * Same as cpu_to_le{16,32}, except that gcc will figure the result is
>   * a compile-time constant if you pass in a constant.  So this can be
>   * used to initialize static variables.
>   */
> 


Reviewed-by: Stefan Weil <sw@weilnetz.de>

[Qemu-devel] [PATCH 6/6] bswap.h: Document cpu_to_* and *_to_cpu conversion functions

[Peter Maydell]

Add a documentation comment describing the functions for
converting between the cpu and little or bigendian formats.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/qemu/bswap.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index a17d9aa..be3233a 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -80,6 +80,64 @@ static inline void bswap64s(uint64_t *s)
 #define be_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0)
 #endif
 
+/**
+ * Endianness conversion functions between host cpu and specified endianness.
+ * (We list the complete set of prototypes produced by the macros below
+ * to assist people who search the headers to find their definitions.)
+ *
+ * uint16_t le16_to_cpu(uint16_t v);
+ * uint32_t le32_to_cpu(uint32_t v);
+ * uint64_t le64_to_cpu(uint64_t v);
+ * uint16_t be16_to_cpu(uint16_t v);
+ * uint32_t be32_to_cpu(uint32_t v);
+ * uint64_t be64_to_cpu(uint64_t v);
+ *
+ * Convert the value @v from the specified format to the native
+ * endianness of the host CPU by byteswapping if necessary, and
+ * return the converted value.
+ *
+ * uint16_t cpu_to_le16(uint16_t v);
+ * uint32_t cpu_to_le32(uint32_t v);
+ * uint64_t cpu_to_le64(uint64_t v);
+ * uint16_t cpu_to_be16(uint16_t v);
+ * uint32_t cpu_to_be32(uint32_t v);
+ * uint64_t cpu_to_be64(uint64_t v);
+ *
+ * Convert the value @v from the native endianness of the host CPU to
+ * the specified format by byteswapping if necessary, and return
+ * the converted value.
+ *
+ * uint16_t le16_to_cpus(uint16_t *v);
+ * uint32_t le32_to_cpus(uint32_t *v);
+ * uint64_t le64_to_cpus(uint64_t *v);
+ * uint16_t be16_to_cpus(uint16_t *v);
+ * uint32_t be32_to_cpus(uint32_t *v);
+ * uint64_t be64_to_cpus(uint64_t *v);
+ *
+ * Do an in-place conversion of the value pointed to by @v from the
+ * specified format to the native endianness of the host CPU.
+ *
+ * uint16_t cpu_to_le16s(uint16_t *v);
+ * uint32_t cpu_to_le32s(uint32_t *v);
+ * uint64_t cpu_to_le64s(uint64_t *v);
+ * uint16_t cpu_to_be16s(uint16_t *v);
+ * uint32_t cpu_to_be32s(uint32_t *v);
+ * uint64_t cpu_to_be64s(uint64_t *v);
+ *
+ * Do an in-place conversion of the value pointed to by @v from the
+ * native endianness of the host CPU to the specified format.
+ *
+ * Both X_to_cpu() and cpu_to_X() perform the same operation; you
+ * should use whichever one is better documenting of the function your
+ * code is performing.
+ *
+ * Do not use these functions for conversion of values which are in guest
+ * memory, since the data may not be sufficiently aligned for the host CPU's
+ * load and store instructions. Instead you should use the ld*_p() and
+ * st*_p() functions, which perform loads and stores of data of any
+ * required size and endianness and handle possible misalignment.
+ */
+
 #define CPU_CONVERT(endian, size, type)\
 static inline type endian ## size ## _to_cpu(type v)\
 {\
-- 
1.9.1

Re: [Qemu-devel] [PATCH 6/6] bswap.h: Document cpu_to_* and *_to_cpu conversion functions

[Peter Maydell]

On 28 June 2016 at 15:50, Peter Maydell <peter.maydell@linaro.org> wrote:
> Add a documentation comment describing the functions for
> converting between the cpu and little or bigendian formats.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/qemu/bswap.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
>
> diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
> index a17d9aa..be3233a 100644
> --- a/include/qemu/bswap.h
> +++ b/include/qemu/bswap.h
> @@ -80,6 +80,64 @@ static inline void bswap64s(uint64_t *s)
>  #define be_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0)
>  #endif
>
> +/**
> + * Endianness conversion functions between host cpu and specified endianness.
> + * (We list the complete set of prototypes produced by the macros below
> + * to assist people who search the headers to find their definitions.)
> + *
> + * uint16_t le16_to_cpu(uint16_t v);
> + * uint32_t le32_to_cpu(uint32_t v);
> + * uint64_t le64_to_cpu(uint64_t v);
> + * uint16_t be16_to_cpu(uint16_t v);
> + * uint32_t be32_to_cpu(uint32_t v);
> + * uint64_t be64_to_cpu(uint64_t v);
> + *
> + * Convert the value @v from the specified format to the native
> + * endianness of the host CPU by byteswapping if necessary, and
> + * return the converted value.
> + *
> + * uint16_t cpu_to_le16(uint16_t v);
> + * uint32_t cpu_to_le32(uint32_t v);
> + * uint64_t cpu_to_le64(uint64_t v);
> + * uint16_t cpu_to_be16(uint16_t v);
> + * uint32_t cpu_to_be32(uint32_t v);
> + * uint64_t cpu_to_be64(uint64_t v);
> + *
> + * Convert the value @v from the native endianness of the host CPU to
> + * the specified format by byteswapping if necessary, and return
> + * the converted value.
> + *
> + * uint16_t le16_to_cpus(uint16_t *v);
> + * uint32_t le32_to_cpus(uint32_t *v);
> + * uint64_t le64_to_cpus(uint64_t *v);
> + * uint16_t be16_to_cpus(uint16_t *v);
> + * uint32_t be32_to_cpus(uint32_t *v);
> + * uint64_t be64_to_cpus(uint64_t *v);

Doh. All these prototypes, and the ones in the block below,
should be 'void' return type rather than the integer type.

> + *
> + * Do an in-place conversion of the value pointed to by @v from the
> + * specified format to the native endianness of the host CPU.
> + *
> + * uint16_t cpu_to_le16s(uint16_t *v);
> + * uint32_t cpu_to_le32s(uint32_t *v);
> + * uint64_t cpu_to_le64s(uint64_t *v);
> + * uint16_t cpu_to_be16s(uint16_t *v);
> + * uint32_t cpu_to_be32s(uint32_t *v);
> + * uint64_t cpu_to_be64s(uint64_t *v);
> + *
> + * Do an in-place conversion of the value pointed to by @v from the
> + * native endianness of the host CPU to the specified format.
> + *
> + * Both X_to_cpu() and cpu_to_X() perform the same operation; you
> + * should use whichever one is better documenting of the function your
> + * code is performing.
> + *
> + * Do not use these functions for conversion of values which are in guest
> + * memory, since the data may not be sufficiently aligned for the host CPU's
> + * load and store instructions. Instead you should use the ld*_p() and
> + * st*_p() functions, which perform loads and stores of data of any
> + * required size and endianness and handle possible misalignment.
> + */
> +
>  #define CPU_CONVERT(endian, size, type)\
>  static inline type endian ## size ## _to_cpu(type v)\
>  {\
> --
> 1.9.1
>
>


thanks
-- PMM

Re: [Qemu-devel] [PATCH 6/6] bswap.h: Document cpu_to_* and *_to_cpu conversion functions

[Eric Blake]

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On 06/28/2016 08:50 AM, Peter Maydell wrote:
> Add a documentation comment describing the functions for
> converting between the cpu and little or bigendian formats.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  include/qemu/bswap.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 

With your followup patch for returning void on the in-place functions,

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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