On 19/5/23 18:24, Jonathan Cameron wrote:
On Fri, 19 May 2023 18:08:30 +0200
Philippe Mathieu-Daudé <phi...@linaro.org> wrote:
On 19/5/23 16:18, Jonathan Cameron wrote:
From: Ira Weiny <ira.we...@intel.com>
CXL has 24 bit unaligned fields which need to be stored to. CXL is
specified as little endian.
Define st24_le_p() and the supporting functions to store such a field
from a 32 bit host native value.
The use of b, w, l, q as the size specifier is limiting. So "24" was
used for the size part of the function name.
Signed-off-by: Ira Weiny <ira.we...@intel.com>
Signed-off-by: Jonathan Cameron <jonathan.came...@huawei.com>
---
docs/devel/loads-stores.rst | 1 +
include/qemu/bswap.h | 27 +++++++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/docs/devel/loads-stores.rst b/docs/devel/loads-stores.rst
index d2cefc77a2..82a79e91d9 100644
--- a/docs/devel/loads-stores.rst
+++ b/docs/devel/loads-stores.rst
@@ -36,6 +36,7 @@ store: ``st{size}_{endian}_p(ptr, val)``
``size``
- ``b`` : 8 bits
- ``w`` : 16 bits
+ - ``24`` : 24 bits
- ``l`` : 32 bits
- ``q`` : 64 bits
diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index 15a78c0db5..f546b1fc06 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -8,11 +8,25 @@
#undef bswap64
#define bswap64(_x) __builtin_bswap64(_x)
+static inline uint32_t bswap24(uint32_t x)
+{
+ assert((x & 0xff000000U) == 0);
Asserting here is a bit violent. In particular because there is no
contract description that x should be less than N bits for bswapN()
in "qemu/bswap.h" API.
But if you rather to assert ...
I'm fine either way. You asked for it when reviewing v4...
https://lore.kernel.org/all/28a9d97a-b252-a33f-1ac0-cd36264b2...@linaro.org/
Never too late to improve oneself ;)
One month later I'm afraid the assertion would fire too often,
resulting in unnecessary pain to developers (in particular the
non-QEMU ones).
+
+ return (((x & 0x000000ffU) << 16) |
+ ((x & 0x0000ff00U) << 0) |
+ ((x & 0x00ff0000U) >> 16));
+}
+
static inline void bswap16s(uint16_t *s)
{
*s = __builtin_bswap16(*s);
}
+static inline void bswap24s(uint32_t *s)
+{
+ *s = bswap24(*s & 0x00ffffffU);
... and sanitize the value here ...
+}
+
static inline void bswap32s(uint32_t *s)
{
*s = __builtin_bswap32(*s);
@@ -26,11 +40,13 @@ static inline void bswap64s(uint64_t *s)
#if HOST_BIG_ENDIAN
#define be_bswap(v, size) (v)
#define le_bswap(v, size) glue(__builtin_bswap, size)(v)
+#define le_bswap24(v) bswap24(v)
... then shouldn't you sanitize also here?
Good point. I forgot that detail whilst fighting with s390
cross builds earlier ;)
Personally I'd just drop the assertion.
I'm fine with doing that.
Jonathan
#define be_bswaps(v, size)
#define le_bswaps(p, size) \
do { *p = glue(__builtin_bswap, size)(*p); } while (0)
#else
#define le_bswap(v, size) (v)
+#define le_bswap24(v) (v)
#define be_bswap(v, size) glue(__builtin_bswap, size)(v)
#define le_bswaps(v, size)
#define be_bswaps(p, size) \
@@ -176,6 +192,7 @@ CPU_CONVERT(le, 64, uint64_t)
* size is:
* b: 8 bits
* w: 16 bits
+ * 24: 24 bits
* l: 32 bits
* q: 64 bits
*
@@ -248,6 +265,11 @@ static inline void stw_he_p(void *ptr, uint16_t v)
__builtin_memcpy(ptr, &v, sizeof(v));
}
+static inline void st24_he_p(void *ptr, uint32_t v)
+{
+ __builtin_memcpy(ptr, &v, 3);
+}
+
static inline int ldl_he_p(const void *ptr)
{
int32_t r;
@@ -297,6 +319,11 @@ static inline void stw_le_p(void *ptr, uint16_t v)
stw_he_p(ptr, le_bswap(v, 16));
}
+static inline void st24_le_p(void *ptr, uint32_t v)
+{
+ st24_he_p(ptr, le_bswap24(v));
+}
+
static inline void stl_le_p(void *ptr, uint32_t v)
{
stl_he_p(ptr, le_bswap(v, 32));
Conditional to removing the assertion in bswap24():
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
