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Subject[PATCH v2] staging: android: ashmem: Add support for 32bit ashmem calls in a 64bit kernel
Date
Android's shared memory subsystem, Ashmem, does not support calls from a
32bit userspace in a 64 bit kernel. This patch adds support for syscalls
coming from a 32bit userspace in a 64bit kernel.

The patch has been successfully tested on ARMv8 AEM(64bit
platform model) and Versatile Express A9(32bit platform).

v2: Fix missing compat.h include.

Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
Acked-by: Arve Hjønnevåg <arve@android.com>
Acked-by: John Stultz <john.stultz@linaro.org>
---
drivers/staging/android/ashmem.c | 21 ++++++++++++++++++++-
drivers/staging/android/ashmem.h | 7 +++++++
2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 72064fc..268f0b4 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -674,6 +674,23 @@ static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
return ret;
}

+/* support of 32bit userspace on 64bit platforms */
+#ifdef CONFIG_COMPAT
+static long compat_ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+
+ switch (cmd) {
+ case COMPAT_ASHMEM_SET_SIZE:
+ cmd = ASHMEM_SET_SIZE;
+ break;
+ case COMPAT_ASHMEM_SET_PROT_MASK:
+ cmd = ASHMEM_SET_PROT_MASK;
+ break;
+ }
+ return ashmem_ioctl(file, cmd, arg);
+}
+#endif
+
static const struct file_operations ashmem_fops = {
.owner = THIS_MODULE,
.open = ashmem_open,
@@ -682,7 +699,9 @@ static const struct file_operations ashmem_fops = {
.llseek = ashmem_llseek,
.mmap = ashmem_mmap,
.unlocked_ioctl = ashmem_ioctl,
- .compat_ioctl = ashmem_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = compat_ashmem_ioctl,
+#endif
};

static struct miscdevice ashmem_misc = {
diff --git a/drivers/staging/android/ashmem.h b/drivers/staging/android/ashmem.h
index 1976b10..8dc0f0d 100644
--- a/drivers/staging/android/ashmem.h
+++ b/drivers/staging/android/ashmem.h
@@ -14,6 +14,7 @@

#include <linux/limits.h>
#include <linux/ioctl.h>
+#include <linux/compat.h>

#define ASHMEM_NAME_LEN 256

@@ -45,4 +46,10 @@ struct ashmem_pin {
#define ASHMEM_GET_PIN_STATUS _IO(__ASHMEMIOC, 9)
#define ASHMEM_PURGE_ALL_CACHES _IO(__ASHMEMIOC, 10)

+/* support of 32bit userspace on 64bit platforms */
+#ifdef CONFIG_COMPAT
+#define COMPAT_ASHMEM_SET_SIZE _IOW(__ASHMEMIOC, 3, compat_size_t)
+#define COMPAT_ASHMEM_SET_PROT_MASK _IOW(__ASHMEMIOC, 5, unsigned int)
+#endif
+
#endif /* _LINUX_ASHMEM_H */
--
1.7.9.5
--
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