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authorBrian Norris <computersforpeace@gmail.com>2015-09-21 13:26:59 -0700
committerBrian Norris <computersforpeace@gmail.com>2015-09-29 13:37:04 -0700
commit53bb724f94f57b67213e08a4c155c8c5eb74c644 (patch)
tree3acf74aec5e263a96c6f8a43161a8264d5ee0ed2 /include/linux/blkpg.h
parent4404bd742db767a7f316b1207c46a04a38ca7198 (diff)
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op-kernel-dev-53bb724f94f57b67213e08a4c155c8c5eb74c644.tar.gz
mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG
After a bit of poking around wondering why my 32-bit user-space can't seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel (ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty unsuitable for use in the ioctl() ABI, due to its use of raw pointers, and its lack of alignment/packing restrictions (32-bit arch'es tend to pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add padding after the third int, and make this 6 32-bit words). Anyway, this means BLKPG deserves some special compat_ioctl handling. Do the conversion in a small shim for MTD. block/compat_ioctl.c already has compat support for the block subsystem, but it does so by a re-marshalling data to/from user-space (see compat_blkpg_ioctl()). Personally, I think this approach is cleaner. Tested only on MTD, with an ARM32 user space on an ARM64 kernel. Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'include/linux/blkpg.h')
-rw-r--r--include/linux/blkpg.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/blkpg.h b/include/linux/blkpg.h
new file mode 100644
index 0000000..bef124f
--- /dev/null
+++ b/include/linux/blkpg.h
@@ -0,0 +1,21 @@
+#ifndef _LINUX_BLKPG_H
+#define _LINUX_BLKPG_H
+
+/*
+ * Partition table and disk geometry handling
+ */
+
+#include <linux/compat.h>
+#include <uapi/linux/blkpg.h>
+
+#ifdef CONFIG_COMPAT
+/* For 32-bit/64-bit compatibility of struct blkpg_ioctl_arg */
+struct blkpg_compat_ioctl_arg {
+ compat_int_t op;
+ compat_int_t flags;
+ compat_int_t datalen;
+ compat_uptr_t data;
+};
+#endif
+
+#endif /* _LINUX_BLKPG_H */
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