[ARM] 3108/2: old ABI compat: statfs64 and fstatfs64

Patch from Nicolas Pitre

struct statfs64 has extra padding with EABI growing its size from 84 to
88. This struct is now __attribute__((packed,aligned(4))) with a small
assembly wrapper to force the sz argument to 84 if it is 88 to avoid
copying the extra padding over user space memory unexpecting it.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 49 insertions, 3 deletions

diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 55076a75e5bf..8c0bf04814b1 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -280,8 +280,8 @@ __syscall_start:
                 .long   sys_clock_gettime
                 .long   sys_clock_getres
 /* 265 */       .long   sys_clock_nanosleep
-                .long   sys_statfs64
-                .long   sys_fstatfs64
+                .long   sys_statfs64_wrapper
+                .long   sys_fstatfs64_wrapper
                 .long   sys_tgkill
                 .long   sys_utimes
 /* 270 */       .long   sys_arm_fadvise64_64
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 34826bcceb7a..ee63ee78d84f 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -262,6 +262,16 @@ sys_sigaltstack_wrapper:
                 ldr     r2, [sp, #S_OFF + S_SP]
                 b       do_sigaltstack
 
+sys_statfs64_wrapper:
+                teq     r1, #88
+                moveq   r1, #84
+                b       sys_statfs64
+
+sys_fstatfs64_wrapper:
+                teq     r1, #88
+                moveq   r1, #84
+                b       sys_fstatfs64
+
 /*
  * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
  * offset, we return EINVAL.
diff --git a/include/asm-arm/statfs.h b/include/asm-arm/statfs.h
index e81f82783b87..a02e6a8c3d70 100644
--- a/include/asm-arm/statfs.h
+++ b/include/asm-arm/statfs.h
@@ -1,6 +1,42 @@
 #ifndef _ASMARM_STATFS_H
 #define _ASMARM_STATFS_H
 
-#include <asm-generic/statfs.h>
+#ifndef __KERNEL_STRICT_NAMES
+# include <linux/types.h>
+typedef __kernel_fsid_t fsid_t;
+#endif
+
+struct statfs {
+        __u32 f_type;
+        __u32 f_bsize;
+        __u32 f_blocks;
+        __u32 f_bfree;
+        __u32 f_bavail;
+        __u32 f_files;
+        __u32 f_ffree;
+        __kernel_fsid_t f_fsid;
+        __u32 f_namelen;
+        __u32 f_frsize;
+        __u32 f_spare[5];
+};
+
+/*
+ * With EABI there is 4 bytes of padding added to this structure.
+ * Let's pack it so the padding goes away to simplify dual ABI support.
+ * Note that user space does NOT have to pack this structure.
+ */
+struct statfs64 {
+        __u32 f_type;
+        __u32 f_bsize;
+        __u64 f_blocks;
+        __u64 f_bfree;
+        __u64 f_bavail;
+        __u64 f_files;
+        __u64 f_ffree;
+        __kernel_fsid_t f_fsid;
+        __u32 f_namelen;
+        __u32 f_frsize;
+        __u32 f_spare[5];
+} __attribute__ ((packed,aligned(4)));
 
 #endif