compat: fs: Generic compat_sys_sendfile implementation

This function is used by sparc, powerpc and arm64 for compat support.
The patch adds a generic implementation which calls do_sendfile()
directly and avoids set_fs().

The sparc architecture has wrappers for the sign extensions while
powerpc relies on the compiler to do the this. The patch adds wrappers
for powerpc to handle the u32->int type conversion.

compat_sys_sendfile64() can be replaced by a sys_sendfile() call since
compat_loff_t has the same size as off_t on a 64-bit system.

On powerpc, the patch also changes the 64-bit sendfile call from
sys_sendile64 to sys_sendfile.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 10 insertions, 40 deletions

diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 559ae1e..8408387 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -189,7 +189,7 @@ SYSCALL_SPU(getcwd)
 SYSCALL_SPU(capget)
 SYSCALL_SPU(capset)
 COMPAT_SYS(sigaltstack)
-SYSX_SPU(sys_sendfile64,compat_sys_sendfile,sys_sendfile)
+SYSX_SPU(sys_sendfile,compat_sys_sendfile_wrapper,sys_sendfile)
 SYSCALL(ni_syscall)
 SYSCALL(ni_syscall)
 PPC_SYS(vfork)
@@ -229,7 +229,7 @@ COMPAT_SYS_SPU(sched_setaffinity)
 COMPAT_SYS_SPU(sched_getaffinity)
 SYSCALL(ni_syscall)
 SYSCALL(ni_syscall)
-SYS32ONLY(sendfile64)
+SYSX(sys_ni_syscall,compat_sys_sendfile64_wrapper,sys_sendfile64)
 COMPAT_SYS_SPU(io_setup)
 SYSCALL_SPU(io_destroy)
 COMPAT_SYS_SPU(io_getevents)
diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index bd377a3..c683fa3 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h
@@ -419,6 +419,7 @@
 #define __ARCH_WANT_COMPAT_SYS_TIME
 #define __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_NEWFSTATAT
+#define __ARCH_WANT_COMPAT_SYS_SENDFILE
 #endif
 
 /*
diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index 81c5706..abd1112 100644
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -143,48 +143,17 @@ long compat_sys_ipc(u32 call, u32 first, u32 second, u32 third, compat_uptr_t pt
  * proper conversion (sign extension) between the register representation of a signed int (msr in 32-bit mode)
  * and the register representation of a signed int (msr in 64-bit mode) is performed.
  */
-asmlinkage long compat_sys_sendfile(u32 out_fd, u32 in_fd, compat_off_t __user * offset, u32 count)
+asmlinkage long compat_sys_sendfile_wrapper(u32 out_fd, u32 in_fd,
+					    compat_off_t __user *offset, u32 count)
 {
-	mm_segment_t old_fs = get_fs();
-	int ret;
-	off_t of;
-	off_t __user *up;
-
-	if (offset && get_user(of, offset))
-		return -EFAULT;
-
-	/* The __user pointer cast is valid because of the set_fs() */		
-	set_fs(KERNEL_DS);
-	up = offset ? (off_t __user *) &of : NULL;
-	ret = sys_sendfile((int)out_fd, (int)in_fd, up, count);
-	set_fs(old_fs);
-	
-	if (offset && put_user(of, offset))
-		return -EFAULT;
-		
-	return ret;
+	return compat_sys_sendfile((int)out_fd, (int)in_fd, offset, count);
 }
 
-asmlinkage int compat_sys_sendfile64(int out_fd, int in_fd, compat_loff_t __user *offset, s32 count)
+asmlinkage long compat_sys_sendfile64_wrapper(u32 out_fd, u32 in_fd,
+					      compat_loff_t __user *offset, u32 count)
 {
-	mm_segment_t old_fs = get_fs();
-	int ret;
-	loff_t lof;
-	loff_t __user *up;
-	
-	if (offset && get_user(lof, offset))
-		return -EFAULT;
-		
-	/* The __user pointer cast is valid because of the set_fs() */		
-	set_fs(KERNEL_DS);
-	up = offset ? (loff_t __user *) &lof : NULL;
-	ret = sys_sendfile64(out_fd, in_fd, up, count);
-	set_fs(old_fs);
-	
-	if (offset && put_user(lof, offset))
-		return -EFAULT;
-		
-	return ret;
+	return sys_sendfile((int)out_fd, (int)in_fd,
+			    (off_t __user *)offset, count);
 }
 
 long compat_sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,