[PATCH] compat: fs: Generic compat_sys_sendfile implementation

From: Catalin Marinas
Date: Tue Sep 18 2012 - 13:02:55 EST


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 a wrapper
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,
similar wrapper needs to be added for the u32->int conversion.

The reason for a single patch covering both powerpc and sparc is to keep
it bisectable (and simple), otherwise kernel building may fail with
mismatched function declarations.

Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

Please note that the patch has only been compile-tested on sparc and
powerpc (run-time tested on arm64).

arch/powerpc/include/asm/systbl.h | 4 +-
arch/powerpc/include/asm/unistd.h | 1 +
arch/powerpc/kernel/sys_ppc32.c | 45 +++++------------------------------
arch/sparc/include/asm/unistd.h | 1 +
arch/sparc/kernel/sys32.S | 2 +-
arch/sparc/kernel/sys_sparc32.c | 46 -------------------------------------
fs/compat.c | 22 +++++++++++++++++
fs/read_write.c | 4 +-
fs/read_write.h | 2 +
include/linux/compat.h | 3 ++
10 files changed, 41 insertions(+), 89 deletions(-)

diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 559ae1e..8fb2429 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_sendfile64,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)
+SYS32ONLY(sendfile64_wrapper)
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,
diff --git a/arch/sparc/include/asm/unistd.h b/arch/sparc/include/asm/unistd.h
index fb26934..d9a677c 100644
--- a/arch/sparc/include/asm/unistd.h
+++ b/arch/sparc/include/asm/unistd.h
@@ -447,6 +447,7 @@
#else
#define __ARCH_WANT_COMPAT_SYS_TIME
#define __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND
+#define __ARCH_WANT_COMPAT_SYS_SENDFILE
#endif

/*
diff --git a/arch/sparc/kernel/sys32.S b/arch/sparc/kernel/sys32.S
index d97f3eb..44025f4 100644
--- a/arch/sparc/kernel/sys32.S
+++ b/arch/sparc/kernel/sys32.S
@@ -90,7 +90,7 @@ SIGN1(sys32_mkdir, sys_mkdir, %o1)
SIGN3(sys32_futex, compat_sys_futex, %o1, %o2, %o5)
SIGN1(sys32_sysfs, compat_sys_sysfs, %o0)
SIGN2(sys32_sendfile, compat_sys_sendfile, %o0, %o1)
-SIGN2(sys32_sendfile64, compat_sys_sendfile64, %o0, %o1)
+SIGN2(sys32_sendfile64, sys_sendfile, %o0, %o1)
SIGN1(sys32_prctl, sys_prctl, %o0)
SIGN1(sys32_sched_rr_get_interval, compat_sys_sched_rr_get_interval, %o0)
SIGN2(sys32_waitpid, sys_waitpid, %o0, %o2)
diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
index f739233..d862499 100644
--- a/arch/sparc/kernel/sys_sparc32.c
+++ b/arch/sparc/kernel/sys_sparc32.c
@@ -506,52 +506,6 @@ long compat_sys_fadvise64_64(int fd,
advice);
}

-asmlinkage long compat_sys_sendfile(int out_fd, int in_fd,
- compat_off_t __user *offset,
- compat_size_t count)
-{
- mm_segment_t old_fs = get_fs();
- int ret;
- off_t of;
-
- if (offset && get_user(of, offset))
- return -EFAULT;
-
- set_fs(KERNEL_DS);
- ret = sys_sendfile(out_fd, in_fd,
- offset ? (off_t __user *) &of : NULL,
- count);
- set_fs(old_fs);
-
- if (offset && put_user(of, offset))
- return -EFAULT;
-
- return ret;
-}
-
-asmlinkage long compat_sys_sendfile64(int out_fd, int in_fd,
- compat_loff_t __user *offset,
- compat_size_t count)
-{
- mm_segment_t old_fs = get_fs();
- int ret;
- loff_t lof;
-
- if (offset && get_user(lof, offset))
- return -EFAULT;
-
- set_fs(KERNEL_DS);
- ret = sys_sendfile64(out_fd, in_fd,
- offset ? (loff_t __user *) &lof : NULL,
- count);
- set_fs(old_fs);
-
- if (offset && put_user(lof, offset))
- return -EFAULT;
-
- return ret;
-}
-
/* This is just a version for 32-bit applications which does
* not force O_LARGEFILE on.
*/
diff --git a/fs/compat.c b/fs/compat.c
index 1bdb350..a241da9 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1802,3 +1802,25 @@ compat_sys_open_by_handle_at(int mountdirfd,
return do_handle_open(mountdirfd, handle, flags);
}
#endif
+
+#ifdef __ARCH_WANT_COMPAT_SYS_SENDFILE
+asmlinkage long compat_sys_sendfile(int out_fd, int in_fd,
+ compat_off_t __user *offset, compat_size_t count)
+{
+ loff_t pos;
+ off_t off;
+ ssize_t ret;
+
+ if (offset) {
+ if (unlikely(get_user(off, offset)))
+ return -EFAULT;
+ pos = off;
+ ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
+ if (unlikely(put_user(pos, offset)))
+ return -EFAULT;
+ return ret;
+ }
+
+ return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+#endif /* __ARCH_WANT_COMPAT_SYS_SENDFILE */
diff --git a/fs/read_write.c b/fs/read_write.c
index 1adfb69..d8e88fe 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -884,8 +884,8 @@ SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
return ret;
}

-static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
- size_t count, loff_t max)
+ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, size_t count,
+ loff_t max)
{
struct file * in_file, * out_file;
struct inode * in_inode, * out_inode;
diff --git a/fs/read_write.h b/fs/read_write.h
index d07b954..d3e00ef 100644
--- a/fs/read_write.h
+++ b/fs/read_write.h
@@ -12,3 +12,5 @@ ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn);
ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
unsigned long nr_segs, loff_t *ppos, io_fn_t fn);
+ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, size_t count,
+ loff_t max);
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 09b28b7..fd4e299 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -590,6 +590,9 @@ asmlinkage ssize_t compat_sys_process_vm_writev(compat_pid_t pid,
unsigned long liovcnt, const struct compat_iovec __user *rvec,
unsigned long riovcnt, unsigned long flags);

+asmlinkage long compat_sys_sendfile(int out_fd, int in_fd,
+ compat_off_t __user *offset, compat_size_t count);
+
#else

#define is_compat_task() (0)
--
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