[S390] Wire up sys_fallocate.

This patch implements support of fallocate system call on s390(x)
platform.  A wrapper is added to address the issue which s390 ABI has with
the arguments of this system call.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/compat_wrapper.S b/arch/s390/kernel/compat_wrapper.S
index acc4154..6ee1bed 100644 (file)
--- a/arch/s390/kernel/compat_wrapper.S
+++ b/arch/s390/kernel/compat_wrapper.S
@@ -1710,3 +1710,13 @@ compat_sys_timerfd_wrapper:
 sys_eventfd_wrapper:
        llgfr   %r2,%r2                 # unsigned int
        jg      sys_eventfd
+
+       .globl  sys_fallocate_wrapper
+sys_fallocate_wrapper:
+       lgfr    %r2,%r2                 # int
+       lgfr    %r3,%r3                 # int
+       sllg    %r4,%r4,32              # get high word of 64bit loff_t
+       lr      %r4,%r5                 # get low word of 64bit loff_t
+       sllg    %r5,%r6,32              # get high word of 64bit loff_t
+       l       %r5,164(%r15)           # get low word of 64bit loff_t
+       jg      sys_fallocate

diff --git a/arch/s390/kernel/sys_s390.c b/arch/s390/kernel/sys_s390.c
index 1c90c7e..13e27bd 100644 (file)
--- a/arch/s390/kernel/sys_s390.c
+++ b/arch/s390/kernel/sys_s390.c
@@ -265,3 +265,23 @@ s390_fadvise64_64(struct fadvise64_64_args __user *args)
                return -EFAULT;
        return sys_fadvise64_64(a.fd, a.offset, a.len, a.advice);
 }
+
+#ifndef CONFIG_64BIT
+/*
+ * This is a wrapper to call sys_fallocate(). For 31 bit s390 the last
+ * 64 bit argument "len" is split into the upper and lower 32 bits. The
+ * system call wrapper in the user space loads the value to %r6/%r7.
+ * The code in entry.S keeps the values in %r2 - %r6 where they are and
+ * stores %r7 to 96(%r15). But the standard C linkage requires that
+ * the whole 64 bit value for len is stored on the stack and doesn't
+ * use %r6 at all. So s390_fallocate has to convert the arguments from
+ *   %r2: fd, %r3: mode, %r4/%r5: offset, %r6/96(%r15)-99(%r15): len
+ * to
+ *   %r2: fd, %r3: mode, %r4/%r5: offset, 96(%r15)-103(%r15): len
+ */
+asmlinkage long s390_fallocate(int fd, int mode, loff_t offset,
+                              u32 len_high, u32 len_low)
+{
+       return sys_fallocate(fd, mode, offset, ((u64)len_high << 32) | len_low);
+}
+#endif

diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index 738feb4..9e26ed9 100644 (file)
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -322,7 +322,7 @@ NI_SYSCALL                                                  /* 310 sys_move_pages */
 SYSCALL(sys_getcpu,sys_getcpu,sys_getcpu_wrapper)
 SYSCALL(sys_epoll_pwait,sys_epoll_pwait,compat_sys_epoll_pwait_wrapper)
 SYSCALL(sys_utimes,sys_utimes,compat_sys_utimes_wrapper)
-NI_SYSCALL                                                     /* 314 sys_fallocate */
+SYSCALL(s390_fallocate,sys_fallocate,sys_fallocate_wrapper)
 SYSCALL(sys_utimensat,sys_utimensat,compat_sys_utimensat_wrapper)      /* 315 */
 SYSCALL(sys_signalfd,sys_signalfd,compat_sys_signalfd_wrapper)
 SYSCALL(sys_timerfd,sys_timerfd,compat_sys_timerfd_wrapper)

diff --git a/include/asm-s390/unistd.h b/include/asm-s390/unistd.h
index 790c1c5..f04acb2 100644 (file)
--- a/include/asm-s390/unistd.h
+++ b/include/asm-s390/unistd.h
@@ -251,7 +251,7 @@
 #define __NR_getcpu            311
 #define __NR_epoll_pwait       312
 #define __NR_utimes            313
-/* Number 314 is reserved for new sys_fallocate */
+#define __NR_fallocate         314
 #define __NR_utimensat         315
 #define __NR_signalfd          316
 #define __NR_timerfd           317