The patch titled
fallocate() on s390
has been added to the -mm tree. Its filename is
fallocate-on-s390.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fallocate() on s390
From: "Amit K. Arora" <aarora@xxxxxxxxxxxxxxxxxx>
This is the patch suggested by Martin Schwidefsky to support sys_fallocate()
on s390(x) platform.
He also suggested a wrapper in glibc to handle this system call on s390.
Posting it here so that we get feedback for this too.
.globl __fallocate
ENTRY(__fallocate)
stm %r6,%r7,28(%r15) /* save %r6/%r7 on stack */
cfi_offset (%r7, -68)
cfi_offset (%r6, -72)
lm %r6,%r7,96(%r15) /* load loff_t len from stack */
svc SYS_ify(fallocate)
lm %r6,%r7,28(%r15) /* restore %r6/%r7 from stack */
br %r14
PSEUDO_END(__fallocate)
Here are the comments and the patch to linux kernel from him.
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@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/compat_wrapper.S | 10 +++++++++
arch/s390/kernel/sys_s390.c | 29 ++++++++++++++++++++++++++++
arch/s390/kernel/syscalls.S | 1
include/asm-s390/unistd.h | 3 +-
4 files changed, 42 insertions(+), 1 deletion(-)
diff -puN arch/s390/kernel/compat_wrapper.S~fallocate-on-s390 arch/s390/kernel/compat_wrapper.S
--- a/arch/s390/kernel/compat_wrapper.S~fallocate-on-s390
+++ a/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 -puN arch/s390/kernel/sys_s390.c~fallocate-on-s390 arch/s390/kernel/sys_s390.c
--- a/arch/s390/kernel/sys_s390.c~fallocate-on-s390
+++ a/arch/s390/kernel/sys_s390.c
@@ -265,3 +265,32 @@ s390_fadvise64_64(struct fadvise64_64_ar
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)
+{
+ union {
+ u64 len;
+ struct {
+ u32 high;
+ u32 low;
+ };
+ } cv;
+ cv.high = len_high;
+ cv.low = len_low;
+ return sys_fallocate(fd, mode, offset, cv.len);
+}
+#endif
diff -puN arch/s390/kernel/syscalls.S~fallocate-on-s390 arch/s390/kernel/syscalls.S
--- a/arch/s390/kernel/syscalls.S~fallocate-on-s390
+++ a/arch/s390/kernel/syscalls.S
@@ -327,3 +327,4 @@ SYSCALL(sys_utimensat,sys_utimensat,comp
SYSCALL(sys_signalfd,sys_signalfd,compat_sys_signalfd_wrapper)
SYSCALL(sys_timerfd,sys_timerfd,compat_sys_timerfd_wrapper)
SYSCALL(sys_eventfd,sys_eventfd,sys_eventfd_wrapper)
+SYSCALL(s390_fallocate,sys_fallocate,sys_fallocate_wrapper)
diff -puN include/asm-s390/unistd.h~fallocate-on-s390 include/asm-s390/unistd.h
--- a/include/asm-s390/unistd.h~fallocate-on-s390
+++ a/include/asm-s390/unistd.h
@@ -256,7 +256,8 @@
#define __NR_signalfd 316
#define __NR_timerfd 317
#define __NR_eventfd 318
-#define NR_syscalls 319
+#define __NR_fallocate 319
+#define NR_syscalls 320
/*
* There are some system calls that are not present on 64 bit, some
_
Patches currently in -mm which might be from aarora@xxxxxxxxxxxxxxxxxx are
fallocate-implementation-on-i86-x86_64-and-powerpc.patch
fallocate-on-s390.patch
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