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Re: fadvise on MIPS

To: linux-mips@linux-mips.org
Subject: Re: fadvise on MIPS
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Sat, 03 Mar 2007 01:29:14 +0900 (JST)
In-reply-to: <20070217.004812.03978264.anemo@mba.ocn.ne.jp> <20070217.004329.108739438.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070217.004329.108739438.anemo@mba.ocn.ne.jp> <20070217.004812.03978264.anemo@mba.ocn.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
On Sat, 17 Feb 2007 00:43:29 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> 
wrote:
> 1) unistd.h defines __NR_fadvise64 for all ABI but no
> __NR_fadvise64_64.  But sys_fadvise64_64 is used for all syscall
> entries.  For N64, sys_fadvise64 and sys_fadvise64_64 are same so no
> problem, but for other ABIs size of 'len' argument cause mismatch
> between kernel and libc.
> 
> 2) On O32, glibc pass a 'long long' argument by hi and lo words, but
> kernel needs padding word between 'fd' and 'offset' argument.
> 
> 3) On N32, glibc pass a 'long long' argument by hi and lo words, but
> kernel expects a single register value for 'long long' argument.
> 
> 4) __ARCH_WANT_SYS_FADVISE64 is defined in unistd.h but sys_fadvise64
> is not used.
> 
> What is preferred way to fix those issues?
> 
> It seems N64 do not need any fix.
> 
> For N32 and O32, kernel should be fixed anyway, but which syscall
> should be supported?  And whether kernel or libc should take care of
> 'long long' issue?

Then how about this absolutely untested patch?

diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index 7c0b393..4d46b1d 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -596,7 +596,7 @@ einval:     li      v0, -EINVAL
        sys     sys_remap_file_pages    5
        sys     sys_set_tid_address     1
        sys     sys_restart_syscall     0
-       sys     sys_fadvise64_64        7
+       sys     _sys_fadvise64          5
        sys     sys_statfs64            3       /* 4255 */
        sys     sys_fstatfs64           2
        sys     sys_timer_create        3
@@ -647,7 +647,7 @@ einval:     li      v0, -EINVAL
        sys     sys_ppoll               5
        sys     sys_unshare             1
        sys     sys_splice              4
-       sys     sys_sync_file_range     7       /* 4305 */
+       sys     _sys_sync_file_range    6       /* 4305 */
        sys     sys_tee                 4
        sys     sys_vmsplice            4
        sys     sys_move_pages          6
@@ -656,6 +656,7 @@ einval:     li      v0, -EINVAL
        sys     sys_kexec_load          4
        sys     sys_getcpu              3
        sys     sys_epoll_pwait         6
+       sys     _sys_fadvise64_64       6
        .endm
 
        /* We pre-compute the number of _instruction_ bytes needed to
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index f17e31e..2013773 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -336,7 +336,7 @@ EXPORT(sysn32_call_table)
        PTR     sys_set_tid_address
        PTR     sys_restart_syscall
        PTR     compat_sys_semtimedop                   /* 6215 */
-       PTR     sys_fadvise64_64
+       PTR     _sys_fadvise64
        PTR     compat_sys_statfs64
        PTR     compat_sys_fstatfs64
        PTR     sys_sendfile64
@@ -397,3 +397,4 @@ EXPORT(sysn32_call_table)
        PTR     compat_sys_kexec_load
        PTR     sys_getcpu
        PTR     compat_sys_epoll_pwait
+       PTR     _sys_fadvise64_64
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index 142c9b7..3cc443b 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -459,7 +459,7 @@ sys_call_table:
        PTR     sys_remap_file_pages
        PTR     sys_set_tid_address
        PTR     sys_restart_syscall
-       PTR     sys_fadvise64_64
+       PTR     _sys_fadvise64
        PTR     compat_sys_statfs64             /* 4255 */
        PTR     compat_sys_fstatfs64
        PTR     compat_sys_timer_create
@@ -519,4 +519,5 @@ sys_call_table:
        PTR     compat_sys_kexec_load
        PTR     sys_getcpu
        PTR     compat_sys_epoll_pwait
+       PTR     _sys_fadvise64_64
        .size   sys_call_table,.-sys_call_table
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index 26e1a7e..ab8af1c 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -435,3 +435,29 @@ int kernel_execve(const char *filename,
 
        return -__v0;
 }
+
+#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_COMPAT)
+#ifdef __BIG_ENDIAN
+#define merge_64(r1,r2)        (((u64)(r1) << 32) + ((u32)(r2)))
+#else
+#define merge_64(r1,r2)        (((u64)(r2) << 32) + ((u32)(r1)))
+#endif
+asmlinkage long _sys_fadvise64_64(int fd, long a1, long a2, long a3, long a4,
+                                 int advice)
+{
+       return sys_fadvise64_64(fd, merge_64(a1, a2), merge_64(a3, a4),
+                               advice);
+}
+
+asmlinkage long _sys_fadvise64(int fd, long a1, long a2, size_t len, int 
advice)
+{
+       return sys_fadvise64_64(fd, merge_64(a1, a2), len, advice);
+}
+
+asmlinkage long _sys_sync_file_range(int fd, long a1, long a2, long a3, long 
a4,
+                                    unsigned int flags)
+{
+       return sys_sync_file_range(fd, merge_64(a1, a2), merge_64(a3, a4),
+                                  flags);
+}
+#endif
diff --git a/include/asm-mips/unistd.h b/include/asm-mips/unistd.h
index 696cff3..bf3ff4a 100644
--- a/include/asm-mips/unistd.h
+++ b/include/asm-mips/unistd.h
@@ -334,6 +334,7 @@
 #define __NR_kexec_load                        (__NR_Linux + 311)
 #define __NR_getcpu                    (__NR_Linux + 312)
 #define __NR_epoll_pwait               (__NR_Linux + 313)
+#define __NR_fadvise64_64              (__NR_Linux + 314)
 
 /*
  * Offset of the last Linux o32 flavoured syscall
@@ -918,6 +919,7 @@
 #define __NR_kexec_load                        (__NR_Linux + 274)
 #define __NR_getcpu                    (__NR_Linux + 275)
 #define __NR_epoll_pwait               (__NR_Linux + 276)
+#define __NR_fadvise64_64              (__NR_Linux + 277)
 
 /*
  * Offset of the last N32 flavoured syscall

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