[PATCH] 2.6: improved fdmap

From: Matt Miller
Date: Thu Mar 25 2004 - 23:42:12 EST

Hi everyone,

This post includes an updated patch (for 2.6.4) that corrects some
ugliness related to #ifdef's in the system call tables for each
architecture. It also addresses Al Viro's concerns that were pointed out
previously. Below are some concerns and questions related to the
advantages and uses for fdmap.

Comments are welcome and encouraged!

CW> Why is this needed? I mean, it sems logical enough but I wonder if
CW> there is a real use/need for it.

I answered this question in the previous thread, so in order to reduce spam
I'll give a brief highlight of what the advantages are and why it's useful:

Advantages:

1. No mountpoint required.
2. No permission control problems associated with creating and opening files
on a mounted filesystem.
3. Mapping arbitrary memory ranges, such as a task's stack, does not require
duplication of memory.

Uses:

1. Embedded devices with limited disk space can benefit from having
completely memory resident files.
2. Integrating with APIs that require a file descriptor is made possible by
this mechanism.
3. Keeping a file completely memory resident (no swap) by locking the pages
that the file descriptor is associated with in memory.

Granted, the first two uses can also be accomplished with tmpfs. However,
tmpfs does not have the three advantages listed above and as such is less
optimal. The unnecessary performance impact of memory duplication is a big
negative in my mind, especially when dealing with larger files.

A concrete example of where fdmap could be made useful in the future involves
modifying mk*fs and mount to take a file descriptor, thus allowing one to
create non-swapped memory resident file systems for critical data. Embedded
devices that use flash greatly benefit from this as it can be used as an
intermediate, transactional step between writing to flash. By mounting the
filesystem through a file descriptor that directly maps to memory, one is
able to update the memory resident copy of the filesystem without actually
writing to flash, thus allowing for greater reliability and reduces wear-level
problems associated with flash devices. Once all write operations are
complete, one can unmount the memory resident file system and copy the memory
directly to flash.

Here's a (subjectively) good analogy: mmap allows one to map a file descriptor
to a memory range, thus eliminating the need for one to read the contents of
the file into a buffer. As a complement to mmap, fdmap allows one to map a
memory range to a file descriptor, and thus eliminate the need to write the
contents of the memory range into a file. Both either have the advantage of
conserving memory or are more efficient than their alternatives (or both in
the case of fdmap).

CW> Argh, for testing/example patches I would drop the #ifdef's there it
CW> makes it icky if nothing else.

This has been corrected by making use of cond_syscall (handy).

Matt

-------

Patched file list:

arch/alpha/kernel/systbls.S | 2
arch/arm/kernel/calls.S | 1
arch/i386/kernel/entry.S | 1
arch/ia64/kernel/entry.S | 2
arch/m68k/kernel/entry.S | 1
arch/mips/kernel/scall32-o32.S | 1
arch/mips/kernel/scall64-64.S | 1
arch/mips/kernel/scall64-n32.S | 1
arch/mips/kernel/scall64-o32.S | 1
arch/parisc/kernel/syscall_table.S | 1
arch/ppc/kernel/misc.S | 1
arch/ppc64/kernel/misc.S | 1
arch/s390/kernel/syscalls.S | 1
arch/sh/kernel/entry.S | 1
arch/sparc/kernel/systbls.S | 2
arch/sparc64/kernel/systbls.S | 4
arch/um/kernel/sys_call_table.c | 1
arch/v850/kernel/entry.S | 2
fs/Kconfig | 6
fs/Makefile | 2
fs/fdmap.c | 606 +++++++++++++++++++++++++++++++++++++
include/asm-alpha/unistd.h | 2
include/asm-arm/unistd.h | 1
include/asm-i386/unistd.h | 3
include/asm-ia64/unistd.h | 3
include/asm-m68k/unistd.h | 3
include/asm-mips/unistd.h | 15
include/asm-parisc/unistd.h | 3
include/asm-ppc/unistd.h | 3
include/asm-ppc64/unistd.h | 3
include/asm-s390/unistd.h | 5
include/asm-sparc/unistd.h | 2
include/asm-sparc64/unistd.h | 2
include/asm-v850/unistd.h | 1
kernel/sys.c | 1
35 files changed, 664 insertions(+), 22 deletions(-)

Patch contents:

-- CUT HERE --

diff -X dontdiff -uprN linux-2.6.4/arch/alpha/kernel/systbls.S linux-2.6.4-fdmap/arch/alpha/kernel/systbls.S
--- linux-2.6.4/arch/alpha/kernel/systbls.S Wed Mar 10 20:55:35 2004
+++ linux-2.6.4-fdmap/arch/alpha/kernel/systbls.S Thu Mar 25 05:04:20 2004
@@ -292,7 +292,7 @@ sys_call_table:
.quad alpha_ni_syscall
.quad alpha_ni_syscall
.quad alpha_ni_syscall
- .quad alpha_ni_syscall
+ .quad sys_fdmap
.quad alpha_ni_syscall /* 275 */
.quad alpha_ni_syscall
.quad alpha_ni_syscall
diff -X dontdiff -uprN linux-2.6.4/arch/arm/kernel/calls.S linux-2.6.4-fdmap/arch/arm/kernel/calls.S
--- linux-2.6.4/arch/arm/kernel/calls.S Wed Mar 10 20:55:55 2004
+++ linux-2.6.4-fdmap/arch/arm/kernel/calls.S Thu Mar 25 05:04:31 2004
@@ -288,6 +288,7 @@ __syscall_start:
.long sys_pciconfig_iobase
.long sys_pciconfig_read
.long sys_pciconfig_write
+ .long sys_fdmap
__syscall_end:

.rept NR_syscalls - (__syscall_end - __syscall_start) / 4
diff -X dontdiff -uprN linux-2.6.4/arch/i386/kernel/entry.S linux-2.6.4-fdmap/arch/i386/kernel/entry.S
--- linux-2.6.4/arch/i386/kernel/entry.S Wed Mar 10 20:55:24 2004
+++ linux-2.6.4-fdmap/arch/i386/kernel/entry.S Thu Mar 25 05:04:39 2004
@@ -882,5 +882,6 @@ ENTRY(sys_call_table)
.long sys_utimes
.long sys_fadvise64_64
.long sys_ni_syscall /* sys_vserver */
+ .long sys_fdmap /* 274 */

syscall_table_size=(.-sys_call_table)
diff -X dontdiff -uprN linux-2.6.4/arch/ia64/kernel/entry.S linux-2.6.4-fdmap/arch/ia64/kernel/entry.S
--- linux-2.6.4/arch/ia64/kernel/entry.S Wed Mar 10 20:55:24 2004
+++ linux-2.6.4-fdmap/arch/ia64/kernel/entry.S Thu Mar 25 05:04:49 2004
@@ -1501,7 +1501,7 @@ sys_call_table:
data8 sys_clock_nanosleep
data8 sys_fstatfs64
data8 sys_statfs64
- data8 sys_ni_syscall
+ data8 sys_fdmap
data8 sys_ni_syscall // 1260
data8 sys_ni_syscall
data8 sys_ni_syscall
diff -X dontdiff -uprN linux-2.6.4/arch/m68k/kernel/entry.S linux-2.6.4-fdmap/arch/m68k/kernel/entry.S
--- linux-2.6.4/arch/m68k/kernel/entry.S Wed Mar 10 20:55:21 2004
+++ linux-2.6.4-fdmap/arch/m68k/kernel/entry.S Thu Mar 25 05:04:59 2004
@@ -663,3 +663,4 @@ sys_call_table:
.long sys_lremovexattr
.long sys_fremovexattr
.long sys_futex /* 235 */
+ .long sys_fdmap
diff -X dontdiff -uprN linux-2.6.4/arch/mips/kernel/scall32-o32.S linux-2.6.4-fdmap/arch/mips/kernel/scall32-o32.S
--- linux-2.6.4/arch/mips/kernel/scall32-o32.S Wed Mar 10 20:55:22 2004
+++ linux-2.6.4-fdmap/arch/mips/kernel/scall32-o32.S Thu Mar 25 05:05:09 2004
@@ -614,6 +614,7 @@ out: jr ra
sys sys_clock_nanosleep 4 /* 4265 */
sys sys_tgkill 3
sys sys_utimes 2
+ sys sys_fdmap 3

.endm

diff -X dontdiff -uprN linux-2.6.4/arch/mips/kernel/scall64-64.S linux-2.6.4-fdmap/arch/mips/kernel/scall64-64.S
--- linux-2.6.4/arch/mips/kernel/scall64-64.S Wed Mar 10 20:55:36 2004
+++ linux-2.6.4-fdmap/arch/mips/kernel/scall64-64.S Thu Mar 25 05:05:17 2004
@@ -432,3 +432,4 @@ sys_call_table:
PTR sys_clock_nanosleep
PTR sys_tgkill /* 5225 */
PTR sys_utimes
+ PTR sys_fdmap
diff -X dontdiff -uprN linux-2.6.4/arch/mips/kernel/scall64-n32.S linux-2.6.4-fdmap/arch/mips/kernel/scall64-n32.S
--- linux-2.6.4/arch/mips/kernel/scall64-n32.S Wed Mar 10 20:55:44 2004
+++ linux-2.6.4-fdmap/arch/mips/kernel/scall64-n32.S Thu Mar 25 05:05:25 2004
@@ -341,3 +341,4 @@ EXPORT(sysn32_call_table)
PTR sys_clock_nanosleep
PTR sys_tgkill
PTR compat_sys_utimes /* 6230 */
+ PTR sys_fdmap
diff -X dontdiff -uprN linux-2.6.4/arch/mips/kernel/scall64-o32.S linux-2.6.4-fdmap/arch/mips/kernel/scall64-o32.S
--- linux-2.6.4/arch/mips/kernel/scall64-o32.S Wed Mar 10 20:55:20 2004
+++ linux-2.6.4-fdmap/arch/mips/kernel/scall64-o32.S Thu Mar 25 05:05:32 2004
@@ -523,6 +523,7 @@ out: jr ra
sys sys_clock_nanosleep 4 /* 4265 */
sys sys_tgkill 3
sys compat_sys_utimes 2
+ sys sys_fdmap 3

.endm

diff -X dontdiff -uprN linux-2.6.4/arch/parisc/kernel/syscall_table.S linux-2.6.4-fdmap/arch/parisc/kernel/syscall_table.S
--- linux-2.6.4/arch/parisc/kernel/syscall_table.S Wed Mar 10 20:55:21 2004
+++ linux-2.6.4-fdmap/arch/parisc/kernel/syscall_table.S Thu Mar 25 05:26:02 2004
@@ -334,3 +334,4 @@
ENTRY_SAME(epoll_ctl) /* 225 */
ENTRY_SAME(epoll_wait)
ENTRY_SAME(remap_file_pages)
+ ENTRY_SAME(fdmap)
diff -X dontdiff -uprN linux-2.6.4/arch/ppc/kernel/misc.S linux-2.6.4-fdmap/arch/ppc/kernel/misc.S
--- linux-2.6.4/arch/ppc/kernel/misc.S Wed Mar 10 20:55:44 2004
+++ linux-2.6.4-fdmap/arch/ppc/kernel/misc.S Thu Mar 25 05:06:15 2004
@@ -1380,3 +1380,4 @@ _GLOBAL(sys_call_table)
.long sys_fstatfs64
.long ppc_fadvise64_64
.long sys_ni_syscall /* 255 - rtas (used on ppc64) */
+ .long sys_fdmap
diff -X dontdiff -uprN linux-2.6.4/arch/ppc64/kernel/misc.S linux-2.6.4-fdmap/arch/ppc64/kernel/misc.S
--- linux-2.6.4/arch/ppc64/kernel/misc.S Wed Mar 10 20:55:44 2004
+++ linux-2.6.4-fdmap/arch/ppc64/kernel/misc.S Thu Mar 25 05:06:27 2004
@@ -1116,3 +1116,4 @@ _GLOBAL(sys_call_table)
.llong .sys_fstatfs64
.llong .sys_ni_syscall /* 32bit only fadvise64_64 */
.llong .ppc_rtas /* 255 */
+ .llong .sys_fdmap
diff -X dontdiff -uprN linux-2.6.4/arch/s390/kernel/syscalls.S linux-2.6.4-fdmap/arch/s390/kernel/syscalls.S
--- linux-2.6.4/arch/s390/kernel/syscalls.S Wed Mar 10 20:55:22 2004
+++ linux-2.6.4-fdmap/arch/s390/kernel/syscalls.S Thu Mar 25 05:06:44 2004
@@ -273,3 +273,4 @@ SYSCALL(sys_clock_getres,sys_clock_getre
SYSCALL(sys_clock_nanosleep,sys_clock_nanosleep,sys32_clock_nanosleep_wrapper)
NI_SYSCALL /* reserved for vserver */
SYSCALL(s390_fadvise64_64,sys_ni_syscall,sys32_fadvise64_64_wrapper)
+SYSCALL(sys_fdmap,sys_fdmap,sys_fdmap) /* 265 */
diff -X dontdiff -uprN linux-2.6.4/arch/sh/kernel/entry.S linux-2.6.4-fdmap/arch/sh/kernel/entry.S
--- linux-2.6.4/arch/sh/kernel/entry.S Wed Mar 10 20:55:25 2004
+++ linux-2.6.4-fdmap/arch/sh/kernel/entry.S Thu Mar 25 05:07:13 2004
@@ -1129,6 +1129,7 @@ ENTRY(sys_call_table)
.long sys_utimes
.long sys_fadvise64_64_wrapper
.long sys_ni_syscall /* Reserved for vserver */
+ .long sys_fdmap

.rept NR_syscalls-(.-sys_call_table)/4
.long sys_ni_syscall
diff -X dontdiff -uprN linux-2.6.4/arch/sparc/kernel/systbls.S linux-2.6.4-fdmap/arch/sparc/kernel/systbls.S
--- linux-2.6.4/arch/sparc/kernel/systbls.S Wed Mar 10 20:55:27 2004
+++ linux-2.6.4-fdmap/arch/sparc/kernel/systbls.S Thu Mar 25 05:09:38 2004
@@ -61,7 +61,7 @@ sys_call_table:
/*200*/ .long sys_ssetmask, sys_sigsuspend, sys_newlstat, sys_uselib, old_readdir
/*205*/ .long sys_readahead, sys_socketcall, sys_syslog, sys_lookup_dcookie, sys_fadvise64
/*210*/ .long sys_fadvise64_64, sys_tgkill, sys_waitpid, sys_swapoff, sys_sysinfo
-/*215*/ .long sys_ipc, sys_sigreturn, sys_clone, sys_nis_syscall, sys_adjtimex
+/*215*/ .long sys_ipc, sys_sigreturn, sys_clone, sys_fdmap, sys_adjtimex
/*220*/ .long sys_sigprocmask, sys_ni_syscall, sys_delete_module, sys_ni_syscall, sys_getpgid
/*225*/ .long sys_bdflush, sys_sysfs, sys_nis_syscall, sys_setfsuid16, sys_setfsgid16
/*230*/ .long sys_select, sys_time, sys_nis_syscall, sys_stime, sys_statfs64
diff -X dontdiff -uprN linux-2.6.4/arch/sparc64/kernel/systbls.S linux-2.6.4-fdmap/arch/sparc64/kernel/systbls.S
--- linux-2.6.4/arch/sparc64/kernel/systbls.S Wed Mar 10 20:55:26 2004
+++ linux-2.6.4-fdmap/arch/sparc64/kernel/systbls.S Thu Mar 25 05:09:23 2004
@@ -62,7 +62,7 @@ sys_call_table32:
/*200*/ .word sys_ssetmask, sys_sigsuspend, compat_sys_newlstat, sys_uselib, old32_readdir
.word sys32_readahead, sys32_socketcall, sys_syslog, sys32_lookup_dcookie, sys32_fadvise64
/*210*/ .word sys32_fadvise64_64, sys_tgkill, sys_waitpid, sys_swapoff, sys32_sysinfo
- .word sys32_ipc, sys32_sigreturn, sys_clone, sys_nis_syscall, sys32_adjtimex
+/*215*/ .word sys32_ipc, sys32_sigreturn, sys_clone, sys_fdmap, sys32_adjtimex
/*220*/ .word compat_sys_sigprocmask, sys_ni_syscall, sys32_delete_module, sys_ni_syscall, sys_getpgid
.word sys32_bdflush, sys32_sysfs, sys_nis_syscall, sys32_setfsuid16, sys32_setfsgid16
/*230*/ .word sys32_select, sys_time, sys_nis_syscall, sys_stime, compat_statfs64
@@ -124,7 +124,7 @@ sys_call_table:
/*200*/ .word sys_ssetmask, sys_nis_syscall, sys_newlstat, sys_uselib, sys_nis_syscall
.word sys_readahead, sys_socketcall, sys_syslog, sys_lookup_dcookie, sys_fadvise64
/*210*/ .word sys_fadvise64_64, sys_tgkill, sys_waitpid, sys_swapoff, sys_sysinfo
- .word sys_ipc, sys_nis_syscall, sys_clone, sys_nis_syscall, sys_adjtimex
+ .word sys_ipc, sys_nis_syscall, sys_clone, sys_fdmap, sys_adjtimex
/*220*/ .word sys_nis_syscall, sys_ni_syscall, sys_delete_module, sys_ni_syscall, sys_getpgid
.word sys_bdflush, sys_sysfs, sys_nis_syscall, sys_setfsuid, sys_setfsgid
/*230*/ .word sys_select, sys_nis_syscall, sys_nis_syscall, sys_stime, sys_statfs64
diff -X dontdiff -uprN linux-2.6.4/arch/um/kernel/sys_call_table.c linux-2.6.4-fdmap/arch/um/kernel/sys_call_table.c
--- linux-2.6.4/arch/um/kernel/sys_call_table.c Wed Mar 10 20:55:43 2004
+++ linux-2.6.4-fdmap/arch/um/kernel/sys_call_table.c Thu Mar 25 05:08:09 2004
@@ -489,6 +489,7 @@ syscall_handler_t *sys_call_table[] = {
[ __NR_epoll_wait ] = sys_epoll_wait,
[ __NR_remap_file_pages ] = sys_remap_file_pages,
[ __NR_set_tid_address ] = sys_set_tid_address,
+ [ __NR_fdmap ] = sys_fdmap,

ARCH_SYSCALLS
[ LAST_SYSCALL + 1 ... NR_syscalls ] =
diff -X dontdiff -uprN linux-2.6.4/arch/v850/kernel/entry.S linux-2.6.4-fdmap/arch/v850/kernel/entry.S
--- linux-2.6.4/arch/v850/kernel/entry.S Wed Mar 10 20:55:44 2004
+++ linux-2.6.4-fdmap/arch/v850/kernel/entry.S Thu Mar 25 05:08:18 2004
@@ -1117,5 +1117,7 @@ C_DATA(sys_call_table):
.long CSYM(sys_pivot_root) // 200
.long CSYM(sys_gettid)
.long CSYM(sys_tkill)
+ .long CSYM(sys_fdmap)
+
sys_call_table_end:
C_END(sys_call_table)
diff -X dontdiff -uprN linux-2.6.4/fs/Kconfig linux-2.6.4-fdmap/fs/Kconfig
--- linux-2.6.4/fs/Kconfig Wed Mar 10 20:55:29 2004
+++ linux-2.6.4-fdmap/fs/Kconfig Wed Mar 24 06:39:29 2004
@@ -864,6 +864,12 @@ config TMPFS

See <file:Documentation/filesystems/tmpfs.txt> for details.

+config FDMAP
+ bool "Virtual memory file descriptor mapping support"
+ help
+ Fdmap allows a process to access memory as if it were a file. The
+ functionality it provides can be seen as a logical complement to mmap.
+
config HUGETLBFS
bool "HugeTLB file system support"
depends X86 || IA64 || PPC64 || SPARC64 || X86_64 || BROKEN
diff -X dontdiff -uprN linux-2.6.4/fs/Makefile linux-2.6.4-fdmap/fs/Makefile
--- linux-2.6.4/fs/Makefile Wed Mar 10 20:55:29 2004
+++ linux-2.6.4-fdmap/fs/Makefile Sat Mar 20 15:22:17 2004
@@ -44,6 +44,8 @@ obj-y += devpts/

obj-$(CONFIG_PROFILING) += dcookies.o

+obj-$(CONFIG_FDMAP) += fdmap.o
+
# Do not add any filesystems before this line
obj-$(CONFIG_REISERFS_FS) += reiserfs/
obj-$(CONFIG_EXT3_FS) += ext3/ # Before ext2 so root fs can be ext3
diff -X dontdiff -uprN linux-2.6.4/fs/fdmap.c linux-2.6.4-fdmap/fs/fdmap.c
--- linux-2.6.4/fs/fdmap.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.4-fdmap/fs/fdmap.c Tue Mar 23 11:49:48 2004
@@ -0,0 +1,606 @@
+/*
+ * purpose
+ *
+ * Map process memory ranges to virtual file descriptors. This can be
+ * thought of as being the opposite of mmap, simply, instead of mapping
+ * a file's contents to a memory range, fdmap maps a memory range to
+ * a virtual file. This allows one to read, write, seek, and even
+ * mmap the virtual file's contents as if it were a real file on disk.
+ *
+ * interface
+ *
+ * fdmap exposes a new system call identifier. The system call takes
+ * arguments as the following prototype conveys:
+ *
+ * int fdmap(void *addr, size_t len, int flags);
+ *
+ * ``flags'' can be one of O_RDONLY, O_WRONLY, or O_RDWR.
+ *
+ * syscall number
+ *
+ * alpha, arm, ia32, sh: 274
+ * sparc, sparc64: 218
+ * ia64: 1259
+ * m68k: 236
+ * mips: 32b=4268 64b=5227 64be32=6231
+ * parisc: 229
+ * ppc, ppc64: 256
+ * s390: 265
+ * v850: 203
+ *
+ * based on
+ *
+ * The underlying virtual filesystem code was adapted from sockfs.
+ *
+ * Matt Miller
+ * mmiller@xxxxxxxx
+ */
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/utime.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/cache.h>
+#include <linux/sched.h>
+#include <asm/uaccess.h>
+
+typedef struct {
+ struct task_struct *task;
+ unsigned long vma;
+ size_t vma_len;
+} fdmap_context;
+
+typedef struct {
+ fdmap_context fdmap;
+ struct inode vfs_inode;
+} fdmap_alloc;
+
+static struct super_block *fdmap_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev, void *data);
+
+static void fdmap_init_once(void *ctx, kmem_cache_t *cachep,
+ unsigned long flags);
+static struct inode *fdmap_alloc_inode(struct super_block *sb);
+static void fdmap_destroy_inode(struct inode *inode);
+
+static int fdmap_delete_dentry(struct dentry *dentry);
+
+static struct page* fdmap_nopage(struct vm_area_struct *area,
+ unsigned long address, int *type);
+
+static int fdmap_open_mem(unsigned long addr, size_t len, int flags);
+
+static loff_t fdmap_llseek(struct file *f, loff_t off, int whence);
+static ssize_t fdmap_read(struct file *f, char *buf, size_t size, loff_t *off);
+static ssize_t fdmap_write(struct file *f, const char *buf, size_t size,
+ loff_t *off);
+static int fdmap_mmap(struct file *f, struct vm_area_struct *vma);
+static int fdmap_release(struct inode *i, struct file *f);
+
+static unsigned int fdmap_copy_from_task_to_task(struct task_struct *src_task,
+ struct task_struct *dst_task, unsigned long base_dst,
+ unsigned long base_src, unsigned int total);
+static fdmap_context *fdmap_get_context(struct inode *inode);
+
+static struct super_operations fdmap_super_ops =
+{
+ .alloc_inode = fdmap_alloc_inode,
+ .destroy_inode = fdmap_destroy_inode,
+};
+
+static struct file_system_type fdmap_fs_type =
+{
+ .name = "fdmapfs",
+ .get_sb = fdmap_get_sb,
+ .kill_sb = kill_anon_super,
+};
+
+static struct dentry_operations fdmap_dentry_ops =
+{
+ .d_delete = fdmap_delete_dentry,
+};
+
+static struct vm_operations_struct fdmap_vm_ops =
+{
+ .nopage = fdmap_nopage,
+};
+
+static struct file_operations fdmap_file_ops =
+{
+ .llseek = fdmap_llseek,
+ .read = fdmap_read,
+ .write = fdmap_write,
+ .mmap = fdmap_mmap,
+ .release = fdmap_release
+};
+
+#define FDMAP_MAGIC 0x46444d41 // FDMA
+
+static kmem_cache_t *fdmap_inode_cachep;
+static struct vfsmount *fdmap_mnt;
+static atomic_t fdmap_initialized = { 1 };
+
+/*
+ * register and mount the fdmapfs
+ */
+static void fdmap_initialize(void)
+{
+ fdmap_inode_cachep = kmem_cache_create("fdmap_inode_cache",
+ sizeof(fdmap_alloc), 0,
+ SLAB_HWCACHE_ALIGN | SLAB_RECLAIM_ACCOUNT,
+ fdmap_init_once, NULL);
+
+ if (!fdmap_inode_cachep) {
+ printk(KERN_WARNING "fdmap: failed to allocate cache.\n");
+ goto out;
+ }
+
+ register_filesystem(&fdmap_fs_type);
+
+ if (!(fdmap_mnt = kern_mount(&fdmap_fs_type))) {
+ printk(KERN_WARNING "fdmap: failed to mount fdmapfs.\n");
+ }
+
+out:
+}
+
+static struct super_block *fdmap_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev, void *data)
+{
+ return get_sb_pseudo(fs_type, "fdmap:", &fdmap_super_ops, FDMAP_MAGIC);
+}
+
+static void fdmap_init_once(void *ctx, kmem_cache_t *cachep,
+ unsigned long flags)
+{
+ fdmap_alloc *fma = (fdmap_alloc *)ctx;
+
+ if ((flags & SLAB_CTOR_CONSTRUCTOR))
+ inode_init_once(&fma->vfs_inode);
+}
+
+static struct inode *fdmap_alloc_inode(struct super_block *sb)
+{
+ fdmap_alloc *fma = (fdmap_alloc *)kmem_cache_alloc(fdmap_inode_cachep,
+ SLAB_KERNEL);
+
+ if (!fma)
+ return NULL;
+
+ return &fma->vfs_inode;
+}
+
+static void fdmap_destroy_inode(struct inode *inode)
+{
+ kmem_cache_free(fdmap_inode_cachep,
+ container_of(inode, fdmap_alloc, vfs_inode));
+}
+
+static int fdmap_delete_dentry(struct dentry *dentry)
+{
+ return 1;
+}
+
+/*
+ * used in conjunction with mmap of the virtual file, fdmap_nopage will
+ * copy the contents of the mapped memory range at the offset
+ * relative to the address being requested
+ */
+static struct page* fdmap_nopage(struct vm_area_struct *area,
+ unsigned long addr, int *type)
+{
+ struct page *page = NULL, *fpage = NULL;
+ struct file *f = area->vm_file;
+ struct mm_struct *mm;
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+ unsigned long offset;
+ void *saddr, *daddr;
+ int len = PAGE_SIZE;
+
+ mm = get_task_mm(fmc->task);
+
+ if (!mm)
+ goto out;
+
+ addr &= PAGE_MASK;
+ offset = addr - area->vm_start + (area->vm_pgoff << PAGE_SHIFT);
+
+ if (addr + PAGE_SIZE > area->vm_end)
+ len = area->vm_end - addr;
+
+ if (get_user_pages(fmc->task, mm, fmc->vma + offset, 1, 0, 0,
+ &fpage, NULL) < 0)
+ goto out;
+
+ /* inc ref count and re-use this page if the tasks are not the same */
+ if (current != fmc->task)
+ {
+ page = fpage;
+ goto out_mm;
+ }
+
+ if (!(page = alloc_page(GFP_USER)))
+ {
+ kunmap(fpage);
+ goto cleanup;
+ }
+
+ daddr = kmap(page);
+ saddr = kmap(fpage);
+
+ memcpy(daddr, saddr, len);
+
+ kunmap(fpage);
+ kunmap(page);
+
+ if (type)
+ *type = VM_FAULT_MINOR;
+
+ set_page_dirty(page);
+
+cleanup:
+ put_page(fpage);
+
+out_mm:
+ mmput(mm);
+
+out:
+ return page;
+}
+
+/*
+ * entry point for the fdmap syscall
+ */
+asmlinkage int sys_fdmap(void *vma, size_t len, int flags)
+{
+ unsigned long addr = (unsigned long)vma;
+ int fd = -EINVAL;
+
+ if ((atomic_read(&fdmap_initialized) == 1) &&
+ (atomic_dec_and_test(&fdmap_initialized)))
+ fdmap_initialize();
+
+ if ((!len) ||
+ ((addr + len) > TASK_SIZE) ||
+ ((addr + len) < addr)) {
+ fd = -EINVAL;
+ goto out;
+ }
+
+ fd = fdmap_open_mem(addr, len, flags);
+
+out:
+ return fd;
+}
+
+/*
+ * open a virtual file and corresponding file descriptor that is tied
+ * to the passed in memory range.
+ */
+static int fdmap_open_mem(unsigned long addr, size_t len, int flags)
+{
+ struct inode *inode = NULL;
+ fdmap_context *fmc = NULL;
+ struct file *file = NULL;
+ struct qstr this;
+ int fd = 0,
+ res = -ENFILE;
+ char name[32];
+
+ flags &= (O_RDONLY | O_WRONLY | O_RDWR);
+
+ if (flags & O_RDONLY)
+ flags &= ~O_WRONLY;
+ if (flags & O_WRONLY)
+ flags &= ~O_RDONLY;
+
+ if (!(inode = new_inode(fdmap_mnt->mnt_sb)))
+ goto out;
+
+ inode->i_mode = S_IRWXUGO;
+ inode->i_uid = current->fsuid;
+ inode->i_gid = current->fsgid;
+ inode->i_size = (loff_t)len;
+
+ fmc = fdmap_get_context(inode);
+
+ if ((fd = get_unused_fd()) < 0)
+ goto cleanup;
+
+ if (!(file = get_empty_filp()))
+ goto cleanup;
+
+ sprintf(name, "[%lu]", inode->i_ino);
+
+ this.name = name;
+ this.len = strlen(name);
+ this.hash = inode->i_ino;
+
+ file->f_dentry = d_alloc(fdmap_mnt->mnt_sb->s_root, &this);
+
+ if (!file->f_dentry) {
+ res = -ENOMEM;
+ goto cleanup;
+ }
+
+ file->f_dentry->d_op = &fdmap_dentry_ops;
+
+ d_add(file->f_dentry, inode);
+
+ file->f_vfsmnt = mntget(fdmap_mnt);
+ file->f_mapping = file->f_dentry->d_inode->i_mapping;
+ file->f_op = inode->i_fop = &fdmap_file_ops;
+ file->f_mode = 3;
+ file->f_flags = flags;
+ file->f_pos = 0;
+ file->private_data = fmc;
+
+ fd_install(fd, file);
+
+ /* reference the caller's task struct and keep it for later calls */
+ get_task_struct(current);
+ fmc->task = current;
+ fmc->vma = addr;
+ fmc->vma_len = len;
+
+ res = fd;
+
+ goto out;
+
+cleanup:
+ if (file)
+ put_filp(file);
+
+ if (fd >= 0)
+ put_unused_fd(fd);
+out:
+ return res;
+}
+
+static loff_t fdmap_llseek(struct file *f, loff_t off, int whence)
+{
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+ int res = -EINVAL;
+
+ if (!fmc)
+ goto out;
+
+ switch (whence) {
+
+ case 0: // SEEK_SET
+ if ((off < 0) || (off > fmc->vma_len))
+ break;
+
+ f->f_pos = off;
+ res = 0;
+ break;
+ case 1: // SEEK_CUR
+ if (((f->f_pos + off < 0) ||
+ (f->f_pos + off >= fmc->vma_len)))
+ break;
+
+ f->f_pos += off;
+ res = 0;
+ break;
+ case 2: // SEEK_END
+ if ((off > 0) || (fmc->vma_len + off < 0))
+ break;
+
+ f->f_pos = fmc->vma_len + off;
+ res = 0;
+ break;
+ default:
+ break;
+ }
+
+out:
+ return (res < 0) ? res : f->f_pos;
+}
+
+static ssize_t fdmap_read(struct file *f, char *buf, size_t size, loff_t *off)
+{
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+ ssize_t total = -EINVAL;
+
+ if ((!fmc) ||
+ (!buf) ||
+ ((unsigned long)(buf + size) > TASK_SIZE) ||
+ ((unsigned long)(buf + size) < (unsigned long)buf))
+ goto out;
+
+
+ if (f->f_flags == O_WRONLY) {
+ total = -EACCES;
+ goto out;
+ }
+
+ total = (size > fmc->vma_len - f->f_pos) ? fmc->vma_len - f->f_pos
+ : size;
+
+ if (total)
+ total = fdmap_copy_from_task_to_task(fmc->task, current,
+ (unsigned long)buf, fmc->vma + f->f_pos,
+ (unsigned int)total);
+
+ f->f_pos += total;
+
+ if (off)
+ *off = f->f_pos;
+
+out:
+ return total;
+}
+
+static ssize_t fdmap_write(struct file *f, const char *buf, size_t size,
+ loff_t *off)
+{
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+ ssize_t total = -EINVAL;
+
+ if ((!fmc) ||
+ (!buf) ||
+ ((unsigned long)(buf + size) > TASK_SIZE) ||
+ ((unsigned long)(buf + size) < (unsigned long)buf))
+ goto out;
+
+ if (f->f_flags == O_RDONLY) {
+ total = -EACCES;
+ goto out;
+ }
+
+ total = (size > fmc->vma_len - f->f_pos) ? fmc->vma_len - f->f_pos
+ : size;
+
+ /*
+ * if there is enough room to write, do so, otherwise notify the
+ * caller that there is no space for this write.
+ */
+ if (total)
+ total = fdmap_copy_from_task_to_task(current, fmc->task,
+ fmc->vma + f->f_pos, (unsigned long)buf,
+ (unsigned int)total);
+ else
+ {
+ total = -ENOSPC;
+ goto out;
+ }
+
+ f->f_pos += total;
+
+ if (off)
+ *off = f->f_pos;
+
+out:
+ return total;
+}
+
+/*
+ * disallow mmap'ing to a fixed address that is the same as
+ * the describe vma range, but only for the task that
+ * did the original mapping.
+ */
+static int fdmap_mmap(struct file *f, struct vm_area_struct *vma)
+{
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+
+ if ((current == fmc->task) &&
+ (((vma->vm_start >= fmc->vma) &&
+ (vma->vm_start < fmc->vma + fmc->vma_len)) ||
+ ((vma->vm_end <= fmc->vma + fmc->vma_len) &&
+ (vma->vm_end > fmc->vma))))
+ return -EINVAL;
+
+ if (vma->vm_end - (vma->vm_start + vma->vm_pgoff) > fmc->vma_len)
+ return -EFBIG;
+
+ vma->vm_ops = &fdmap_vm_ops;
+
+ return 0;
+}
+
+/*
+ * loses the reference to the task that opened the file
+ */
+static int fdmap_release(struct inode *i, struct file *f)
+{
+ fdmap_context *fmc = (fdmap_context *)f->private_data;
+
+ if (fmc->task) {
+ put_task_struct(fmc->task);
+ }
+
+ return 0;
+}
+
+/*
+ * copy memory from one task to another or from one task to itself.
+ */
+static unsigned int fdmap_copy_from_task_to_task(struct task_struct *src_task,
+ struct task_struct *dst_task, unsigned long base_dst,
+ unsigned long base_src, unsigned int total)
+{
+ unsigned int curr = 0;
+ struct mm_struct *src_mm = get_task_mm(src_task);
+ struct mm_struct *dst_mm = NULL;
+ int intra_copy = 0;
+
+ if (src_task == dst_task) {
+ dst_mm = src_mm;
+ intra_copy = 1;
+ } else {
+ dst_mm = get_task_mm(dst_task);
+ }
+
+ if (!src_mm || !dst_mm)
+ goto out_mm;
+
+ down_read(&src_mm->mmap_sem);
+
+ if (!intra_copy)
+ down_read(&dst_mm->mmap_sem);
+
+ while (curr < total) {
+
+ unsigned long src = (unsigned long)(base_src + curr);
+ unsigned long src_offset = src % PAGE_SIZE;
+ unsigned long dst = (unsigned long)(base_dst + curr);
+ unsigned long dst_offset = dst % PAGE_SIZE;
+ unsigned long len = total - curr;
+ struct page *spage, *dpage;
+ void *skaddr, *dkaddr;
+
+ if (len > PAGE_SIZE)
+ len = PAGE_SIZE;
+
+ spage = dpage = NULL;
+
+ if ((get_user_pages(src_task, src_mm, src, 1, 0, 0, &spage,
+ NULL) < 0) ||
+ (get_user_pages(dst_task, dst_mm, dst, 1, 1, 0, &dpage,
+ NULL) < 0)) {
+
+ if (spage)
+ put_page(spage);
+
+ goto cleanup;
+ }
+
+ skaddr = kmap_atomic(spage, KM_USER0);
+ dkaddr = kmap_atomic(dpage, KM_USER0);
+
+ memcpy(dkaddr + dst_offset, skaddr + src_offset, len);
+
+ kunmap_atomic(dkaddr, KM_USER0);
+ kunmap_atomic(skaddr, KM_USER0);
+
+ set_page_dirty_lock(dpage);
+
+ put_page(dpage);
+ put_page(spage);
+
+ curr += len;
+ }
+
+cleanup:
+ up_read(&src_mm->mmap_sem);
+
+ if (!intra_copy)
+ up_read(&dst_mm->mmap_sem);
+
+out_mm:
+ if (src_mm)
+ mmput(src_mm);
+ if ((dst_mm) && (!intra_copy))
+ mmput(dst_mm);
+
+ return curr;
+}
+
+static fdmap_context *fdmap_get_context(struct inode *inode)
+{
+ return &container_of(inode, fdmap_alloc, vfs_inode)->fdmap;
+}
diff -X dontdiff -uprN linux-2.6.4/include/asm-alpha/unistd.h linux-2.6.4-fdmap/include/asm-alpha/unistd.h
--- linux-2.6.4/include/asm-alpha/unistd.h Wed Mar 10 20:55:26 2004
+++ linux-2.6.4-fdmap/include/asm-alpha/unistd.h Sun Mar 21 03:53:01 2004
@@ -232,7 +232,7 @@
#define __NR_osf_swapctl 259 /* not implemented */
#define __NR_osf_memcntl 260 /* not implemented */
#define __NR_osf_fdatasync 261 /* not implemented */
-
+#define __NR_fdmap 274

/*
* Linux-specific system calls begin at 300
diff -X dontdiff -uprN linux-2.6.4/include/asm-arm/unistd.h linux-2.6.4-fdmap/include/asm-arm/unistd.h
--- linux-2.6.4/include/asm-arm/unistd.h Wed Mar 10 20:55:44 2004
+++ linux-2.6.4-fdmap/include/asm-arm/unistd.h Sun Mar 21 03:55:24 2004
@@ -299,6 +299,7 @@
#define __NR_pciconfig_iobase (__NR_SYSCALL_BASE+271)
#define __NR_pciconfig_read (__NR_SYSCALL_BASE+272)
#define __NR_pciconfig_write (__NR_SYSCALL_BASE+273)
+#define __NR_fdmap (__NR_SYSCALL_BASE+274)

/*
* The following SWIs are ARM private.
diff -X dontdiff -uprN linux-2.6.4/include/asm-i386/unistd.h linux-2.6.4-fdmap/include/asm-i386/unistd.h
--- linux-2.6.4/include/asm-i386/unistd.h Wed Mar 10 20:55:35 2004
+++ linux-2.6.4-fdmap/include/asm-i386/unistd.h Sun Mar 21 03:55:54 2004
@@ -279,8 +279,9 @@
#define __NR_utimes 271
#define __NR_fadvise64_64 272
#define __NR_vserver 273
+#define __NR_fdmap 274

-#define NR_syscalls 274
+#define NR_syscalls 275

/* user-visible error numbers are in the range -1 - -124: see <asm-i386/errno.h> */

diff -X dontdiff -uprN linux-2.6.4/include/asm-ia64/unistd.h linux-2.6.4-fdmap/include/asm-ia64/unistd.h
--- linux-2.6.4/include/asm-ia64/unistd.h Wed Mar 10 20:55:22 2004
+++ linux-2.6.4-fdmap/include/asm-ia64/unistd.h Sun Mar 21 04:01:10 2004
@@ -248,10 +248,11 @@
#define __NR_clock_nanosleep 1256
#define __NR_fstatfs64 1257
#define __NR_statfs64 1258
+#define __NR_fdmap 1259

#ifdef __KERNEL__

-#define NR_syscalls 256 /* length of syscall table */
+#define NR_syscalls 257 /* length of syscall table */

#if !defined(__ASSEMBLY__) && !defined(ASSEMBLER)

diff -X dontdiff -uprN linux-2.6.4/include/asm-m68k/unistd.h linux-2.6.4-fdmap/include/asm-m68k/unistd.h
--- linux-2.6.4/include/asm-m68k/unistd.h Wed Mar 10 20:55:27 2004
+++ linux-2.6.4-fdmap/include/asm-m68k/unistd.h Sun Mar 21 04:01:35 2004
@@ -238,8 +238,9 @@
#define __NR_lremovexattr 233
#define __NR_fremovexattr 234
#define __NR_futex 235
+#define __NR_fdmap 236

-#define NR_syscalls 236
+#define NR_syscalls 237

/* user-visible error numbers are in the range -1 - -124: see
<asm-m68k/errno.h> */
diff -X dontdiff -uprN linux-2.6.4/include/asm-mips/unistd.h linux-2.6.4-fdmap/include/asm-mips/unistd.h
--- linux-2.6.4/include/asm-mips/unistd.h Wed Mar 10 20:55:21 2004
+++ linux-2.6.4-fdmap/include/asm-mips/unistd.h Sun Mar 21 04:06:08 2004
@@ -288,16 +288,17 @@
#define __NR_clock_nanosleep (__NR_Linux + 265)
#define __NR_tgkill (__NR_Linux + 266)
#define __NR_utimes (__NR_Linux + 267)
+#define __NR_fdmap (__NR_Linux + 268)

/*
* Offset of the last Linux o32 flavoured syscall
*/
-#define __NR_Linux_syscalls 267
+#define __NR_Linux_syscalls 268

#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */

#define __NR_O32_Linux 4000
-#define __NR_O32_Linux_syscalls 267
+#define __NR_O32_Linux_syscalls 268

#if _MIPS_SIM == _MIPS_SIM_ABI64

@@ -532,16 +533,17 @@
#define __NR_clock_nanosleep (__NR_Linux + 224)
#define __NR_tgkill (__NR_Linux + 225)
#define __NR_utimes (__NR_Linux + 226)
+#define __NR_fdmap (__NR_Linux + 227)

/*
* Offset of the last Linux flavoured syscall
*/
-#define __NR_Linux_syscalls 226
+#define __NR_Linux_syscalls 227

#endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */

#define __NR_64_Linux 5000
-#define __NR_64_Linux_syscalls 226
+#define __NR_64_Linux_syscalls 227

#if _MIPS_SIM == _MIPS_SIM_NABI32

@@ -780,16 +782,17 @@
#define __NR_clock_nanosleep (__NR_Linux + 228)
#define __NR_tgkill (__NR_Linux + 229)
#define __NR_utimes (__NR_Linux + 230)
+#define __NR_fdmap (__NR_Linux + 231)

/*
* Offset of the last N32 flavoured syscall
*/
-#define __NR_Linux_syscalls 230
+#define __NR_Linux_syscalls 231

#endif /* _MIPS_SIM == _MIPS_SIM_NABI32 */

#define __NR_N32_Linux 6000
-#define __NR_N32_Linux_syscalls 230
+#define __NR_N32_Linux_syscalls 231

#ifndef __ASSEMBLY__

diff -X dontdiff -uprN linux-2.6.4/include/asm-parisc/unistd.h linux-2.6.4-fdmap/include/asm-parisc/unistd.h
--- linux-2.6.4/include/asm-parisc/unistd.h Wed Mar 10 20:55:20 2004
+++ linux-2.6.4-fdmap/include/asm-parisc/unistd.h Sun Mar 21 04:06:54 2004
@@ -721,9 +721,10 @@
#define __NR_epoll_wait (__NR_Linux + 226)
#define __NR_remap_file_pages (__NR_Linux + 227)
#define __NR_semtimedop (__NR_Linux + 228)
+#define __NR_fdmap (__NR_Linux + 229)


-#define __NR_Linux_syscalls 228
+#define __NR_Linux_syscalls 229

#define HPUX_GATEWAY_ADDR 0xC0000004
#define LINUX_GATEWAY_ADDR 0x100
diff -X dontdiff -uprN linux-2.6.4/include/asm-ppc/unistd.h linux-2.6.4-fdmap/include/asm-ppc/unistd.h
--- linux-2.6.4/include/asm-ppc/unistd.h Wed Mar 10 20:55:23 2004
+++ linux-2.6.4-fdmap/include/asm-ppc/unistd.h Sun Mar 21 04:08:40 2004
@@ -260,8 +260,9 @@
#define __NR_fstatfs64 253
#define __NR_fadvise64_64 254
#define __NR_rtas 255
+#define __NR_fdmap 256

-#define __NR_syscalls 256
+#define __NR_syscalls 257

#define __NR(n) #n

diff -X dontdiff -uprN linux-2.6.4/include/asm-ppc64/unistd.h linux-2.6.4-fdmap/include/asm-ppc64/unistd.h
--- linux-2.6.4/include/asm-ppc64/unistd.h Wed Mar 10 20:55:21 2004
+++ linux-2.6.4-fdmap/include/asm-ppc64/unistd.h Sun Mar 21 04:09:16 2004
@@ -266,8 +266,9 @@
#define __NR_fstatfs64 253
#define __NR_fadvise64_64 254
#define __NR_rtas 255
+#define __NR_fdmap 256

-#define __NR_syscalls 256
+#define __NR_syscalls 257
#ifdef __KERNEL__
#define NR_syscalls __NR_syscalls
#endif
diff -X dontdiff -uprN linux-2.6.4/include/asm-s390/unistd.h linux-2.6.4-fdmap/include/asm-s390/unistd.h
--- linux-2.6.4/include/asm-s390/unistd.h Wed Mar 10 20:55:55 2004
+++ linux-2.6.4-fdmap/include/asm-s390/unistd.h Sun Mar 21 04:09:53 2004
@@ -256,12 +256,13 @@
#define __NR_clock_gettime (__NR_timer_create+6)
#define __NR_clock_getres (__NR_timer_create+7)
#define __NR_clock_nanosleep (__NR_timer_create+8)
+#define __NR_fdmap 265
/*
* Number 263 is reserved for vserver
*/
-#define __NR_fadvise64_64 264
+#define __NR_fadvise64_64 265

-#define NR_syscalls 265
+#define NR_syscalls 266

/*
* There are some system calls that are not present on 64 bit, some
diff -X dontdiff -uprN linux-2.6.4/include/asm-sparc/unistd.h linux-2.6.4-fdmap/include/asm-sparc/unistd.h
--- linux-2.6.4/include/asm-sparc/unistd.h Wed Mar 10 20:55:22 2004
+++ linux-2.6.4-fdmap/include/asm-sparc/unistd.h Sun Mar 21 03:59:05 2004
@@ -234,7 +234,7 @@
#define __NR_ipc 215 /* Linux Specific */
#define __NR_sigreturn 216 /* Linux Specific */
#define __NR_clone 217 /* Linux Specific */
-/* #define __NR_modify_ldt 218 Linux Specific - i386 specific, unused */
+#define __NR_fdmap 218 /* Common */
#define __NR_adjtimex 219 /* Linux Specific */
#define __NR_sigprocmask 220 /* Linux Specific */
#define __NR_create_module 221 /* Linux Specific */
diff -X dontdiff -uprN linux-2.6.4/include/asm-sparc64/unistd.h linux-2.6.4-fdmap/include/asm-sparc64/unistd.h
--- linux-2.6.4/include/asm-sparc64/unistd.h Wed Mar 10 20:55:23 2004
+++ linux-2.6.4-fdmap/include/asm-sparc64/unistd.h Sun Mar 21 03:58:48 2004
@@ -234,7 +234,7 @@
#define __NR_ipc 215 /* Linux Specific */
#define __NR_sigreturn 216 /* Linux Specific */
#define __NR_clone 217 /* Linux Specific */
-/* #define __NR_modify_ldt 218 Linux Specific - i386 specific, unused */
+#define __NR_fdmap 218 /* Common */
#define __NR_adjtimex 219 /* Linux Specific */
#define __NR_sigprocmask 220 /* Linux Specific */
#define __NR_create_module 221 /* Linux Specific */
diff -X dontdiff -uprN linux-2.6.4/include/asm-v850/unistd.h linux-2.6.4-fdmap/include/asm-v850/unistd.h
--- linux-2.6.4/include/asm-v850/unistd.h Wed Mar 10 20:55:50 2004
+++ linux-2.6.4-fdmap/include/asm-v850/unistd.h Sun Mar 21 04:10:21 2004
@@ -205,6 +205,7 @@
#define __NR_pivot_root 200
#define __NR_gettid 201
#define __NR_tkill 202
+#define __NR_fdmap 203


/* Syscall protocol:
diff -X dontdiff -uprN linux-2.6.4/kernel/sys.c linux-2.6.4-fdmap/kernel/sys.c
--- linux-2.6.4/kernel/sys.c Wed Mar 10 20:55:22 2004
+++ linux-2.6.4-fdmap/kernel/sys.c Thu Mar 25 05:03:48 2004
@@ -260,6 +260,7 @@ cond_syscall(sys_msgctl)
cond_syscall(sys_shmget)
cond_syscall(sys_shmdt)
cond_syscall(sys_shmctl)
+cond_syscall(sys_fdmap)

/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read)
-
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