[PATCH] lightweight robust futexes: i386

i386: add the futex_atomic_cmpxchg_inuser() assembly implementation, and wire
up the new syscalls.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S
index ac687d0..326595f 100644 (file)
--- a/arch/i386/kernel/syscall_table.S
+++ b/arch/i386/kernel/syscall_table.S
@@ -310,3 +310,5 @@ ENTRY(sys_call_table)
        .long sys_pselect6
        .long sys_ppoll
        .long sys_unshare               /* 310 */
+       .long sys_set_robust_list
+       .long sys_get_robust_list

diff --git a/include/asm-i386/futex.h b/include/asm-i386/futex.h
index 1f39ad9..41184a3 100644 (file)
--- a/include/asm-i386/futex.h
+++ b/include/asm-i386/futex.h
@@ -107,7 +107,28 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
 static inline int
 futex_atomic_cmpxchg_inuser(int __user *uaddr, int oldval, int newval)
 {
-       return -ENOSYS;
+       if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+               return -EFAULT;
+
+       __asm__ __volatile__(
+               "1:     " LOCK_PREFIX "cmpxchgl %3, %1          \n"
+
+               "2:     .section .fixup, \"ax\"                 \n"
+               "3:     mov     %2, %0                          \n"
+               "       jmp     2b                              \n"
+               "       .previous                               \n"
+
+               "       .section __ex_table, \"a\"              \n"
+               "       .align  8                               \n"
+               "       .long   1b,3b                           \n"
+               "       .previous                               \n"
+
+               : "=a" (oldval), "=m" (*uaddr)
+               : "i" (-EFAULT), "r" (newval), "0" (oldval)
+               : "memory"
+       );
+
+       return oldval;
 }
 
 #endif

diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h
index d8afd0e..014e356 100644 (file)
--- a/include/asm-i386/unistd.h
+++ b/include/asm-i386/unistd.h
@@ -316,8 +316,10 @@
 #define __NR_pselect6          308
 #define __NR_ppoll             309
 #define __NR_unshare           310
+#define __NR_set_robust_list   311
+#define __NR_get_robust_list   312
 
-#define NR_syscalls 311
+#define NR_syscalls 313
 
 /*
  * user-visible error numbers are in the range -1 - -128: see