[PATCH] lightweight robust futexes: x86_64

x86_64: 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>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S
index 7549a4389fbfbfb761188fe271a7e780ed0042f3..35b2faccdc6c28af5169f0e02d4a060acc4e2133 100644 (file)
--- a/arch/x86_64/ia32/ia32entry.S
+++ b/arch/x86_64/ia32/ia32entry.S
@@ -688,6 +688,8 @@ ia32_sys_call_table:
        .quad sys_ni_syscall            /* pselect6 for now */
        .quad sys_ni_syscall            /* ppoll for now */
        .quad sys_unshare               /* 310 */
+       .quad compat_sys_set_robust_list
+       .quad compat_sys_get_robust_list
 ia32_syscall_end:              
        .rept IA32_NR_syscalls-(ia32_syscall_end-ia32_sys_call_table)/8
                .quad ni_syscall

diff --git a/include/asm-x86_64/futex.h b/include/asm-x86_64/futex.h
index 4f4cb3410d0698b694437d66c68628804214170a..7d9eb1a845467f17654b940c6c36b46df61f5672 100644 (file)
--- a/include/asm-x86_64/futex.h
+++ b/include/asm-x86_64/futex.h
@@ -97,7 +97,28 @@ 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"
+               "       .quad   1b,3b                           \n"
+               "       .previous                               \n"
+
+               : "=a" (oldval), "=m" (*uaddr)
+               : "i" (-EFAULT), "r" (newval), "0" (oldval)
+               : "memory"
+       );
+
+       return oldval;
 }
 
 #endif

diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h
index da0341c57949717e17b59a9c16499b4b31e5d8c1..fcc5163530873bf7437d8509231db03a2165501d 100644 (file)
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -605,8 +605,12 @@ __SYSCALL(__NR_pselect6, sys_ni_syscall)   /* for now */
 __SYSCALL(__NR_ppoll,  sys_ni_syscall)         /* for now */
 #define __NR_unshare           272
 __SYSCALL(__NR_unshare,        sys_unshare)
+#define __NR_set_robust_list   273
+__SYSCALL(__NR_set_robust_list, sys_set_robust_list)
+#define __NR_get_robust_list   274
+__SYSCALL(__NR_get_robust_list, sys_get_robust_list)
 
-#define __NR_syscall_max __NR_unshare
+#define __NR_syscall_max __NR_get_robust_list
 
 #ifndef __NO_STUBS