bitkeeper revision 1.1713.2.9 (42b3588569-8TLyTABHy5VPCdbAQmQ)

Implement cmpxchg_user for ia64 (hopefully correct :-)

Signed-off-by: Dan Magenheimer <dan.magenheimer@hp.com>

xen/arch/ia64/grant_table.c

@@ -35,10 +35,7 @@
 #ifdef __ia64__
 #define __addr_ok(a) 1	// FIXME-ia64: a variant of access_ok??
 // FIXME-ia64: need to implement real cmpxchg_user on ia64
-#define cmpxchg_user(_p,_o,_n) ((*_p == _o) ? ((*_p = _n), 0) : ((_o = *_p), 0))
-// FIXME-ia64: the following are meaningless on ia64? move to some header file
-#define put_page(x) do { } while (0)
-#define put_page_type(x) do { } while (0)
+//#define cmpxchg_user(_p,_o,_n) ((*_p == _o) ? ((*_p = _n), 0) : ((_o = *_p), 0))
 // FIXME-ia64: these belong in an asm/grant_table.h... PAGE_SIZE different
 #undef ORDER_GRANT_FRAMES
 //#undef NUM_GRANT_FRAMES

xen/include/asm-ia64/xensystem.h

@@ -61,5 +61,37 @@ extern struct task_struct *vmx_ia64_switch_to (void *next_task);
 } while (0)
 #endif // CONFIG_VTI
 
+#define __cmpxchg_user(ptr, new, old, _size)				\
+({									\
+	register long __gu_r8 asm ("r8");				\
+	register long __gu_r9 asm ("r9");				\
+	asm volatile ("mov ar.ccv=%0;;" :: "rO"(old));			\
+	asm volatile ("mov %2=r0;;\n"					\
+		"[1:]\tcmpxchg"_size".acq %0=[%3],%4,ar.ccv\n"		\
+		"\t.xdata4 \"__ex_table\", 1b-., 1f.+4\n"		\
+		"[1:]"							\
+		: "=r"(old), "=r"(__gu_r9), "=r"(__gu_r8) :		\
+		"r"(ptr), "r"(new) : "memory");				\
+	(old) = __gu_r9;						\
+	__gu_r8;							\
+})
+
+
+// NOTE: Xen defines args as pointer,old,new whereas ia64 uses pointer,new,old
+//  so reverse them here
+#define cmpxchg_user(_p,_o,_n)					\
+({								\
+	register long _rc;					\
+	ia64_mf();						\
+	switch ( sizeof(*(_p)) ) {				\
+	    case 1: _rc = __cmpxchg_user(_p,_n,_o,"1"); break;	\
+	    case 2: _rc = __cmpxchg_user(_p,_n,_o,"2"); break;	\
+	    case 4: _rc = __cmpxchg_user(_p,_n,_o,"4"); break;	\
+	    case 8: _rc = __cmpxchg_user(_p,_n,_o,"8"); break;	\
+	}							\
+	ia64_mf();						\
+	_rc;							\
+})
+
 #endif // __ASSEMBLY__
 #endif // _ASM_IA64_XENSYSTEM_H