[SPARC64]: Implement force_successful_syscall().

arch/sparc64/kernel/entry.S

@@ -1749,8 +1749,8 @@ ret_sys_call:
 	cmp		%o0, -ENOIOCTLCMD
 	sllx		%g2, 32, %g2
 	bgeu,pn		%xcc, 1f
-
 	 andcc		%l0, _TIF_SYSCALL_TRACE, %l6	
+80:
 	andn		%g3, %g2, %g3		/* System call success, clear Carry condition code. */
 	stx		%g3, [%sp + PTREGS_OFF + PT_V9_TSTATE]	
 	bne,pn		%icc, linux_syscall_trace2
@@ -1760,9 +1760,21 @@ ret_sys_call:
 	 stx		%l2, [%sp + PTREGS_OFF + PT_V9_TNPC]
 
 1:
+	/* Really a failure?  Check if force_successful_syscall_return()
+	 * was invoked.
+	 */
+	ldx		[%curptr + TI_FLAGS], %l0		! Load
+	andcc		%l0, _TIF_SYSCALL_SUCCESS, %g0
+	be,pt		%icc, 1f
+	 andcc		%l0, _TIF_SYSCALL_TRACE, %l6	
+	andn		%l0, _TIF_SYSCALL_SUCCESS, %l0
+	ba,pt		%xcc, 80b
+	 stx		%l0, [%curptr + TI_FLAGS]
+
 	/* System call failure, set Carry condition code.
 	 * Also, get abs(errno) to return to the process.
 	 */
+1:
 	sub		%g0, %o0, %o0
 	or		%g3, %g2, %g3
 	stx		%o0, [%sp + PTREGS_OFF + PT_V9_I0]

include/asm-sparc64/ptrace.h

@@ -94,6 +94,8 @@ struct sparc_trapf {
 #define STACKFRAME32_SZ	sizeof(struct sparc_stackf32)
 
 #ifdef __KERNEL__
+#define force_successful_syscall_return()	\
+	set_thread_flag(TIF_SYSCALL_SUCCESS)
 #define user_mode(regs) (!((regs)->tstate & TSTATE_PRIV))
 #define instruction_pointer(regs) ((regs)->tpc)
 extern void show_regs(struct pt_regs *);

include/asm-sparc64/thread_info.h

@@ -205,7 +205,12 @@ register struct thread_info *current_thread_info_reg asm("g6");
 #define TIF_BLKCOMMIT		9	/* use ASI_BLK_COMMIT_* in copy_user_page */
 
 #define TIF_POLLING_NRFLAG	10
-#define TIF_ABI_PENDING		11
+#define TIF_SYSCALL_SUCCESS	11
+/* NOTE: Thread flags >= 12 should be ones we have no interest
+ *       in using in assembly, else we can't use the mask as
+ *       an immediate value in instructions such as andcc.
+ */
+#define TIF_ABI_PENDING		12
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
@@ -219,6 +224,7 @@ register struct thread_info *current_thread_info_reg asm("g6");
 #define _TIF_BLKCOMMIT		(1<<TIF_BLKCOMMIT)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_ABI_PENDING	(1<<TIF_ABI_PENDING)
+#define _TIF_SYSCALL_SUCCESS	(1<<TIF_SYSCALL_SUCCESS)
 
 #define _TIF_USER_WORK_MASK	((0xff << TI_FLAG_WSAVED_SHIFT) | \
 				 (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \