LoongArch: Check TIF_LOAD_WATCH to enable user space watchpoint

Currently, there are some places to set CSR.PRMD.PWE, the first one is
in hw_breakpoint_thread_switch() to enable user space singlestep via
checking TIF_SINGLESTEP, the second one is in hw_breakpoint_control() to
enable user space watchpoint. For the latter case, it should also check
TIF_LOAD_WATCH to make the logic correct and clear.

Fixes: c8e57ab0 ("LoongArch: Trigger user-space watchpoints correctly")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/kernel/hw_breakpoint.c

@@ -221,7 +221,7 @@ static int hw_breakpoint_control(struct perf_event *bp,
 		}
 		enable = csr_read64(LOONGARCH_CSR_CRMD);
 		csr_write64(CSR_CRMD_WE | enable, LOONGARCH_CSR_CRMD);
-		if (bp->hw.target)
+		if (bp->hw.target && test_tsk_thread_flag(bp->hw.target, TIF_LOAD_WATCH))
 			regs->csr_prmd |= CSR_PRMD_PWE;
 		break;
 	case HW_BREAKPOINT_UNINSTALL:

arch/loongarch/kernel/ptrace.c

@@ -589,6 +589,7 @@ static int ptrace_hbp_set_ctrl(unsigned int note_type,
 	struct perf_event *bp;
 	struct perf_event_attr attr;
 	struct arch_hw_breakpoint_ctrl ctrl;
+	struct thread_info *ti = task_thread_info(tsk);
 
 	bp = ptrace_hbp_get_initialised_bp(note_type, tsk, idx);
 	if (IS_ERR(bp))
@@ -613,8 +614,10 @@ static int ptrace_hbp_set_ctrl(unsigned int note_type,
 		if (err)
 			return err;
 		attr.disabled = 0;
+		set_ti_thread_flag(ti, TIF_LOAD_WATCH);
 	} else {
 		attr.disabled = 1;
+		clear_ti_thread_flag(ti, TIF_LOAD_WATCH);
 	}
 
 	return modify_user_hw_breakpoint(bp, &attr);