riscv-011: Don't trigger semihosting before the target is examined

In riscv-011 target, the handle_halt() function, and thus also
riscv_semihosting(), can get called from within examine() before
the examination is actually complete!

The chain of the function calls is:

- examine() -> riscv011_poll() -> poll_target()
  -> handle_halt() -> riscv_semihosting()

If the target is already halted due to a breakpoint (dcsr.cause = SWBP)
at the time OpenOCD connects to it, semihosting will be attempted before
completing the examination, and the examination will fail.

This issue was observed on HiFive1 Rev A01.

Hot-fix this by making shure that semihosting is not attempted
before the target gets successfully examined.

Change-Id: Iccfa0da35d47a430d8674131ebd2eb8e5e2922c0
Signed-off-by: Jan Matyas <[email protected]>

Author: JanMatCodasip

src/target/riscv/riscv-011.c

@@ -1889,8 +1889,16 @@ static int handle_halt(struct target *target, bool announce)
 
 	if (target->debug_reason == DBG_REASON_BREAKPOINT) {
 		int retval;
-		if (riscv_semihosting(target, &retval) != 0)
-			return retval;
+		/* Hotfix: Don't try to handle semihosting before the target is marked as examined. */
+		/* TODO: The code should be rearranged so that:
+		 * - Semihosting is not attempted before the target is examined.
+		 * - When the target is already halted on a semihosting magic sequence
+		 *   at the time when OpenOCD connects to it, this semihosting attempt
+		 *   gets handled right after the examination.
+		 */
+		if (target_was_examined(target))
+			if (riscv_semihosting(target, &retval) != SEMIHOSTING_NONE)
+				return retval;
 	}
 
 	if (announce)