cortex_m.c: Use two byte breakpoint for 32bit Thumb-2 request

When GDB requests a breakpoint on a 32bit Thumb-2 instruction it
sends a length of 3 which the current code rejects. Using the
existing two byte breakpoint for this case appears to work fine.

The use of length==3 for this case is mentioned in a few places:
https://sourceware.org/gdb/onlinedocs/gdb/ARM-Breakpoint-Kinds.html
http://sourceforge.net/p/openocd/mailman/message/30012280/

Change-Id: I59cd69ba4d1bc9a37b86569738c6bb2a67c3eb7a
Signed-off-by: Jon Burgess <jburgess777@gmail.com>
Reviewed-on: http://openocd.zylin.com/2312
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index 72dbe9ee6085a2c5a83a69091ba125af1282d93a..a5230b75c737adabe6b8874e215282705ec693e5 100644 (file)
--- a/src/target/cortex_m.c
+++ b/src/target/cortex_m.c
@@ -1262,6 +1262,11 @@ int cortex_m_add_breakpoint(struct target *target, struct breakpoint *breakpoint
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
        }
 
+       if (breakpoint->length == 3) {
+               LOG_DEBUG("Using a two byte breakpoint for 32bit Thumb-2 request");
+               breakpoint->length = 2;
+       }
+
        if ((breakpoint->length != 2)) {
                LOG_INFO("only breakpoints of two bytes length supported");
                return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;