Raymond Toy pushed to branch issue-97-define-ud2-inst at cmucl / cmucl

Commits: b8498f43 by Raymond Toy at 2021-05-21T19:52:05-07:00 Flame out if single-stepping didn't move far enough

After single-stepping, we MUST be past the place where the breakpoint instruction was inserted. If not, call lose to get to LDB.

- - - - -

1 changed file:

- src/lisp/x86-arch.c

Changes:

===================================== src/lisp/x86-arch.c ===================================== @@ -501,13 +501,20 @@ sigtrap_handler(HANDLER_ARGS) (stderr, "* Maybe reinstall breakpoint for pc %p with single_stepping %p\n", (void*) SC_PC(os_context), single_stepping));

- if ((unsigned long) SC_PC(os_context) <= (unsigned long) single_stepping) - fprintf(stderr, "* Breakpoint not re-install\n"); - else { - char *ptr = (char *) single_stepping; + /* + * Lose if single-stepping didn't move us past where the + * breakpoint instruction was inserted. + */ + if ((unsigned long) SC_PC(os_context) <= (unsigned long) single_stepping) { + lose("Single-stepping did not advance past the breakpoint at %p\n", + single_stepping); + }

- ptr[0] = BREAKPOINT_INST; /* x86 INT3 */ - } + /* + * Put back the breakpoint since we skipped over it. + */ + char *ptr = (char *) single_stepping; + ptr[0] = BREAKPOINT_INST; /* x86 INT3 */

single_stepping = NULL; return;

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/b8498f43cd9fd407ff2dddf0...