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

Commits: 62d67c1e by Raymond Toy at 2021-04-10T09:24:32-07:00 More cleanups

When installing a breakpoint, we only need to save the single byte. When removing a breakpoint, we only need to restore the single byte.

- - - - -

1 changed file:

- src/lisp/x86-arch.c

Changes:

===================================== src/lisp/x86-arch.c ===================================== @@ -213,17 +213,21 @@ arch_set_pseudo_atomic_interrupted(os_context_t * context)

+/* + * Installs a breakpoint (INT3) at |pc|. We return the byte that was + * replaced by the int3 instruction. + */ unsigned long arch_install_breakpoint(void *pc) { unsigned char* ptr = (unsigned char *) pc; - unsigned long result = ptr[0] | (ptr[1] << 8) | (ptr[2] << 16) | (ptr[3] << 24); + unsigned long result = *ptr;

DPRINTF(debug_handlers, (stderr, "arch_install_breakpoint at %p, old code = 0x%lx\n", pc, result));

- *(char *) pc = BREAKPOINT_INST; /* x86 INT3 */ + *ptr = BREAKPOINT_INST; /* x86 INT3 */ return result; }

@@ -235,14 +239,9 @@ arch_remove_breakpoint(void *pc, unsigned long orig_inst) pc, orig_inst)); unsigned char *ptr = (unsigned char *) pc; /* - * Just restore all the bytes from orig_inst. Should we just - * re-install just the one byte that was taken by the int3 - * instruction? + * Just restore the byte from orig_inst. */ ptr[0] = orig_inst & 0xff; - ptr[1] = (orig_inst >> 8) & 0xff; - ptr[2] = (orig_inst >> 16) & 0xff; - ptr[3] = (orig_inst >> 24) & 0xff; }

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/62d67c1ed634686a0bc1ac58...