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

Commits: 8817798f by Raymond Toy at 2021-03-22T19:57:09-07:00 Add sigtrap handler to handle single-stepping traps

Needed to handle single-stepping. There's also a lot of other changes used to debug this. They eventually need to be cleaned up.

- - - - -

1 changed file:

- src/lisp/x86-arch.c

Changes:

===================================== src/lisp/x86-arch.c ===================================== @@ -142,7 +142,7 @@ arch_skip_instruction(os_context_t * context) { int vlen, code;

- DPRINTF(0, (stderr, "[arch_skip_inst at %lx>]\n", SC_PC(context))); + DPRINTF(1, (stderr, "[arch_skip_inst at %lx>]\n", SC_PC(context)));

/* Get and skip the lisp error code. */ char* pc = (char *) SC_PC(context); @@ -206,8 +206,8 @@ arch_set_pseudo_atomic_interrupted(os_context_t * context) unsigned long arch_install_breakpoint(void *pc) { - char* ptr = (char *) pc; - unsigned long result = *(unsigned long *) pc; + unsigned char* ptr = (unsigned char *) pc; + unsigned long result = ptr[0] | (ptr[1] << 8) | (ptr[2] << 16) | (ptr[3] << 24);

fprintf(stderr, "arch_install_breakpoint at %p, old code = 0x%lx\n", pc, result); @@ -227,8 +227,13 @@ arch_install_breakpoint(void *pc) void arch_remove_breakpoint(void *pc, unsigned long orig_inst) { - *((char *) pc) = orig_inst & 0xff; - *((char *) pc + 1) = (orig_inst & 0xff00) >> 8; + fprintf(stderr, "arch_remove_breakpoint: %p orig %lx\n", + pc, orig_inst); + unsigned char *ptr = (unsigned char *) pc; + ptr[0] = orig_inst & 0xff; + ptr[1] = (orig_inst >> 8) & 0xff; + ptr[2] = (orig_inst >> 16) & 0xff; + ptr[3] = (orig_inst >> 24) & 0xff; }

@@ -249,14 +254,23 @@ unsigned int single_step_save3; void arch_do_displaced_inst(os_context_t * context, unsigned long orig_inst) { - unsigned int *pc = (unsigned int *) SC_PC(context); + unsigned char *pc = (unsigned char *) SC_PC(context);

+ fprintf(stderr, "arch_do_displaced_inst: pc %p orig_inst %lx\n", + pc, orig_inst); + /* * Put the original instruction back. */

+#if 0 *((char *) pc) = orig_inst & 0xff; *((char *) pc + 1) = (orig_inst & 0xff00) >> 8; +#else + pc[0] = orig_inst & 0xff; + pc[1] = (orig_inst >> 8) & 0xff; + pc[2] = (orig_inst >> 16) & 0xff; +#endif

#ifdef SC_EFLAGS /* Enable single-stepping */ @@ -319,8 +333,8 @@ sigill_handler(HANDLER_ARGS) fprintf(stderr, "sigtrap(%d %d %p)\n", signal, CODE(code), os_context); #endif

- if (single_stepping && (signal == SIGTRAP)) { -#if 0 + if (single_stepping && (signal == SIGILL)) { +#if 1 fprintf(stderr, "* Single step trap %p\n", single_stepping); #endif

@@ -338,7 +352,9 @@ sigill_handler(HANDLER_ARGS) /* * Re-install the breakpoint if possible. */ - if ((int) SC_PC(os_context) == (int) single_stepping + 1) + fprintf(stderr, "* Reinstall breakpoint at single_stepping %p\n", single_stepping); + + if ((int) SC_PC(os_context) >= (int) single_stepping + 3) fprintf(stderr, "* Breakpoint not re-install\n"); else { char *ptr = (char *) single_stepping; @@ -460,10 +476,70 @@ sigill_handler(HANDLER_ARGS) } }

+void +sigtrap_handler(HANDLER_ARGS) +{ + os_context_t* os_context = (os_context_t *) context; + +#if 1 + fprintf(stderr,"sigtrap: fp=%lx sp=%lx pc=%lx { %x, %x, %x, %x, %x }\n", + SC_REG(context, reg_FP), + SC_REG(context, reg_SP), + SC_PC(context), + *(unsigned char*)(SC_PC(context) + 0), /* 0x0F */ + *(unsigned char*)(SC_PC(context) + 1), /* 0x0B */ + *(unsigned char*)(SC_PC(context) + 2), + *(unsigned char*)(SC_PC(context) + 3), + *(unsigned char*)(SC_PC(context) + 4)); +#endif + if (single_stepping && (signal == SIGTRAP)) { +#if 1 + fprintf(stderr, "* Single step trap %p\n", single_stepping); +#endif + +#ifdef SC_EFLAGS + /* Disable single-stepping */ + SC_EFLAGS(os_context) ^= 0x100; +#else + /* Un-install single step helper instructions. */ + *(single_stepping - 3) = single_step_save1; + *(single_stepping - 2) = single_step_save2; + *(single_stepping - 1) = single_step_save3; + DPRINTF(0, (stderr, "Uninstalling helper instructions\n")); +#endif + + /* + * Re-install the breakpoint if possible. + */ + fprintf(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 + 3) + fprintf(stderr, "* Breakpoint not re-install\n"); + else { + char *ptr = (char *) single_stepping; + +#if 0 + ptr[0] = BREAKPOINT_INST; /* x86 INT3 */ + ptr[1] = trap_Breakpoint; +#else + ptr[0] = 0x0f; + ptr[1] = 0x0b; + ptr[2] = trap_Breakpoint; +#endif + } + + single_stepping = NULL; + return; + } +} + + void arch_install_interrupt_handlers(void) { interrupt_install_low_level_handler(SIGILL, sigill_handler); + interrupt_install_low_level_handler(SIGTRAP, sigtrap_handler); }

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/8817798f004ea8e745201c5a...