X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fx86-64-arch.c;h=6ee2690f6a09ec74504114a213b6f50e55ac8357;hb=6cb4f9ea3f4e35a5a8e75922833e14575ae92180;hp=a0d8276717c24d7f6701b18473890e37e7990d07;hpb=f35f14479a64dd97f93d2d91dc154bdc141d6842;p=sbcl.git

diff --git a/src/runtime/x86-64-arch.c b/src/runtime/x86-64-arch.c
index a0d8276..6ee2690 100644
--- a/src/runtime/x86-64-arch.c
+++ b/src/runtime/x86-64-arch.c
@@ -162,6 +162,9 @@ arch_remove_breakpoint(void *pc, unsigned int orig_inst)
     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
 }
 
+/* When single stepping, single_stepping holds the original instruction
+ * PC location. */
+unsigned int *single_stepping = NULL;
 
 void
 arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
@@ -171,7 +174,12 @@ arch_do_displaced_inst(os_context_t *context, unsigned int orig_inst)
     /* Put the original instruction back. */
     *((char *)pc) = orig_inst & 0xff;
     *((char *)pc + 1) = (orig_inst & 0xff00) >> 8;
+
+    *context_eflags_addr(context) |= 0x100;
+
+    single_stepping = pc;
 }
+
 
 void
 sigtrap_handler(int signal, siginfo_t *info, void *void_context)
@@ -180,11 +188,33 @@ sigtrap_handler(int signal, siginfo_t *info, void *void_context)
     os_context_t *context = (os_context_t*)void_context;
     unsigned int trap;
 
+    if (single_stepping && (signal==SIGTRAP))
+    {
+        *context_eflags_addr(context) ^= 0x100;
+
+        /* Re-install the breakpoint if possible. */
+        if (*os_context_pc_addr(context) == (int)single_stepping + 1) {
+            fprintf(stderr, "warning: couldn't reinstall breakpoint\n");
+        } else {
+            *((char *)single_stepping) = BREAKPOINT_INST;       /* x86 INT3 */
+            *((char *)single_stepping+1) = trap_Breakpoint;
+        }
+
+        single_stepping = NULL;
+        return;
+    }
+
     /* This is just for info in case the monitor wants to print an
      * approximation. */
     current_control_stack_pointer =
         (lispobj *)*os_context_sp_addr(context);
 
+    /* FIXME: CMUCL puts the float control restoration code here.
+       Thus, it seems to me that single-stepping won't restore the
+       float control.  Since SBCL currently doesn't support
+       single-stepping (as far as I can tell) this is somewhat moot,
+       but it might be worth either moving this code up or deleting
+       the single-stepping code entirely.  -- CSR, 2002-07-15 */
 #ifdef LISP_FEATURE_LINUX
     os_restore_fp_control(context);
 #endif