[src/trunk]: src/sys/arch/alpha/alpha - Clean up ddb_trap() somewhat, and han...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/bd7490850cbe
branches:  trunk
changeset: 472092:bd7490850cbe
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Tue Apr 20 21:19:48 1999 +0000

description:
- Clean up ddb_trap() somewhat, and handle exceptions that happen while we're
  in DDB (e.g. if a bad pointer was dereferenced; the debugger will recover).
- Change a comment to indicate that we are on the debugger stack when we get
  to ddb_trap().
- Fix possible buglet in computation of the branch target in db_branch_taken().

diffstat:

 sys/arch/alpha/alpha/db_interface.c |  52 ++++++++----------------------------
 1 files changed, 12 insertions(+), 40 deletions(-)

diffs (117 lines):

diff -r 27553949a8cf -r bd7490850cbe sys/arch/alpha/alpha/db_interface.c
--- a/sys/arch/alpha/alpha/db_interface.c       Tue Apr 20 21:16:59 1999 +0000
+++ b/sys/arch/alpha/alpha/db_interface.c       Tue Apr 20 21:19:48 1999 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: db_interface.c,v 1.5 1999/04/06 20:09:18 pk Exp $ */
+/* $NetBSD: db_interface.c,v 1.6 1999/04/20 21:19:48 thorpej Exp $ */
 
 /* 
  * Mach Operating System
@@ -51,7 +51,7 @@
 
 #include <sys/cdefs.h>                 /* RCS ID & Copyright macro defns */
 
-__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.5 1999/04/06 20:09:18 pk Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.6 1999/04/20 21:19:48 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/proc.h>
@@ -86,9 +86,6 @@
 
 int    db_active = 0;
 
-void   ddbprinttrap __P((unsigned long, unsigned long, unsigned long,
-           unsigned long));
-
 void   db_mach_halt __P((db_expr_t, int, db_expr_t, char *));
 void   db_mach_reboot __P((db_expr_t, int, db_expr_t, char *));
 
@@ -138,21 +135,7 @@
 struct db_variable *db_eregs = db_regs + sizeof(db_regs)/sizeof(db_regs[0]);
 
 /*
- * Print trap reason.
- */
-void
-ddbprinttrap(a0, a1, a2, entry)
-       unsigned long a0, a1, a2, entry;
-{
-
-       /* XXX Implement. */
-
-       printf("ddbprinttrap(0x%lx, 0x%lx, 0x%lx, 0x%lx)\n", a0, a1, a2,
-           entry);
-}
-
-/*
- *  ddb_trap - field a kernel trap
+ * ddb_trap - field a kernel trap
  */
 int
 ddb_trap(a0, a1, a2, entry, regs)
@@ -161,25 +144,11 @@
 {
        int s;
 
-       /*
-        * Don't bother checking for usermode, since a benign entry
-        * by the kernel (call to Debugger() or a breakpoint) has
-        * already checked for usermode.  If neither of those
-        * conditions exist, something Bad has happened.
-        */
-
        if (entry != ALPHA_KENTRY_IF ||
-           (a0 != ALPHA_IF_CODE_BUGCHK && a0 != ALPHA_IF_CODE_BPT)) {
-               db_printf("ddbprinttrap from 0x%lx\n",  /* XXX */
-                   regs->tf_regs[FRAME_PC]);
-               ddbprinttrap(a0, a1, a2, entry);
+           (a0 != ALPHA_IF_CODE_BPT && a0 != ALPHA_IF_CODE_BUGCHK)) {
                if (db_recover != 0) {
-                       /*
-                        * XXX Sould longjump back into command loop!
-                        */
-                       db_printf("Faulted in DDB; continuing...\n");
-                       alpha_pal_halt();               /* XXX */
-                       db_error("Faulted in DDB; continuing...\n");
+                       /* This will longjmp back into db_command_loop() */
+                       db_error("Caught exception in ddb.\n");
                        /* NOTREACHED */
                }
 
@@ -191,7 +160,7 @@
        }
 
        /*
-        * XXX Should switch to DDB's own stack, here.
+        * alpha_debug() switches us to the debugger stack.
         */
 
        ddb_regs = *regs;
@@ -252,7 +221,8 @@
 void
 Debugger()
 {
-       asm("call_pal 0x81");           /* XXX bugchk */
+
+       __asm __volatile("call_pal 0x81");              /* bugchk */
 }
 
 /*
@@ -524,6 +494,7 @@
        db_addr_t pc;
        db_regs_t *regs;
 {
+       long signed_immediate;
        alpha_instruction insn;
        db_addr_t newpc;
 
@@ -556,7 +527,8 @@
        case op_bne:
        case op_bge:
        case op_bgt:
-               newpc = (insn.branch_format.displacement << 2) + (pc + 4);
+               signed_immediate = insn.branch_format.displacement;
+               newpc = (pc + 4) + (signed_immediate << 2);
                break;
 
        default: