[openfirmware] r1007 - cpu/x86

[svn at openfirmware.info]

Author: wmb
Date: 2008-11-17 21:53:53 +0100 (Mon, 17 Nov 2008)
New Revision: 1007

Modified:
   cpu/x86/cpubpsup.fth
   cpu/x86/dtacc.fth
Log:
x86 assembly language debugger - use hardware breakpoint mode when
running standalone, so that single-stepping RET and indirect JMP/CALL
instructions works.  Also support single-stepping RET in software
breakpoint mode (supporting indirect JMP/CALL is hard, requiring full
effective address evaluation, so we don't do it yet).


Modified: cpu/x86/cpubpsup.fth
===================================================================
--- cpu/x86/cpubpsup.fth	2008-11-15 03:06:06 UTC (rev 1006)
+++ cpu/x86/cpubpsup.fth	2008-11-17 20:53:53 UTC (rev 1007)
@@ -10,6 +10,8 @@
 
 : .instruction  ( -- )  %eip pc!dis1  ;
 
+true value hardware-step?   \ True if the environment permits hardware single-step
+
 also hidden also definitions
 
 headerless
@@ -55,10 +57,25 @@
 \ addressing mode bytes.  Returns the address following those addressing
 \ mode bytes, or step-adr if the instruction is not a call or if following-
 \ jsrs is true.
-true value hardware-step?   \ True if the environment permits hardware single-step
+
+: jmp-indirect?  ( -- false | pc1 pc2 true )
+   %eip c@  h# fe and  h# c2 =  if   \ RET NEAR
+      %esp l@  0  true  exit
+   then
+
+   %eip c@  h# ff and  if
+      %eip 1+ c@  3 rshift 7 and  2 5 between  if
+         ." Single-stepping indirect call/jmp doesn't work in software breakpoint mode" cr
+      then
+   then
+   false
+;
+
 : find-successors  ( -- pc1 pc2 )
    hardware-step?  if  step-adr 0  exit  then
 
+   jmp-indirect?  if  exit  then
+
    ['] cr behavior >r  ['] type behavior >r
    ['] noop to cr  ['] 2drop to type
    [ also disassembler ] %eip pc!dis1  pc @  branch-target @  [ previous ]

Modified: cpu/x86/dtacc.fth
===================================================================
--- cpu/x86/dtacc.fth	2008-11-15 03:06:06 UTC (rev 1006)
+++ cpu/x86/dtacc.fth	2008-11-17 20:53:53 UTC (rev 1007)
@@ -42,6 +42,7 @@
 
 stand-init: Exceptions
    make-idt  stand-set-idt  move-gdt
+   true to hardware-step?
 ;
 
 \ LICENSE_BEGIN