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- add patch from SF #704181 bochs-2.0.win32 CPU interrupt function

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fixes a bug in exception handling in v8086 mode

  Here are comments from the author:
   Since the bug of bochs-2.0.win32 was found and
   corrected, it reports. cpu/exception.cpp of src : Within
   an interrupt() function, when present is the V8086 mode,
   a bug is in the portion which processes 386 (286)
   int/trap gate. From the V8086 mode, this portion is
   performed, when it is going to execute an int imm
   command. The portion in which push_32 () is called in
   the state of VM=1 is still a mistake. Although this
   push_32 () tends to write in to the stack of a protected
   mode, if it is still VM=1 of EFLAGS, the
   write_virtual_dword() function called out of push_32 () will
   take out a segment protection exception. After
   performing clear_VM() etc., it is necessary to make it
   call push_32 () correctly, since EFLAGS is saved locally.
This commit is contained in:
Christophe Bothamy 2003-08-08 00:20:44 +00:00
parent a7f871221b
commit 8b6669674d
1 changed files with 121 additions and 0 deletions
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121
bochs/patches/patch.v8086-exception.lightcone Executable file
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@ -0,0 +1,121 @@
----------------------------------------------------------------------
Patch name: patch.v8086-exception.lightcone
Author: LightCone
Date: Thu Aug 7 2003
Status: Proposed
Detailed description:
This is a reformat of SF patch #704181 CPU interrupt function
Here is what the author wrote:
Since the bug of bochs-2.0.win32 was found and
corrected, it reports. cpu/exception.cpp of src : Within
an interrupt() function, when present is the V8086 mode,
a bug is in the portion which processes 386 (286)
int/trap gate. From the V8086 mode, this portion is
performed, when it is going to execute an int imm
command. The portion in which push_32 () is called in
the state of VM=1 is still a mistake. Although this
push_32 () tends to write in to the stack of a protected
mode, if it is still VM=1 of EFLAGS, the
write_virtual_dword() function called out of push_32 () will
take out a segment protection exception. After
performing clear_VM() etc., it is necessary to make it
call push_32 () correctly, since EFLAGS is saved locally.
Patch was created with:
cvs diff -u
Apply patch to what version:
cvs checked out on Thu Aug 7 2003
Instructions:
To patch, go to main bochs directory.
Type "patch -p0 < THIS_PATCH_FILE".
----------------------------------------------------------------------
Index: cpu/exception.cc
===================================================================
RCS file: /cvsroot/bochs/bochs/cpu/exception.cc,v
retrieving revision 1.33
diff -u -r1.33 exception.cc
--- cpu/exception.cc 26 Feb 2003 02:48:12 -0000 1.33
+++ cpu/exception.cc 7 Aug 2003 09:02:24 -0000
@@ -637,9 +637,23 @@
// set RPL of CS to CPL
load_cs(&cs_selector, &cs_descriptor, cs_descriptor.dpl);
EIP = gate_dest_offset;
+
+ // Modified by LightCone
+ Bit32u old_EFLAGS= read_eflags();
+ bx_bool bV8086Mode= v8086_mode();
+
+ // if INTERRUPT GATE set IF to 0
+ if ( !(gate_descriptor.type & 1) ) {// even is int-gate
+ BX_CPU_THIS_PTR clear_IF ();
+ }
+ BX_CPU_THIS_PTR clear_TF ();
+ BX_CPU_THIS_PTR clear_VM ();
+ BX_CPU_THIS_PTR clear_RF ();
+ BX_CPU_THIS_PTR clear_NT ();
+
if (gate_descriptor.type>=14) { // 386 int/trap gate
- if (v8086_mode()) {
+ if (bV8086Mode) {
push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_GS].selector.value);
push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_FS].selector.value);
push_32(BX_CPU_THIS_PTR sregs[BX_SEG_REG_DS].selector.value);
@@ -653,46 +667,43 @@
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].cache.valid = 0;
BX_CPU_THIS_PTR sregs[BX_SEG_REG_ES].selector.value = 0;
}
+
// push long pointer to old stack onto new stack
push_32(old_SS);
push_32(old_ESP);
// push EFLAGS
- push_32(read_eflags());
+ push_32(old_EFLAGS);
// push long pointer to return address onto new stack
push_32(old_CS);
push_32(old_EIP);
- if ( is_error_code )
+ if ( is_error_code ) {
push_32(error_code);
+ }
}
else { // 286 int/trap gate
- if (v8086_mode()) {
+ if (bV8086Mode) {
BX_PANIC(("286 int/trap gate, VM"));
}
+
// push long pointer to old stack onto new stack
push_16(old_SS);
push_16(old_ESP); // ignores upper 16bits
// push FLAGS
- push_16(read_flags());
+ push_16((Bit16u)old_EFLAGS);
// push return address onto new stack
push_16(old_CS);
push_16(old_EIP); // ignores upper 16bits
- if ( is_error_code )
+ if ( is_error_code ) {
push_16(error_code);
+ }
}
- // if INTERRUPT GATE set IF to 0
- if ( !(gate_descriptor.type & 1) ) // even is int-gate
- BX_CPU_THIS_PTR clear_IF ();
- BX_CPU_THIS_PTR clear_TF ();
- BX_CPU_THIS_PTR clear_VM ();
- BX_CPU_THIS_PTR clear_RF ();
- BX_CPU_THIS_PTR clear_NT ();
return;
}