- I applied the patch, so I'm deleting it from here.
This commit is contained in:
Bryce Denney
parent
de51eda5d1
commit
97bfcd24bc
@ -1,139 +0,0 @@
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----------------------------------------------------------------------
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Patch name: patch.triple-fault-recover
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Author: Bryce Denney
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Date: Tue Mar 12 01:10:48 EST 2002
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Detailed description:
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See SF bug [ #526484 ] simulator dumps core
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When a triple fault occurs, Bochs panics. If you continue through the panic,
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it will generally produce another exception and panic again at an even deeper
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stack level. To recover from this potentially infinite recursion, I set
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a boolean variable called special_unwind_stack to true. This variable causes
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the interrupt() and exception() functions to return immediately instead of
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creating more exception conditions, and allows the user to reenter the debugger
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after the triple fault. Note that special_unwind_stack causes bochs to NOT
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emulate the hardware behavior correctly. The correct behavior would be to
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reboot. (Rebooting, if it is ever implemented, will need some kind of
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unwinding too.)
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Patch was created with:
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cvs diff -u
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Apply patch to what version:
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current cvs
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Instructions:
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To patch, go to main bochs directory.
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Type "patch -p0 < THIS_PATCH_FILE".
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----------------------------------------------------------------------
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? debug/Makefile
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? debug/.debug.h.swp
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? cpu/Makefile
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Index: debug/dbg_main.cc
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===================================================================
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RCS file: /cvsroot/bochs/bochs/debug/dbg_main.cc,v
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retrieving revision 1.37
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diff -u -r1.37 dbg_main.cc
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--- debug/dbg_main.cc 15 Feb 2002 22:58:06 -0000 1.37
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+++ debug/dbg_main.cc 12 Mar 2002 09:11:00 -0000
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@@ -1520,6 +1520,7 @@
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#if BX_NUM_SIMULATORS >= 2
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bx_guard.interrupt_requested = 0;
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+ bx_guard.special_unwind_stack = 0;
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while (1) {
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if ( !bx_dbg_cosimulateN(bx_debugger.icount_quantum) )
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break;
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@@ -1533,6 +1534,7 @@
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bx_guard.interrupt_requested = 0;
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+ bx_guard.special_unwind_stack = 0;
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int stop = 0;
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int which = -1;
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while (!stop) {
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@@ -1608,6 +1610,7 @@
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#if BX_NUM_SIMULATORS >= 2
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bx_guard.interrupt_requested = 0;
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+ bx_guard.special_unwind_stack = 0;
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bx_dbg_cosimulateN(count);
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#else
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// single CPU
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Index: debug/debug.h
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===================================================================
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RCS file: /cvsroot/bochs/bochs/debug/debug.h,v
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retrieving revision 1.10
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diff -u -r1.10 debug.h
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--- debug/debug.h 28 Nov 2001 18:37:12 -0000 1.10
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+++ debug/debug.h 12 Mar 2002 09:11:00 -0000
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@@ -257,6 +257,18 @@
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// user typed Ctrl-C, requesting simulator stop at next convient spot
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volatile Boolean interrupt_requested;
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+ // when a triple fault occurs, Bochs panics. If you continue through
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+ // the panic, it will generally produce another exception and panic
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+ // again at an even deeper stack level. To recover from this potentially
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+ // infinite recursion, I set special_unwind_stack to true. This causes
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+ // the interrupt() and exception() functions to return immediately instead
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+ // of creating more exception conditions, and allows the user to reenter the
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+ // debugger after the triple fault. Note that special_unwind_stack causes
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+ // bochs to NOT emulate the hardware behavior correctly. The correct
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+ // behavior would be to reboot. (Rebooting, if it is ever implemented,
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+ // will need some kind of unwinding too.)
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+ Boolean special_unwind_stack;
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+
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// booleans to control whether simulator should report events
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// to debug controller
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struct {
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Index: cpu/exception.cc
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===================================================================
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RCS file: /cvsroot/bochs/bochs/cpu/exception.cc,v
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retrieving revision 1.9
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diff -u -r1.9 exception.cc
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--- cpu/exception.cc 3 Oct 2001 13:10:37 -0000 1.9
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+++ cpu/exception.cc 12 Mar 2002 09:11:01 -0000
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@@ -63,6 +63,10 @@
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#endif
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#endif
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+ if (bx_guard.special_unwind_stack) {
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+ BX_INFO (("interrupt() returning early because special_unwind_stack is set"));
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+ return;
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+ }
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//BX_DEBUG(( "::interrupt(%u)", vector ));
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BX_INSTR_INTERRUPT(vector);
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@@ -572,6 +576,11 @@
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Bit8u exception_type;
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unsigned prev_errno;
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+ if (bx_guard.special_unwind_stack) {
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+ BX_INFO (("exception() returning early because special_unwind_stack is set"));
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+ return;
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+ }
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+
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//BX_DEBUG(( "::exception(%u)", vector ));
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BX_INSTR_EXCEPTION(vector);
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@@ -593,6 +602,9 @@
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BX_CPU_THIS_PTR errorno++;
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if (BX_CPU_THIS_PTR errorno >= 3) {
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BX_PANIC(("exception(): 3rd exception with no resolution"));
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+ BX_ERROR(("WARNING: Any simulation after this point is completely bogus."));
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+ bx_guard.special_unwind_stack = true;
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+ return;
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}
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/* careful not to get here with curr_exception[1]==DOUBLE_FAULT */
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@@ -600,7 +612,10 @@
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/* if 1st was a double fault (software INT?), then shutdown */
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if ( (BX_CPU_THIS_PTR errorno==2) && (BX_CPU_THIS_PTR curr_exception[0]==BX_ET_DOUBLE_FAULT) ) {
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- BX_PANIC(("exception(): tripple fault encountered"));
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+ BX_PANIC(("exception(): triple fault encountered"));
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+ BX_ERROR(("WARNING: Any simulation after this point is completely bogus."));
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+ bx_guard.special_unwind_stack = true;
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+ return;
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}
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/* ??? this is not totally correct, should be done depending on
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