From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 9 Sep 2006 16:53:56 +0000 (+0000)
Subject: Fix issue reported by Godmar Back:
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?p=pintos-anon;a=commitdiff_plain;h=2b4b1acd2d80945294b8786396251857005c0a81

Fix issue reported by Godmar Back:

    I may have found a problem with the triple fault patch, though I don't
    know how to solve it.
    If you add a *(int *)0=42 right after paging_init(), but before
    intr_init(), gdb will just hang:

...

    where it hangs while Pintos prints:

    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    Triple fault: stopping for gdb
    etc.

    It stops properly if I don't next-step (that is, if I just let it run.)
---

diff --git a/src/misc/bochs-2.2.6-triple-fault.patch b/src/misc/bochs-2.2.6-triple-fault.patch
index 06da80e..f6d0871 100644
--- a/src/misc/bochs-2.2.6-triple-fault.patch
+++ b/src/misc/bochs-2.2.6-triple-fault.patch
@@ -1,30 +1,57 @@
---- bochs-2.2.6.orig/cpu/exception.cc 2006-01-25 14:20:00.000000000 -0800
-+++ bochs-2.2.6/cpu/exception.cc 2006-04-08 13:01:18.000000000 -0700
-@@ -841,6 +841,12 @@ void BX_CPU_C::exception(unsigned vector
+diff -u bochs-2.2.6.orig/cpu/exception.cc bochs-2.2.6/cpu/exception.cc
+--- bochs-2.2.6.orig/cpu/exception.cc
++++ bochs-2.2.6/cpu/exception.cc
+@@ -841,6 +841,13 @@ void BX_CPU_C::exception(unsigned vector
  
    BX_CPU_THIS_PTR errorno++;
    if (BX_CPU_THIS_PTR errorno >= 3) {
 +#if BX_GDBSTUB
 +    if (bx_dbg.gdbstub_enabled) {
 +        fprintf(stderr, "Triple fault: stopping for gdb\n");
++        BX_CPU_THIS_PTR ispanic = 1;
 +        longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1);
 +    }
 +#endif
  #if BX_RESET_ON_TRIPLE_FAULT
      BX_ERROR(("exception(): 3rd (%d) exception with no resolution, shutdown status is %02xh, resetting", vector, DEV_cmos_get_reg(0x0f)));
      debug(BX_CPU_THIS_PTR prev_eip);
-@@ -860,6 +866,12 @@ void BX_CPU_C::exception(unsigned vector
+@@ -860,6 +867,13 @@ void BX_CPU_C::exception(unsigned vector
  
    /* if 1st was a double fault (software INT?), then shutdown */
    if ( (BX_CPU_THIS_PTR errorno==2) && (BX_CPU_THIS_PTR curr_exception[0]==BX_ET_DOUBLE_FAULT) ) {
 +#if BX_GDBSTUB
 +    if (bx_dbg.gdbstub_enabled) {
 +        fprintf(stderr, "Triple fault: stopping for gdb\n");
++        BX_CPU_THIS_PTR ispanic = 1;
 +        longjmp(BX_CPU_THIS_PTR jmp_buf_env, 1);
 +    }
 +#endif
  #if BX_RESET_ON_TRIPLE_FAULT
      BX_INFO(("exception(): triple fault encountered, shutdown status is %02xh, resetting", DEV_cmos_get_reg(0x0f)));
      debug(BX_CPU_THIS_PTR prev_eip);
-
-Diff finished at Sat Apr  8 13:07:40
+diff -u bochs-2.2.6.orig/gdbstub.cc bochs-2.2.6/gdbstub.cc
+--- bochs-2.2.6.orig/gdbstub.cc
++++ bochs-2.2.6/gdbstub.cc
+@@ -466,19 +466,19 @@ static void debug_loop(void)
+                  
+                  BX_INFO (("stepping"));
+                  stub_trace_flag = 1;
++                 bx_cpu.ispanic = 0;
+                  bx_cpu.cpu_loop(-1);
+                  DEV_vga_refresh();
+                  stub_trace_flag = 0;
+                  BX_INFO (("stopped with %x", last_stop_reason));
+                  buf[0] = 'S';
+-                 if (last_stop_reason == GDBSTUB_EXECUTION_BREAKPOINT ||
+-                     last_stop_reason == GDBSTUB_TRACE)
++                 if (last_stop_reason == GDBSTUB_TRACE && !bx_cpu.ispanic)
+                    {
+                       write_signal(&buf[1], SIGTRAP);
+                    }
+                  else
+                    {
+-                      write_signal(&buf[1], SIGTRAP);
++                      write_signal(&buf[1], SIGSEGV);
+                    }
+                  put_reply(buf);
+                  break;