libvx32/FreeBSD: better handling of segmentation fault, breakpoint - vx32 - Local 9vx git repository for patches.

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---

commit c82f48a95967c71d4f81debf6ae9c15a3b60ebe9

parent d2d43ccb6890cbd0afaaa45a24db7b8d6b05129c

Author: Russ Cox 

Date:   Sun, 29 Jun 2008 21:46:25 -0400

libvx32/FreeBSD: better handling of segmentation fault, breakpoint

Diffstat:
  src/libvx32/freebsd.c               |      41 +++++++++++++++++--------------

1 file changed, 22 insertions(+), 19 deletions(-)
---

diff --git a/src/libvx32/freebsd.c b/src/libvx32/freebsd.c

@@ -157,13 +157,10 @@ int vx32_sighandler(int signo, siginfo_t *si, void *v)
         vxemu *emu;
         ucontext_t *uc;
         mcontext_t *mc;
-        uint32_t cr2;
 
         uc = v;
         mc = &uc->uc_mcontext;
 
-        cr2 = (uint32_t)si->si_addr;
-
         // We can't be sure that vxemu is running,
         // and thus that %VSEG is actually mapped to a
         // valid vxemu.  The only way to tell is to look at %VSEG.
@@ -207,39 +204,45 @@ int vx32_sighandler(int signo, siginfo_t *si, void *v)
         // so that thread-local storage and such works.
         vxrun_cleanup(emu);
         
-        // dumpmcontext(mc, cr2);
+        // dumpmcontext(mc, (uint32_t)si->si_addr);
 
+        uint32_t addr;
         int newtrap;
+        addr = 0;
         switch(signo){
         case SIGSEGV:
+                newtrap = VXTRAP_PAGEFAULT;
+                addr = (uint32_t)si->si_addr;
+                break;
         case SIGBUS:
+                /*
+                 * On FreeBSD, SIGBUS means segmentation limit fault.
+                 * The supplied address is bogus.
+                 */
                 newtrap = VXTRAP_PAGEFAULT;
+                addr = 0;
                 break;
         
         case SIGFPE:
-                // iprint("fpe %d\n", si->si_code);
+                // vxprint("fpe %d\n", si->si_code);
                 newtrap = VXTRAP_FLOAT;
+                addr = 0;
                 break;
         
         case SIGVTALRM:
                 newtrap = VXTRAP_IRQ + VXIRQ_TIMER;
+                addr = 0;
                 break;
 
         case SIGTRAP:
-#warning "FreeBSD: need to test single-stepping"
-                // Linux sends SIGTRAP when it gets a processor 
+                // FreeBSD sends SIGTRAP when it gets a processor 
                 // debug exception, which is caused by single-stepping
-                // with the TF bit, among other things.  The processor
-                // turns off the TF bit before generating the trap, but
-                // it appears that Linux turns it back on for us.
-                // Let's use it to confirm that this is a single-step trap.
-                if (mc->mc_eflags & EFLAGS_TF){
-                        newtrap = VXTRAP_SINGLESTEP;
-                        mc->mc_eflags &= ~EFLAGS_TF;
-                }else{
-                        vxprint("Unexpected sigtrap eflags=%#x\n", mc->mc_eflags);
-                        newtrap = VXTRAP_SIGNAL + signo;
-                }
+                // with the TF bit, among other things.  
+                // It appears that FreeBSD does not turn the flag back on
+                // before entering the signal handler.
+                addr = 0;
+                newtrap = VXTRAP_SINGLESTEP;
+                mc->mc_eflags &= ~EFLAGS_TF;        // Just in case.
                 break;
 
         default:
@@ -323,7 +326,7 @@ int vx32_sighandler(int signo, siginfo_t *si, void *v)
                 if (emu->trapenv == NULL)
                         return 0;
                 emu->cpu.traperr = mc->mc_err;
-                emu->cpu.trapva = cr2;
+                emu->cpu.trapva = addr;
                 memmove(&mc->mc_gs, &emu->trapenv->mc_gs, 19*4);
                 return 1;
         }