simx86: fix crash when FPU ins modifies code

BreakNode wasn't working correctly if the invalidation happened from
the sigsegv handler instead of via Cpatch().

Make sure InvalidateNodeRange gets the correct JITted code pointer (via pjit)
and if the node is broken, force an exit.

Fixes dosemu2#2708

Author: bartoldeman

src/base/emu-i386/simx86/sigsegv.c

@@ -320,7 +320,7 @@ int e_emu_fault(sigcontext_t *scp, int in_vm86)
 int e_handle_pagefault(dosaddr_t addr, unsigned err, sigcontext_t *scp)
 {
 	int v;
-	unsigned char *p;
+	unsigned char *p, *pjit;
 	int in_dosemu;
 
 	/* err:
@@ -366,12 +366,14 @@ int e_handle_pagefault(dosaddr_t addr, unsigned err, sigcontext_t *scp)
 	if (debug_level('e')) PageFaults++;
 #endif
 	in_dosemu = !(InCompiledCode || in_vm86 || DPMIValidSelector(_scp_cs));
+	p = (unsigned char *) _scp_rip;
+	pjit = InCompiledCode ? GetGenCodeBuf(p) : NULL;
 	if (in_vm86)
 		p = SEG_ADR((unsigned char *), cs, ip);
 	else if (DPMIValidSelector(_scp_cs))
 		p = (unsigned char *)EMU_BASE32(GetSegmentBase(_scp_cs) + _scp_rip);
-	else
-		p = GetGenCodeBuf((unsigned char *) _scp_rip);
+	else if (InCompiledCode)
+		p = pjit;
 	if (debug_level('e')>1 || in_dosemu) {
 		v = *((int *)p);
 		__asm__("bswap %0" : "=r" (v) : "0" (v));
@@ -404,7 +406,9 @@ int e_handle_pagefault(dosaddr_t addr, unsigned err, sigcontext_t *scp)
 	/* We HAVE to invalidate all the code in the page
 	 * if the page is going to be unprotected */
 	addr &= _PAGE_MASK;
-	return InvalidateNodeRange(addr, PAGE_SIZE, p);
+	int ret = InvalidateNodeRange(addr, PAGE_SIZE, pjit);
+	if (TheCPU.err == EXCP_BREAKNODE) e_return_from_jit(scp, 1);
+	return ret;
 }
 
 int e_handle_fault(sigcontext_t *scp)