[LV-kern-commit] CVS: kernel-2.4/arch/vax/kernel ptrace.c,1.4,1.5

[Dave A. <ai...@us...>]

Update of /cvsroot/linux-vax/kernel-2.4/arch/vax/kernel
In directory usw-pr-cvs1:/tmp/cvs-serv5459

Modified Files:
	ptrace.c 
Log Message:
DA: ptrace fixes for segfault


Index: ptrace.c
===================================================================
RCS file: /cvsroot/linux-vax/kernel-2.4/arch/vax/kernel/ptrace.c,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -r1.4 -r1.5
--- ptrace.c	2001/11/09 23:48:40	1.4
+++ ptrace.c	2001/11/13 23:31:16	1.5
@@ -28,17 +28,49 @@
 #include <asm/system.h>
 #include <asm/uaccess.h>
 
+#define VAX_MAX_DIST_BETWEEN_PC 20
+/*
+ * search out does damn regs.. that variable length exception info is evil I
+ * tell you evil.
+ */
+static struct pt_regs *ptrace_find_vax_regs(struct task_struct *child)
+{
+	struct pt_regs *regs_ptr;
+	unsigned long *pc1, *pc2;
+	void *stack_top;
+
+	stack_top = ((union task_union *)child)+1; 
+	stack_top -= 4;
+
+	
+	pc1 = (unsigned long *)stack_top - 2;
+	pc2 = pc1;
+	
+	//printk("pc1 is %8lX at %8lX\n", *pc1, pc1);
+	/* back step looking for second copy of PC */
+	do {
+		pc2 -= 1;
+	} while (*pc1!=*pc2 && pc1-pc2<VAX_MAX_DIST_BETWEEN_PC);
+
+	//printk("difference is %d\n", pc1-pc2);
+	
+	if (pc1-pc2>=VAX_MAX_DIST_BETWEEN_PC)
+		return NULL;
+
+	regs_ptr = ((void *)pc2) + 8 - sizeof(struct pt_regs);
+
+	return regs_ptr;
+}
+
 static int putreg(struct task_struct *child,
 	unsigned long regno, unsigned long value)
 {
   unsigned long retval = ~0UL;
-  void *stack_top;
   struct pt_regs *regs_ptr;
-  
-  stack_top = ((union task_union *)child)+1; 
-  stack_top -= 4;
   
-  regs_ptr = stack_top - 16 - sizeof(struct pt_regs);
+  regs_ptr = ptrace_find_vax_regs(child);
+  if (!regs_ptr)
+	  return 0;
 
   switch(regno >> 2) {
   case 0 ... 16:
@@ -59,18 +91,12 @@
 	unsigned long regno)
 {
 	unsigned long retval = ~0UL;
-	void *stack_top;
 	struct pt_regs *regs_ptr;
 	
-	stack_top = ((union task_union *)child)+1; 
-	stack_top -= 4;
-
-	/* get the registers from where we shoved them on the stack at the last 
-	   exception for this process.. not sure if this is always correct but 
-           will do for now - 4 longwords back from end of stack is end of regs */
-	
-	regs_ptr = stack_top - 16 - sizeof(struct pt_regs);
-
+	/* call helper function to get registers for the VAX */
+	regs_ptr = ptrace_find_vax_regs(child);
+  	if (!regs_ptr)
+		  return 0;
 
 	switch(regno >> 2) {
 	case 0 ... 16:
@@ -81,6 +107,7 @@
 	  retval=0;
 	  break;
 	}
+//	printk("getreg for %d returned %8lX\n", regno>>2, retval);
 	return retval;
 }