x86/stack: adjust boundary conditions for printed stacks

Move the boundary into current.h along with the other stack manipulation code.
The boundary is now the word adjacent to a struct cpu_info on the stack.

This also fixes the somewhat spurious bounds for the case with frame pointers.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 8a01065408352bd42e00b4307cdcf6057a721718..e7cfa3ea28931cdc524daf9a6e991164681d14c5 100644 (file)
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -203,8 +203,9 @@ static void show_guest_stack(struct vcpu *v, struct cpu_user_regs *regs)
 static void _show_trace(unsigned long sp, unsigned long __maybe_unused bp)
 {
     unsigned long *stack = (unsigned long *)sp, addr;
+    unsigned long *bottom = (unsigned long *)get_printable_stack_bottom(sp);
 
-    while ( ((long)stack & (STACK_SIZE-BYTES_PER_LONG)) != 0 )
+    while ( stack <= bottom )
     {
         addr = *stack++;
         if ( is_active_kernel_text(addr) )
@@ -217,12 +218,10 @@ static void _show_trace(unsigned long sp, unsigned long __maybe_unused bp)
 /* Stack trace from frames in the stack, using frame pointers */
 static void _show_trace(unsigned long sp, unsigned long bp)
 {
-    unsigned long *frame, next, addr, low, high;
+    unsigned long *frame, next, addr;
 
     /* Bounds for range of valid frame pointer. */
-    low  = sp - 2*sizeof(unsigned long);
-    high = (low & ~(STACK_SIZE - 1)) + 
-        (STACK_SIZE - sizeof(struct cpu_info) - 2*sizeof(unsigned long));
+    unsigned long low = sp, high = get_printable_stack_bottom(sp);
 
     /* The initial frame pointer. */
     next = bp;

diff --git a/xen/include/asm-x86/current.h b/xen/include/asm-x86/current.h
index bec4dbe792ce0ddb11951589379d49177e55ef9b..c2792ce139a51e119c8743fa3a61963e22ee9e0f 100644 (file)
--- a/xen/include/asm-x86/current.h
+++ b/xen/include/asm-x86/current.h
@@ -50,6 +50,15 @@ static inline struct cpu_info *get_cpu_info(void)
 #define get_stack_bottom()                      \
     ((unsigned long)&get_cpu_info()->guest_cpu_user_regs.es)
 
+/*
+ * Get the bottom-of-stack, as useful for printing stack traces.  This is the
+ * highest word on the stack which might be part of a stack trace, and is the
+ * adjacent word to a struct cpu_info on the stack.
+ */
+#define get_printable_stack_bottom(sp)          \
+    ((sp & (~(STACK_SIZE-1))) +                 \
+     (STACK_SIZE - sizeof(struct cpu_info) - sizeof(unsigned long)))
+
 #define reset_stack_and_jump(__fn)              \
     __asm__ __volatile__ (                      \
         "mov %0,%%"__OP"sp; jmp %c1"            \