[Xen-changelog] [xen master] x86/stack: adjust boundary conditions for printed stacks

[patchbot@xxxxxxx]

commit cc2f01e602d9310f88625b4bdb4dc4ae179f2751
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Nov 22 13:37:25 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Nov 22 13:37:25 2013 +0100

    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@xxxxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/traps.c          |    9 ++++-----
 xen/include/asm-x86/current.h |    9 +++++++++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 8a01065..e7cfa3e 100644
--- 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 bec4dbe..c2792ce 100644
--- 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"            \
--
generated by git-patchbot for /home/xen/git/xen.git#master

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