[Xen-changelog] [xen master] xen/arm64: fix stack dump in show_trace

[patchbot@xxxxxxx]

commit 97e3e84c6dfa94f09b97d21454d4252fc3c190d8
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Tue Jun 4 11:54:10 2013 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Jun 13 17:42:13 2013 +0100

    xen/arm64: fix stack dump in show_trace
    
    On aarch64 the frame pointer points to the next frame pointer and the return
    address is the previous stack slot (so below on the downward growing stack,
    therefore above in memory):
    
           |<RETURN ADDR>      ^addresses grow up
     FP -> |<NEXT FP>          |
           |                   |
           v                   |
           stack grows down.
    
    This is contrary to aarch32 where the frame pointer points to the return
    address and the next frame pointer is the next stack slot (so above on the
    downward growing stack, below in memory):
    
     FP -> |<RETURN ADDR>       ^addresses grow up
           |<NEXT FP>           |
           |                    |
           v                    |
           stack grows down.
    
    In addition print out LR as part of the trace, since it may contain the
    penultimate return address e.g. if the ultimate function is a leaf function.
    
    Lastly nuke some unnecessary braces.
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 xen/arch/arm/traps.c |   69 +++++++++++++++++++++++++++++++------------------
 1 files changed, 44 insertions(+), 25 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 83a7fbc..398d209 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -519,7 +519,41 @@ static void show_guest_stack(struct cpu_user_regs *regs)
 }
 
 #define STACK_BEFORE_EXCEPTION(regs) ((register_t*)(regs)->sp)
-
+#ifdef CONFIG_ARM_32
+/* Frame pointer points to the return address:
+ * (largest address)
+ * | cpu_info
+ * | [...]                                   |
+ * | return addr      <-----------------,    |
+ * | fp --------------------------------+----'
+ * | [...]                              |
+ * | return addr      <------------,    |
+ * | fp ---------------------------+----'
+ * | [...]                         |
+ * | return addr      <- regs->fp  |
+ * | fp ---------------------------'
+ * |
+ * v (smallest address, sp)
+ */
+#define STACK_FRAME_BASE(fp)       ((register_t*)(fp) - 1)
+#else
+/* Frame pointer points to the next frame:
+ * (largest address)
+ * | cpu_info
+ * | [...]                                   |
+ * | return addr                             |
+ * | fp <-------------------------------, >--'
+ * | [...]                              |
+ * | return addr                        |
+ * | fp <--------------------------, >--'
+ * | [...]                         |
+ * | return addr      <- regs->fp  |
+ * | fp ---------------------------'
+ * |
+ * v (smallest address, sp)
+ */
+#define STACK_FRAME_BASE(fp)       ((register_t*)(fp))
+#endif
 static void show_trace(struct cpu_user_regs *regs)
 {
     register_t *frame, next, addr, low, high;
@@ -527,29 +561,15 @@ static void show_trace(struct cpu_user_regs *regs)
     printk("Xen call trace:\n   ");
 
     printk("[<%p>]", _p(regs->pc));
-    print_symbol(" %s\n   ", regs->pc);
+    print_symbol(" %s (PC)\n   ", regs->pc);
+    printk("[<%p>]", _p(regs->lr));
+    print_symbol(" %s (LR)\n   ", regs->lr);
 
     /* Bounds for range of valid frame pointer. */
-    low  = (register_t)(STACK_BEFORE_EXCEPTION(regs)/* - 2*/);
+    low  = (register_t)(STACK_BEFORE_EXCEPTION(regs));
     high = (low & ~(STACK_SIZE - 1)) +
         (STACK_SIZE - sizeof(struct cpu_info));
 
-    /* Frame:
-     * (largest address)
-     * | cpu_info
-     * | [...]                                   |
-     * | return addr      <-----------------,    |
-     * | fp --------------------------------+----'
-     * | [...]                              |
-     * | return addr      <------------,    |
-     * | fp ---------------------------+----'
-     * | [...]                         |
-     * | return addr      <- regs->fp  |
-     * | fp ---------------------------'
-     * |
-     * v (smallest address, sp)
-     */
-
     /* The initial frame pointer. */
     next = regs->fp;
 
@@ -557,12 +577,11 @@ static void show_trace(struct cpu_user_regs *regs)
     {
         if ( (next < low) || (next >= high) )
             break;
-        {
-            /* Ordinary stack frame. */
-            frame = (register_t *)next;
-            next  = frame[-1];
-            addr  = frame[0];
-        }
+
+        /* Ordinary stack frame. */
+        frame = STACK_FRAME_BASE(next);
+        next  = frame[0];
+        addr  = frame[1];
 
         printk("[<%p>]", _p(addr));
         print_symbol(" %s\n   ", addr);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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