4 files changed, 28 insertions, 11 deletions

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 1cb3501636d2..ca2de1b48fac 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -32,13 +32,14 @@ struct thread_info {
         mm_segment_t            addr_limit;
         struct restart_block    restart_block;
         void __user             *sysenter_return;
+        unsigned int            sig_on_uaccess_error:1;
+        unsigned int            uaccess_err:1;  /* uaccess failed */
 #ifdef CONFIG_X86_32
         unsigned long           previous_esp;   /* ESP of the previous stack in
                                                    case of nested (IRQ) stacks
+                                                   (Moved to end, to be removed soon)
                                                 */
 #endif
-        unsigned int            sig_on_uaccess_error:1;
-        unsigned int            uaccess_err:1;  /* uaccess failed */
 };
 
 #define INIT_THREAD_INFO(tsk)                   \
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index f2a1770ca176..187d6a749c19 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -22,6 +22,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                 const struct stacktrace_ops *ops, void *data)
 {
         int graph = 0;
+        u32 *prev_esp;
 
         if (!task)
                 task = current;
@@ -44,9 +45,17 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                         ((unsigned long)stack & (~(THREAD_SIZE - 1)));
                 bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);
 
-                stack = (unsigned long *)context->previous_esp;
+                /* Stop if not on irq stack */
+                if (task_stack_page(task) == context)
+                        break;
+
+                /* The previous esp is just above the context */
+                prev_esp = (u32 *) ((char *)context + sizeof(struct thread_info) -
+                                    sizeof(long));
+                stack = (unsigned long *)*prev_esp;
                 if (!stack)
                         break;
+
                 if (ops->stack(data, "IRQ") < 0)
                         break;
                 touch_nmi_watchdog();
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index d7fcbedc9c43..f135cc2ff301 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -81,7 +81,7 @@ static inline int
 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
 {
         union irq_ctx *curctx, *irqctx;
-        u32 *isp, arg1, arg2;
+        u32 *isp, *prev_esp, arg1, arg2;
 
         curctx = (union irq_ctx *) current_thread_info();
         irqctx = __this_cpu_read(hardirq_ctx);
@@ -98,7 +98,10 @@ execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
         /* build the stack frame on the IRQ stack */
         isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
         irqctx->tinfo.task = curctx->tinfo.task;
-        irqctx->tinfo.previous_esp = current_stack_pointer;
+        /* Save the next esp after thread_info */
+        prev_esp = (u32 *) ((char *)irqctx + sizeof(struct thread_info) -
+                            sizeof(long));
+        *prev_esp = current_stack_pointer;
 
         if (unlikely(overflow))
                 call_on_stack(print_stack_overflow, isp);
@@ -149,16 +152,20 @@ void do_softirq_own_stack(void)
 {
         struct thread_info *curctx;
         union irq_ctx *irqctx;
-        u32 *isp;
+        u32 *isp, *prev_esp;
 
         curctx = current_thread_info();
         irqctx = __this_cpu_read(softirq_ctx);
         irqctx->tinfo.task = curctx->task;
-        irqctx->tinfo.previous_esp = current_stack_pointer;
 
         /* build the stack frame on the softirq stack */
         isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
 
+        /* Push the previous esp onto the stack */
+        prev_esp = (u32 *) ((char *)irqctx + sizeof(struct thread_info) -
+                            sizeof(long));
+        *prev_esp = current_stack_pointer;
+
         call_on_stack(__do_softirq, isp);
 }
 
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7461f50d5bb1..f352a7cc43a1 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -184,14 +184,14 @@ unsigned long kernel_stack_pointer(struct pt_regs *regs)
 {
         unsigned long context = (unsigned long)regs & ~(THREAD_SIZE - 1);
         unsigned long sp = (unsigned long)&regs->sp;
-        struct thread_info *tinfo;
+        u32 *prev_esp;
 
         if (context == (sp & ~(THREAD_SIZE - 1)))
                 return sp;
 
-        tinfo = (struct thread_info *)context;
-        if (tinfo->previous_esp)
-                return tinfo->previous_esp;
+        prev_esp = (u32 *)(context + sizeof(struct thread_info) - sizeof(long));
+        if (prev_esp)
+                return (unsigned long)prev_esp;
 
         return (unsigned long)regs;
 }