#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
+#include <asm/uaccess.h>
struct frame_head {
struct frame_head * ebp;
} __attribute__((packed));
static struct frame_head *
-dump_backtrace(struct frame_head * head)
+dump_kernel_backtrace(struct frame_head * head)
{
oprofile_add_trace(head->ret);
return head->ebp;
}
-/* check that the page(s) containing the frame head are present */
-static int pages_present(struct frame_head * head)
+static struct frame_head *
+dump_user_backtrace(struct frame_head * head)
{
- struct mm_struct * mm = current->mm;
+ struct frame_head bufhead[2];
- /* FIXME: only necessary once per page */
- if (!check_user_page_readable(mm, (unsigned long)head))
- return 0;
+ /* Also check accessibility of one struct frame_head beyond */
+ if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
+ return NULL;
+ if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+ return NULL;
- return check_user_page_readable(mm, (unsigned long)(head + 1));
+ oprofile_add_trace(bufhead[0].ret);
+
+ /* frame pointers should strictly progress back up the stack
+ * (towards higher addresses) */
+ if (head >= bufhead[0].ebp)
+ return NULL;
+
+ return bufhead[0].ebp;
}
/*
* | stack |
* --------------- saved regs->ebp value if valid (frame_head address)
* . .
- * --------------- struct pt_regs stored on stack (struct pt_regs *)
+ * --------------- saved regs->rsp value if x86_64
+ * | |
+ * --------------- struct pt_regs * stored on stack if 32-bit
* | |
* . .
* | |
* | |
* | | \/ Lower addresses
*
- * Thus, &pt_regs <-> stack base restricts the valid(ish) ebp values
+ * Thus, regs (or regs->rsp for x86_64) <-> stack base restricts the
+ * valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
+ * exceptions use special stacks, maintained by the interrupt stack table
+ * (IST). These stacks are set up in trap_init() in
+ * arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
+ * to the kernel stack; instead, it points to some location on the NMI
+ * stack. On the other hand, regs->rsp is the stack pointer saved when the
+ * NMI occurred. (2) For 32-bit, regs->esp is not valid because the
+ * processor does not save %esp on the kernel stack when interrupts occur
+ * in the kernel mode.
*/
#ifdef CONFIG_FRAME_POINTER
static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
{
unsigned long headaddr = (unsigned long)head;
+#ifdef CONFIG_X86_64
+ unsigned long stack = (unsigned long)regs->rsp;
+#else
unsigned long stack = (unsigned long)regs;
+#endif
unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
return headaddr > stack && headaddr < stack_base;
if (!user_mode_vm(regs)) {
while (depth-- && valid_kernel_stack(head, regs))
- head = dump_backtrace(head);
+ head = dump_kernel_backtrace(head);
return;
}
-#ifdef CONFIG_SMP
- if (!spin_trylock(¤t->mm->page_table_lock))
- return;
-#endif
-
- while (depth-- && head && pages_present(head))
- head = dump_backtrace(head);
-
-#ifdef CONFIG_SMP
- spin_unlock(¤t->mm->page_table_lock);
-#endif
+ while (depth-- && head)
+ head = dump_user_backtrace(head);
}