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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/oprofile/backtrace.c
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/i386/oprofile/backtrace.c')
-rw-r--r--arch/i386/oprofile/backtrace.c111
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/i386/oprofile/backtrace.c b/arch/i386/oprofile/backtrace.c
new file mode 100644
index 00000000000..52d72e074f7
--- /dev/null
+++ b/arch/i386/oprofile/backtrace.c
@@ -0,0 +1,111 @@
+/**
+ * @file backtrace.c
+ *
+ * @remark Copyright 2002 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author John Levon
+ * @author David Smith
+ */
+
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+
+struct frame_head {
+ struct frame_head * ebp;
+ unsigned long ret;
+} __attribute__((packed));
+
+static struct frame_head *
+dump_backtrace(struct frame_head * head)
+{
+ oprofile_add_trace(head->ret);
+
+ /* frame pointers should strictly progress back up the stack
+ * (towards higher addresses) */
+ if (head >= head->ebp)
+ return NULL;
+
+ return head->ebp;
+}
+
+/* check that the page(s) containing the frame head are present */
+static int pages_present(struct frame_head * head)
+{
+ struct mm_struct * mm = current->mm;
+
+ /* FIXME: only necessary once per page */
+ if (!check_user_page_readable(mm, (unsigned long)head))
+ return 0;
+
+ return check_user_page_readable(mm, (unsigned long)(head + 1));
+}
+
+/*
+ * | | /\ Higher addresses
+ * | |
+ * --------------- stack base (address of current_thread_info)
+ * | thread info |
+ * . .
+ * | stack |
+ * --------------- saved regs->ebp value if valid (frame_head address)
+ * . .
+ * --------------- struct pt_regs stored on stack (struct pt_regs *)
+ * | |
+ * . .
+ * | |
+ * --------------- %esp
+ * | |
+ * | | \/ Lower addresses
+ *
+ * Thus, &pt_regs <-> stack base restricts the valid(ish) ebp values
+ */
+#ifdef CONFIG_FRAME_POINTER
+static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
+{
+ unsigned long headaddr = (unsigned long)head;
+ unsigned long stack = (unsigned long)regs;
+ unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
+
+ return headaddr > stack && headaddr < stack_base;
+}
+#else
+/* without fp, it's just junk */
+static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
+{
+ return 0;
+}
+#endif
+
+
+void
+x86_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+ struct frame_head *head;
+
+#ifdef CONFIG_X86_64
+ head = (struct frame_head *)regs->rbp;
+#else
+ head = (struct frame_head *)regs->ebp;
+#endif
+
+ if (!user_mode(regs)) {
+ while (depth-- && valid_kernel_stack(head, regs))
+ head = dump_backtrace(head);
+ return;
+ }
+
+#ifdef CONFIG_SMP
+ if (!spin_trylock(&current->mm->page_table_lock))
+ return;
+#endif
+
+ while (depth-- && head && pages_present(head))
+ head = dump_backtrace(head);
+
+#ifdef CONFIG_SMP
+ spin_unlock(&current->mm->page_table_lock);
+#endif
+}