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authorDave Peverley <dpeverley@mpc-data.co.uk>2008-12-16 09:35:40 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-12-22 18:44:43 +0900
commit40a8b421b6a85f7786bf3007d316cd799efe8ea1 (patch)
tree64c422b0897587ceba98b83869dda4c3ddbb0070 /arch/sh/oprofile/backtrace.c
parent60a51fbe5dd2baef0f35bcf79f25ac1ee239a660 (diff)
downloadop-kernel-dev-40a8b421b6a85f7786bf3007d316cd799efe8ea1.zip
op-kernel-dev-40a8b421b6a85f7786bf3007d316cd799efe8ea1.tar.gz
sh: oprofile: Backtrace support.
This patch improves the oprofile support on sh and adds backtrace support. Signed-off-by: Dave Peverley <dpeverley@mpc-data.co.uk> Signed-off-by: Chris Smith <chris.smith@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh/oprofile/backtrace.c')
-rw-r--r--arch/sh/oprofile/backtrace.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/arch/sh/oprofile/backtrace.c b/arch/sh/oprofile/backtrace.c
new file mode 100644
index 0000000..418e834
--- /dev/null
+++ b/arch/sh/oprofile/backtrace.c
@@ -0,0 +1,118 @@
+/*
+ * SH specific backtracing code for oprofile
+ *
+ * Copyright 2007 STMicroelectronics Ltd.
+ *
+ * Author: Dave Peverley <dpeverley@mpc-data.co.uk>
+ *
+ * Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
+ * oprofile backtrace code by John Levon, David Smith
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/kallsyms.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+#include <asm/sections.h>
+
+/* Limit to stop backtracing too far. */
+static int backtrace_limit = 20;
+
+static unsigned long *
+user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
+{
+ unsigned long buf_stack;
+
+ /* Also check accessibility of address */
+ if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
+ return NULL;
+
+ if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
+ return NULL;
+
+ /* Quick paranoia check */
+ if (buf_stack & 3)
+ return NULL;
+
+ oprofile_add_trace(buf_stack);
+
+ stackaddr++;
+
+ return stackaddr;
+}
+
+/*
+ * | | /\ Higher addresses
+ * | |
+ * --------------- stack base (address of current_thread_info)
+ * | thread info |
+ * . .
+ * | stack |
+ * --------------- saved regs->regs[15] value if valid
+ * . .
+ * --------------- struct pt_regs stored on stack (struct pt_regs *)
+ * | |
+ * . .
+ * | |
+ * --------------- ???
+ * | |
+ * | | \/ Lower addresses
+ *
+ * Thus, &pt_regs <-> stack base restricts the valid(ish) fp values
+ */
+static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
+{
+ unsigned long stack = (unsigned long)regs;
+ unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
+
+ return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
+}
+
+static unsigned long *
+kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
+{
+ unsigned long addr;
+
+ /*
+ * If not a valid kernel address, keep going till we find one
+ * or the SP stops being a valid address.
+ */
+ do {
+ addr = *stackaddr++;
+
+ if (__kernel_text_address(addr)) {
+ oprofile_add_trace(addr);
+ break;
+ }
+ } while (valid_kernel_stack(stackaddr, regs));
+
+ return stackaddr;
+}
+
+void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+ unsigned long *stackaddr;
+
+ /*
+ * Paranoia - clip max depth as we could get lost in the weeds.
+ */
+ if (depth > backtrace_limit)
+ depth = backtrace_limit;
+
+ stackaddr = (unsigned long *)regs->regs[15];
+ if (!user_mode(regs)) {
+ while (depth-- && valid_kernel_stack(stackaddr, regs))
+ stackaddr = kernel_backtrace(stackaddr, regs);
+
+ return;
+ }
+
+ while (depth-- && (stackaddr != NULL))
+ stackaddr = user_backtrace(stackaddr, regs);
+}
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