From d75f054a2cf0614ff63d534ff21ca8eaab41e713 Mon Sep 17 00:00:00 2001
From: Helge Deller <deller@gmx.de>
Date: Mon, 9 Feb 2009 00:43:36 +0100
Subject: parisc: add ftrace (function and graph tracer) functionality
This patch adds the ftrace debugging functionality to the parisc kernel.
It will currently only work with 64bit kernels, because the gcc options -pg
and -ffunction-sections can't be enabled at the same time and -ffunction-sections
is still needed to be able to link 32bit kernels.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
---
arch/parisc/kernel/ftrace.c | 185 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 185 insertions(+)
create mode 100644 arch/parisc/kernel/ftrace.c
(limited to 'arch/parisc/kernel/ftrace.c')
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
new file mode 100644
index 0000000..9877372
--- /dev/null
+++ b/arch/parisc/kernel/ftrace.c
@@ -0,0 +1,185 @@
+/*
+ * Code for tracing calls in Linux kernel.
+ * Copyright (C) 2009 Helge Deller <deller@gmx.de>
+ *
+ * based on code for x86 which is:
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ * future possible enhancements:
+ * - add CONFIG_DYNAMIC_FTRACE
+ * - add CONFIG_STACK_TRACER
+ */
+
+#include <linux/init.h>
+#include <linux/ftrace.h>
+
+#include <asm/sections.h>
+#include <asm/ftrace.h>
+
+
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+/* Add a function return address to the trace stack on thread info.*/
+static int push_return_trace(unsigned long ret, unsigned long long time,
+ unsigned long func, int *depth)
+{
+ int index;
+
+ if (!current->ret_stack)
+ return -EBUSY;
+
+ /* The return trace stack is full */
+ if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
+ atomic_inc(¤t->trace_overrun);
+ return -EBUSY;
+ }
+
+ index = ++current->curr_ret_stack;
+ barrier();
+ current->ret_stack[index].ret = ret;
+ current->ret_stack[index].func = func;
+ current->ret_stack[index].calltime = time;
+ *depth = index;
+
+ return 0;
+}
+
+/* Retrieve a function return address to the trace stack on thread info.*/
+static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
+{
+ int index;
+
+ index = current->curr_ret_stack;
+
+ if (unlikely(index < 0)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ /* Might as well panic, otherwise we have no where to go */
+ *ret = (unsigned long)
+ dereference_function_descriptor(&panic);
+ return;
+ }
+
+ *ret = current->ret_stack[index].ret;
+ trace->func = current->ret_stack[index].func;
+ trace->calltime = current->ret_stack[index].calltime;
+ trace->overrun = atomic_read(¤t->trace_overrun);
+ trace->depth = index;
+ barrier();
+ current->curr_ret_stack--;
+
+}
+
+/*
+ * Send the trace to the ring-buffer.
+ * @return the original return address.
+ */
+unsigned long ftrace_return_to_handler(unsigned long retval0,
+ unsigned long retval1)
+{
+ struct ftrace_graph_ret trace;
+ unsigned long ret;
+
+ pop_return_trace(&trace, &ret);
+ trace.rettime = cpu_clock(raw_smp_processor_id());
+ ftrace_graph_return(&trace);
+
+ if (unlikely(!ret)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ /* Might as well panic. What else to do? */
+ ret = (unsigned long)
+ dereference_function_descriptor(&panic);
+ }
+
+ /* HACK: we hand over the old functions' return values
+ in %r23 and %r24. Assembly in entry.S will take care
+ and move those to their final registers %ret0 and %ret1 */
+ asm( "copy %0, %%r23 \n\t"
+ "copy %1, %%r24 \n" : : "r" (retval0), "r" (retval1) );
+
+ return ret;
+}
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+{
+ unsigned long old;
+ unsigned long long calltime;
+ struct ftrace_graph_ent trace;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ old = *parent;
+ *parent = (unsigned long)
+ dereference_function_descriptor(&return_to_handler);
+
+ if (unlikely(!__kernel_text_address(old))) {
+ ftrace_graph_stop();
+ *parent = old;
+ WARN_ON(1);
+ return;
+ }
+
+ calltime = cpu_clock(raw_smp_processor_id());
+
+ if (push_return_trace(old, calltime,
+ self_addr, &trace.depth) == -EBUSY) {
+ *parent = old;
+ return;
+ }
+
+ trace.func = self_addr;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ *parent = old;
+ }
+}
+
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+
+void ftrace_function_trampoline(unsigned long parent,
+ unsigned long self_addr,
+ unsigned long org_sp_gr3)
+{
+ extern ftrace_func_t ftrace_trace_function;
+
+ if (function_trace_stop)
+ return;
+
+ if (ftrace_trace_function != ftrace_stub) {
+ ftrace_trace_function(parent, self_addr);
+ return;
+ }
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ if (ftrace_graph_entry && ftrace_graph_return) {
+ unsigned long sp;
+ unsigned long *parent_rp;
+
+ asm volatile ("copy %%r30, %0" : "=r"(sp));
+ /* sanity check: is stack pointer which we got from
+ assembler function in entry.S in a reasonable
+ range compared to current stack pointer? */
+ if ((sp - org_sp_gr3) > 0x400)
+ return;
+
+ /* calculate pointer to %rp in stack */
+ parent_rp = (unsigned long *) org_sp_gr3 - 0x10;
+ /* sanity check: parent_rp should hold parent */
+ if (*parent_rp != parent)
+ return;
+
+ prepare_ftrace_return(parent_rp, self_addr);
+ return;
+ }
+#endif
+}
+
--
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