[IA64] Add CONFIG_STACKTRACE_SUPPORT

Several Linux features are dependent on stack trace support. Add
it so they can be enabled.

Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/Kconfig

@@ -62,6 +62,9 @@ config NEED_SG_DMA_LENGTH
 config SWIOTLB
        bool
 
+config STACKTRACE_SUPPORT
+	def_bool y
+
 config GENERIC_LOCKBREAK
 	def_bool n
 

arch/ia64/kernel/Makefile

@@ -34,6 +34,7 @@ obj-$(CONFIG_AUDIT)		+= audit.o
 obj-$(CONFIG_PCI_MSI)		+= msi_ia64.o
 mca_recovery-y			+= mca_drv.o mca_drv_asm.o
 obj-$(CONFIG_IA64_MC_ERR_INJECT)+= err_inject.o
+obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
 obj-$(CONFIG_PARAVIRT)		+= paravirt.o paravirtentry.o \
 				   paravirt_patch.o

arch/ia64/kernel/stacktrace.c

@@ -0,0 +1,39 @@
+/*
+ * arch/ia64/kernel/stacktrace.c
+ *
+ * Stack trace management functions
+ *
+ */
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/module.h>
+
+static void
+ia64_do_save_stack(struct unw_frame_info *info, void *arg)
+{
+	struct stack_trace *trace = arg;
+	unsigned long ip;
+	int skip = trace->skip;
+
+	trace->nr_entries = 0;
+	do {
+		unw_get_ip(info, &ip);
+		if (ip == 0)
+			break;
+		if (skip == 0) {
+			trace->entries[trace->nr_entries++] = ip;
+			if (trace->nr_entries == trace->max_entries)
+				break;
+		} else
+			skip--;
+	} while (unw_unwind(info) >= 0);
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+	unw_init_running(ia64_do_save_stack, trace);
+}
+EXPORT_SYMBOL(save_stack_trace);