[PATCH] lockdep: stacktrace subsystem, i386 support
Framework to generate and save stacktraces quickly, without printing anything
to the console. i386 support.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 27d8ddd..076a72c 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -18,6 +18,10 @@
bool
default y
+config STACKTRACE_SUPPORT
+ bool
+ default y
+
config SEMAPHORE_SLEEPERS
bool
default y
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index cbc1184..1b452a1 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -9,6 +9,7 @@
pci-dma.o i386_ksyms.o i387.o bootflag.o \
quirks.o i8237.o topology.o alternative.o i8253.o tsc.o
+obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/
obj-y += acpi/
obj-$(CONFIG_X86_BIOS_REBOOT) += reboot.o
diff --git a/arch/i386/kernel/stacktrace.c b/arch/i386/kernel/stacktrace.c
new file mode 100644
index 0000000..e62a037
--- /dev/null
+++ b/arch/i386/kernel/stacktrace.c
@@ -0,0 +1,98 @@
+/*
+ * arch/i386/kernel/stacktrace.c
+ *
+ * Stack trace management functions
+ *
+ * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ */
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+
+static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
+{
+ return p > (void *)tinfo &&
+ p < (void *)tinfo + THREAD_SIZE - 3;
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer:
+ */
+static inline unsigned long
+save_context_stack(struct stack_trace *trace, unsigned int skip,
+ struct thread_info *tinfo, unsigned long *stack,
+ unsigned long ebp)
+{
+ unsigned long addr;
+
+#ifdef CONFIG_FRAME_POINTER
+ while (valid_stack_ptr(tinfo, (void *)ebp)) {
+ addr = *(unsigned long *)(ebp + 4);
+ if (!skip)
+ trace->entries[trace->nr_entries++] = addr;
+ else
+ skip--;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ /*
+ * break out of recursive entries (such as
+ * end_of_stack_stop_unwind_function):
+ */
+ if (ebp == *(unsigned long *)ebp)
+ break;
+
+ ebp = *(unsigned long *)ebp;
+ }
+#else
+ while (valid_stack_ptr(tinfo, stack)) {
+ addr = *stack++;
+ if (__kernel_text_address(addr)) {
+ if (!skip)
+ trace->entries[trace->nr_entries++] = addr;
+ else
+ skip--;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ }
+ }
+#endif
+
+ return ebp;
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ * If all_contexts is set, all contexts (hardirq, softirq and process)
+ * are saved. If not set then only the current context is saved.
+ */
+void save_stack_trace(struct stack_trace *trace,
+ struct task_struct *task, int all_contexts,
+ unsigned int skip)
+{
+ unsigned long ebp;
+ unsigned long *stack = &ebp;
+
+ WARN_ON(trace->nr_entries || !trace->max_entries);
+
+ if (!task || task == current) {
+ /* Grab ebp right from our regs: */
+ asm ("movl %%ebp, %0" : "=r" (ebp));
+ } else {
+ /* ebp is the last reg pushed by switch_to(): */
+ ebp = *(unsigned long *) task->thread.esp;
+ }
+
+ while (1) {
+ struct thread_info *context = (struct thread_info *)
+ ((unsigned long)stack & (~(THREAD_SIZE - 1)));
+
+ ebp = save_context_stack(trace, skip, context, stack, ebp);
+ stack = (unsigned long *)context->previous_esp;
+ if (!all_contexts || !stack ||
+ trace->nr_entries >= trace->max_entries)
+ break;
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ }
+}
+
