sh: Allow multiple stack unwinders to be setup (bf61ad1f) · Commits · 戴 / test

arch/sh/include/asm/unwinder.h

0 → 100644

+25 −0

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		#ifndef _LINUX_UNWINDER_H
		#define _LINUX_UNWINDER_H

		#include <asm/stacktrace.h>

		struct unwinder {
		const char *name;
		struct list_head list;
		int rating;
		void (dump)(struct task_struct , struct pt_regs *,
		unsigned long , const struct stacktrace_ops , void *);
		};

		extern int unwinder_init(void);
		extern int unwinder_register(struct unwinder *);

		extern void unwind_stack(struct task_struct , struct pt_regs ,
		unsigned long , const struct stacktrace_ops ,
		void *);

		extern void stack_reader_dump(struct task_struct , struct pt_regs ,
		unsigned long , const struct stacktrace_ops ,
		void *);

		#endif /* _LINUX_UNWINDER_H */

arch/sh/kernel/Makefile_32

+2 −2

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		@@ -12,7 +12,7 @@ endif
		obj-y := debugtraps.o dumpstack.o idle.o io.o io_generic.o irq.o \
		machvec.o process_32.o ptrace_32.o setup.o signal_32.o \
		sys_sh.o sys_sh32.o syscalls_32.o time.o topology.o \
		traps.o traps_32.o
		traps.o traps_32.o unwinder.o

		obj-y += cpu/
		obj-$(CONFIG_VSYSCALL) += vsyscall/

arch/sh/kernel/Makefile_64

+1 −1

Original line number	Diff line number	Diff line
		@@ -2,7 +2,7 @@ extra-y := head_64.o init_task.o vmlinux.lds

		obj-y := debugtraps.o idle.o io.o io_generic.o irq.o machvec.o process_64.o \
		ptrace_64.o setup.o signal_64.o sys_sh.o sys_sh64.o \
		syscalls_64.o time.o topology.o traps.o traps_64.o
		syscalls_64.o time.o topology.o traps.o traps_64.o unwinder.o

		obj-y += cpu/
		obj-$(CONFIG_SMP) += smp.o

arch/sh/kernel/unwinder.c

0 → 100644

+162 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2009 Matt Fleming
		*
		* Based, in part, on kernel/time/clocksource.c.
		*
		* This file provides arbitration code for stack unwinders.
		*
		* Multiple stack unwinders can be available on a system, usually with
		* the most accurate unwinder being the currently active one.
		*/
		#include <linux/errno.h>
		#include <linux/list.h>
		#include <linux/spinlock.h>
		#include <asm/unwinder.h>
		#include <asm/atomic.h>

		/*
		* This is the most basic stack unwinder an architecture can
		* provide. For architectures without reliable frame pointers, e.g.
		* RISC CPUs, it can be implemented by looking through the stack for
		* addresses that lie within the kernel text section.
		*
		* Other CPUs, e.g. x86, can use their frame pointer register to
		* construct more accurate stack traces.
		*/
		static struct list_head unwinder_list;
		static struct unwinder stack_reader = {
		.name = "stack-reader",
		.dump = stack_reader_dump,
		.rating = 50,
		.list = {
		.next = &unwinder_list,
		.prev = &unwinder_list,
		},
		};

		/*
		* "curr_unwinder" points to the stack unwinder currently in use. This
		* is the unwinder with the highest rating.
		*
		* "unwinder_list" is a linked-list of all available unwinders, sorted
		* by rating.
		*
		* All modifications of "curr_unwinder" and "unwinder_list" must be
		* performed whilst holding "unwinder_lock".
		*/
		static struct unwinder *curr_unwinder = &stack_reader;

		static struct list_head unwinder_list = {
		.next = &stack_reader.list,
		.prev = &stack_reader.list,
		};

		static DEFINE_SPINLOCK(unwinder_lock);

		static atomic_t unwinder_running = ATOMIC_INIT(0);

		/**
		* select_unwinder - Select the best registered stack unwinder.
		*
		* Private function. Must hold unwinder_lock when called.
		*
		* Select the stack unwinder with the best rating. This is useful for
		* setting up curr_unwinder.
		*/
		static struct unwinder *select_unwinder(void)
		{
		struct unwinder *best;

		if (list_empty(&unwinder_list))
		return NULL;

		best = list_entry(unwinder_list.next, struct unwinder, list);
		if (best == curr_unwinder)
		return NULL;

		return best;
		}

		/*
		* Enqueue the stack unwinder sorted by rating.
		*/
		static int unwinder_enqueue(struct unwinder *ops)
		{
		struct list_head tmp, entry = &unwinder_list;

		list_for_each(tmp, &unwinder_list) {
		struct unwinder *o;

		o = list_entry(tmp, struct unwinder, list);
		if (o == ops)
		return -EBUSY;
		/* Keep track of the place, where to insert */
		if (o->rating >= ops->rating)
		entry = tmp;
		}
		list_add(&ops->list, entry);

		return 0;
		}

		/**
		* unwinder_register - Used to install new stack unwinder
		* @u: unwinder to be registered
		*
		* Install the new stack unwinder on the unwinder list, which is sorted
		* by rating.
		*
		* Returns -EBUSY if registration fails, zero otherwise.
		*/
		int unwinder_register(struct unwinder *u)
		{
		unsigned long flags;
		int ret;

		spin_lock_irqsave(&unwinder_lock, flags);
		ret = unwinder_enqueue(u);
		if (!ret)
		curr_unwinder = select_unwinder();
		spin_unlock_irqrestore(&unwinder_lock, flags);

		return ret;
		}

		/*
		* Unwind the call stack and pass information to the stacktrace_ops
		* functions. Also handle the case where we need to switch to a new
		* stack dumper because the current one faulted unexpectedly.
		*/
		void unwind_stack(struct task_struct task, struct pt_regs regs,
		unsigned long sp, const struct stacktrace_ops ops,
		void *data)
		{
		unsigned long flags;

		/*
		* The problem with unwinders with high ratings is that they are
		* inherently more complicated than the simple ones with lower
		* ratings. We are therefore more likely to fault in the
		* complicated ones, e.g. hitting BUG()s. If we fault in the
		* code for the current stack unwinder we try to downgrade to
		* one with a lower rating.
		*
		* Hopefully this will give us a semi-reliable stacktrace so we
		* can diagnose why curr_unwinder->dump() faulted.
		*/
		if (atomic_inc_return(&unwinder_running) != 1) {
		spin_lock_irqsave(&unwinder_lock, flags);

		if (!list_is_singular(&unwinder_list)) {
		list_del(&curr_unwinder->list);
		curr_unwinder = select_unwinder();
		}

		spin_unlock_irqrestore(&unwinder_lock, flags);
		atomic_dec(&unwinder_running);
		}

		curr_unwinder->dump(task, regs, sp, ops, data);

		atomic_dec(&unwinder_running);
		}

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