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Commit 8a37f520 authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: handle early calls to return_address() when using dwarf unwinder. 



The dwarf unwinder ties in to an early initcall, but it's possible that
return_address() calls will be made prior to that. This implements some
additional error handling in to the dwarf unwinder as well as an exit
path in the return_address() case to bail out if the unwinder hasn't come
up yet.

This fixes a NULL pointer deref in early boot when mempool_alloc() blows
up on the not-yet-ready mempool via dwarf_unwind_stack().

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent e1f42ff4

arch/sh/kernel/dwarf.c

+17 −2
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ static DEFINE_SPINLOCK(dwarf_fde_lock); 


static struct dwarf_cie *cached_cie;



static unsigned int dwarf_unwinder_ready;



/**

 *	dwarf_frame_alloc_reg - allocate memory for a DWARF register

 *	@frame: the DWARF frame whose list of registers we insert on
@@ -581,6 +583,13 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc, 
	struct dwarf_reg *reg;

	unsigned long addr;



	/*

	 * If we've been called in to before initialization has

	 * completed, bail out immediately.

	 */

	if (!dwarf_unwinder_ready)

		return NULL;



	/*

	 * If we're starting at the top of the stack we need get the

	 * contents of a physical register to get the CFA in order to
@@ -1167,7 +1176,7 @@ void module_dwarf_cleanup(struct module *mod) 
 */

static int __init dwarf_unwinder_init(void)

{

	int err;

	int err = -ENOMEM;



	dwarf_frame_cachep = kmem_cache_create("dwarf_frames",

			sizeof(struct dwarf_frame), 0,
@@ -1181,11 +1190,15 @@ static int __init dwarf_unwinder_init(void) 
					  mempool_alloc_slab,

					  mempool_free_slab,

					  dwarf_frame_cachep);

	if (!dwarf_frame_pool)

		goto out;



	dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,

					 mempool_alloc_slab,

					 mempool_free_slab,

					 dwarf_reg_cachep);

	if (!dwarf_reg_pool)

		goto out;



	err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);

	if (err)
@@ -1195,11 +1208,13 @@ static int __init dwarf_unwinder_init(void) 
	if (err)

		goto out;



	dwarf_unwinder_ready = 1;



	return 0;



out:

	printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);

	dwarf_unwinder_cleanup();

	return -EINVAL;

	return err;

}

early_initcall(dwarf_unwinder_init);

arch/sh/kernel/return_address.c

+2 −0
Original line number Diff line number Diff line
@@ -24,6 +24,8 @@ void *return_address(unsigned int depth) 
		struct dwarf_frame *tmp;



		tmp = dwarf_unwind_stack(ra, frame);

		if (!tmp)

			return NULL;



		if (frame)

			dwarf_free_frame(frame);