8a37f52052
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: Paul Mundt <lethal@linux-sh.org>
60 lines
1 KiB
C
60 lines
1 KiB
C
/*
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* arch/sh/kernel/return_address.c
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*
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* Copyright (C) 2009 Matt Fleming
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* Copyright (C) 2009 Paul Mundt
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <asm/dwarf.h>
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#ifdef CONFIG_DWARF_UNWINDER
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void *return_address(unsigned int depth)
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{
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struct dwarf_frame *frame;
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unsigned long ra;
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int i;
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for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
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struct dwarf_frame *tmp;
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tmp = dwarf_unwind_stack(ra, frame);
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if (!tmp)
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return NULL;
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if (frame)
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dwarf_free_frame(frame);
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frame = tmp;
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if (!frame || !frame->return_addr)
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break;
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ra = frame->return_addr;
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}
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/* Failed to unwind the stack to the specified depth. */
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WARN_ON(i != depth + 1);
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if (frame)
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dwarf_free_frame(frame);
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return (void *)ra;
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}
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#else
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void *return_address(unsigned int depth)
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{
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return NULL;
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}
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#endif
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EXPORT_SYMBOL_GPL(return_address);
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