110 lines
2.6 KiB
C
110 lines
2.6 KiB
C
/*
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* Copyright (C) 2001 Ben. Herrenschmidt (benh@kernel.crashing.org)
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*
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* Modifications for ppc64:
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* Copyright (C) 2003 Dave Engebretsen <engebret@us.ibm.com>
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*
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* Copyright 2008 Michael Ellerman, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <asm/cputable.h>
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#include <asm/code-patching.h>
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struct fixup_entry {
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unsigned long mask;
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unsigned long value;
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long start_off;
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long end_off;
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long alt_start_off;
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long alt_end_off;
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};
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static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
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{
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/*
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* We store the offset to the code as a negative offset from
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* the start of the alt_entry, to support the VDSO. This
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* routine converts that back into an actual address.
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*/
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return (unsigned int *)((unsigned long)fcur + offset);
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}
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static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
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unsigned int *alt_start, unsigned int *alt_end)
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{
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unsigned int instr;
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instr = *src;
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if (instr_is_relative_branch(*src)) {
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unsigned int *target = (unsigned int *)branch_target(src);
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/* Branch within the section doesn't need translating */
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if (target < alt_start || target >= alt_end) {
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instr = translate_branch(dest, src);
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if (!instr)
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return 1;
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}
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}
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patch_instruction(dest, instr);
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return 0;
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}
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static int patch_feature_section(unsigned long value, struct fixup_entry *fcur)
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{
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unsigned int *start, *end, *alt_start, *alt_end, *src, *dest;
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start = calc_addr(fcur, fcur->start_off);
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end = calc_addr(fcur, fcur->end_off);
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alt_start = calc_addr(fcur, fcur->alt_start_off);
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alt_end = calc_addr(fcur, fcur->alt_end_off);
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if ((alt_end - alt_start) > (end - start))
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return 1;
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if ((value & fcur->mask) == fcur->value)
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return 0;
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src = alt_start;
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dest = start;
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for (; src < alt_end; src++, dest++) {
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if (patch_alt_instruction(src, dest, alt_start, alt_end))
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return 1;
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}
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for (; dest < end; dest++)
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patch_instruction(dest, PPC_NOP_INSTR);
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return 0;
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}
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void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
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{
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struct fixup_entry *fcur, *fend;
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fcur = fixup_start;
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fend = fixup_end;
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for (; fcur < fend; fcur++) {
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if (patch_feature_section(value, fcur)) {
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__WARN();
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printk("Unable to patch feature section at %p - %p" \
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" with %p - %p\n",
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calc_addr(fcur, fcur->start_off),
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calc_addr(fcur, fcur->end_off),
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calc_addr(fcur, fcur->alt_start_off),
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calc_addr(fcur, fcur->alt_end_off));
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}
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}
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}
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