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