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linux/arch/powerpc/lib/feature-fixups.c
Kumar Gala 2d1b202762 powerpc: Fixup lwsync at runtime 
To allow for a single kernel image on e500 v1/v2/mc we need to fixup lwsync
at runtime.  On e500v1/v2 lwsync causes an illop so we need to patch up
the code.  We default to 'sync' since that is always safe and if the cpu
is capable we will replace 'sync' with 'lwsync'.

We introduce CPU_FTR_LWSYNC as a way to determine at runtime if this is
needed.  This flag could be moved elsewhere since we dont really use it
for the normal CPU_FTR purpose.

Finally we only store the relative offset in the fixup section to keep it
as small as possible rather than using a full fixup_entry.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-07-03 16:58:10 +10:00

352 lines
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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 <linux/string.h>
#include <linux/init.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));
}
}
}
void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
{
unsigned int *start, *end, *dest;
if (!(value & CPU_FTR_LWSYNC))
return ;
start = fixup_start;
end = fixup_end;
for (; start < end; start++) {
dest = (void *)start + *start;
patch_instruction(dest, PPC_LWSYNC_INSTR);
}
}
#ifdef CONFIG_FTR_FIXUP_SELFTEST
#define check(x) \
if (!(x)) printk("feature-fixups: test failed at line %d\n", __LINE__);
/* This must be after the text it fixes up, vmlinux.lds.S enforces that atm */
static struct fixup_entry fixup;
static long calc_offset(struct fixup_entry *entry, unsigned int *p)
{
return (unsigned long)p - (unsigned long)entry;
}
void test_basic_patching(void)
{
extern unsigned int ftr_fixup_test1;
extern unsigned int end_ftr_fixup_test1;
extern unsigned int ftr_fixup_test1_orig;
extern unsigned int ftr_fixup_test1_expected;
int size = &end_ftr_fixup_test1 - &ftr_fixup_test1;
fixup.value = fixup.mask = 8;
fixup.start_off = calc_offset(&fixup, &ftr_fixup_test1 + 1);
fixup.end_off = calc_offset(&fixup, &ftr_fixup_test1 + 2);
fixup.alt_start_off = fixup.alt_end_off = 0;
/* Sanity check */
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(8, &fixup);
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
memcpy(&ftr_fixup_test1, &ftr_fixup_test1_orig, size);
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_orig, size) == 0);
patch_feature_section(~8, &fixup);
check(memcmp(&ftr_fixup_test1, &ftr_fixup_test1_expected, size) == 0);
}
static void test_alternative_patching(void)
{
extern unsigned int ftr_fixup_test2;
extern unsigned int end_ftr_fixup_test2;
extern unsigned int ftr_fixup_test2_orig;
extern unsigned int ftr_fixup_test2_alt;
extern unsigned int ftr_fixup_test2_expected;
int size = &end_ftr_fixup_test2 - &ftr_fixup_test2;
fixup.value = fixup.mask = 0xF;
fixup.start_off = calc_offset(&fixup, &ftr_fixup_test2 + 1);
fixup.end_off = calc_offset(&fixup, &ftr_fixup_test2 + 2);
fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test2_alt);
fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test2_alt + 1);
/* Sanity check */
check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(0xF, &fixup);
check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
memcpy(&ftr_fixup_test2, &ftr_fixup_test2_orig, size);
check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_orig, size) == 0);
patch_feature_section(~0xF, &fixup);
check(memcmp(&ftr_fixup_test2, &ftr_fixup_test2_expected, size) == 0);
}
static void test_alternative_case_too_big(void)
{
extern unsigned int ftr_fixup_test3;
extern unsigned int end_ftr_fixup_test3;
extern unsigned int ftr_fixup_test3_orig;
extern unsigned int ftr_fixup_test3_alt;
int size = &end_ftr_fixup_test3 - &ftr_fixup_test3;
fixup.value = fixup.mask = 0xC;
fixup.start_off = calc_offset(&fixup, &ftr_fixup_test3 + 1);
fixup.end_off = calc_offset(&fixup, &ftr_fixup_test3 + 2);
fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test3_alt);
fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test3_alt + 2);
/* Sanity check */
check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
/* Expect nothing to be patched, and the error returned to us */
check(patch_feature_section(0xF, &fixup) == 1);
check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
check(patch_feature_section(0, &fixup) == 1);
check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
check(patch_feature_section(~0xF, &fixup) == 1);
check(memcmp(&ftr_fixup_test3, &ftr_fixup_test3_orig, size) == 0);
}
static void test_alternative_case_too_small(void)
{
extern unsigned int ftr_fixup_test4;
extern unsigned int end_ftr_fixup_test4;
extern unsigned int ftr_fixup_test4_orig;
extern unsigned int ftr_fixup_test4_alt;
extern unsigned int ftr_fixup_test4_expected;
int size = &end_ftr_fixup_test4 - &ftr_fixup_test4;
unsigned long flag;
/* Check a high-bit flag */
flag = 1UL << ((sizeof(unsigned long) - 1) * 8);
fixup.value = fixup.mask = flag;
fixup.start_off = calc_offset(&fixup, &ftr_fixup_test4 + 1);
fixup.end_off = calc_offset(&fixup, &ftr_fixup_test4 + 5);
fixup.alt_start_off = calc_offset(&fixup, &ftr_fixup_test4_alt);
fixup.alt_end_off = calc_offset(&fixup, &ftr_fixup_test4_alt + 2);
/* Sanity check */
check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
/* Check we don't patch if the value matches */
patch_feature_section(flag, &fixup);
check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
/* Check we do patch if the value doesn't match */
patch_feature_section(0, &fixup);
check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
/* Check we do patch if the mask doesn't match */
memcpy(&ftr_fixup_test4, &ftr_fixup_test4_orig, size);
check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_orig, size) == 0);
patch_feature_section(~flag, &fixup);
check(memcmp(&ftr_fixup_test4, &ftr_fixup_test4_expected, size) == 0);
}
static void test_alternative_case_with_branch(void)
{
extern unsigned int ftr_fixup_test5;
extern unsigned int end_ftr_fixup_test5;
extern unsigned int ftr_fixup_test5_expected;
int size = &end_ftr_fixup_test5 - &ftr_fixup_test5;
check(memcmp(&ftr_fixup_test5, &ftr_fixup_test5_expected, size) == 0);
}
static void test_alternative_case_with_external_branch(void)
{
extern unsigned int ftr_fixup_test6;
extern unsigned int end_ftr_fixup_test6;
extern unsigned int ftr_fixup_test6_expected;
int size = &end_ftr_fixup_test6 - &ftr_fixup_test6;
check(memcmp(&ftr_fixup_test6, &ftr_fixup_test6_expected, size) == 0);
}
static void test_cpu_macros(void)
{
extern void ftr_fixup_test_FTR_macros;
extern void ftr_fixup_test_FTR_macros_expected;
unsigned long size = &ftr_fixup_test_FTR_macros_expected -
&ftr_fixup_test_FTR_macros;
/* The fixups have already been done for us during boot */
check(memcmp(&ftr_fixup_test_FTR_macros,
&ftr_fixup_test_FTR_macros_expected, size) == 0);
}
static void test_fw_macros(void)
{
#ifdef CONFIG_PPC64
extern void ftr_fixup_test_FW_FTR_macros;
extern void ftr_fixup_test_FW_FTR_macros_expected;
unsigned long size = &ftr_fixup_test_FW_FTR_macros_expected -
&ftr_fixup_test_FW_FTR_macros;
/* The fixups have already been done for us during boot */
check(memcmp(&ftr_fixup_test_FW_FTR_macros,
&ftr_fixup_test_FW_FTR_macros_expected, size) == 0);
#endif
}
static void test_lwsync_macros(void)
{
extern void lwsync_fixup_test;
extern void end_lwsync_fixup_test;
extern void lwsync_fixup_test_expected_LWSYNC;
extern void lwsync_fixup_test_expected_SYNC;
unsigned long size = &end_lwsync_fixup_test -
&lwsync_fixup_test;
/* The fixups have already been done for us during boot */
if (cur_cpu_spec->cpu_features & CPU_FTR_LWSYNC) {
check(memcmp(&lwsync_fixup_test,
&lwsync_fixup_test_expected_LWSYNC, size) == 0);
} else {
check(memcmp(&lwsync_fixup_test,
&lwsync_fixup_test_expected_SYNC, size) == 0);
}
}
static int __init test_feature_fixups(void)
{
printk(KERN_DEBUG "Running feature fixup self-tests ...\n");
test_basic_patching();
test_alternative_patching();
test_alternative_case_too_big();
test_alternative_case_too_small();
test_alternative_case_with_branch();
test_alternative_case_with_external_branch();
test_cpu_macros();
test_fw_macros();
test_lwsync_macros();
return 0;
}
late_initcall(test_feature_fixups);
#endif /* CONFIG_FTR_FIXUP_SELFTEST */
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