android_kernel_xiaomi_sm8350/arch/powerpc/lib/feature-fixups.c

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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;
powerpc: Introduce infrastructure for feature sections with alternatives The current feature section logic only supports nop'ing out code, this means if you want to choose at runtime between instruction sequences, one or both cases will have to execute the nop'ed out contents of the other section, eg: BEGIN_FTR_SECTION or 1,1,1 END_FTR_SECTION_IFSET(FOO) BEGIN_FTR_SECTION or 2,2,2 END_FTR_SECTION_IFCLR(FOO) and the resulting code will be either, or 1,1,1 nop or, nop or 2,2,2 For small code segments this is fine, but for larger code blocks and in performance criticial code segments, it would be nice to avoid the nops. This commit starts to implement logic to allow the following: BEGIN_FTR_SECTION or 1,1,1 FTR_SECTION_ELSE or 2,2,2 ALT_FTR_SECTION_END_IFSET(FOO) and the resulting code will be: or 1,1,1 or, or 2,2,2 We achieve this by extending the existing FTR macros. The current feature section semantic just becomes a special case, ie. if the else case is empty we nop out the default case. The key limitation is that the size of the else case must be less than or equal to the size of the default case. If the else case is smaller the remainder of the section is nop'ed. We let the linker put the else case code in with the rest of the text, so that relative branches from the else case are more likley to link, this has the disadvantage that we can't free the unused else cases. This commit introduces the required macro and linker script changes, but does not enable the patching of the alternative sections. We also need to update two hand-made section entries in reg.h and timex.h Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-06-23 21:32:54 -04:00
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 */