/*
 *  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/types.h>
#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/init.h>
#include <asm/cputable.h>
#include <asm/code-patching.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/firmware.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_INST_NOP);

        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_ON(1);
                        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)
{
        long *start, *end;
        unsigned int *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_INST_LWSYNC);
        }
}

static void do_final_fixups(void)
{
#if defined(CONFIG_PPC64) && defined(CONFIG_RELOCATABLE)
        int *src, *dest;
        unsigned long length;

        if (PHYSICAL_START == 0)
                return;

        src = (int *)(KERNELBASE + PHYSICAL_START);
        dest = (int *)KERNELBASE;
        length = (__end_interrupts - _stext) / sizeof(int);

        while (length--) {
                patch_instruction(dest, *src);
                src++;
                dest++;
        }
#endif
}

static unsigned long __initdata saved_cpu_features;
static unsigned int __initdata saved_mmu_features;
#ifdef CONFIG_PPC64
static unsigned long __initdata saved_firmware_features;
#endif

void __init apply_feature_fixups(void)
{
        struct cpu_spec *spec = PTRRELOC(*PTRRELOC(&cur_cpu_spec));

        *PTRRELOC(&saved_cpu_features) = spec->cpu_features;
        *PTRRELOC(&saved_mmu_features) = spec->mmu_features;

        /*
         * Apply the CPU-specific and firmware specific fixups to kernel text
         * (nop out sections not relevant to this CPU or this firmware).
         */
        do_feature_fixups(spec->cpu_features,
                          PTRRELOC(&__start___ftr_fixup),
                          PTRRELOC(&__stop___ftr_fixup));

        do_feature_fixups(spec->mmu_features,
                          PTRRELOC(&__start___mmu_ftr_fixup),
                          PTRRELOC(&__stop___mmu_ftr_fixup));

        do_lwsync_fixups(spec->cpu_features,
                         PTRRELOC(&__start___lwsync_fixup),
                         PTRRELOC(&__stop___lwsync_fixup));

#ifdef CONFIG_PPC64
        saved_firmware_features = powerpc_firmware_features;
        do_feature_fixups(powerpc_firmware_features,
                          &__start___fw_ftr_fixup, &__stop___fw_ftr_fixup);
#endif
        do_final_fixups();
}

void __init setup_feature_keys(void)
{
        /*
         * Initialise jump label. This causes all the cpu/mmu_has_feature()
         * checks to take on their correct polarity based on the current set of
         * CPU/MMU features.
         */
        jump_label_init();
        cpu_feature_keys_init();
        mmu_feature_keys_init();
}

static int __init check_features(void)
{
        WARN(saved_cpu_features != cur_cpu_spec->cpu_features,
             "CPU features changed after feature patching!\n");
        WARN(saved_mmu_features != cur_cpu_spec->mmu_features,
             "MMU features changed after feature patching!\n");
#ifdef CONFIG_PPC64
        WARN(saved_firmware_features != powerpc_firmware_features,
             "Firmware features changed after feature patching!\n");
#endif

        return 0;
}
late_initcall(check_features);

#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;
}

static 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 u8 ftr_fixup_test_FTR_macros;
        extern u8 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 u8 ftr_fixup_test_FW_FTR_macros;
        extern u8 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 u8 lwsync_fixup_test;
        extern u8 end_lwsync_fixup_test;
        extern u8 lwsync_fixup_test_expected_LWSYNC;
        extern u8 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 */