feature-fixups.c

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/*
 *  Copyright (C) 2001 Ben. Herrenschmidt ([email protected])
 *
 *  Modifications for ppc64:
 *      Copyright (C) 2003 Dave Engebretsen <[email protected]>
 *
 *  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/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>


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);
    }
}

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
}

#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 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 */