ofw/libfdt/fdt_sw.c

// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
/*
 * libfdt - Flat Device Tree manipulation
 * Copyright (C) 2006 David Gibson, IBM Corporation.
 */
#include "libfdt_env.h"

#include <fdt.h>
#include <libfdt.h>

#include "libfdt_internal.h"

static int fdt_sw_probe_(void *fdt)
{
    if (!can_assume(VALID_INPUT)) {
        if (fdt_magic(fdt) == FDT_MAGIC)
            return -FDT_ERR_BADSTATE;
        else if (fdt_magic(fdt) != FDT_SW_MAGIC)
            return -FDT_ERR_BADMAGIC;
    }

    return 0;
}

#define FDT_SW_PROBE(fdt) \
    { \
        int err; \
        if ((err = fdt_sw_probe_(fdt)) != 0) \
            return err; \
    }

/* 'memrsv' state:  Initial state after fdt_create()
 *
 * Allowed functions:
 *  fdt_add_reservemap_entry()
 *  fdt_finish_reservemap()     [moves to 'struct' state]
 */
static int fdt_sw_probe_memrsv_(void *fdt)
{
    int err = fdt_sw_probe_(fdt);
    if (err)
        return err;

    if (!can_assume(VALID_INPUT) && fdt_off_dt_strings(fdt) != 0)
        return -FDT_ERR_BADSTATE;
    return 0;
}

#define FDT_SW_PROBE_MEMRSV(fdt) \
    { \
        int err; \
        if ((err = fdt_sw_probe_memrsv_(fdt)) != 0) \
            return err; \
    }

/* 'struct' state:  Enter this state after fdt_finish_reservemap()
 *
 * Allowed functions:
 *  fdt_begin_node()
 *  fdt_end_node()
 *  fdt_property*()
 *  fdt_finish()            [moves to 'complete' state]
 */
static int fdt_sw_probe_struct_(void *fdt)
{
    int err = fdt_sw_probe_(fdt);
    if (err)
        return err;

    if (!can_assume(VALID_INPUT) &&
        fdt_off_dt_strings(fdt) != fdt_totalsize(fdt))
        return -FDT_ERR_BADSTATE;
    return 0;
}

#define FDT_SW_PROBE_STRUCT(fdt) \
    { \
        int err; \
        if ((err = fdt_sw_probe_struct_(fdt)) != 0) \
            return err; \
    }

static inline uint32_t sw_flags(void *fdt)
{
    /* assert: (fdt_magic(fdt) == FDT_SW_MAGIC) */
    return fdt_last_comp_version(fdt);
}

/* 'complete' state:    Enter this state after fdt_finish()
 *
 * Allowed functions: none
 */

static void *fdt_grab_space_(void *fdt, size_t len)
{
    unsigned int offset = fdt_size_dt_struct(fdt);
    unsigned int spaceleft;

    spaceleft = fdt_totalsize(fdt) - fdt_off_dt_struct(fdt)
        - fdt_size_dt_strings(fdt);

    if ((offset + len < offset) || (offset + len > spaceleft))
        return NULL;

    fdt_set_size_dt_struct(fdt, offset + len);
    return fdt_offset_ptr_w_(fdt, offset);
}

int fdt_create_with_flags(void *buf, int bufsize, uint32_t flags)
{
    const int hdrsize = FDT_ALIGN(sizeof(struct fdt_header),
                      sizeof(struct fdt_reserve_entry));
    void *fdt = buf;

    if (bufsize < hdrsize)
        return -FDT_ERR_NOSPACE;

    if (flags & ~FDT_CREATE_FLAGS_ALL)
        return -FDT_ERR_BADFLAGS;

    memset(buf, 0, bufsize);

    /*
     * magic and last_comp_version keep intermediate state during the fdt
     * creation process, which is replaced with the proper FDT format by
     * fdt_finish().
     *
     * flags should be accessed with sw_flags().
     */
    fdt_set_magic(fdt, FDT_SW_MAGIC);
    fdt_set_version(fdt, FDT_LAST_SUPPORTED_VERSION);
    fdt_set_last_comp_version(fdt, flags);

    fdt_set_totalsize(fdt,  bufsize);

    fdt_set_off_mem_rsvmap(fdt, hdrsize);
    fdt_set_off_dt_struct(fdt, fdt_off_mem_rsvmap(fdt));
    fdt_set_off_dt_strings(fdt, 0);

    return 0;
}

int fdt_create(void *buf, int bufsize)
{
    return fdt_create_with_flags(buf, bufsize, 0);
}

int fdt_resize(void *fdt, void *buf, int bufsize)
{
    size_t headsize, tailsize;
    char *oldtail, *newtail;

    FDT_SW_PROBE(fdt);

    if (bufsize < 0)
        return -FDT_ERR_NOSPACE;

    headsize = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
    tailsize = fdt_size_dt_strings(fdt);

    if (!can_assume(VALID_DTB) &&
        headsize + tailsize > fdt_totalsize(fdt))
        return -FDT_ERR_INTERNAL;

    if ((headsize + tailsize) > (unsigned)bufsize)
        return -FDT_ERR_NOSPACE;

    oldtail = (char *)fdt + fdt_totalsize(fdt) - tailsize;
    newtail = (char *)buf + bufsize - tailsize;

    /* Two cases to avoid clobbering data if the old and new
     * buffers partially overlap */
    if (buf <= fdt) {
        memmove(buf, fdt, headsize);
        memmove(newtail, oldtail, tailsize);
    } else {
        memmove(newtail, oldtail, tailsize);
        memmove(buf, fdt, headsize);
    }

    fdt_set_totalsize(buf, bufsize);
    if (fdt_off_dt_strings(buf))
        fdt_set_off_dt_strings(buf, bufsize);

    return 0;
}

int fdt_add_reservemap_entry(void *fdt, uint64_t addr, uint64_t size)
{
    struct fdt_reserve_entry *re;
    int offset;

    FDT_SW_PROBE_MEMRSV(fdt);

    offset = fdt_off_dt_struct(fdt);
    if ((offset + sizeof(*re)) > fdt_totalsize(fdt))
        return -FDT_ERR_NOSPACE;

    re = (struct fdt_reserve_entry *)((char *)fdt + offset);
    re->address = cpu_to_fdt64(addr);
    re->size = cpu_to_fdt64(size);

    fdt_set_off_dt_struct(fdt, offset + sizeof(*re));

    return 0;
}

int fdt_finish_reservemap(void *fdt)
{
    int err = fdt_add_reservemap_entry(fdt, 0, 0);

    if (err)
        return err;

    fdt_set_off_dt_strings(fdt, fdt_totalsize(fdt));
    return 0;
}

int fdt_begin_node(void *fdt, const char *name)
{
    struct fdt_node_header *nh;
    int namelen;

    FDT_SW_PROBE_STRUCT(fdt);

    namelen = strlen(name) + 1;
    nh = fdt_grab_space_(fdt, sizeof(*nh) + FDT_TAGALIGN(namelen));
    if (! nh)
        return -FDT_ERR_NOSPACE;

    nh->tag = cpu_to_fdt32(FDT_BEGIN_NODE);
    memcpy(nh->name, name, namelen);
    return 0;
}

int fdt_end_node(void *fdt)
{
    fdt32_t *en;

    FDT_SW_PROBE_STRUCT(fdt);

    en = fdt_grab_space_(fdt, FDT_TAGSIZE);
    if (! en)
        return -FDT_ERR_NOSPACE;

    *en = cpu_to_fdt32(FDT_END_NODE);
    return 0;
}

static int fdt_add_string_(void *fdt, const char *s)
{
    char *strtab = (char *)fdt + fdt_totalsize(fdt);
    unsigned int strtabsize = fdt_size_dt_strings(fdt);
    unsigned int len = strlen(s) + 1;
    unsigned int struct_top, offset;

    offset = strtabsize + len;
    struct_top = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
    if (fdt_totalsize(fdt) - offset < struct_top)
        return 0; /* no more room :( */

    memcpy(strtab - offset, s, len);
    fdt_set_size_dt_strings(fdt, strtabsize + len);
    return -offset;
}

/* Must only be used to roll back in case of error */
static void fdt_del_last_string_(void *fdt, const char *s)
{
    int strtabsize = fdt_size_dt_strings(fdt);
    int len = strlen(s) + 1;

    fdt_set_size_dt_strings(fdt, strtabsize - len);
}

static int fdt_find_add_string_(void *fdt, const char *s, int *allocated)
{
    char *strtab = (char *)fdt + fdt_totalsize(fdt);
    int strtabsize = fdt_size_dt_strings(fdt);
    const char *p;

    *allocated = 0;

    p = fdt_find_string_(strtab - strtabsize, strtabsize, s);
    if (p)
        return p - strtab;

    *allocated = 1;

    return fdt_add_string_(fdt, s);
}

int fdt_property_placeholder(void *fdt, const char *name, int len, void **valp)
{
    struct fdt_property *prop;
    int nameoff;
    int allocated;

    FDT_SW_PROBE_STRUCT(fdt);

    /* String de-duplication can be slow, _NO_NAME_DEDUP skips it */
    if (sw_flags(fdt) & FDT_CREATE_FLAG_NO_NAME_DEDUP) {
        allocated = 1;
        nameoff = fdt_add_string_(fdt, name);
    } else {
        nameoff = fdt_find_add_string_(fdt, name, &allocated);
    }
    if (nameoff == 0)
        return -FDT_ERR_NOSPACE;

    prop = fdt_grab_space_(fdt, sizeof(*prop) + FDT_TAGALIGN(len));
    if (! prop) {
        if (allocated)
            fdt_del_last_string_(fdt, name);
        return -FDT_ERR_NOSPACE;
    }

    prop->tag = cpu_to_fdt32(FDT_PROP);
    prop->nameoff = cpu_to_fdt32(nameoff);
    prop->len = cpu_to_fdt32(len);
    *valp = prop->data;
    return 0;
}

int fdt_property(void *fdt, const char *name, const void *val, int len)
{
    void *ptr;
    int ret;

    ret = fdt_property_placeholder(fdt, name, len, &ptr);
    if (ret)
        return ret;
    memcpy(ptr, val, len);
    return 0;
}

int fdt_finish(void *fdt)
{
    char *p = (char *)fdt;
    fdt32_t *end;
    int oldstroffset, newstroffset;
    uint32_t tag;
    int offset, nextoffset;

    FDT_SW_PROBE_STRUCT(fdt);

    /* Add terminator */
    end = fdt_grab_space_(fdt, sizeof(*end));
    if (! end)
        return -FDT_ERR_NOSPACE;
    *end = cpu_to_fdt32(FDT_END);

    /* Relocate the string table */
    oldstroffset = fdt_totalsize(fdt) - fdt_size_dt_strings(fdt);
    newstroffset = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
    memmove(p + newstroffset, p + oldstroffset, fdt_size_dt_strings(fdt));
    fdt_set_off_dt_strings(fdt, newstroffset);

    /* Walk the structure, correcting string offsets */
    offset = 0;
    while ((tag = fdt_next_tag(fdt, offset, &nextoffset)) != FDT_END) {
        if (tag == FDT_PROP) {
            struct fdt_property *prop =
                fdt_offset_ptr_w_(fdt, offset);
            int nameoff;

            nameoff = fdt32_to_cpu(prop->nameoff);
            nameoff += fdt_size_dt_strings(fdt);
            prop->nameoff = cpu_to_fdt32(nameoff);
        }
        offset = nextoffset;
    }
    if (nextoffset < 0)
        return nextoffset;

    /* Finally, adjust the header */
    fdt_set_totalsize(fdt, newstroffset + fdt_size_dt_strings(fdt));

    /* And fix up fields that were keeping intermediate state. */
    fdt_set_last_comp_version(fdt, FDT_LAST_COMPATIBLE_VERSION);
    fdt_set_magic(fdt, FDT_MAGIC);

    return 0;
}