// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Program to hack in a PT_NOTE program header entry in an ELF file.
 * This is needed for OF on RS/6000s to load an image correctly.
 * Note that OF needs a program header entry for the note, not an
 * ELF section.
 *
 * Copyright 2000 Paul Mackerras.
 *
 * Adapted for 64 bit little endian images by Andrew Tauferner.
 *
 * Usage: addnote zImage
 */
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

/* CHRP note section */
static const char arch[] = "PowerPC";

#define N_DESCR 6
unsigned int descr[N_DESCR] = {
        0xffffffff,             /* real-mode = true */
        0x02000000,             /* real-base, i.e. where we expect OF to be */
        0xffffffff,             /* real-size */
        0xffffffff,             /* virt-base */
        0xffffffff,             /* virt-size */
        0x4000,                 /* load-base */
};

/* RPA note section */
static const char rpaname[] = "IBM,RPA-Client-Config";

/*
 * Note: setting ignore_my_client_config *should* mean that OF ignores
 * all the other fields, but there is a firmware bug which means that
 * it looks at the splpar field at least.  So these values need to be
 * reasonable.
 */
#define N_RPA_DESCR     8
unsigned int rpanote[N_RPA_DESCR] = {
        0,                      /* lparaffinity */
        64,                     /* min_rmo_size */
        0,                      /* min_rmo_percent */
        40,                     /* max_pft_size */
        1,                      /* splpar */
        -1,                     /* min_load */
        0,                      /* new_mem_def */
        1,                      /* ignore_my_client_config */
};

#define ROUNDUP(len)    (((len) + 3) & ~3)

unsigned char buf[1024];
#define ELFDATA2LSB     1
#define ELFDATA2MSB     2
static int e_data = ELFDATA2MSB;
#define ELFCLASS32      1
#define ELFCLASS64      2
static int e_class = ELFCLASS32;

#define GET_16BE(off)   ((buf[off] << 8) + (buf[(off)+1]))
#define GET_32BE(off)   ((GET_16BE(off) << 16U) + GET_16BE((off)+2U))
#define GET_64BE(off)   ((((unsigned long long)GET_32BE(off)) << 32ULL) + \
                        ((unsigned long long)GET_32BE((off)+4ULL)))
#define PUT_16BE(off, v)(buf[off] = ((v) >> 8) & 0xff, \
                         buf[(off) + 1] = (v) & 0xff)
#define PUT_32BE(off, v)(PUT_16BE((off), (v) >> 16L), PUT_16BE((off) + 2, (v)))
#define PUT_64BE(off, v)((PUT_32BE((off), (unsigned long long)(v) >> 32L), \
                          PUT_32BE((off) + 4, (unsigned long long)(v))))

#define GET_16LE(off)   ((buf[off]) + (buf[(off)+1] << 8))
#define GET_32LE(off)   (GET_16LE(off) + (GET_16LE((off)+2U) << 16U))
#define GET_64LE(off)   ((unsigned long long)GET_32LE(off) + \
                        (((unsigned long long)GET_32LE((off)+4ULL)) << 32ULL))
#define PUT_16LE(off, v) (buf[off] = (v) & 0xff, \
                          buf[(off) + 1] = ((v) >> 8) & 0xff)
#define PUT_32LE(off, v) (PUT_16LE((off), (v)), PUT_16LE((off) + 2, (v) >> 16L))
#define PUT_64LE(off, v) (PUT_32LE((off), (unsigned long long)(v)), \
                          PUT_32LE((off) + 4, (unsigned long long)(v) >> 32L))

#define GET_16(off)     (e_data == ELFDATA2MSB ? GET_16BE(off) : GET_16LE(off))
#define GET_32(off)     (e_data == ELFDATA2MSB ? GET_32BE(off) : GET_32LE(off))
#define GET_64(off)     (e_data == ELFDATA2MSB ? GET_64BE(off) : GET_64LE(off))
#define PUT_16(off, v)  (e_data == ELFDATA2MSB ? PUT_16BE(off, v) : \
                         PUT_16LE(off, v))
#define PUT_32(off, v)  (e_data == ELFDATA2MSB ? PUT_32BE(off, v) : \
                         PUT_32LE(off, v))
#define PUT_64(off, v)  (e_data == ELFDATA2MSB ? PUT_64BE(off, v) : \
                         PUT_64LE(off, v))

/* Structure of an ELF file */
#define E_IDENT         0       /* ELF header */
#define E_PHOFF         (e_class == ELFCLASS32 ? 28 : 32)
#define E_PHENTSIZE     (e_class == ELFCLASS32 ? 42 : 54)
#define E_PHNUM         (e_class == ELFCLASS32 ? 44 : 56)
#define E_HSIZE         (e_class == ELFCLASS32 ? 52 : 64)

#define EI_MAGIC        0       /* offsets in E_IDENT area */
#define EI_CLASS        4
#define EI_DATA         5

#define PH_TYPE         0       /* ELF program header */
#define PH_OFFSET       (e_class == ELFCLASS32 ? 4 : 8)
#define PH_FILESZ       (e_class == ELFCLASS32 ? 16 : 32)
#define PH_HSIZE        (e_class == ELFCLASS32 ? 32 : 56)

#define PT_NOTE         4       /* Program header type = note */


unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };

int
main(int ac, char **av)
{
        int fd, n, i;
        unsigned long ph, ps, np;
        long nnote, nnote2, ns;

        if (ac != 2) {
                fprintf(stderr, "Usage: %s elf-file\n", av[0]);
                exit(1);
        }
        fd = open(av[1], O_RDWR);
        if (fd < 0) {
                perror(av[1]);
                exit(1);
        }

        nnote = 12 + ROUNDUP(strlen(arch) + 1) + sizeof(descr);
        nnote2 = 12 + ROUNDUP(strlen(rpaname) + 1) + sizeof(rpanote);

        n = read(fd, buf, sizeof(buf));
        if (n < 0) {
                perror("read");
                exit(1);
        }

        if (memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
                goto notelf;
        e_class = buf[E_IDENT+EI_CLASS];
        if (e_class != ELFCLASS32 && e_class != ELFCLASS64)
                goto notelf;
        e_data = buf[E_IDENT+EI_DATA];
        if (e_data != ELFDATA2MSB && e_data != ELFDATA2LSB)
                goto notelf;
        if (n < E_HSIZE)
                goto notelf;

        ph = (e_class == ELFCLASS32 ? GET_32(E_PHOFF) : GET_64(E_PHOFF));
        ps = GET_16(E_PHENTSIZE);
        np = GET_16(E_PHNUM);
        if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
                goto notelf;
        if (ph + (np + 2) * ps + nnote + nnote2 > n)
                goto nospace;

        for (i = 0; i < np; ++i) {
                if (GET_32(ph + PH_TYPE) == PT_NOTE) {
                        fprintf(stderr, "%s already has a note entry\n",
                                av[1]);
                        exit(0);
                }
                ph += ps;
        }

        /* XXX check that the area we want to use is all zeroes */
        for (i = 0; i < 2 * ps + nnote + nnote2; ++i)
                if (buf[ph + i] != 0)
                        goto nospace;

        /* fill in the program header entry */
        ns = ph + 2 * ps;
        PUT_32(ph + PH_TYPE, PT_NOTE);
        if (e_class == ELFCLASS32)
                PUT_32(ph + PH_OFFSET, ns);
        else
                PUT_64(ph + PH_OFFSET, ns);

        if (e_class == ELFCLASS32)
                PUT_32(ph + PH_FILESZ, nnote);
        else
                PUT_64(ph + PH_FILESZ, nnote);

        /* fill in the note area we point to */
        /* XXX we should probably make this a proper section */
        PUT_32(ns, strlen(arch) + 1);
        PUT_32(ns + 4, N_DESCR * 4);
        PUT_32(ns + 8, 0x1275);
        strcpy((char *) &buf[ns + 12], arch);
        ns += 12 + strlen(arch) + 1;
        for (i = 0; i < N_DESCR; ++i, ns += 4)
                PUT_32BE(ns, descr[i]);

        /* fill in the second program header entry and the RPA note area */
        ph += ps;
        PUT_32(ph + PH_TYPE, PT_NOTE);
        if (e_class == ELFCLASS32)
                PUT_32(ph + PH_OFFSET, ns);
        else
                PUT_64(ph + PH_OFFSET, ns);

        if (e_class == ELFCLASS32)
                PUT_32(ph + PH_FILESZ, nnote);
        else
                PUT_64(ph + PH_FILESZ, nnote2);

        /* fill in the note area we point to */
        PUT_32(ns, strlen(rpaname) + 1);
        PUT_32(ns + 4, sizeof(rpanote));
        PUT_32(ns + 8, 0x12759999);
        strcpy((char *) &buf[ns + 12], rpaname);
        ns += 12 + ROUNDUP(strlen(rpaname) + 1);
        for (i = 0; i < N_RPA_DESCR; ++i, ns += 4)
                PUT_32BE(ns, rpanote[i]);

        /* Update the number of program headers */
        PUT_16(E_PHNUM, np + 2);

        /* write back */
        i = lseek(fd, (long) 0, SEEK_SET);
        if (i < 0) {
                perror("lseek");
                exit(1);
        }
        i = write(fd, buf, n);
        if (i < 0) {
                perror("write");
                exit(1);
        }
        if (i < n) {
                fprintf(stderr, "%s: write truncated\n", av[1]);
                exit(1);
        }

        exit(0);

 notelf:
        fprintf(stderr, "%s does not appear to be an ELF file\n", av[1]);
        exit(1);

 nospace:
        fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
                av[1]);
        exit(1);
}