Commit yaboot 1.3.0

[tonyb-yaboot.git] / util / addnote.c

diff --git a/util/addnote.c b/util/addnote.c
new file mode 100644 (file)
index 0000000..4088c32
--- /dev/null
+++ b/util/addnote.c
@@ -0,0 +1,163 @@
+/*
+ * 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.
+ *
+ * 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.
+ *
+ * Usage: addnote zImage
+ */
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+char arch[] = "PowerPC";
+
+#define N_DESCR        6
+unsigned int descr[N_DESCR] = {
+       0xffffffff,             /* real-mode = true */
+       0x00c00000,             /* real-base, i.e. where we expect OF to be */
+       0xffffffff,             /* real-size */
+       0xffffffff,             /* virt-base */
+       0xffffffff,             /* virt-size */
+       0x4000,                 /* load-base */
+};
+
+unsigned char buf[512];
+
+#define GET_16BE(off)  ((buf[off] << 8) + (buf[(off)+1]))
+#define GET_32BE(off)  ((GET_16BE(off) << 16) + GET_16BE((off)+2))
+#define PUT_16BE(off, v)       (buf[off] = ((v) >> 8) & 0xff, \
+                        buf[(off) + 1] = (v) & 0xff)
+#define PUT_32BE(off, v)       (PUT_16BE((off), (v) >> 16), \
+                                PUT_16BE((off) + 2, (v)))
+
+/* Structure of an ELF file */
+#define E_IDENT                0       /* ELF header */
+#define        E_PHOFF         28
+#define E_PHENTSIZE    42
+#define E_PHNUM                44
+#define E_HSIZE                52      /* size of ELF header */
+
+#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      4
+#define PH_FILESZ      16
+#define PH_HSIZE       32      /* size of program header */
+
+#define PT_NOTE                4       /* Program header type = note */
+
+#define ELFCLASS32     1
+#define ELFDATA2MSB    2
+
+unsigned char elf_magic[4] = { 0x7f, 'E', 'L', 'F' };
+
+int
+main(int ac, char **av)
+{
+       int fd, n, i;
+       int ph, ps, np;
+       int nnote, 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 = strlen(arch) + 1 + (N_DESCR + 3) * 4;
+
+       n = read(fd, buf, sizeof(buf));
+       if (n < 0) {
+               perror("read");
+               exit(1);
+       }
+
+       if (n < E_HSIZE || memcmp(&buf[E_IDENT+EI_MAGIC], elf_magic, 4) != 0)
+               goto notelf;
+
+       if (buf[E_IDENT+EI_CLASS] != ELFCLASS32
+           || buf[E_IDENT+EI_DATA] != ELFDATA2MSB) {
+               fprintf(stderr, "%s is not a big-endian 32-bit ELF image\n",
+                       av[1]);
+               exit(1);
+       }
+
+       ph = GET_32BE(E_PHOFF);
+       ps = GET_16BE(E_PHENTSIZE);
+       np = GET_16BE(E_PHNUM);
+       if (ph < E_HSIZE || ps < PH_HSIZE || np < 1)
+               goto notelf;
+       if (ph + (np + 1) * ps + nnote > n)
+               goto nospace;
+
+       for (i = 0; i < np; ++i) {
+               if (GET_32BE(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 < ps + nnote; ++i)
+               if (buf[ph + i] != 0)
+                       goto nospace;
+
+       /* fill in the program header entry */
+       ns = ph + ps;
+       PUT_32BE(ph + PH_TYPE, PT_NOTE);
+       PUT_32BE(ph + PH_OFFSET, ns);
+       PUT_32BE(ph + PH_FILESZ, nnote);
+
+       /* fill in the note area we point to */
+       /* XXX we should probably make this a proper section */
+       PUT_32BE(ns, strlen(arch) + 1);
+       PUT_32BE(ns + 4, N_DESCR * 4);
+       PUT_32BE(ns + 8, 0x1275);
+       strcpy(&buf[ns + 12], arch);
+       ns += 12 + strlen(arch) + 1;
+       for (i = 0; i < N_DESCR; ++i)
+               PUT_32BE(ns + i * 4, descr[i]);
+
+       /* Update the number of program headers */
+       PUT_16BE(E_PHNUM, np + 1);
+
+       /* write back */
+       lseek(fd, (long) 0, SEEK_SET);
+       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[0]);
+       exit(1);
+
+ nospace:
+       fprintf(stderr, "sorry, I can't find space in %s to put the note\n",
+               av[1]);
+       exit(1);
+}