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authorhpa <hpa>2005-05-08 21:47:03 +0000
committerhpa <hpa>2005-05-08 21:47:03 +0000
commitdab010fba1ef01f60751114657452db16248ba9d (patch)
tree45eda2cb91bd1fb333aa74a2df2dd0ea94bf08cf /com32/modules/mboot.c
parent25b68a8eb102118d7db99b7b5bdc6682caef701f (diff)
downloadsyslinux.git-dab010fba1ef01f60751114657452db16248ba9d.tar.gz
syslinux.git-dab010fba1ef01f60751114657452db16248ba9d.tar.xz
syslinux.git-dab010fba1ef01f60751114657452db16248ba9d.zip
New Multiboot module; increase command line limit to 1023syslinux-3.08
Diffstat (limited to 'com32/modules/mboot.c')
-rw-r--r--com32/modules/mboot.c979
1 files changed, 979 insertions, 0 deletions
diff --git a/com32/modules/mboot.c b/com32/modules/mboot.c
new file mode 100644
index 00000000..4238c5cb
--- /dev/null
+++ b/com32/modules/mboot.c
@@ -0,0 +1,979 @@
+/*
+ * mboot.c
+ *
+ * Loader for Multiboot-compliant kernels and modules.
+ *
+ * Copyright (C) 2005 Tim Deegan <Tim.Deegan@cl.cam.ac.uk>
+ * Parts based on GNU GRUB, Copyright (C) 2000 Free Software Foundation, Inc.
+ * Parts based on SYSLINUX, Copyright (C) 1994-2005 H. Peter Anvin.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <string.h>
+#include <malloc.h>
+#include <consoles.h>
+#include <zlib.h>
+#include <com32.h>
+
+#include "i386-elf.h"
+#include "mb_info.h"
+#include "mb_header.h"
+
+#include <klibc/compiler.h> /* For __constructor */
+
+#define MIN(_x, _y) (((_x)<(_y))?(_x):(_y))
+#define MAX(_x, _y) (((_x)>(_y))?(_x):(_y))
+
+/* Define this for some more printout */
+#undef DEBUG
+
+/* Memory magic numbers */
+#define STACK_SIZE 0x20000 /* XXX Could be much smaller */
+#define MALLOC_SIZE 0x100000 /* XXX Could be much smaller */
+#define MIN_RUN_ADDR 0x10000 /* Lowest address we'll consider using */
+#define MEM_HOLE_START 0xa0000 /* Memory hole runs from 640k ... */
+#define MEM_HOLE_END 0x100000 /* ... to 1MB */
+#define X86_PAGE_SIZE 0x1000
+
+size_t __stack_size = STACK_SIZE; /* How much stack we'll use */
+extern void *__mem_end; /* Start of malloc() heap */
+extern char _end[]; /* End of static data */
+
+/* Pointer to free memory for loading into: load area is between here
+ * and section_addr */
+static char *next_load_addr;
+
+/* Memory map for run-time */
+typedef struct section section_t;
+struct section {
+ size_t dest; /* Start of run-time allocation */
+ char *src; /* Current location of data for memmove(),
+ * or NULL for bzero() */
+ size_t size; /* Length of allocation */
+};
+static char *section_addr;
+static int section_count;
+
+static size_t max_run_addr; /* Highest address we'll consider using */
+static size_t next_mod_run_addr; /* Where the next module will be put */
+
+/* File loads are in units of this much */
+#define LOAD_CHUNK 0x20000
+
+/* Layout of the input to the 32-bit lidt instruction */
+struct lidt_operand {
+ unsigned int limit:16;
+ unsigned int base:32;
+} __attribute__((packed));
+
+/* Magic strings */
+static const char version_string[] = "COM32 Multiboot loader v0.1";
+static const char copyright_string[] = "Copyright (C) 2005 Tim Deegan.";
+static const char module_separator[] = "---";
+
+
+/*
+ * Start of day magic, run from __start during library init.
+ */
+
+static void __constructor check_version(void)
+ /* Check the SYSLINUX version. Docs say we should be OK from v2.08,
+ * but in fact we crash on anything below v2.12 (when libc came in). */
+{
+ com32sys_t regs_in, regs_out;
+ const char *p, *too_old = "Fatal: SYSLINUX image is too old; "
+ "mboot.c32 needs at least version 2.12.\r\n";
+
+ memset(&regs_in, 0, sizeof(regs_in));
+ regs_in.eax.l = 0x0001; /* "Get version" */
+ __intcall(0x22, &regs_in, &regs_out);
+ if (regs_out.ecx.w[0] >= 0x020c) return;
+
+ /* Pointless: on older versions this print fails too. :( */
+ for (p = too_old ; *p ; p++) {
+ memset(&regs_in, 0, sizeof(regs_in));
+ regs_in.eax.b[1] = 0x02; /* "Write character" */
+ regs_in.edx.b[0] = *p;
+ __intcall(0x21, &regs_in, &regs_out);
+ }
+
+ __intcall(0x20, &regs_in, &regs_out); /* "Terminate program" */
+}
+
+
+static void __constructor grab_memory(void)
+ /* Runs before init_memory_arena() (com32/lib/malloc.c) to let
+ * the malloc() code know how much space it's allowed to use.
+ * We don't use malloc() directly, but some of the library code
+ * does (zlib, for example). */
+{
+ /* Find the stack pointer */
+ register char * sp;
+ asm volatile("movl %%esp, %0" : "=r" (sp));
+
+ /* Initialize the allocation of *run-time* memory: don't let ourselves
+ * overwrite the stack during the relocation later. */
+ max_run_addr = (size_t) sp - (MALLOC_SIZE + STACK_SIZE);
+
+ /* Move the end-of-memory marker: malloc() will use only memory
+ * above __mem_end and below the stack. We will load files starting
+ * at the old __mem_end and working towards the new one, and allocate
+ * section descriptors at the top of that area, working down. */
+ next_load_addr = __mem_end;
+ section_addr = sp - (MALLOC_SIZE + STACK_SIZE);
+ section_count = 0;
+
+ /* But be careful not to move it the wrong direction if memory is
+ * tight. Instead we'll fail more gracefully later, when we try to
+ * load a file and find that next_load_addr > section_addr. */
+ __mem_end = MAX(section_addr, next_load_addr);
+}
+
+
+
+
+/*
+ * Run-time memory map functions: allocating and recording allocations.
+ */
+
+static int cmp_sections(const void *a, const void *b)
+ /* For sorting section descriptors by destination address */
+{
+ const section_t *sa = a;
+ const section_t *sb = b;
+ if (sa->dest < sb->dest) return -1;
+ if (sa->dest > sb->dest) return 1;
+ return 0;
+}
+
+
+static void add_section(size_t dest, char *src, size_t size)
+ /* Adds something to the list of sections to relocate. */
+{
+ section_t *sec;
+
+#ifdef DEBUG
+ printf("SECTION: %#8.8x --> %#8.8x (%#x)\n", (size_t) src, dest, size);
+#endif
+
+ section_addr -= sizeof (section_t);
+ if (section_addr < next_load_addr) {
+ printf("Fatal: out of memory allocating section descriptor.\n");
+ exit(1);
+ }
+ sec = (section_t *) section_addr;
+ section_count++;
+
+ sec->src = src;
+ sec->dest = dest;
+ sec->size = size;
+
+ /* Keep the list sorted */
+ qsort(sec, section_count, sizeof (section_t), cmp_sections);
+}
+
+
+static size_t place_low_section(size_t size, size_t align)
+ /* Find a space in the run-time memory map, below 640K */
+{
+ int i;
+ size_t start;
+ section_t *sections = (section_t *) section_addr;
+
+ start = MIN_RUN_ADDR;
+ start = (start + (align-1)) & ~(align-1);
+
+ /* Section list is sorted by destination, so can do this in one pass */
+ for (i = 0; i < section_count; i++) {
+ if (sections[i].dest < start + size) {
+ /* Hit the bottom of this section */
+ start = sections[i].dest + sections[i].size;
+ start = (start + (align-1)) & ~(align-1);
+ }
+ }
+ if (start + size < MEM_HOLE_START) return start;
+ else return 0;
+}
+
+
+static size_t place_module_section(size_t size, size_t align)
+ /* Find a space in the run-time memory map for this module. */
+{
+ /* Ideally we'd run through the sections looking for a free space
+ * like place_low_section() does, but some OSes (Xen, at least)
+ * assume that the bootloader has loaded all the modules
+ * consecutively, above the kernel. So, what we actually do is
+ * keep a pointer to the highest address allocated so far, and
+ * always allocate modules there. */
+
+ size_t start = next_mod_run_addr;
+ start = (start + (align-1)) & ~(align-1);
+
+ if (start + size > max_run_addr) return 0;
+
+ next_mod_run_addr = start + size;
+ return start;
+}
+
+
+static void place_kernel_section(size_t start, size_t size)
+ /* Allocate run-time space for part of the kernel, checking for
+ * sanity. We assume the kernel isn't broken enough to have
+ * overlapping segments. */
+{
+ /* We always place modules above the kernel */
+ next_mod_run_addr = MAX(next_mod_run_addr, start + size);
+
+ if (start > max_run_addr || start + size > max_run_addr) {
+ /* Overruns the end of memory */
+ printf("Fatal: kernel loads too high (%#8.8x+%#x > %#8.8x).\n",
+ start, size, max_run_addr);
+ exit(1);
+ }
+ if (start >= MEM_HOLE_END) {
+ /* Above the memory hole: easy */
+#ifdef DEBUG
+ printf("Placed kernel section (%#8.8x+%#x)\n", start, size);
+#endif
+ return;
+ }
+ if (start >= MEM_HOLE_START) {
+ /* In the memory hole. Not so good */
+ printf("Fatal: kernel load address (%#8.8x) is in the memory hole.\n",
+ start);
+ exit(1);
+ }
+ if (start + size > MEM_HOLE_START) {
+ /* Too big for low memory */
+ printf("Fatal: kernel (%#8.8x+%#x) runs into the memory hole.\n",
+ start, size);
+ exit(1);
+ }
+ if (start < MIN_RUN_ADDR) {
+ /* Loads too low */
+ printf("Fatal: kernel load address (%#8.8x) is too low (<%#8.8x).\n",
+ start, MIN_RUN_ADDR);
+ exit(1);
+ }
+ /* Kernel loads below the memory hole: OK */
+#ifdef DEBUG
+ printf("Placed kernel section (%#8.8x+%#x)\n", start, size);
+#endif
+}
+
+
+static void reorder_sections(void)
+ /* Reorders sections into a safe order, where no relocation
+ * overwrites the source of a later one. */
+{
+ section_t *secs = (section_t *) section_addr;
+ section_t tmp;
+ int i, j, tries;
+
+#ifdef DEBUG
+ printf("Relocations:\n");
+ for (i = 0; i < section_count ; i++) {
+ printf(" %#8.8x --> %#8.8x (%#x)\n",
+ (size_t)secs[i].src, secs[i].dest, secs[i].size);
+ }
+#endif
+
+ for (i = 0; i < section_count; i++) {
+ tries = 0;
+ scan_again:
+ for (j = i + 1 ; j < section_count; j++) {
+ if (secs[j].src != NULL
+ && secs[i].dest + secs[i].size > (size_t) secs[j].src
+ && secs[i].dest < (size_t) secs[j].src + secs[j].size) {
+ /* Would overwrite the source of the later move */
+ if (++tries > section_count) {
+ /* Deadlock! */
+ /* XXX Try to break deadlocks? */
+ printf("Fatal: circular dependence in relocations.\n");
+ exit(1);
+ }
+ /* Swap these sections (using struct copies) */
+ tmp = secs[i]; secs[i] = secs[j]; secs[j] = tmp;
+ /* Start scanning again from the new secs[i]... */
+ goto scan_again;
+ }
+ }
+ }
+
+#ifdef DEBUG
+ printf("Relocations:\n");
+ for (i = 0; i < section_count ; i++) {
+ printf(" %#8.8x --> %#8.8x (%#x)\n",
+ (size_t)secs[i].src, secs[i].dest, secs[i].size);
+ }
+#endif
+}
+
+
+static void init_mmap(struct multiboot_info *mbi)
+ /* Get a full memory map from the BIOS to pass to the kernel. */
+{
+ com32sys_t regs_in, regs_out;
+ struct AddrRangeDesc *e820;
+ int e820_slots;
+ size_t mem_lower, mem_upper, run_addr, mmap_size;
+ register size_t sp;
+
+ /* Default values for mem_lower and mem_upper in case the BIOS won't
+ * tell us: 640K, and all memory up to the stack. */
+ asm volatile("movl %%esp, %0" : "=r" (sp));
+ mem_upper = (sp - MEM_HOLE_END) / 1024;
+ mem_lower = (MEM_HOLE_START) / 1024;
+
+#ifdef DEBUG
+ printf("Requesting memory map from BIOS:\n");
+#endif
+
+ /* Ask the BIOS for the full memory map of the machine. We'll
+ * build it in Multiboot format (i.e. with size fields) in the
+ * bounce buffer, and then allocate some high memory to keep it in
+ * until boot time. */
+ e820 = __com32.cs_bounce;
+ e820_slots = 0;
+ regs_out.ebx.l = 0;
+
+ while(((void *)(e820 + 1)) < __com32.cs_bounce + __com32.cs_bounce_size)
+ {
+
+ e820->size = sizeof(*e820) - sizeof(e820->size);
+
+ /* Ask the BIOS to fill in this descriptor */
+ regs_in.eax.l = 0xe820; /* "Get system memory map" */
+ regs_in.ebx.l = regs_out.ebx.l; /* Continuation value from last call */
+ regs_in.ecx.l = 20; /* Size of buffer to write into */
+ regs_in.edx.l = 0x534d4150; /* "SMAP" */
+ regs_in.es = SEG(&e820->BaseAddr);
+ regs_in.edi.w[0] = OFFS(&e820->BaseAddr);
+ __intcall(0x15, &regs_in, &regs_out);
+
+ if ((regs_out.eflags.l & EFLAGS_CF) != 0 && regs_out.ebx.l != 0)
+ break; /* End of map */
+
+ if (((regs_out.eflags.l & EFLAGS_CF) != 0 && regs_out.ebx.l == 0)
+ || (regs_out.eax.l != 0x534d4150))
+ {
+ /* Error */
+ printf("Error %x reading E820 memory map: %s.\n",
+ (int) regs_out.eax.b[0],
+ (regs_out.eax.b[0] == 0x80) ? "invalid command" :
+ (regs_out.eax.b[0] == 0x86) ? "not supported" :
+ "unknown error");
+ break;
+ }
+
+ /* Success */
+#ifdef DEBUG
+ printf(" %#16.16Lx -- %#16.16Lx : ",
+ e820->BaseAddr, e820->BaseAddr + e820->Length);
+ switch (e820->Type) {
+ case 1: printf("Available\n"); break;
+ case 2: printf("Reserved\n"); break;
+ case 3: printf("ACPI Reclaim\n"); break;
+ case 4: printf("ACPI NVS\n"); break;
+ default: printf("? (Reserved)\n"); break;
+ }
+#endif
+
+ if (e820->Type == 1) {
+ if (e820->BaseAddr == 0) {
+ mem_lower = MIN(MEM_HOLE_START, e820->Length) / 1024;
+ } else if (e820->BaseAddr == MEM_HOLE_END) {
+ mem_upper = MIN(0xfff00000, e820->Length) / 1024;
+ }
+ }
+
+ /* Move to next slot */
+ e820++;
+ e820_slots++;
+
+ /* Done? */
+ if (regs_out.ebx.l == 0)
+ break;
+ }
+
+ /* Record the simple information in the MBI */
+ mbi->flags |= MB_INFO_MEMORY;
+ mbi->mem_lower = mem_lower;
+ mbi->mem_upper = mem_upper;
+
+ /* Record the full memory map in the MBI */
+ if (e820_slots != 0) {
+ mmap_size = e820_slots * sizeof(*e820);
+ /* Where will it live at run time? */
+ run_addr = place_low_section(mmap_size, 1);
+ if (run_addr == 0) {
+ printf("Fatal: can't find space for the e820 mmap.\n");
+ exit(1);
+ }
+ /* Where will it live now? */
+ e820 = (struct AddrRangeDesc *) next_load_addr;
+ if (next_load_addr + mmap_size > section_addr) {
+ printf("Fatal: out of memory storing the e820 mmap.\n");
+ exit(1);
+ }
+ next_load_addr += mmap_size;
+ /* Copy it out of the bounce buffer */
+ memcpy(e820, __com32.cs_bounce, mmap_size);
+ /* Remember to copy it again at run time */
+ add_section(run_addr, (char *) e820, mmap_size);
+ /* Record it in the MBI */
+ mbi->flags |= MB_INFO_MEM_MAP;
+ mbi->mmap_length = mmap_size;
+ mbi->mmap_addr = run_addr;
+ }
+}
+
+
+
+
+/*
+ * Code for loading and parsing files.
+ */
+
+static void load_file(char *filename, char **startp, size_t *sizep)
+ /* Load a file into memory. Returns where it is and how big via
+ * startp and sizep */
+{
+ gzFile fp;
+ char *start;
+ int bsize;
+
+ printf("Loading %s.", filename);
+
+ start = next_load_addr;
+ startp[0] = start;
+ sizep[0] = 0;
+
+ /* Open the file */
+ if ((fp = gzopen(filename, "r")) == NULL) {
+ printf("\nFatal: cannot open %s\n", filename);
+ exit(1);
+ }
+
+ while (next_load_addr + LOAD_CHUNK <= section_addr) {
+ bsize = gzread(fp, next_load_addr, LOAD_CHUNK);
+ printf("%s",".");
+
+ if (bsize < 0) {
+ printf("\nFatal: read error in %s\n", filename);
+ gzclose(fp);
+ exit(1);
+ }
+
+ next_load_addr += bsize;
+ sizep[0] += bsize;
+
+ if (bsize < LOAD_CHUNK) {
+ printf("%s","\n");
+ gzclose(fp);
+ return;
+ }
+ }
+
+ /* Running out of memory. Try and use up the last bit */
+ if (section_addr > next_load_addr) {
+ bsize = gzread(fp, next_load_addr, section_addr - next_load_addr);
+ printf("%s",".");
+ } else {
+ bsize = 0;
+ }
+
+ if (bsize < 0) {
+ gzclose(fp);
+ printf("\nFatal: read error in %s\n", filename);
+ exit(1);
+ }
+
+ next_load_addr += bsize;
+ sizep[0] += bsize;
+
+ if (!gzeof(fp)) {
+ gzclose(fp);
+ printf("\nFatal: out of memory reading %s\n", filename);
+ exit(1);
+ }
+
+ printf("%s","\n");
+ gzclose(fp);
+ return;
+}
+
+
+static size_t load_kernel(char *cmdline)
+ /* Load a multiboot/elf32 kernel and allocate run-time memory for it.
+ * Returns the kernel's entry address. */
+{
+ unsigned int i;
+ char *load_addr; /* Where the image was loaded */
+ size_t load_size; /* How big it is */
+ char *seg_addr; /* Where a segment was loaded */
+ size_t seg_size, bss_size; /* How big it is */
+ size_t run_addr, run_size; /* Where it should be put */
+ char *p;
+ Elf32_Ehdr *ehdr;
+ Elf32_Phdr *phdr;
+ struct multiboot_header *mbh;
+
+ printf("Kernel: %s\n", cmdline);
+
+ load_addr = 0;
+ load_size = 0;
+ p = strchr(cmdline, ' ');
+ if (p != NULL) *p = 0;
+ load_file(cmdline, &load_addr, &load_size);
+ if (load_size < 12) {
+ printf("Fatal: %s is too short to be a multiboot kernel.",
+ cmdline);
+ exit(1);
+ }
+ if (p != NULL) *p = ' ';
+
+
+ /* Look for a multiboot header in the first 8k of the file */
+ for (i = 0; i <= MIN(load_size - 12, MULTIBOOT_SEARCH - 12); i += 4)
+ {
+ mbh = (struct multiboot_header *)(load_addr + i);
+ if (mbh->magic != MULTIBOOT_MAGIC
+ || ((mbh->magic+mbh->flags+mbh->checksum) & 0xffffffff))
+ {
+ /* Not a multiboot header */
+ continue;
+ }
+ if (mbh->flags & (MULTIBOOT_UNSUPPORTED | MULTIBOOT_VIDEO_MODE)) {
+ /* Requires options we don't support */
+ printf("Fatal: Kernel requires multiboot options "
+ "that I don't support: %#x.\n",
+ mbh->flags & (MULTIBOOT_UNSUPPORTED|MULTIBOOT_VIDEO_MODE));
+ exit(1);
+ }
+
+ /* This kernel will do: figure out where all the pieces will live */
+
+ if (mbh->flags & MULTIBOOT_AOUT_KLUDGE) {
+
+ /* Use the offsets in the multiboot header */
+#ifdef DEBUG
+ printf("Using multiboot header.\n");
+#endif
+
+ /* Where is the code in the loaded file? */
+ seg_addr = ((char *)mbh) - (mbh->header_addr - mbh->load_addr);
+
+ /* How much code is there? */
+ run_addr = mbh->load_addr;
+ if (mbh->load_end_addr != 0)
+ seg_size = mbh->load_end_addr - mbh->load_addr;
+ else
+ seg_size = load_size - (seg_addr - load_addr);
+
+ /* How much memory will it take up? */
+ if (mbh->bss_end_addr != 0)
+ run_size = mbh->bss_end_addr - mbh->load_addr;
+ else
+ run_size = seg_size;
+
+ if (seg_size > run_size) {
+ printf("Fatal: can't put %i bytes of kernel into %i bytes "
+ "of memory.\n", seg_size, run_size);
+ exit(1);
+ }
+ if (seg_addr + seg_size > load_addr + load_size) {
+ printf("Fatal: multiboot load segment runs off the "
+ "end of the file.\n");
+ exit(1);
+ }
+
+ /* Does it fit where it wants to be? */
+ place_kernel_section(run_addr, run_size);
+
+ /* Put it on the relocation list */
+ if (seg_size < run_size) {
+ /* Set up the kernel BSS too */
+ if (seg_size > 0)
+ add_section(run_addr, seg_addr, seg_size);
+ bss_size = run_size - seg_size;
+ add_section(run_addr + seg_size, NULL, bss_size);
+ } else {
+ /* No BSS */
+ add_section(run_addr, seg_addr, run_size);
+ }
+
+ /* Done. */
+ return mbh->entry_addr;
+
+ } else {
+
+ /* Now look for an ELF32 header */
+ ehdr = (Elf32_Ehdr *)load_addr;
+ if (*(unsigned long *)ehdr != 0x464c457f
+ || ehdr->e_ident[EI_DATA] != ELFDATA2LSB
+ || ehdr->e_ident[EI_CLASS] != ELFCLASS32
+ || ehdr->e_machine != EM_386)
+ {
+ printf("Fatal: kernel has neither ELF32/x86 nor multiboot load"
+ " headers.\n");
+ exit(1);
+ }
+ if (ehdr->e_phoff + ehdr->e_phnum*sizeof (*phdr) > load_size) {
+ printf("Fatal: malformed ELF header overruns EOF.\n");
+ exit(1);
+ }
+ if (ehdr->e_phnum <= 0) {
+ printf("Fatal: ELF kernel has no program headers.\n");
+ exit(1);
+ }
+
+#ifdef DEBUG
+ printf("Using ELF header.\n");
+#endif
+
+ if (ehdr->e_type != ET_EXEC
+ || ehdr->e_version != EV_CURRENT
+ || ehdr->e_phentsize != sizeof (Elf32_Phdr)) {
+ printf("Warning: funny-looking ELF header.\n");
+ }
+ phdr = (Elf32_Phdr *)(load_addr + ehdr->e_phoff);
+
+ /* Obey the program headers to load the kernel */
+ for(i = 0; i < ehdr->e_phnum; i++) {
+
+ /* How much is in this segment? */
+ run_size = phdr[i].p_memsz;
+ if (phdr[i].p_type != PT_LOAD)
+ seg_size = 0;
+ else
+ seg_size = (size_t)phdr[i].p_filesz;
+
+ /* Where is it in the loaded file? */
+ seg_addr = load_addr + phdr[i].p_offset;
+ if (seg_addr + seg_size > load_addr + load_size) {
+ printf("Fatal: ELF load segment runs off the "
+ "end of the file.\n");
+ exit(1);
+ }
+
+ /* Skip segments that don't take up any memory */
+ if (run_size == 0) continue;
+
+ /* Place the segment where it wants to be */
+ run_addr = phdr[i].p_paddr;
+ place_kernel_section(run_addr, run_size);
+
+ /* Put it on the relocation list */
+ if (seg_size < run_size) {
+ /* Set up the kernel BSS too */
+ if (seg_size > 0)
+ add_section(run_addr, seg_addr, seg_size);
+ bss_size = run_size - seg_size;
+ add_section(run_addr + seg_size, NULL, bss_size);
+ } else {
+ /* No BSS */
+ add_section(run_addr, seg_addr, run_size);
+ }
+ }
+
+ /* Done! */
+ return ehdr->e_entry;
+ }
+ }
+
+ /* This is not a multiboot kernel */
+ printf("Fatal: not a multiboot kernel.\n");
+ exit(1);
+}
+
+
+
+static void load_module(struct mod_list *mod, char *cmdline)
+ /* Load a multiboot module and allocate a memory area for it */
+{
+ char *load_addr, *p;
+ size_t load_size, run_addr;
+
+ printf("Module: %s\n", cmdline);
+
+ load_addr = 0;
+ load_size = 0;
+ p = strchr(cmdline, ' ');
+ if (p != NULL) *p = 0;
+ load_file(cmdline, &load_addr, &load_size);
+ if (p != NULL) *p = ' ';
+
+ /* Decide where it's going to live */
+ run_addr = place_module_section(load_size, X86_PAGE_SIZE);
+ if (run_addr == 0) {
+ printf("Fatal: can't find space for this module.\n");
+ exit(1);
+ }
+ add_section(run_addr, load_addr, load_size);
+
+ /* Remember where we put it */
+ mod->mod_start = run_addr;
+ mod->mod_end = run_addr + load_size;
+ mod->pad = 0;
+
+#ifdef DEBUG
+ printf("Placed module (%#8.8x+%#x)\n", run_addr, load_size);
+#endif
+}
+
+
+
+
+/*
+ * Code for shuffling sections into place and booting the new kernel
+ */
+
+static void trampoline_start(section_t *secs, int sec_count,
+ size_t mbi_run_addr, size_t entry)
+ /* Final shuffle-and-boot code. Running on the stack; no external code
+ * or data can be relied on. */
+{
+ int i;
+ struct lidt_operand idt;
+
+ /* SYSLINUX has set up SS, DS and ES as 32-bit 0--4G data segments,
+ * but doesn't specify FS and GS. Multiboot wants them all to be
+ * the same, so we'd better do that before we overwrite the GDT. */
+ asm volatile("movl %ds, %ecx; movl %ecx, %fs; movl %ecx, %gs");
+
+ /* Turn off interrupts */
+ asm volatile("cli");
+
+ /* SYSLINUX has set up an IDT at 0x100000 that does all the
+ * comboot calls, and we're about to overwrite it. The Multiboot
+ * spec says that the kernel must set up its own IDT before turning
+ * on interrupts, but it's still entitled to use BIOS calls, so we'll
+ * put the IDT back to the BIOS one at the base of memory. */
+ idt.base = 0;
+ idt.limit = 0x800;
+ asm volatile("lidt %0" : : "m" (idt));
+
+ /* Now, shuffle the sections */
+ for (i = 0; i < sec_count; i++) {
+ if (secs[i].src == NULL) {
+ /* asm bzero() code from com32/lib/memset.c */
+ char *q = (char *) secs[i].dest;
+ size_t nl = secs[i].size >> 2;
+ asm volatile("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb"
+ : "+c" (nl), "+D" (q)
+ : "a" (0x0U), "r" (secs[i].size & 3));
+ } else {
+ /* asm memmove() code from com32/lib/memmove.c */
+ const char *p = secs[i].src;
+ char *q = (char *) secs[i].dest;
+ size_t n = secs[i].size;
+ if ( q < p ) {
+ asm volatile("cld ; rep ; movsb"
+ : "+c" (n), "+S" (p), "+D" (q));
+ } else {
+ p += (n-1);
+ q += (n-1);
+ asm volatile("std ; rep ; movsb"
+ : "+c" (n), "+S" (p), "+D" (q));
+ }
+ }
+ }
+
+ /* Now set up the last tiny bit of Multiboot environment... */
+
+ asm volatile(
+
+ /* A20 is already enabled.
+ * CR0 already has PG cleared and PE set.
+ * EFLAGS already has VM and IF cleared.
+ * ESP is the kernels' problem.
+ * GDTR is the kernel's problem.
+ * CS is already a 32-bit, 0--4G code segments.
+ * DS, ES, FS and GS are already 32-bit, 0--4G data segments.
+ * EBX must point to the MBI: */
+
+ "movl %0, %%ebx;"
+
+ /* EAX must be the Multiboot magic number. */
+
+ "movl $0x2badb002, %%eax;"
+
+ /* Start the kernel. */
+
+ "jmp *%1"
+
+ : : "m" (mbi_run_addr), "r" (entry));
+
+}
+static void trampoline_end(void) {}
+
+
+static void boot(size_t mbi_run_addr, size_t entry)
+ /* Tidy up SYSLINUX, shuffle memory and boot the kernel */
+{
+ com32sys_t regs;
+ section_t *tr_sections;
+ void (*trampoline)(section_t *, int, size_t, size_t);
+ size_t trampoline_size;
+
+ /* Make sure the relocations are safe. */
+ reorder_sections();
+
+ /* Copy the shuffle-and-boot code and the array of relocations
+ * onto the memory we previously used for malloc() heap. This is
+ * safe because it's not the source or the destination of any
+ * copies, and there'll be no more library calls after the copy. */
+
+ tr_sections = ((section_t *) section_addr) + section_count;
+ trampoline = (void *) (tr_sections + section_count);
+ trampoline_size = (void *)&trampoline_end - (void *)&trampoline_start;
+
+#ifdef DEBUG
+ printf("tr_sections: %p\n"
+ "trampoline: %p\n"
+ "trampoline_size: %#8.8x\n"
+ "max_run_addr: %#8.8x\n",
+ tr_sections, trampoline, trampoline_size, max_run_addr);
+#endif
+
+ printf("Booting: MBI=%#8.8x, entry=%#8.8x\n", mbi_run_addr, entry);
+
+ memmove(tr_sections, section_addr, section_count * sizeof (section_t));
+ memmove(trampoline, trampoline_start, trampoline_size);
+
+ /* Tell SYSLINUX to clean up */
+ regs.eax.l = 0x000c; /* "Perform final cleanup" */
+ regs.edx.l = 0; /* "Normal cleanup" */
+ __intcall(0x22, &regs, NULL);
+
+ /* Into the unknown */
+ trampoline(tr_sections, section_count, mbi_run_addr, entry);
+}
+
+
+int main(int argc, char **argv)
+ /* Parse the command-line and invoke loaders */
+{
+ struct multiboot_info *mbi;
+ struct mod_list *modp;
+ int modules;
+ int mbi_reloc_offset;
+ char *p;
+ size_t mbi_run_addr, mbi_size, entry;
+ int i;
+
+ /* Say hello */
+ console_ansi_std();
+ printf("%s. %s\n", version_string, copyright_string);
+
+ if (argc < 2 || !strcmp(argv[1], module_separator)) {
+ printf("Fatal: No kernel filename!\n");
+ exit(1);
+ }
+
+#ifdef DEBUG
+ printf("_end: %p\n"
+ "argv[1]: %p\n"
+ "next_load_addr: %p\n"
+ "section_addr %p\n"
+ "__mem_end: %p\n"
+ "argv[0]: %p\n",
+ &_end, argv[1], next_load_addr, section_addr, __mem_end, argv[0]);
+#endif
+
+ /* How much space will the MBI need? */
+ modules = 0;
+ mbi_size = sizeof(struct multiboot_info) + strlen(version_string) + 5;
+ for (i = 1 ; i < argc ; i++) {
+ if (!strcmp(argv[i], module_separator)) {
+ modules++;
+ mbi_size += sizeof(struct mod_list) + 1;
+ } else {
+ mbi_size += strlen(argv[i]) + 1;
+ }
+ }
+
+ /* Allocate space in the load buffer for the MBI, all the command
+ * lines, and all the module details. */
+ mbi = (struct multiboot_info *)next_load_addr;
+ next_load_addr += mbi_size;
+ if (next_load_addr > section_addr) {
+ printf("Fatal: out of memory allocating for boot metadata.\n");
+ exit(1);
+ }
+ memset(mbi, 0, sizeof (struct multiboot_info));
+ p = (char *)(mbi + 1);
+ mbi->flags = MB_INFO_CMDLINE | MB_INFO_BOOT_LOADER_NAME;
+
+ /* Figure out the memory map.
+ * N.B. Must happen before place_section() is called */
+ init_mmap(mbi);
+
+ mbi_run_addr = place_low_section(mbi_size, 4);
+ if (mbi_run_addr == 0) {
+ printf("Fatal: can't find space for the MBI!\n");
+ exit(1);
+ }
+ mbi_reloc_offset = (size_t)mbi - mbi_run_addr;
+ add_section(mbi_run_addr, (void *)mbi, mbi_size);
+
+ /* Module info structs */
+ modp = (struct mod_list *) (((size_t)p + 3) & ~3);
+ if (modules > 0) mbi->flags |= MB_INFO_MODS;
+ mbi->mods_count = modules;
+ mbi->mods_addr = ((size_t)modp) - mbi_reloc_offset;
+ p = (char *)(modp + modules);
+
+ /* Command lines: first kernel, then modules */
+ mbi->cmdline = ((size_t)p) - mbi_reloc_offset;
+ modules = 0;
+ for (i = 1 ; i < argc ; i++) {
+ if (!strcmp(argv[i], module_separator)) {
+ *p++ = '\0';
+ modp[modules++].cmdline = ((size_t)p) - mbi_reloc_offset;
+ } else {
+ strcpy(p, argv[i]);
+ p += strlen(argv[i]);
+ *p++ = ' ';
+ }
+ }
+ *p++ = '\0';
+
+ /* Bootloader ID */
+ strcpy(p, version_string);
+ mbi->boot_loader_name = ((size_t)p) - mbi_reloc_offset;
+ p += strlen(version_string) + 1;
+
+ /* Now, do all the loading, and boot it */
+ entry = load_kernel((char *)(mbi->cmdline + mbi_reloc_offset));
+ for (i=0; i<modules; i++) {
+ load_module(&(modp[i]), (char *)(modp[i].cmdline + mbi_reloc_offset));
+ }
+ boot(mbi_run_addr, entry);
+
+ return 1;
+}
+
+/*
+ * EOF
+ */