[syslinux] [PATCH] Extend Multiboot1 with support for ELF64 file format
Ady
ady-sf at hotmail.com
Sat Oct 10 01:14:27 PDT 2015
This patch is just a (shameless) copy from bug #28 [1].
The original patch has been sitting there for a couple of years now,
and it was based on Syslinux v 4.05.
The patch I am posting here is just a re-base on v.6.03. Whichever
inadequate formatting (tabs, trailing spaces...), or any kind of
correction that was required for the original patch to be accepted, is
probably still required now.
I have not tested this patch in any way, at all. I do not know whether
it is formatted adequately, whether it actually builds correctly, nor
whether the potential resulting binaries would work as expected in any
case.
The only "credit" (for lack of a better term) that could be attributed
to me could be bringing up the existence of this pending-patch to the
official Syslinux mailing list, after 2 years of being initially posted
to the official Syslinux Bugzilla tracker. Credit should go to the
original poster.
I am hoping this pending-for-review-patch can be evaluated, (corrected,
improved) and eventually accepted and merged in the official Syslinux
code.
Please don't leave this patch awaiting another 2 years.
TIA,
Ady.
[1]:
http://bugzilla.syslinux.org/show_bug.cgi?id=28
Extend Multiboot1 with support for ELF64 file format
diff U3 syslinux-6.03/com32/mboot/map.c syslinux-6.03_mbootELF64/com32/mboot/map.c
--- syslinux-6.03/com32/mboot/map.c Mon Oct 06 19:27:44 2014
+++ syslinux-6.03_mbootELF64/com32/mboot/map.c Sat Oct 10 09:13:45 2015
@@ -106,6 +106,11 @@
Elf32_Ehdr *eh = ptr;
Elf32_Phdr *ph;
Elf32_Shdr *sh;
+
+ Elf64_Ehdr *eh64 = ptr;
+ Elf64_Phdr *ph64;
+ Elf64_Shdr *sh64;
+
unsigned int i, mbh_offset;
uint32_t bad_flags;
@@ -150,6 +155,17 @@
!eh->e_phnum || eh->e_phoff + eh->e_phentsize * eh->e_phnum > len)
eh = NULL; /* No valid ELF header found */
+ /* Determine 64-bit images */
+ if ((eh != NULL) ||
+ len < sizeof(Elf64_Ehdr) ||
+ memcmp(eh64->e_ident, "\x7f" "ELF\2\1\1", 6) ||
+ (eh64->e_machine != EM_X86_64) ||
+ eh64->e_version != EV_CURRENT ||
+ eh64->e_ehsize < sizeof(Elf64_Ehdr) || eh64->e_ehsize >= len ||
+ eh64->e_phentsize < sizeof(Elf64_Phdr) ||
+ !eh64->e_phnum || eh64->e_phoff + eh64->e_phentsize * eh64->e_phnum > len)
+ eh64 = NULL; /* No valid ELF64 header found */
+
/* Is this a Solaris kernel? */
if (!set.solaris && eh && kernel_is_solaris(eh))
opt.solaris = true;
@@ -263,6 +279,112 @@
return NULL;
}
sh[i].sh_addr = addr;
+ }
+ }
+ } else if (eh64 && !(opt.aout && mbh_len &&
+ (mbh->flags & MULTIBOOT_AOUT_KLUDGE))) {
+ /* Load 64-bit ELF */
+ regs.eip = eh64->e_entry; /* Can be overridden further down... */
+
+ ph64 = (Elf64_Phdr *) (cptr + eh64->e_phoff);
+
+ for (i = 0; i < eh64->e_phnum; i++) {
+ if (ph64->p_type == PT_LOAD || ph64->p_type == PT_PHDR) {
+ /*
+ * This loads at p_paddr, which matches Grub. However, if
+ * e_entry falls within the p_vaddr range of this PHDR, then
+ * adjust it to match the p_paddr range... this is how Grub
+ * behaves, so it's by definition correct (it doesn't have to
+ * make sense...)
+ */
+ addr_t addr = ph64->p_paddr;
+ addr_t msize = ph64->p_memsz;
+ addr_t dsize = min(msize, ph64->p_filesz);
+
+ if (eh64->e_entry >= ph64->p_vaddr
+ && eh64->e_entry < ph64->p_vaddr + msize)
+ regs.eip = eh64->e_entry + (ph64->p_paddr - ph64->p_vaddr);
+
+ dprintf("Segment at 0x%08x data 0x%08x len 0x%08x\n",
+ addr, dsize, msize);
+
+ if (syslinux_memmap_type(amap, addr, msize) != SMT_FREE) {
+ printf
+ ("Memory segment at 0x%08x (len 0x%08x) is unavailable\n",
+ addr, msize);
+ return NULL; /* Memory region unavailable */
+ }
+
+ /* Mark this region as allocated in the available map */
+ if (syslinux_add_memmap(&amap, addr, msize, SMT_ALLOC)) {
+ error("Overlapping segments found in ELF header\n");
+ return NULL;
+ }
+
+ if (ph64->p_filesz) {
+ /* Data present region. Create a move entry for it. */
+ if (syslinux_add_movelist
+ (&ml, addr, (addr_t) cptr + ph64->p_offset, dsize)) {
+ error("Failed to map PHDR data\n");
+ return NULL;
+ }
+ }
+ if (msize > dsize) {
+ /* Zero-filled region. Mark as a zero region in the memory map. */
+ if (syslinux_add_memmap
+ (&mmap, addr + dsize, msize - dsize, SMT_ZERO)) {
+ error("Failed to map PHDR zero region\n");
+ return NULL;
+ }
+ }
+ if (addr + msize > mboot_high_water_mark)
+ mboot_high_water_mark = addr + msize;
+ } else {
+ /* Ignore this program header */
+ }
+
+ ph64 = (Elf64_Phdr *) ((char *)ph64 + eh64->e_phentsize);
+ }
+
+ /* Load the ELF symbol table */
+ if (eh64->e_shoff) {
+ addr_t addr, len;
+
+ sh64 = (Elf64_Shdr *) ((char *)eh64 + eh64->e_shoff);
+
+ len = eh64->e_shentsize * eh64->e_shnum;
+ /*
+ * Align this, but don't pad -- in general this means a bunch of
+ * smaller sections gets packed into a single page.
+ */
+ addr = map_data(sh64, len, 4096, MAP_HIGH | MAP_NOPAD);
+ if (!addr) {
+ error("Failed to map symbol table\n");
+ return NULL;
+ }
+
+ mbinfo.flags |= MB_INFO_ELF_SHDR;
+ mbinfo.syms.e.addr = addr;
+ mbinfo.syms.e.num = eh64->e_shnum;
+ mbinfo.syms.e.size = eh64->e_shentsize;
+ mbinfo.syms.e.shndx = eh64->e_shstrndx;
+
+ for (i = 0; i < eh64->e_shnum; i++) {
+ addr_t align;
+
+ if (!sh64[i].sh_size)
+ continue; /* Empty section */
+ if (sh64[i].sh_flags & SHF_ALLOC)
+ continue; /* SHF_ALLOC sections should have PHDRs */
+
+ align = sh64[i].sh_addralign ? sh64[i].sh_addralign : 0;
+ addr = map_data((char *)ptr + sh64[i].sh_offset,
+ sh64[i].sh_size, align, MAP_HIGH);
+ if (!addr) {
+ error("Failed to map symbol section\n");
+ return NULL;
+ }
+ sh64[i].sh_addr = addr;
}
}
} else if (mbh_len && (mbh->flags & MULTIBOOT_AOUT_KLUDGE)) {
diff U3 syslinux-6.03/com32/mboot/mboot.h syslinux-6.03_mbootELF64/com32/mboot/mboot.h
--- syslinux-6.03/com32/mboot/mboot.h Mon Oct 06 19:27:44 2014
+++ syslinux-6.03_mbootELF64/com32/mboot/mboot.h Sat Oct 10 09:11:57 2015
@@ -46,6 +46,7 @@
#include <minmax.h>
#include <sys/stat.h>
#include <elf.h>
+#include <sys/elf64.h>
#include <console.h>
#include <syslinux/loadfile.h>
--
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