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-rw-r--r--Documentation/lguest/lguest.c42
1 files changed, 13 insertions, 29 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index cbf4becd2667..004c5c6aba6a 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -251,23 +251,6 @@ static void *get_pages(unsigned int num)
251 return addr; 251 return addr;
252} 252}
253 253
254/* To find out where to start we look for the magic Guest string, which marks
255 * the code we see in lguest_asm.S. This is a hack which we are currently
256 * plotting to replace with the normal Linux entry point. */
257static unsigned long entry_point(const void *start, const void *end)
258{
259 const void *p;
260
261 /* The scan gives us the physical starting address. We boot with
262 * pagetables set up with virtual and physical the same, so that's
263 * OK. */
264 for (p = start; p < end; p++)
265 if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0)
266 return to_guest_phys(p + strlen("GenuineLguest"));
267
268 errx(1, "Is this image a genuine lguest?");
269}
270
271/* This routine is used to load the kernel or initrd. It tries mmap, but if 254/* This routine is used to load the kernel or initrd. It tries mmap, but if
272 * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), 255 * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
273 * it falls back to reading the memory in. */ 256 * it falls back to reading the memory in. */
@@ -303,7 +286,6 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
303 * We return the starting address. */ 286 * We return the starting address. */
304static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) 287static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
305{ 288{
306 void *start = (void *)-1, *end = NULL;
307 Elf32_Phdr phdr[ehdr->e_phnum]; 289 Elf32_Phdr phdr[ehdr->e_phnum];
308 unsigned int i; 290 unsigned int i;
309 291
@@ -335,19 +317,13 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
335 verbose("Section %i: size %i addr %p\n", 317 verbose("Section %i: size %i addr %p\n",
336 i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); 318 i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
337 319
338 /* We track the first and last address we mapped, so we can
339 * tell entry_point() where to scan. */
340 if (from_guest_phys(phdr[i].p_paddr) < start)
341 start = from_guest_phys(phdr[i].p_paddr);
342 if (from_guest_phys(phdr[i].p_paddr) + phdr[i].p_filesz > end)
343 end=from_guest_phys(phdr[i].p_paddr)+phdr[i].p_filesz;
344
345 /* We map this section of the file at its physical address. */ 320 /* We map this section of the file at its physical address. */
346 map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), 321 map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
347 phdr[i].p_offset, phdr[i].p_filesz); 322 phdr[i].p_offset, phdr[i].p_filesz);
348 } 323 }
349 324
350 return entry_point(start, end); 325 /* The entry point is given in the ELF header. */
326 return ehdr->e_entry;
351} 327}
352 328
353/*L:160 Unfortunately the entire ELF image isn't compressed: the segments 329/*L:160 Unfortunately the entire ELF image isn't compressed: the segments
@@ -374,7 +350,8 @@ static unsigned long unpack_bzimage(int fd)
374 350
375 verbose("Unpacked size %i addr %p\n", len, img); 351 verbose("Unpacked size %i addr %p\n", len, img);
376 352
377 return entry_point(img, img + len); 353 /* The entry point for a bzImage is always the first byte */
354 return (unsigned long)img;
378} 355}
379 356
380/*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're 357/*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're
@@ -1684,8 +1661,15 @@ int main(int argc, char *argv[])
1684 *(u32 *)(boot + 0x228) = 4096; 1661 *(u32 *)(boot + 0x228) = 4096;
1685 concat(boot + 4096, argv+optind+2); 1662 concat(boot + 4096, argv+optind+2);
1686 1663
1687 /* The guest type value of "1" tells the Guest it's under lguest. */ 1664 /* Boot protocol version: 2.07 supports the fields for lguest. */
1688 *(int *)(boot + 0x23c) = 1; 1665 *(u16 *)(boot + 0x206) = 0x207;
1666
1667 /* The hardware_subarch value of "1" tells the Guest it's an lguest. */
1668 *(u32 *)(boot + 0x23c) = 1;
1669
1670 /* Set bit 6 of the loadflags (aka. KEEP_SEGMENTS) so the entry path
1671 * does not try to reload segment registers. */
1672 *(u8 *)(boot + 0x211) |= (1 << 6);
1689 1673
1690 /* We tell the kernel to initialize the Guest: this returns the open 1674 /* We tell the kernel to initialize the Guest: this returns the open
1691 * /dev/lguest file descriptor. */ 1675 * /dev/lguest file descriptor. */