Boot with virtual == physical to get closer to native Linux.
1) This allows us to get alot closer to booting bzImages. 2) It means we don't have to know page_offset. 3) The Guest needs to modify the boot pagetables to create the PAGE_OFFSET mapping before jumping to C code. 4) guest_pa() walks the page tables rather than using page_offset. 5) We don't use page_offset to figure out whether to emulate: it was always kinda quesationable, and won't work for instructions done before remapping (bzImage unpacking in particular). 6) We still want the kernel address for tlb flushing: have the initial hypercall give us that, too. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
Родитель
c18acd73ff
Коммит
47436aa4ad
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@ -178,19 +178,16 @@ static void *get_pages(unsigned int num)
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/* To find out where to start we look for the magic Guest string, which marks
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* the code we see in lguest_asm.S. This is a hack which we are currently
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* plotting to replace with the normal Linux entry point. */
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static unsigned long entry_point(const void *start, const void *end,
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unsigned long page_offset)
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static unsigned long entry_point(const void *start, const void *end)
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{
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const void *p;
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/* The scan gives us the physical starting address. We want the
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* virtual address in this case, and fortunately, we already figured
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* out the physical-virtual difference and passed it here in
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* "page_offset". */
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/* The scan gives us the physical starting address. We boot with
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* pagetables set up with virtual and physical the same, so that's
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* OK. */
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for (p = start; p < end; p++)
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if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0)
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return to_guest_phys(p + strlen("GenuineLguest"))
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+ page_offset;
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return to_guest_phys(p + strlen("GenuineLguest"));
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errx(1, "Is this image a genuine lguest?");
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}
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@ -224,14 +221,11 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
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* by all modern binaries on Linux including the kernel.
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*
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* The ELF headers give *two* addresses: a physical address, and a virtual
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* address. The Guest kernel expects to be placed in memory at the physical
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* address, and the page tables set up so it will correspond to that virtual
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* address. We return the difference between the virtual and physical
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* addresses in the "page_offset" pointer.
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* address. We use the physical address; the Guest will map itself to the
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* virtual address.
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*
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* We return the starting address. */
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static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr,
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unsigned long *page_offset)
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static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
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{
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void *start = (void *)-1, *end = NULL;
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Elf32_Phdr phdr[ehdr->e_phnum];
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@ -255,9 +249,6 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr,
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if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
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err(1, "Reading program headers");
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/* We don't know page_offset yet. */
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*page_offset = 0;
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/* Try all the headers: there are usually only three. A read-only one,
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* a read-write one, and a "note" section which isn't loadable. */
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for (i = 0; i < ehdr->e_phnum; i++) {
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@ -268,14 +259,6 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr,
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verbose("Section %i: size %i addr %p\n",
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i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
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/* We expect a simple linear address space: every segment must
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* have the same difference between virtual (p_vaddr) and
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* physical (p_paddr) address. */
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if (!*page_offset)
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*page_offset = phdr[i].p_vaddr - phdr[i].p_paddr;
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else if (*page_offset != phdr[i].p_vaddr - phdr[i].p_paddr)
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errx(1, "Page offset of section %i different", i);
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/* We track the first and last address we mapped, so we can
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* tell entry_point() where to scan. */
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if (from_guest_phys(phdr[i].p_paddr) < start)
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@ -288,50 +271,13 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr,
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phdr[i].p_offset, phdr[i].p_filesz);
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}
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return entry_point(start, end, *page_offset);
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}
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/*L:170 Prepare to be SHOCKED and AMAZED. And possibly a trifle nauseated.
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*
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* We know that CONFIG_PAGE_OFFSET sets what virtual address the kernel expects
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* to be. We don't know what that option was, but we can figure it out
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* approximately by looking at the addresses in the code. I chose the common
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* case of reading a memory location into the %eax register:
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*
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* movl <some-address>, %eax
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*
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* This gets encoded as five bytes: "0xA1 <4-byte-address>". For example,
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* "0xA1 0x18 0x60 0x47 0xC0" reads the address 0xC0476018 into %eax.
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*
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* In this example can guess that the kernel was compiled with
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* CONFIG_PAGE_OFFSET set to 0xC0000000 (it's always a round number). If the
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* kernel were larger than 16MB, we might see 0xC1 addresses show up, but our
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* kernel isn't that bloated yet.
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*
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* Unfortunately, x86 has variable-length instructions, so finding this
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* particular instruction properly involves writing a disassembler. Instead,
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* we rely on statistics. We look for "0xA1" and tally the different bytes
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* which occur 4 bytes later (the "0xC0" in our example above). When one of
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* those bytes appears three times, we can be reasonably confident that it
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* forms the start of CONFIG_PAGE_OFFSET.
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*
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* This is amazingly reliable. */
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static unsigned long intuit_page_offset(unsigned char *img, unsigned long len)
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{
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unsigned int i, possibilities[256] = { 0 };
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for (i = 0; i + 4 < len; i++) {
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/* mov 0xXXXXXXXX,%eax */
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if (img[i] == 0xA1 && ++possibilities[img[i+4]] > 3)
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return (unsigned long)img[i+4] << 24;
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}
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errx(1, "could not determine page offset");
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return entry_point(start, end);
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}
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/*L:160 Unfortunately the entire ELF image isn't compressed: the segments
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* which need loading are extracted and compressed raw. This denies us the
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* information we need to make a fully-general loader. */
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static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)
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static unsigned long unpack_bzimage(int fd)
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{
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gzFile f;
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int ret, len = 0;
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@ -352,12 +298,7 @@ static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)
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verbose("Unpacked size %i addr %p\n", len, img);
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/* Without the ELF header, we can't tell virtual-physical gap. This is
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* CONFIG_PAGE_OFFSET, and people do actually change it. Fortunately,
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* I have a clever way of figuring it out from the code itself. */
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*page_offset = intuit_page_offset(img, len);
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return entry_point(img, img + len, *page_offset);
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return entry_point(img, img + len);
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}
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/*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're
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@ -368,7 +309,7 @@ static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)
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* The bzImage is formed by putting the decompressing code in front of the
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* compressed kernel code. So we can simple scan through it looking for the
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* first "gzip" header, and start decompressing from there. */
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static unsigned long load_bzimage(int fd, unsigned long *page_offset)
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static unsigned long load_bzimage(int fd)
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{
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unsigned char c;
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int state = 0;
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@ -396,7 +337,7 @@ static unsigned long load_bzimage(int fd, unsigned long *page_offset)
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if (c != 0x03)
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state = -1;
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else
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return unpack_bzimage(fd, page_offset);
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return unpack_bzimage(fd);
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}
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}
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errx(1, "Could not find kernel in bzImage");
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@ -405,7 +346,7 @@ static unsigned long load_bzimage(int fd, unsigned long *page_offset)
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/*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels
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* come wrapped up in the self-decompressing "bzImage" format. With some funky
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* coding, we can load those, too. */
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static unsigned long load_kernel(int fd, unsigned long *page_offset)
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static unsigned long load_kernel(int fd)
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{
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Elf32_Ehdr hdr;
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@ -415,10 +356,10 @@ static unsigned long load_kernel(int fd, unsigned long *page_offset)
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/* If it's an ELF file, it starts with "\177ELF" */
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if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
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return map_elf(fd, &hdr, page_offset);
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return map_elf(fd, &hdr);
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/* Otherwise we assume it's a bzImage, and try to unpack it */
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return load_bzimage(fd, page_offset);
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return load_bzimage(fd);
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}
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/* This is a trivial little helper to align pages. Andi Kleen hated it because
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@ -463,27 +404,20 @@ static unsigned long load_initrd(const char *name, unsigned long mem)
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return len;
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}
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/* Once we know the address the Guest kernel expects, we can construct simple
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* linear page tables for all of memory which will get the Guest far enough
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/* Once we know how much memory we have, we can construct simple linear page
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* tables which set virtual == physical which will get the Guest far enough
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* into the boot to create its own.
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*
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* We lay them out of the way, just below the initrd (which is why we need to
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* know its size). */
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static unsigned long setup_pagetables(unsigned long mem,
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unsigned long initrd_size,
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unsigned long page_offset)
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unsigned long initrd_size)
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{
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unsigned long *pgdir, *linear;
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unsigned int mapped_pages, i, linear_pages;
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unsigned int ptes_per_page = getpagesize()/sizeof(void *);
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/* Ideally we map all physical memory starting at page_offset.
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* However, if page_offset is 0xC0000000 we can only map 1G of physical
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* (0xC0000000 + 1G overflows). */
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if (mem <= -page_offset)
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mapped_pages = mem/getpagesize();
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else
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mapped_pages = -page_offset/getpagesize();
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mapped_pages = mem/getpagesize();
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/* Each PTE page can map ptes_per_page pages: how many do we need? */
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linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page;
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@ -500,11 +434,9 @@ static unsigned long setup_pagetables(unsigned long mem,
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for (i = 0; i < mapped_pages; i++)
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linear[i] = ((i * getpagesize()) | PAGE_PRESENT);
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/* The top level points to the linear page table pages above. The
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* entry representing page_offset points to the first one, and they
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* continue from there. */
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/* The top level points to the linear page table pages above. */
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for (i = 0; i < mapped_pages; i += ptes_per_page) {
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pgdir[(i + page_offset/getpagesize())/ptes_per_page]
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pgdir[i/ptes_per_page]
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= ((to_guest_phys(linear) + i*sizeof(void *))
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| PAGE_PRESENT);
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}
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@ -535,15 +467,12 @@ static void concat(char *dst, char *args[])
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/* This is where we actually tell the kernel to initialize the Guest. We saw
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* the arguments it expects when we looked at initialize() in lguest_user.c:
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* the base of guest "physical" memory, the top physical page to allow, the
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* top level pagetable, the entry point and the page_offset constant for the
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* Guest. */
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static int tell_kernel(unsigned long pgdir, unsigned long start,
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unsigned long page_offset)
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* top level pagetable and the entry point for the Guest. */
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static int tell_kernel(unsigned long pgdir, unsigned long start)
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{
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unsigned long args[] = { LHREQ_INITIALIZE,
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(unsigned long)guest_base,
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guest_limit / getpagesize(),
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pgdir, start, page_offset };
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guest_limit / getpagesize(), pgdir, start };
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int fd;
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verbose("Guest: %p - %p (%#lx)\n",
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@ -1424,9 +1353,9 @@ static void usage(void)
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/*L:105 The main routine is where the real work begins: */
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int main(int argc, char *argv[])
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{
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/* Memory, top-level pagetable, code startpoint, PAGE_OFFSET and size
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* of the (optional) initrd. */
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unsigned long mem = 0, pgdir, start, page_offset, initrd_size = 0;
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/* Memory, top-level pagetable, code startpoint and size of the
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* (optional) initrd. */
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unsigned long mem = 0, pgdir, start, initrd_size = 0;
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/* A temporary and the /dev/lguest file descriptor. */
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int i, c, lguest_fd;
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/* The list of Guest devices, based on command line arguments. */
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@ -1500,8 +1429,7 @@ int main(int argc, char *argv[])
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setup_console(&device_list);
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/* Now we load the kernel */
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start = load_kernel(open_or_die(argv[optind+1], O_RDONLY),
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&page_offset);
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start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
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/* Boot information is stashed at physical address 0 */
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boot = from_guest_phys(0);
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@ -1518,7 +1446,7 @@ int main(int argc, char *argv[])
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}
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/* Set up the initial linear pagetables, starting below the initrd. */
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pgdir = setup_pagetables(mem, initrd_size, page_offset);
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pgdir = setup_pagetables(mem, initrd_size);
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/* The Linux boot header contains an "E820" memory map: ours is a
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* simple, single region. */
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@ -1535,7 +1463,7 @@ int main(int argc, char *argv[])
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/* We tell the kernel to initialize the Guest: this returns the open
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* /dev/lguest file descriptor. */
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lguest_fd = tell_kernel(pgdir, start, page_offset);
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lguest_fd = tell_kernel(pgdir, start);
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/* We fork off a child process, which wakes the Launcher whenever one
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* of the input file descriptors needs attention. Otherwise we would
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|
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@ -136,6 +136,7 @@ void foo(void)
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#ifdef CONFIG_LGUEST_GUEST
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BLANK();
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OFFSET(LGUEST_DATA_irq_enabled, lguest_data, irq_enabled);
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OFFSET(LGUEST_DATA_pgdir, lguest_data, pgdir);
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OFFSET(LGUEST_PAGES_host_gdt_desc, lguest_pages, state.host_gdt_desc);
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OFFSET(LGUEST_PAGES_host_idt_desc, lguest_pages, state.host_idt_desc);
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OFFSET(LGUEST_PAGES_host_cr3, lguest_pages, state.host_cr3);
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|
|
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@ -86,6 +86,7 @@ struct lguest_data lguest_data = {
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.hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
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.noirq_start = (u32)lguest_noirq_start,
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.noirq_end = (u32)lguest_noirq_end,
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.kernel_address = PAGE_OFFSET,
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.blocked_interrupts = { 1 }, /* Block timer interrupts */
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.syscall_vec = SYSCALL_VECTOR,
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};
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@ -1033,11 +1034,7 @@ __init void lguest_init(void *boot)
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/*G:070 Now we've seen all the paravirt_ops, we return to
|
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* lguest_init() where the rest of the fairly chaotic boot setup
|
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* occurs.
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*
|
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* The Host expects our first hypercall to tell it where our "struct
|
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* lguest_data" is, so we do that first. */
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hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
|
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* occurs. */
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/* The native boot code sets up initial page tables immediately after
|
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* the kernel itself, and sets init_pg_tables_end so they're not
|
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|
|
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|
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@ -1,5 +1,6 @@
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#include <linux/linkage.h>
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#include <linux/lguest.h>
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#include <asm/lguest_hcall.h>
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#include <asm/asm-offsets.h>
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#include <asm/thread_info.h>
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#include <asm/processor-flags.h>
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|
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@ -8,18 +9,48 @@
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* looks for. The plan is that the Linux boot protocol will be extended with a
|
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* "platform type" field which will guide us here from the normal entry point,
|
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* but for the moment this suffices. The normal boot code uses %esi for the
|
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* boot header, so we do too. We convert it to a virtual address by adding
|
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* PAGE_OFFSET, and hand it to lguest_init() as its argument (ie. %eax).
|
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* boot header, so we do too.
|
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*
|
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* WARNING: be very careful here! We're running at addresses equal to physical
|
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* addesses (around 0), not above PAGE_OFFSET as most code expectes
|
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* (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any
|
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* data.
|
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*
|
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* The .section line puts this code in .init.text so it will be discarded after
|
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* boot. */
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.section .init.text, "ax", @progbits
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.ascii "GenuineLguest"
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/* Set up initial stack. */
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movl $(init_thread_union+THREAD_SIZE),%esp
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/* Make initial hypercall now, so we can set up the pagetables. */
|
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movl $LHCALL_LGUEST_INIT, %eax
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movl $lguest_data - __PAGE_OFFSET, %edx
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int $LGUEST_TRAP_ENTRY
|
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|
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/* Set up boot information pointer to hand to lguest_init(): it wants
|
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* a virtual address. */
|
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movl %esi, %eax
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addl $__PAGE_OFFSET, %eax
|
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jmp lguest_init
|
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|
||||
/* The Host put the toplevel pagetable in lguest_data.pgdir. The movsl
|
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* instruction uses %esi, so we needed to save it above. */
|
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movl lguest_data - __PAGE_OFFSET + LGUEST_DATA_pgdir, %esi
|
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|
||||
/* Copy first 32 entries of page directory to __PAGE_OFFSET entries.
|
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* This means the first 128M of kernel memory will be mapped at
|
||||
* PAGE_OFFSET where the kernel expects to run. This will get it far
|
||||
* enough through boot to switch to its own pagetables. */
|
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movl $32, %ecx
|
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movl %esi, %edi
|
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addl $((__PAGE_OFFSET >> 22) * 4), %edi
|
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rep
|
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movsl
|
||||
|
||||
/* Set up the initial stack so we can run C code. */
|
||||
movl $(init_thread_union+THREAD_SIZE),%esp
|
||||
|
||||
|
||||
/* Jumps are relative, and we're running __PAGE_OFFSET too low at the
|
||||
* moment. */
|
||||
jmp lguest_init+__PAGE_OFFSET
|
||||
|
||||
/*G:055 We create a macro which puts the assembler code between lgstart_ and
|
||||
* lgend_ markers. These templates are put in the .text section: they can't be
|
||||
|
|
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|||
|
|
@ -181,15 +181,15 @@ static void initialize(struct lguest *lg)
|
|||
/* The Guest tells us where we're not to deliver interrupts by putting
|
||||
* the range of addresses into "struct lguest_data". */
|
||||
if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
|
||||
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
|
||||
/* We tell the Guest that it can't use the top 4MB of virtual
|
||||
* addresses used by the Switcher. */
|
||||
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem))
|
||||
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end))
|
||||
kill_guest(lg, "bad guest page %p", lg->lguest_data);
|
||||
|
||||
/* We write the current time into the Guest's data page once now. */
|
||||
write_timestamp(lg);
|
||||
|
||||
/* page_tables.c will also do some setup. */
|
||||
page_table_guest_data_init(lg);
|
||||
|
||||
/* This is the one case where the above accesses might have been the
|
||||
* first write to a Guest page. This may have caused a copy-on-write
|
||||
* fault, but the Guest might be referring to the old (read-only)
|
||||
|
|
|
|||
|
|
@ -62,8 +62,9 @@ static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val)
|
|||
* it). */
|
||||
static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
|
||||
{
|
||||
unsigned long gstack;
|
||||
unsigned long gstack, origstack;
|
||||
u32 eflags, ss, irq_enable;
|
||||
unsigned long virtstack;
|
||||
|
||||
/* There are two cases for interrupts: one where the Guest is already
|
||||
* in the kernel, and a more complex one where the Guest is in
|
||||
|
|
@ -71,8 +72,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
|
|||
if ((lg->regs->ss&0x3) != GUEST_PL) {
|
||||
/* The Guest told us their kernel stack with the SET_STACK
|
||||
* hypercall: both the virtual address and the segment */
|
||||
gstack = guest_pa(lg, lg->esp1);
|
||||
virtstack = lg->esp1;
|
||||
ss = lg->ss1;
|
||||
|
||||
origstack = gstack = guest_pa(lg, virtstack);
|
||||
/* We push the old stack segment and pointer onto the new
|
||||
* stack: when the Guest does an "iret" back from the interrupt
|
||||
* handler the CPU will notice they're dropping privilege
|
||||
|
|
@ -81,8 +84,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
|
|||
push_guest_stack(lg, &gstack, lg->regs->esp);
|
||||
} else {
|
||||
/* We're staying on the same Guest (kernel) stack. */
|
||||
gstack = guest_pa(lg, lg->regs->esp);
|
||||
virtstack = lg->regs->esp;
|
||||
ss = lg->regs->ss;
|
||||
|
||||
origstack = gstack = guest_pa(lg, virtstack);
|
||||
}
|
||||
|
||||
/* Remember that we never let the Guest actually disable interrupts, so
|
||||
|
|
@ -108,7 +113,7 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err)
|
|||
/* Now we've pushed all the old state, we change the stack, the code
|
||||
* segment and the address to execute. */
|
||||
lg->regs->ss = ss;
|
||||
lg->regs->esp = gstack + lg->page_offset;
|
||||
lg->regs->esp = virtstack + (gstack - origstack);
|
||||
lg->regs->cs = (__KERNEL_CS|GUEST_PL);
|
||||
lg->regs->eip = idt_address(lo, hi);
|
||||
|
||||
|
|
|
|||
|
|
@ -63,7 +63,7 @@ struct lguest
|
|||
/* This provides the offset to the base of guest-physical
|
||||
* memory in the Launcher. */
|
||||
void __user *mem_base;
|
||||
u32 page_offset;
|
||||
unsigned long kernel_address;
|
||||
u32 cr2;
|
||||
int halted;
|
||||
int ts;
|
||||
|
|
@ -165,6 +165,8 @@ void guest_set_pte(struct lguest *lg, unsigned long gpgdir,
|
|||
void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages);
|
||||
int demand_page(struct lguest *info, unsigned long cr2, int errcode);
|
||||
void pin_page(struct lguest *lg, unsigned long vaddr);
|
||||
unsigned long guest_pa(struct lguest *lg, unsigned long vaddr);
|
||||
void page_table_guest_data_init(struct lguest *lg);
|
||||
|
||||
/* <arch>/core.c: */
|
||||
void lguest_arch_host_init(void);
|
||||
|
|
@ -229,9 +231,5 @@ do { \
|
|||
} while(0)
|
||||
/* (End of aside) :*/
|
||||
|
||||
static inline unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
|
||||
{
|
||||
return vaddr - lg->page_offset;
|
||||
}
|
||||
#endif /* __ASSEMBLY__ */
|
||||
#endif /* _LGUEST_H */
|
||||
|
|
|
|||
|
|
@ -111,7 +111,7 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
|
|||
return run_guest(lg, (unsigned long __user *)user);
|
||||
}
|
||||
|
||||
/*L:020 The initialization write supplies 5 pointer sized (32 or 64 bit)
|
||||
/*L:020 The initialization write supplies 4 pointer sized (32 or 64 bit)
|
||||
* values (in addition to the LHREQ_INITIALIZE value). These are:
|
||||
*
|
||||
* base: The start of the Guest-physical memory inside the Launcher memory.
|
||||
|
|
@ -124,12 +124,6 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
|
|||
* pagetables (which are set up by the Launcher).
|
||||
*
|
||||
* start: The first instruction to execute ("eip" in x86-speak).
|
||||
*
|
||||
* page_offset: The PAGE_OFFSET constant in the Guest kernel. We should
|
||||
* probably wean the code off this, but it's a very useful constant! Any
|
||||
* address above this is within the Guest kernel, and any kernel address can
|
||||
* quickly converted from physical to virtual by adding PAGE_OFFSET. It's
|
||||
* 0xC0000000 (3G) by default, but it's configurable at kernel build time.
|
||||
*/
|
||||
static int initialize(struct file *file, const unsigned long __user *input)
|
||||
{
|
||||
|
|
@ -137,7 +131,7 @@ static int initialize(struct file *file, const unsigned long __user *input)
|
|||
* Guest. */
|
||||
struct lguest *lg;
|
||||
int err;
|
||||
unsigned long args[5];
|
||||
unsigned long args[4];
|
||||
|
||||
/* We grab the Big Lguest lock, which protects against multiple
|
||||
* simultaneous initializations. */
|
||||
|
|
@ -162,7 +156,6 @@ static int initialize(struct file *file, const unsigned long __user *input)
|
|||
/* Populate the easy fields of our "struct lguest" */
|
||||
lg->mem_base = (void __user *)(long)args[0];
|
||||
lg->pfn_limit = args[1];
|
||||
lg->page_offset = args[4];
|
||||
|
||||
/* We need a complete page for the Guest registers: they are accessible
|
||||
* to the Guest and we can only grant it access to whole pages. */
|
||||
|
|
|
|||
|
|
@ -13,6 +13,7 @@
|
|||
#include <linux/random.h>
|
||||
#include <linux/percpu.h>
|
||||
#include <asm/tlbflush.h>
|
||||
#include <asm/uaccess.h>
|
||||
#include "lg.h"
|
||||
|
||||
/*M:008 We hold reference to pages, which prevents them from being swapped.
|
||||
|
|
@ -345,7 +346,7 @@ static void flush_user_mappings(struct lguest *lg, int idx)
|
|||
{
|
||||
unsigned int i;
|
||||
/* Release every pgd entry up to the kernel's address. */
|
||||
for (i = 0; i < pgd_index(lg->page_offset); i++)
|
||||
for (i = 0; i < pgd_index(lg->kernel_address); i++)
|
||||
release_pgd(lg, lg->pgdirs[idx].pgdir + i);
|
||||
}
|
||||
|
||||
|
|
@ -358,6 +359,25 @@ void guest_pagetable_flush_user(struct lguest *lg)
|
|||
}
|
||||
/*:*/
|
||||
|
||||
/* We walk down the guest page tables to get a guest-physical address */
|
||||
unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
|
||||
{
|
||||
pgd_t gpgd;
|
||||
pte_t gpte;
|
||||
|
||||
/* First step: get the top-level Guest page table entry. */
|
||||
gpgd = __pgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
|
||||
/* Toplevel not present? We can't map it in. */
|
||||
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
|
||||
kill_guest(lg, "Bad address %#lx", vaddr);
|
||||
|
||||
gpte = __pte(lgread_u32(lg, gpte_addr(lg, gpgd, vaddr)));
|
||||
if (!(pte_flags(gpte) & _PAGE_PRESENT))
|
||||
kill_guest(lg, "Bad address %#lx", vaddr);
|
||||
|
||||
return pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
|
||||
}
|
||||
|
||||
/* We keep several page tables. This is a simple routine to find the page
|
||||
* table (if any) corresponding to this top-level address the Guest has given
|
||||
* us. */
|
||||
|
|
@ -500,7 +520,7 @@ void guest_set_pte(struct lguest *lg,
|
|||
{
|
||||
/* Kernel mappings must be changed on all top levels. Slow, but
|
||||
* doesn't happen often. */
|
||||
if (vaddr >= lg->page_offset) {
|
||||
if (vaddr >= lg->kernel_address) {
|
||||
unsigned int i;
|
||||
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
|
||||
if (lg->pgdirs[i].pgdir)
|
||||
|
|
@ -550,11 +570,6 @@ void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 idx)
|
|||
* its first page table is. We set some things up here: */
|
||||
int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
|
||||
{
|
||||
/* In flush_user_mappings() we loop from 0 to
|
||||
* "pgd_index(lg->page_offset)". This assumes it won't hit
|
||||
* the Switcher mappings, so check that now. */
|
||||
if (pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
|
||||
return -EINVAL;
|
||||
/* We start on the first shadow page table, and give it a blank PGD
|
||||
* page. */
|
||||
lg->pgdidx = 0;
|
||||
|
|
@ -565,6 +580,24 @@ int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
|
|||
return 0;
|
||||
}
|
||||
|
||||
/* When the Guest calls LHCALL_LGUEST_INIT we do more setup. */
|
||||
void page_table_guest_data_init(struct lguest *lg)
|
||||
{
|
||||
/* We get the kernel address: above this is all kernel memory. */
|
||||
if (get_user(lg->kernel_address, &lg->lguest_data->kernel_address)
|
||||
/* We tell the Guest that it can't use the top 4MB of virtual
|
||||
* addresses used by the Switcher. */
|
||||
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
|
||||
|| put_user(lg->pgdirs[lg->pgdidx].gpgdir,&lg->lguest_data->pgdir))
|
||||
kill_guest(lg, "bad guest page %p", lg->lguest_data);
|
||||
|
||||
/* In flush_user_mappings() we loop from 0 to
|
||||
* "pgd_index(lg->kernel_address)". This assumes it won't hit the
|
||||
* Switcher mappings, so check that now. */
|
||||
if (pgd_index(lg->kernel_address) >= SWITCHER_PGD_INDEX)
|
||||
kill_guest(lg, "bad kernel address %#lx", lg->kernel_address);
|
||||
}
|
||||
|
||||
/* When a Guest dies, our cleanup is fairly simple. */
|
||||
void free_guest_pagetable(struct lguest *lg)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -216,9 +216,10 @@ static int emulate_insn(struct lguest *lg)
|
|||
* guest_pa just subtracts the Guest's page_offset. */
|
||||
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
|
||||
|
||||
/* The guest_pa() function only works for Guest kernel addresses, but
|
||||
* that's all we're trying to do anyway. */
|
||||
if (lg->regs->eip < lg->page_offset)
|
||||
/* This must be the Guest kernel trying to do something, not userspace!
|
||||
* The bottom two bits of the CS segment register are the privilege
|
||||
* level. */
|
||||
if ((lg->regs->cs & 3) != GUEST_PL)
|
||||
return 0;
|
||||
|
||||
/* Decoding x86 instructions is icky. */
|
||||
|
|
|
|||
|
|
@ -2,8 +2,6 @@
|
|||
#ifndef _X86_LGUEST_HCALL_H
|
||||
#define _X86_LGUEST_HCALL_H
|
||||
|
||||
#include <asm/hw_irq.h>
|
||||
|
||||
#define LHCALL_FLUSH_ASYNC 0
|
||||
#define LHCALL_LGUEST_INIT 1
|
||||
#define LHCALL_CRASH 2
|
||||
|
|
@ -36,6 +34,9 @@
|
|||
* definition of a gentleman: "someone who is only rude intentionally". */
|
||||
#define LGUEST_TRAP_ENTRY 0x1F
|
||||
|
||||
#ifndef __ASSEMBLY__
|
||||
#include <asm/hw_irq.h>
|
||||
|
||||
static inline unsigned long
|
||||
hcall(unsigned long call,
|
||||
unsigned long arg1, unsigned long arg2, unsigned long arg3)
|
||||
|
|
@ -66,4 +67,6 @@ struct hcall_args
|
|||
/* These map directly onto eax, ebx, ecx, edx in struct lguest_regs */
|
||||
unsigned long arg0, arg2, arg3, arg1;
|
||||
};
|
||||
|
||||
#endif /* !__ASSEMBLY__ */
|
||||
#endif /* _I386_LGUEST_HCALL_H */
|
||||
|
|
|
|||
|
|
@ -44,11 +44,14 @@ struct lguest_data
|
|||
unsigned long reserve_mem;
|
||||
/* KHz for the TSC clock. */
|
||||
u32 tsc_khz;
|
||||
/* Page where the top-level pagetable is */
|
||||
unsigned long pgdir;
|
||||
|
||||
/* Fields initialized by the Guest at boot: */
|
||||
/* Instruction range to suppress interrupts even if enabled */
|
||||
unsigned long noirq_start, noirq_end;
|
||||
|
||||
/* Address above which page tables are all identical. */
|
||||
unsigned long kernel_address;
|
||||
/* The vector to try to use for system calls (0x40 or 0x80). */
|
||||
unsigned int syscall_vec;
|
||||
};
|
||||
|
|
|
|||
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