diff options
| -rw-r--r-- | Documentation/lguest/Makefile | 26 | ||||
| -rw-r--r-- | Documentation/lguest/lguest.c | 189 | ||||
| -rw-r--r-- | drivers/lguest/core.c | 22 | ||||
| -rw-r--r-- | drivers/lguest/hypercalls.c | 15 | ||||
| -rw-r--r-- | drivers/lguest/io.c | 18 | ||||
| -rw-r--r-- | drivers/lguest/lg.h | 3 | ||||
| -rw-r--r-- | drivers/lguest/lguest_user.c | 23 | ||||
| -rw-r--r-- | drivers/lguest/page_tables.c | 7 |
8 files changed, 163 insertions, 140 deletions
diff --git a/Documentation/lguest/Makefile b/Documentation/lguest/Makefile index 526c15f..bac037e 100644 --- a/Documentation/lguest/Makefile +++ b/Documentation/lguest/Makefile @@ -1,28 +1,8 @@ # This creates the demonstration utility "lguest" which runs a Linux guest. - -# For those people that have a separate object dir, look there for .config -KBUILD_OUTPUT := ../.. -ifdef O - ifeq ("$(origin O)", "command line") - KBUILD_OUTPUT := $(O) - endif -endif -# We rely on CONFIG_PAGE_OFFSET to know where to put lguest binary. -include $(KBUILD_OUTPUT)/.config -LGUEST_GUEST_TOP := ($(CONFIG_PAGE_OFFSET) - 0x08000000) - -CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include -Wl,-T,lguest.lds +CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include LDLIBS:=-lz -# Removing this works for some versions of ld.so (eg. Ubuntu Feisty) and -# not others (eg. FC7). -LDFLAGS+=-static -all: lguest.lds lguest -# The linker script on x86 is so complex the only way of creating one -# which will link our binary in the right place is to mangle the -# default one. -lguest.lds: - $(LD) --verbose | awk '/^==========/ { PRINT=1; next; } /SIZEOF_HEADERS/ { gsub(/0x[0-9A-F]*/, "$(LGUEST_GUEST_TOP)") } { if (PRINT) print $$0; }' > $@ +all: lguest clean: - rm -f lguest.lds lguest + rm -f lguest diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 401d26b..140bd98 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -1,10 +1,7 @@ /*P:100 This is the Launcher code, a simple program which lays out the * "physical" memory for the new Guest by mapping the kernel image and the * virtual devices, then reads repeatedly from /dev/lguest to run the Guest. - * - * The only trick: the Makefile links it at a high address so it will be clear - * of the guest memory region. It means that each Guest cannot have more than - * about 2.5G of memory on a normally configured Host. :*/ +:*/ #define _LARGEFILE64_SOURCE #define _GNU_SOURCE #include <stdio.h> @@ -56,6 +53,8 @@ typedef uint8_t u8; #ifndef SIOCBRADDIF #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ #endif +/* We can have up to 256 pages for devices. */ +#define DEVICE_PAGES 256 /*L:120 verbose is both a global flag and a macro. The C preprocessor allows * this, and although I wouldn't recommend it, it works quite nicely here. */ @@ -66,8 +65,10 @@ static bool verbose; /* The pipe to send commands to the waker process */ static int waker_fd; -/* The top of guest physical memory. */ -static u32 top; +/* The pointer to the start of guest memory. */ +static void *guest_base; +/* The maximum guest physical address allowed, and maximum possible. */ +static unsigned long guest_limit, guest_max; /* This is our list of devices. */ struct device_list @@ -111,6 +112,29 @@ struct device void *priv; }; +/*L:100 The Launcher code itself takes us out into userspace, that scary place + * where pointers run wild and free! Unfortunately, like most userspace + * programs, it's quite boring (which is why everyone likes to hack on the + * kernel!). Perhaps if you make up an Lguest Drinking Game at this point, it + * will get you through this section. Or, maybe not. + * + * The Launcher sets up a big chunk of memory to be the Guest's "physical" + * memory and stores it in "guest_base". In other words, Guest physical == + * Launcher virtual with an offset. + * + * This can be tough to get your head around, but usually it just means that we + * use these trivial conversion functions when the Guest gives us it's + * "physical" addresses: */ +static void *from_guest_phys(unsigned long addr) +{ + return guest_base + addr; +} + +static unsigned long to_guest_phys(const void *addr) +{ + return (addr - guest_base); +} + /*L:130 * Loading the Kernel. * @@ -124,33 +148,40 @@ static int open_or_die(const char *name, int flags) return fd; } -/* map_zeroed_pages() takes a (page-aligned) address and a number of pages. */ -static void *map_zeroed_pages(unsigned long addr, unsigned int num) +/* map_zeroed_pages() takes a number of pages. */ +static void *map_zeroed_pages(unsigned int num) { - /* We cache the /dev/zero file-descriptor so we only open it once. */ - static int fd = -1; - - if (fd == -1) - fd = open_or_die("/dev/zero", O_RDONLY); + int fd = open_or_die("/dev/zero", O_RDONLY); + void *addr; /* We use a private mapping (ie. if we write to the page, it will be - * copied), and obviously we insist that it be mapped where we ask. */ - if (mmap((void *)addr, getpagesize() * num, - PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, 0) - != (void *)addr) - err(1, "Mmaping %u pages of /dev/zero @%p", num, (void *)addr); - - /* Returning the address is just a courtesy: can simplify callers. */ - return (void *)addr; + * copied). */ + addr = mmap(NULL, getpagesize() * num, + PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, fd, 0); + if (addr == MAP_FAILED) + err(1, "Mmaping %u pages of /dev/zero", num); + + return addr; +} + +/* Get some more pages for a device. */ +static void *get_pages(unsigned int num) +{ + void *addr = from_guest_phys(guest_limit); + + guest_limit += num * getpagesize(); + if (guest_limit > guest_max) + errx(1, "Not enough memory for devices"); + return addr; } /* To find out where to start we look for the magic Guest string, which marks * the code we see in lguest_asm.S. This is a hack which we are currently * plotting to replace with the normal Linux entry point. */ -static unsigned long entry_point(void *start, void *end, +static unsigned long entry_point(const void *start, const void *end, unsigned long page_offset) { - void *p; + const void *p; /* The scan gives us the physical starting address. We want the * virtual address in this case, and fortunately, we already figured @@ -158,7 +189,8 @@ static unsigned long entry_point(void *start, void *end, * "page_offset". */ for (p = start; p < end; p++) if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0) - return (long)p + strlen("GenuineLguest") + page_offset; + return to_guest_phys(p + strlen("GenuineLguest")) + + page_offset; errx(1, "Is this image a genuine lguest?"); } @@ -201,9 +233,9 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr, unsigned long *page_offset) { + void *start = (void *)-1, *end = NULL; Elf32_Phdr phdr[ehdr->e_phnum]; unsigned int i; - unsigned long start = -1UL, end = 0; /* Sanity checks on the main ELF header: an x86 executable with a * reasonable number of correctly-sized program headers. */ @@ -246,17 +278,17 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr, /* We track the first and last address we mapped, so we can * tell entry_point() where to scan. */ - if (phdr[i].p_paddr < start) - start = phdr[i].p_paddr; - if (phdr[i].p_paddr + phdr[i].p_filesz > end) - end = phdr[i].p_paddr + phdr[i].p_filesz; + if (from_guest_phys(phdr[i].p_paddr) < start) + start = from_guest_phys(phdr[i].p_paddr); + if (from_guest_phys(phdr[i].p_paddr) + phdr[i].p_filesz > end) + end=from_guest_phys(phdr[i].p_paddr)+phdr[i].p_filesz; /* We map this section of the file at its physical address. */ - map_at(elf_fd, (void *)phdr[i].p_paddr, + map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), phdr[i].p_offset, phdr[i].p_filesz); } - return entry_point((void *)start, (void *)end, *page_offset); + return entry_point(start, end, *page_offset); } /*L:170 Prepare to be SHOCKED and AMAZED. And possibly a trifle nauseated. @@ -307,7 +339,7 @@ static unsigned long unpack_bzimage(int fd, unsigned long *page_offset) * actually configurable as CONFIG_PHYSICAL_START, but as the comment * there says, "Don't change this unless you know what you are doing". * Indeed. */ - void *img = (void *)0x100000; + void *img = from_guest_phys(0x100000); /* gzdopen takes our file descriptor (carefully placed at the start of * the GZIP header we found) and returns a gzFile. */ @@ -421,7 +453,7 @@ static unsigned long load_initrd(const char *name, unsigned long mem) /* We map the initrd at the top of memory, but mmap wants it to be * page-aligned, so we round the size up for that. */ len = page_align(st.st_size); - map_at(ifd, (void *)mem - len, 0, st.st_size); + map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); /* Once a file is mapped, you can close the file descriptor. It's a * little odd, but quite useful. */ close(ifd); @@ -431,9 +463,9 @@ static unsigned long load_initrd(const char *name, unsigned long mem) return len; } -/* Once we know how much memory we have, and the address the Guest kernel - * expects, we can construct simple linear page tables which will get the Guest - * far enough into the boot to create its own. +/* Once we know the address the Guest kernel expects, we can construct simple + * linear page tables for all of memory which will get the Guest far enough + * into the boot to create its own. * * We lay them out of the way, just below the initrd (which is why we need to * know its size). */ @@ -457,7 +489,7 @@ static unsigned long setup_pagetables(unsigned long mem, linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page; /* We put the toplevel page directory page at the top of memory. */ - pgdir = (void *)mem - initrd_size - getpagesize(); + pgdir = from_guest_phys(mem) - initrd_size - getpagesize(); /* Now we use the next linear_pages pages as pte pages */ linear = (void *)pgdir - linear_pages*getpagesize(); @@ -473,15 +505,16 @@ static unsigned long setup_pagetables(unsigned long mem, * continue from there. */ for (i = 0; i < mapped_pages; i += ptes_per_page) { pgdir[(i + page_offset/getpagesize())/ptes_per_page] - = (((u32)linear + i*sizeof(u32)) | PAGE_PRESENT); + = ((to_guest_phys(linear) + i*sizeof(u32)) + | PAGE_PRESENT); } - verbose("Linear mapping of %u pages in %u pte pages at %p\n", - mapped_pages, linear_pages, linear); + verbose("Linear mapping of %u pages in %u pte pages at %#lx\n", + mapped_pages, linear_pages, to_guest_phys(linear)); /* We return the top level (guest-physical) address: the kernel needs * to know where it is. */ - return (unsigned long)pgdir; + return to_guest_phys(pgdir); } /* Simple routine to roll all the commandline arguments together with spaces @@ -501,14 +534,19 @@ static void concat(char *dst, char *args[]) /* This is where we actually tell the kernel to initialize the Guest. We saw * the arguments it expects when we looked at initialize() in lguest_user.c: - * the top physical page to allow, the top level pagetable, the entry point and - * the page_offset constant for the Guest. */ + * the base of guest "physical" memory, the top physical page to allow, the + * top level pagetable, the entry point and the page_offset constant for the + * Guest. */ static int tell_kernel(u32 pgdir, u32 start, u32 page_offset) { u32 args[] = { LHREQ_INITIALIZE, - top/getpagesize(), pgdir, start, page_offset }; + (unsigned long)guest_base, + guest_limit / getpagesize(), + pgdir, start, page_offset }; int fd; + verbose("Guest: %p - %p (%#lx)\n", + guest_base, guest_base + guest_limit, guest_limit); fd = open_or_die("/dev/lguest", O_RDWR); if (write(fd, args, sizeof(args)) < 0) err(1, "Writing to /dev/lguest"); @@ -605,11 +643,11 @@ static void *_check_pointer(unsigned long addr, unsigned int size, { /* We have to separately check addr and addr+size, because size could * be huge and addr + size might wrap around. */ - if (addr >= top || addr + size >= top) + if (addr >= guest_limit || addr + size >= guest_limit) errx(1, "%s:%i: Invalid address %li", __FILE__, line, addr); /* We return a pointer for the caller's convenience, now we know it's * safe to use. */ - return (void *)addr; + return from_guest_phys(addr); } /* A macro which transparently hands the line number to the real function. */ #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) @@ -646,7 +684,7 @@ static u32 *dma2iov(unsigned long dma, struct iovec iov[], unsigned *num) static u32 *get_dma_buffer(int fd, void *key, struct iovec iov[], unsigned int *num, u32 *irq) { - u32 buf[] = { LHREQ_GETDMA, (u32)key }; + u32 buf[] = { LHREQ_GETDMA, to_guest_phys(key) }; unsigned long udma; u32 *res; @@ -998,11 +1036,11 @@ new_dev_desc(struct lguest_device_desc *descs, descs[i].features = features; descs[i].num_pages = num_pages; /* If they said the device needs memory, we allocate - * that now, bumping up the top of Guest memory. */ + * that now. */ if (num_pages) { - map_zeroed_pages(top, num_pages); - descs[i].pfn = top/getpagesize(); - top += num_pages*getpagesize(); + unsigned long pa; + pa = to_guest_phys(get_pages(num_pages)); + descs[i].pfn = pa / getpagesize(); } return &descs[i]; } @@ -1040,9 +1078,9 @@ static struct device *new_device(struct device_list *devices, if (handle_input) set_fd(dev->fd, devices); dev->desc = new_dev_desc(devices->descs, type, features, num_pages); - dev->mem = (void *)(dev->desc->pfn * getpagesize()); + dev->mem = from_guest_phys(dev->desc->pfn * getpagesize()); dev->handle_input = handle_input; - dev->watch_key = (unsigned long)dev->mem + watch_off; + dev->watch_key = to_guest_phys(dev->mem) + watch_off; dev->handle_output = handle_output; return dev; } @@ -1382,21 +1420,7 @@ static void usage(void) "<mem-in-mb> vmlinux [args...]"); } -/*L:100 The Launcher code itself takes us out into userspace, that scary place - * where pointers run wild and free! Unfortunately, like most userspace - * programs, it's quite boring (which is why everyone like to hack on the - * kernel!). Perhaps if you make up an Lguest Drinking Game at this point, it - * will get you through this section. Or, maybe not. - * - * The Launcher binary sits up high, usually starting at address 0xB8000000. - * Everything below this is the "physical" memory for the Guest. For example, - * if the Guest were to write a "1" at physical address 0, we would see a "1" - * in the Launcher at "(int *)0". Guest physical == Launcher virtual. - * - * This can be tough to get your head around, but usually it just means that we - * don't need to do any conversion when the Guest gives us it's "physical" - * addresses. - */ +/*L:105 The main routine is where the real work begins: */ int main(int argc, char *argv[]) { /* Memory, top-level pagetable, code startpoint, PAGE_OFFSET and size @@ -1406,8 +1430,8 @@ int main(int argc, char *argv[]) int i, c, lguest_fd; /* The list of Guest devices, based on command line arguments. */ struct device_list device_list; - /* The boot information for the Guest: at guest-physical address 0. */ - void *boot = (void *)0; + /* The boot information for the Guest. */ + void *boot; /* If they specify an initrd file to load. */ const char *initrd_name = NULL; @@ -1427,9 +1451,16 @@ int main(int argc, char *argv[]) * of memory now. */ for (i = 1; i < argc; i++) { if (argv[i][0] != '-') { - mem = top = atoi(argv[i]) * 1024 * 1024; - device_list.descs = map_zeroed_pages(top, 1); - top += getpagesize(); + mem = atoi(argv[i]) * 1024 * 1024; + /* We start by mapping anonymous pages over all of + * guest-physical memory range. This fills it with 0, + * and ensures that the Guest won't be killed when it + * tries to access it. */ + guest_base = map_zeroed_pages(mem / getpagesize() + + DEVICE_PAGES); + guest_limit = mem; + guest_max = mem + DEVICE_PAGES*getpagesize(); + device_list.descs = get_pages(1); break; } } @@ -1462,18 +1493,18 @@ int main(int argc, char *argv[]) if (optind + 2 > argc) usage(); + verbose("Guest base is at %p\n", guest_base); + /* We always have a console device */ setup_console(&device_list); - /* We start by mapping anonymous pages over all of guest-physical - * memory range. This fills it with 0, and ensures that the Guest - * won't be killed when it tries to access it. */ - map_zeroed_pages(0, mem / getpagesize()); - /* Now we load the kernel */ start = load_kernel(open_or_die(argv[optind+1], O_RDONLY), &page_offset); + /* Boot information is stashed at physical address 0 */ + boot = from_guest_phys(0); + /* Map the initrd image if requested (at top of physical memory) */ if (initrd_name) { initrd_size = load_initrd(initrd_name, mem); @@ -1495,7 +1526,7 @@ int main(int argc, char *argv[]) = ((struct e820entry) { 0, mem, E820_RAM }); /* The boot header contains a command line pointer: we put the command * line after the boot header (at address 4096) */ - *(void **)(boot + 0x228) = boot + 4096; + *(u32 *)(boot + 0x228) = 4096; concat(boot + 4096, argv+optind+2); /* The guest type value of "1" tells the Guest it's under lguest. */ diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index a0788c1..eb95860 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -325,8 +325,8 @@ static int emulate_insn(struct lguest *lg) * Dealing With Guest Memory. * * When the Guest gives us (what it thinks is) a physical address, we can use - * the normal copy_from_user() & copy_to_user() on that address: remember, - * Guest physical == Launcher virtual. + * the normal copy_from_user() & copy_to_user() on the corresponding place in + * the memory region allocated by the Launcher. * * But we can't trust the Guest: it might be trying to access the Launcher * code. We have to check that the range is below the pfn_limit the Launcher @@ -348,8 +348,8 @@ u32 lgread_u32(struct lguest *lg, unsigned long addr) /* Don't let them access lguest binary. */ if (!lguest_address_ok(lg, addr, sizeof(val)) - || get_user(val, (u32 __user *)addr) != 0) - kill_guest(lg, "bad read address %#lx", addr); + || get_user(val, (u32 *)(lg->mem_base + addr)) != 0) + kill_guest(lg, "bad read address %#lx: pfn_limit=%u membase=%p", addr, lg->pfn_limit, lg->mem_base); return val; } @@ -357,7 +357,7 @@ u32 lgread_u32(struct lguest *lg, unsigned long addr) void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val) { if (!lguest_address_ok(lg, addr, sizeof(val)) - || put_user(val, (u32 __user *)addr) != 0) + || put_user(val, (u32 *)(lg->mem_base + addr)) != 0) kill_guest(lg, "bad write address %#lx", addr); } @@ -367,7 +367,7 @@ void lgwrite_u32(struct lguest *lg, unsigned long addr, u32 val) void lgread(struct lguest *lg, void *b, unsigned long addr, unsigned bytes) { if (!lguest_address_ok(lg, addr, bytes) - || copy_from_user(b, (void __user *)addr, bytes) != 0) { + || copy_from_user(b, lg->mem_base + addr, bytes) != 0) { /* copy_from_user should do this, but as we rely on it... */ memset(b, 0, bytes); kill_guest(lg, "bad read address %#lx len %u", addr, bytes); @@ -379,7 +379,7 @@ void lgwrite(struct lguest *lg, unsigned long addr, const void *b, unsigned bytes) { if (!lguest_address_ok(lg, addr, bytes) - || copy_to_user((void __user *)addr, b, bytes) != 0) + || copy_to_user(lg->mem_base + addr, b, bytes) != 0) kill_guest(lg, "bad write address %#lx len %u", addr, bytes); } /* (end of memory access helper routines) :*/ @@ -616,11 +616,9 @@ int run_guest(struct lguest *lg, unsigned long __user *user) * * Note that if the Guest were really messed up, this * could happen before it's done the INITIALIZE - * hypercall, so lg->lguest_data will be NULL, so - * &lg->lguest_data->cr2 will be address 8. Writing - * into that address won't hurt the Host at all, - * though. */ - if (put_user(cr2, &lg->lguest_data->cr2)) + * hypercall, so lg->lguest_data will be NULL */ + if (lg->lguest_data + && put_user(cr2, &lg->lguest_data->cr2)) kill_guest(lg, "Writing cr2"); break; case 7: /* We've intercepted a Device Not Available fault. */ diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c index 5ecd60b..02e67b4 100644 --- a/drivers/lguest/hypercalls.c +++ b/drivers/lguest/hypercalls.c @@ -205,16 +205,19 @@ static void initialize(struct lguest *lg) tsc_speed = 0; /* The pointer to the Guest's "struct lguest_data" is the only - * argument. */ - lg->lguest_data = (struct lguest_data __user *)lg->regs->edx; - /* If we check the address they gave is OK now, we can simply - * copy_to_user/from_user from now on rather than using lgread/lgwrite. - * I put this in to show that I'm not immune to writing stupid - * optimizations. */ + * argument. We check that address now. */ if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) { kill_guest(lg, "bad guest page %p", lg->lguest_data); return; } + + /* Having checked it, we simply set lg->lguest_data to point straight + * into the Launcher's memory at the right place and then use + * copy_to_user/from_user from now on, instead of lgread/write. I put + * this in to show that I'm not immune to writing stupid + * optimizations. */ + lg->lguest_data = lg->mem_base + lg->regs->edx; + /* 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) diff --git a/drivers/lguest/io.c b/drivers/lguest/io.c index ea68613..3a84533 100644 --- a/drivers/lguest/io.c +++ b/drivers/lguest/io.c @@ -186,7 +186,7 @@ int bind_dma(struct lguest *lg, * we're doing this. */ mutex_lock(&lguest_lock); down_read(fshared); - if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) { + if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) { kill_guest(lg, "bad dma key %#lx", ukey); goto unlock; } @@ -247,7 +247,8 @@ static int lgread_other(struct lguest *lg, void *buf, u32 addr, unsigned bytes) { if (!lguest_address_ok(lg, addr, bytes) - || access_process_vm(lg->tsk, addr, buf, bytes, 0) != bytes) { + || access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr, + buf, bytes, 0) != bytes) { memset(buf, 0, bytes); kill_guest(lg, "bad address in registered DMA struct"); return 0; @@ -261,8 +262,8 @@ static int lgwrite_other(struct lguest *lg, u32 addr, const void *buf, unsigned bytes) { if (!lguest_address_ok(lg, addr, bytes) - || (access_process_vm(lg->tsk, addr, (void *)buf, bytes, 1) - != bytes)) { + || access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr, + (void *)buf, bytes, 1) != bytes) { kill_guest(lg, "bad address writing to registered DMA"); return 0; } @@ -318,7 +319,7 @@ static u32 copy_data(struct lguest *srclg, * copy_to_user_page(), and some arch's seem to need special * flushes. x86 is fine. */ if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE, - (void __user *)src->addr[si], len) != 0) { + srclg->mem_base+src->addr[si], len) != 0) { /* If a copy failed, it's the source's fault. */ kill_guest(srclg, "bad address in sending DMA"); totlen = 0; @@ -377,7 +378,8 @@ static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src, * number of pages. Note that we're holding the destination's * mmap_sem, as get_user_pages() requires. */ if (get_user_pages(dstlg->tsk, dstlg->mm, - dst->addr[i], 1, 1, 1, pages+i, NULL) + (unsigned long)dstlg->mem_base+dst->addr[i], + 1, 1, 1, pages+i, NULL) != 1) { /* This means the destination gave us a bogus buffer */ kill_guest(dstlg, "Error mapping DMA pages"); @@ -493,7 +495,7 @@ again: mutex_lock(&lguest_lock); down_read(fshared); /* Get the futex key for the key the Guest gave us */ - if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) { + if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) { kill_guest(lg, "bad sending DMA key"); goto unlock; } @@ -584,7 +586,7 @@ unsigned long get_dma_buffer(struct lguest *lg, /* This can fail if it's not a valid address, or if the address is not * divisible by 4 (the futex code needs that, we don't really). */ - if (get_futex_key((u32 __user *)ukey, fshared, &key) != 0) { + if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) { kill_guest(lg, "bad registered DMA buffer"); goto unlock; } diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h index 399eab8..54f2c24 100644 --- a/drivers/lguest/lg.h +++ b/drivers/lguest/lg.h @@ -142,6 +142,9 @@ struct lguest struct mm_struct *mm; /* == tsk->mm, but that becomes NULL on exit */ u16 guestid; u32 pfn_limit; + /* This provides the offset to the base of guest-physical + * memory in the Launcher. */ + void __user *mem_base; u32 page_offset; u32 cr2; int halted; diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c index 80d1b58..816d4d1 100644 --- a/drivers/lguest/lguest_user.c +++ b/drivers/lguest/lguest_user.c @@ -1,9 +1,9 @@ /*P:200 This contains all the /dev/lguest code, whereby the userspace launcher * controls and communicates with the Guest. For example, the first write will - * tell us the memory size, pagetable, entry point and kernel address offset. - * A read will run the Guest until a signal is pending (-EINTR), or the Guest - * does a DMA out to the Launcher. Writes are also used to get a DMA buffer - * registered by the Guest and to send the Guest an interrupt. :*/ + * tell us the Guest's memory layout, pagetable, entry point and kernel address + * offset. A read will run the Guest until something happens, such as a signal + * or the Guest doing a DMA out to the Launcher. Writes are also used to get a + * DMA buffer registered by the Guest and to send the Guest an interrupt. :*/ #include <linux/uaccess.h> #include <linux/miscdevice.h> #include <linux/fs.h> @@ -142,9 +142,11 @@ 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 4 32-bit values (in addition to the +/*L:020 The initialization write supplies 5 32-bit values (in addition to the * 32-bit LHREQ_INITIALIZE value). These are: * + * base: The start of the Guest-physical memory inside the Launcher memory. + * * pfnlimit: The highest (Guest-physical) page number the Guest should be * allowed to access. The Launcher has to live in Guest memory, so it sets * this to ensure the Guest can't reach it. @@ -166,7 +168,7 @@ static int initialize(struct file *file, const u32 __user *input) * Guest. */ struct lguest *lg; int err, i; - u32 args[4]; + u32 args[5]; /* We grab the Big Lguest lock, which protects the global array * "lguests" and multiple simultaneous initializations. */ @@ -194,8 +196,9 @@ static int initialize(struct file *file, const u32 __user *input) /* Populate the easy fields of our "struct lguest" */ lg->guestid = i; - lg->pfn_limit = args[0]; - lg->page_offset = args[3]; + 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. */ @@ -210,13 +213,13 @@ static int initialize(struct file *file, const u32 __user *input) /* Initialize the Guest's shadow page tables, using the toplevel * address the Launcher gave us. This allocates memory, so can * fail. */ - err = init_guest_pagetable(lg, args[1]); + err = init_guest_pagetable(lg, args[2]); if (err) goto free_regs; /* Now we initialize the Guest's registers, handing it the start * address. */ - setup_regs(lg->regs, args[2]); + setup_regs(lg->regs, args[3]); /* There are a couple of GDT entries the Guest expects when first * booting. */ diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index b7a924a..9cd2fac 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -152,7 +152,7 @@ static unsigned long get_pfn(unsigned long virtpfn, int write) static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write) { spte_t spte; - unsigned long pfn; + unsigned long pfn, base; /* The Guest sets the global flag, because it thinks that it is using * PGE. We only told it to use PGE so it would tell us whether it was @@ -160,11 +160,14 @@ static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write) * use the global bit, so throw it away. */ spte.flags = (gpte.flags & ~_PAGE_GLOBAL); + /* The Guest's pages are offset inside the Launcher. */ + base = (unsigned long)lg->mem_base / PAGE_SIZE; + /* We need a temporary "unsigned long" variable to hold the answer from * get_pfn(), because it returns 0xFFFFFFFF on failure, which wouldn't * fit in spte.pfn. get_pfn() finds the real physical number of the * page, given the virtual number. */ - pfn = get_pfn(gpte.pfn, write); + pfn = get_pfn(base + gpte.pfn, write); if (pfn == -1UL) { kill_guest(lg, "failed to get page %u", gpte.pfn); /* When we destroy the Guest, we'll go through the shadow page |
