diff options
Diffstat (limited to 'arch/um/os-Linux/sys-x86/task_size.c')
-rw-r--r-- | arch/um/os-Linux/sys-x86/task_size.c | 150 |
1 files changed, 0 insertions, 150 deletions
diff --git a/arch/um/os-Linux/sys-x86/task_size.c b/arch/um/os-Linux/sys-x86/task_size.c deleted file mode 100644 index efb16c5c9bcf..000000000000 --- a/arch/um/os-Linux/sys-x86/task_size.c +++ /dev/null @@ -1,150 +0,0 @@ -#include <stdio.h> -#include <stdlib.h> -#include <signal.h> -#include <sys/mman.h> -#include "longjmp.h" - -#ifdef __i386__ - -static jmp_buf buf; - -static void segfault(int sig) -{ - longjmp(buf, 1); -} - -static int page_ok(unsigned long page) -{ - unsigned long *address = (unsigned long *) (page << UM_KERN_PAGE_SHIFT); - unsigned long n = ~0UL; - void *mapped = NULL; - int ok = 0; - - /* - * First see if the page is readable. If it is, it may still - * be a VDSO, so we go on to see if it's writable. If not - * then try mapping memory there. If that fails, then we're - * still in the kernel area. As a sanity check, we'll fail if - * the mmap succeeds, but gives us an address different from - * what we wanted. - */ - if (setjmp(buf) == 0) - n = *address; - else { - mapped = mmap(address, UM_KERN_PAGE_SIZE, - PROT_READ | PROT_WRITE, - MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - if (mapped == MAP_FAILED) - return 0; - if (mapped != address) - goto out; - } - - /* - * Now, is it writeable? If so, then we're in user address - * space. If not, then try mprotecting it and try the write - * again. - */ - if (setjmp(buf) == 0) { - *address = n; - ok = 1; - goto out; - } else if (mprotect(address, UM_KERN_PAGE_SIZE, - PROT_READ | PROT_WRITE) != 0) - goto out; - - if (setjmp(buf) == 0) { - *address = n; - ok = 1; - } - - out: - if (mapped != NULL) - munmap(mapped, UM_KERN_PAGE_SIZE); - return ok; -} - -unsigned long os_get_top_address(void) -{ - struct sigaction sa, old; - unsigned long bottom = 0; - /* - * A 32-bit UML on a 64-bit host gets confused about the VDSO at - * 0xffffe000. It is mapped, is readable, can be reprotected writeable - * and written. However, exec discovers later that it can't be - * unmapped. So, just set the highest address to be checked to just - * below it. This might waste some address space on 4G/4G 32-bit - * hosts, but shouldn't hurt otherwise. - */ - unsigned long top = 0xffffd000 >> UM_KERN_PAGE_SHIFT; - unsigned long test, original; - - printf("Locating the bottom of the address space ... "); - fflush(stdout); - - /* - * We're going to be longjmping out of the signal handler, so - * SA_DEFER needs to be set. - */ - sa.sa_handler = segfault; - sigemptyset(&sa.sa_mask); - sa.sa_flags = SA_NODEFER; - if (sigaction(SIGSEGV, &sa, &old)) { - perror("os_get_top_address"); - exit(1); - } - - /* Manually scan the address space, bottom-up, until we find - * the first valid page (or run out of them). - */ - for (bottom = 0; bottom < top; bottom++) { - if (page_ok(bottom)) - break; - } - - /* If we've got this far, we ran out of pages. */ - if (bottom == top) { - fprintf(stderr, "Unable to determine bottom of address " - "space.\n"); - exit(1); - } - - printf("0x%x\n", bottom << UM_KERN_PAGE_SHIFT); - printf("Locating the top of the address space ... "); - fflush(stdout); - - original = bottom; - - /* This could happen with a 4G/4G split */ - if (page_ok(top)) - goto out; - - do { - test = bottom + (top - bottom) / 2; - if (page_ok(test)) - bottom = test; - else - top = test; - } while (top - bottom > 1); - -out: - /* Restore the old SIGSEGV handling */ - if (sigaction(SIGSEGV, &old, NULL)) { - perror("os_get_top_address"); - exit(1); - } - top <<= UM_KERN_PAGE_SHIFT; - printf("0x%x\n", top); - - return top; -} - -#else - -unsigned long os_get_top_address(void) -{ - /* The old value of CONFIG_TOP_ADDR */ - return 0x7fc0000000; -} - -#endif |