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authorAl Viro <viro@ftp.linux.org.uk>2011-08-18 20:03:49 +0100
committerRichard Weinberger <richard@nod.at>2011-11-02 14:14:53 +0100
commit51d34749051a6369093e5067ef67c17f17694921 (patch)
tree765e499c73e2797cc5d525f1b4cf590f17aa4132 /arch/um/os-Linux/sys-i386/task_size.c
parent7eb122555c8583e1601b7a620c5a88c1e06c3eac (diff)
um: merge arch/um/os-Linux/sys-{i386,x86_64}
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/os-Linux/sys-i386/task_size.c')
-rw-r--r--arch/um/os-Linux/sys-i386/task_size.c138
1 files changed, 0 insertions, 138 deletions
diff --git a/arch/um/os-Linux/sys-i386/task_size.c b/arch/um/os-Linux/sys-i386/task_size.c
deleted file mode 100644
index 4ce09b8e99c9..000000000000
--- a/arch/um/os-Linux/sys-i386/task_size.c
+++ /dev/null
@@ -1,138 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <signal.h>
-#include <sys/mman.h>
-#include "longjmp.h"
-
-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;
-}