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Diffstat (limited to 'arch/um/os-Linux/sys-i386/task_size.c')
-rw-r--r--arch/um/os-Linux/sys-i386/task_size.c31
1 files changed, 23 insertions, 8 deletions
diff --git a/arch/um/os-Linux/sys-i386/task_size.c b/arch/um/os-Linux/sys-i386/task_size.c
index ccb49b0..be04c1e 100644
--- a/arch/um/os-Linux/sys-i386/task_size.c
+++ b/arch/um/os-Linux/sys-i386/task_size.c
@@ -63,7 +63,7 @@ static int page_ok(unsigned long page)
return ok;
}
-unsigned long os_get_task_size(void)
+unsigned long os_get_top_address(void)
{
struct sigaction sa, old;
unsigned long bottom = 0;
@@ -76,9 +76,9 @@ unsigned long os_get_task_size(void)
* hosts, but shouldn't hurt otherwise.
*/
unsigned long top = 0xffffd000 >> UM_KERN_PAGE_SHIFT;
- unsigned long test;
+ unsigned long test, original;
- printf("Locating the top of the address space ... ");
+ printf("Locating the bottom of the address space ... ");
fflush(stdout);
/*
@@ -89,16 +89,31 @@ unsigned long os_get_task_size(void)
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_NODEFER;
if (sigaction(SIGSEGV, &sa, &old)) {
- perror("os_get_task_size");
+ perror("os_get_top_address");
exit(1);
}
- if (!page_ok(bottom)) {
- fprintf(stderr, "Address 0x%x no good?\n",
- bottom << UM_KERN_PAGE_SHIFT);
+ /* 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;
@@ -114,7 +129,7 @@ unsigned long os_get_task_size(void)
out:
/* Restore the old SIGSEGV handling */
if (sigaction(SIGSEGV, &old, NULL)) {
- perror("os_get_task_size");
+ perror("os_get_top_address");
exit(1);
}
top <<= UM_KERN_PAGE_SHIFT;