uml: deal with inaccessible address space start

[karo-tx-linux.git] / arch / um / kernel / um_arch.c

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 468aba990dbd1652add865bb88f1006ece3a7d16..d1fe2224ddab898dd12817124f6b18fb3217dae3 100644 (file)
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -241,6 +241,11 @@ static struct notifier_block panic_exit_notifier = {
 };
 
 /* Set during early boot */
+unsigned long task_size;
+EXPORT_SYMBOL(task_size);
+
+unsigned long host_task_size;
+
 unsigned long brk_start;
 unsigned long end_iomem;
 EXPORT_SYMBOL(end_iomem);
@@ -254,6 +259,7 @@ int __init linux_main(int argc, char **argv)
        unsigned long avail, diff;
        unsigned long virtmem_size, max_physmem;
        unsigned int i, add;
+       unsigned long stack;
        char * mode;
 
        for (i = 1; i < argc; i++) {
@@ -267,6 +273,13 @@ int __init linux_main(int argc, char **argv)
        if (have_root == 0)
                add_arg(DEFAULT_COMMAND_LINE);
 
+       host_task_size = os_get_top_address();
+       /*
+        * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
+        * out
+        */
+       task_size = host_task_size & PGDIR_MASK;
+
        /* OS sanity checks that need to happen before the kernel runs */
        os_early_checks();
 
@@ -303,7 +316,7 @@ int __init linux_main(int argc, char **argv)
 
        highmem = 0;
        iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
-       max_physmem = CONFIG_TOP_ADDR - uml_physmem - iomem_size - MIN_VMALLOC;
+       max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
 
        /*
         * Zones have to begin on a 1 << MAX_ORDER page boundary,
@@ -335,7 +348,9 @@ int __init linux_main(int argc, char **argv)
        }
 
        virtmem_size = physmem_size;
-       avail = CONFIG_TOP_ADDR - start_vm;
+       stack = (unsigned long) argv;
+       stack &= ~(1024 * 1024 - 1);
+       avail = stack - start_vm;
        if (physmem_size > avail)
                virtmem_size = avail;
        end_vm = start_vm + virtmem_size;