uml: clean up TASK_SIZE usage

Clean up the calculation and use of the usable address space size on the host.

task_size is gone, replaced with TASK_SIZE, which is calculated from
CONFIG_TOP_ADDR.  get_kmem_end and set_task_sizes_skas are also gone.

host_task_size, which refers to the entire address space usable by the UML
kernel and which may be larger than the address space usable by a UML process,
since that has to end on a pgdir boundary, is replaced by CONFIG_TOP_ADDR.

STACK_TOP is now TASK_SIZE minus the two stub pages.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 20 insertions, 41 deletions

diff --git a/arch/um/include/as-layout.h b/arch/um/include/as-layout.h
index 2b859e020ac6..a2008f550fee 100644
--- a/arch/um/include/as-layout.h
+++ b/arch/um/include/as-layout.h
@@ -29,9 +29,20 @@
 #define _AC(X, Y)       __AC(X, Y)
 #endif
 
+/*
+ * The "- 1"'s are to avoid gcc complaining about integer overflows
+ * and unrepresentable decimal constants.  With 3-level page tables,
+ * TASK_SIZE is 0x80000000, which gets turned into its signed decimal
+ * equivalent in asm-offsets.s.  gcc then complains about that being
+ * unsigned only in C90.  To avoid that, UM_TASK_SIZE is defined as
+ * TASK_SIZE - 1.  To compensate, we need to add the 1 back here.
+ * However, adding it back to UM_TASK_SIZE produces more gcc
+ * complaints.  So, I adjust the thing being subtracted from
+ * UM_TASK_SIZE instead.  Bah.
+ */
 #define STUB_CODE _AC((unsigned long), \
-                      UML_CONFIG_TOP_ADDR - 2 * UM_KERN_PAGE_SIZE)
-#define STUB_DATA _AC((unsigned long), UML_CONFIG_TOP_ADDR - UM_KERN_PAGE_SIZE)
+                      UM_TASK_SIZE - (2 * UM_KERN_PAGE_SIZE - 1))
+#define STUB_DATA _AC((unsigned long), UM_TASK_SIZE - (UM_KERN_PAGE_SIZE - 1))
 #define STUB_START _AC(, STUB_CODE)
 
 #ifndef __ASSEMBLY__
diff --git a/arch/um/include/common-offsets.h b/arch/um/include/common-offsets.h
index b54bd35585c2..5b67d7ced2a7 100644
--- a/arch/um/include/common-offsets.h
+++ b/arch/um/include/common-offsets.h
@@ -39,3 +39,6 @@ DEFINE(UM_HZ, HZ);
 DEFINE(UM_USEC_PER_SEC, USEC_PER_SEC);
 DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
 DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
+
+/* See as-layout.h for an explanation of the "- 1".  Bah. */
+DEFINE(UM_TASK_SIZE, TASK_SIZE - 1);
diff --git a/arch/um/include/mem_user.h b/arch/um/include/mem_user.h
index a54514d2cc3a..4e6707bd0a08 100644
--- a/arch/um/include/mem_user.h
+++ b/arch/um/include/mem_user.h
@@ -46,9 +46,6 @@ extern int iomem_size;
 
 #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
 
-extern unsigned long host_task_size;
-extern unsigned long task_size;
-
 extern int init_mem_user(void);
 extern void setup_memory(void *entry);
 extern unsigned long find_iomem(char *driver, unsigned long *len_out);
@@ -62,6 +59,5 @@ extern unsigned long phys_offset(unsigned long phys);
 extern void unmap_physmem(void);
 extern void map_memory(unsigned long virt, unsigned long phys,
                        unsigned long len, int r, int w, int x);
-extern unsigned long get_kmem_end(void);
 
 #endif
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index 8196450451cd..bf66b5b7bc68 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -19,7 +19,7 @@
 void flush_thread(void)
 {
         void *data = NULL;
-        unsigned long end = proc_mm ? task_size : STUB_START;
+        unsigned long end = proc_mm ? TASK_SIZE : STUB_START;
         int ret;
 
         arch_flush_thread(&current->thread.arch);
diff --git a/arch/um/kernel/ksyms.c b/arch/um/kernel/ksyms.c
index f0ced9840a27..187a756f3e5b 100644
--- a/arch/um/kernel/ksyms.c
+++ b/arch/um/kernel/ksyms.c
@@ -18,11 +18,8 @@ EXPORT_SYMBOL(set_signals);
 EXPORT_SYMBOL(get_signals);
 EXPORT_SYMBOL(kernel_thread);
 EXPORT_SYMBOL(sys_waitpid);
-EXPORT_SYMBOL(task_size);
 EXPORT_SYMBOL(flush_tlb_range);
-EXPORT_SYMBOL(host_task_size);
 EXPORT_SYMBOL(arch_validate);
-EXPORT_SYMBOL(get_kmem_end);
 
 EXPORT_SYMBOL(high_physmem);
 EXPORT_SYMBOL(empty_zero_page);
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index e66432f42485..9c9290005792 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -55,16 +55,6 @@ int __init init_maps(unsigned long physmem, unsigned long iomem,
         return 0;
 }
 
-/* Changed during early boot */
-static unsigned long kmem_top = 0;
-
-unsigned long get_kmem_end(void)
-{
-        if (kmem_top == 0)
-                kmem_top = host_task_size - 1024 * 1024;
-        return kmem_top;
-}
-
 void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
                 int r, int w, int x)
 {
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 96e097879f5b..429fed2f66b2 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -511,7 +511,7 @@ void flush_tlb_mm(struct mm_struct *mm)
         if (atomic_read(&mm->mm_users) == 0)
                 return;
 
-        end = proc_mm ? task_size : STUB_START;
+        end = proc_mm ? TASK_SIZE : STUB_START;
         fix_range(mm, 0, end, 0);
 }
 
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 1139e07b968f..9ba39ab5f4bd 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -101,8 +101,6 @@ const struct seq_operations cpuinfo_op = {
 };
 
 /* Set in linux_main */
-unsigned long host_task_size;
-unsigned long task_size;
 unsigned long uml_physmem;
 unsigned long uml_reserved; /* Also modified in mem_init */
 unsigned long start_vm;
@@ -234,20 +232,6 @@ EXPORT_SYMBOL(end_iomem);
 
 extern char __binary_start;
 
-static unsigned long set_task_sizes_skas(unsigned long *task_size_out)
-{
-        /* Round up to the nearest 4M */
-        unsigned long host_task_size = ROUND_4M((unsigned long)
-                                                &host_task_size);
-
-        if (!skas_needs_stub)
-                *task_size_out = host_task_size;
-        else
-                *task_size_out = STUB_START & PGDIR_MASK;
-
-        return host_task_size;
-}
-
 int __init linux_main(int argc, char **argv)
 {
         unsigned long avail, diff;
@@ -278,8 +262,6 @@ int __init linux_main(int argc, char **argv)
 
         printf("UML running in %s mode\n", mode);
 
-        host_task_size = set_task_sizes_skas(&task_size);
-
         brk_start = (unsigned long) sbrk(0);
 
         /*
@@ -304,7 +286,7 @@ int __init linux_main(int argc, char **argv)
 
         highmem = 0;
         iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
-        max_physmem = get_kmem_end() - uml_physmem - iomem_size - MIN_VMALLOC;
+        max_physmem = CONFIG_TOP_ADDR - uml_physmem - iomem_size - MIN_VMALLOC;
 
         /*
          * Zones have to begin on a 1 << MAX_ORDER page boundary,
@@ -336,7 +318,7 @@ int __init linux_main(int argc, char **argv)
         }
 
         virtmem_size = physmem_size;
-        avail = get_kmem_end() - start_vm;
+        avail = CONFIG_TOP_ADDR - start_vm;
         if (physmem_size > avail)
                 virtmem_size = avail;
         end_vm = start_vm + virtmem_size;