[PATCH 1/2] UML - Clean up TASK_SIZE usage

Jeff Dike
2007-11-26T21:03:36Z

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>
---
arch/um/include/as-layout.h | 15 +++++++++++++--
arch/um/include/common-offsets.h | 3 +++
arch/um/include/mem_user.h | 4 ----
arch/um/kernel/exec.c | 2 +-
arch/um/kernel/ksyms.c | 3 ---
arch/um/kernel/physmem.c | 10 ----------
arch/um/kernel/tlb.c | 2 +-
arch/um/kernel/um_arch.c | 22 ++--------------------
include/asm-um/fixmap.h | 3 +--
include/asm-um/processor-generic.h | 7 +++----
10 files changed, 24 insertions(+), 47 deletions(-)

Index: linux-2.6.22/arch/um/include/as-layout.h
===================================================================
--- linux-2.6.22.orig/arch/um/include/as-layout.h 2007-11-21 11:49:33.000000000 -0500
+++ linux-2.6.22/arch/um/include/as-layout.h 2007-11-21 11:53:02.000000000 -0500
@@ -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__
Index: linux-2.6.22/arch/um/include/common-offsets.h
===================================================================
--- linux-2.6.22.orig/arch/um/include/common-offsets.h 2007-11-21 11:49:33.000000000 -0500
+++ linux-2.6.22/arch/um/include/common-offsets.h 2007-11-21 11:53:02.000000000 -0500
@@ -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);
Index: linux-2.6.22/arch/um/include/mem_user.h
===================================================================
--- linux-2.6.22.orig/arch/um/include/mem_user.h 2007-11-21 11:43:52.000000000 -0500
+++ linux-2.6.22/arch/um/include/mem_user.h 2007-11-21 11:53:02.000000000 -0500
@@ -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(unsigne
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
Index: linux-2.6.22/arch/um/kernel/exec.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/exec.c 2007-11-21 11:43:52.000000000 -0500
+++ linux-2.6.22/arch/um/kernel/exec.c 2007-11-21 11:53:02.000000000 -0500
@@ -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);
Index: linux-2.6.22/arch/um/kernel/ksyms.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/ksyms.c 2007-11-21 11:49:33.000000000 -0500
+++ linux-2.6.22/arch/um/kernel/ksyms.c 2007-11-21 11:53:02.000000000 -0500
@@ -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);
Index: linux-2.6.22/arch/um/kernel/physmem.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/physmem.c 2007-11-21 11:43:52.000000000 -0500
+++ linux-2.6.22/arch/um/kernel/physmem.c 2007-11-21 11:53:02.000000000 -0500
@@ -55,16 +55,6 @@ int __init init_maps(unsigned long physm
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)
{
Index: linux-2.6.22/arch/um/kernel/tlb.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/tlb.c 2007-11-21 11:49:33.000000000 -0500
+++ linux-2.6.22/arch/um/kernel/tlb.c 2007-11-21 11:53:02.000000000 -0500
@@ -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);
}

Index: linux-2.6.22/arch/um/kernel/um_arch.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/um_arch.c 2007-11-21 11:51:11.000000000 -0500
+++ linux-2.6.22/arch/um/kernel/um_arch.c 2007-11-21 11:53:02.000000000 -0500
@@ -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 **a

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 **a

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 **a
}

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;
Index: linux-2.6.22/include/asm-um/fixmap.h
===================================================================
--- linux-2.6.22.orig/include/asm-um/fixmap.h 2007-11-21 11:49:53.000000000 -0500
+++ linux-2.6.22/include/asm-um/fixmap.h 2007-11-21 11:53:02.000000000 -0500
@@ -56,9 +56,8 @@ extern void __set_fixmap (enum fixed_add
* the start of the fixmap, and leave one page empty
* at the top of mem..
*/
-extern unsigned long get_kmem_end(void);

-#define FIXADDR_TOP (get_kmem_end() - 0x2000)
+#define FIXADDR_TOP (CONFIG_TOP_ADDR - 2 * PAGE_SIZE)
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)

Index: linux-2.6.22/include/asm-um/processor-generic.h
===================================================================
--- linux-2.6.22.orig/include/asm-um/processor-generic.h 2007-11-21 11:49:53.000000000 -0500
+++ linux-2.6.22/include/asm-um/processor-generic.h 2007-11-21 11:53:45.000000000 -0500
@@ -94,9 +94,7 @@ static inline void mm_copy_segments(stru
/*
* User space process size: 3GB (default).
*/
-extern unsigned long task_size;
-
-#define TASK_SIZE (task_size)
+#define TASK_SIZE (CONFIG_TOP_ADDR & PGDIR_MASK)

/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
Index: linux-2.6.22/include/asm-um/a.out.h
===================================================================
--- linux-2.6.22.orig/include/asm-um/a.out.h 2007-11-21 11:44:49.000000000 -0500
+++ linux-2.6.22/include/asm-um/a.out.h 2007-11-21 11:54:30.000000000 -0500
@@ -13,11 +13,9 @@

extern unsigned long stacksizelim;

-extern unsigned long host_task_size;
-
#define STACK_ROOM (stacksizelim)

-#define STACK_TOP task_size
+#define STACK_TOP (TASK_SIZE - 2 * PAGE_SIZE)

#define STACK_TOP_MAX STACK_TOP