maps4: rework TASK_SIZE macros

The following replaces the earlier patches sent.  It should address
David Rientjes's comments, and has been compile tested on all the
architectures that it touches, save for parisc.

For the /proc/<pid>/pagemap code[1], we need to able to query how
much virtual address space a particular task has.  The trick is
that we do it through /proc and can't use TASK_SIZE since it
references "current" on some arches.  The process opening the
/proc file might be a 32-bit process opening a 64-bit process's
pagemap file.

x86_64 already has a TASK_SIZE_OF() macro:

#define TASK_SIZE_OF(child)     ((test_tsk_thread_flag(child, TIF_IA32)) ? IA32_PAGE_OFFSET : TASK_SIZE64)

I'd like to have that for other architectures.  So, add it
for all the architectures that actually use "current" in
their TASK_SIZE.  For the others, just add a quick #define
in sched.h to use plain old TASK_SIZE.

1. http://www.linuxworld.com/news/2007/042407-kernel.html

- MIPS portion from Ralf Baechle <ralf@linux-mips.org>

[akpm@linux-foundation.org: fix mips build]
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 14 insertions, 4 deletions

diff --git a/include/asm-ia64/processor.h b/include/asm-ia64/processor.h
index be3b0ae43270..666385b68820 100644
--- a/include/asm-ia64/processor.h
+++ b/include/asm-ia64/processor.h
@@ -31,7 +31,8 @@
  * each (assuming 8KB page size), for a total of 8TB of user virtual
  * address space.
  */
-#define TASK_SIZE               (current->thread.task_size)
+#define TASK_SIZE_OF(tsk)       ((tsk)->thread.task_size)
+#define TASK_SIZE               TASK_SIZE_OF(current)
 
 /*
  * This decides where the kernel will search for a free chunk of vm
diff --git a/include/asm-mips/processor.h b/include/asm-mips/processor.h
index 83bc94534084..36f42de59409 100644
--- a/include/asm-mips/processor.h
+++ b/include/asm-mips/processor.h
@@ -65,6 +65,8 @@ extern unsigned int vced_count, vcei_count;
 #define TASK_UNMAPPED_BASE                                              \
         (test_thread_flag(TIF_32BIT_ADDR) ?                             \
                 PAGE_ALIGN(TASK_SIZE32 / 3) : PAGE_ALIGN(TASK_SIZE / 3))
+#define TASK_SIZE_OF(tsk)                                               \
+        (test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE)
 #endif
 
 #define NUM_FPU_REGS    32
diff --git a/include/asm-parisc/processor.h b/include/asm-parisc/processor.h
index 6b294fb07a23..3bb06e898fde 100644
--- a/include/asm-parisc/processor.h
+++ b/include/asm-parisc/processor.h
@@ -32,7 +32,8 @@
 #endif
 #define current_text_addr() ({ void *pc; current_ia(pc); pc; })
 
-#define TASK_SIZE               (current->thread.task_size)
+#define TASK_SIZE_OF(tsk)       ((tsk)->thread.task_size)
+#define TASK_SIZE               TASK_SIZE_OF(current)
 #define TASK_UNMAPPED_BASE      (current->thread.map_base)
 
 #define DEFAULT_TASK_SIZE32     (0xFFF00000UL)
diff --git a/include/asm-powerpc/processor.h b/include/asm-powerpc/processor.h
index dba7c948189d..1f4765d6546f 100644
--- a/include/asm-powerpc/processor.h
+++ b/include/asm-powerpc/processor.h
@@ -99,8 +99,9 @@ extern struct task_struct *last_task_used_spe;
  */
 #define TASK_SIZE_USER32 (0x0000000100000000UL - (1*PAGE_SIZE))
 
-#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
+#define TASK_SIZE_OF(tsk) (test_tsk_thread_flag(tsk, TIF_32BIT) ? \
                 TASK_SIZE_USER32 : TASK_SIZE_USER64)
+#define TASK_SIZE         TASK_SIZE_OF(current)
 
 /* This decides where the kernel will search for a free chunk of vm
  * space during mmap's.
diff --git a/include/asm-s390/processor.h b/include/asm-s390/processor.h
index c86b982aef5a..4f744609cd11 100644
--- a/include/asm-s390/processor.h
+++ b/include/asm-s390/processor.h
@@ -70,8 +70,9 @@ extern int get_cpu_capability(unsigned int *);
 
 #else /* __s390x__ */
 
-# define TASK_SIZE              (test_thread_flag(TIF_31BIT) ? \
+# define TASK_SIZE_OF(tsk)      (test_tsk_thread_flag(tsk, TIF_31BIT) ? \
                                         (0x80000000UL) : (0x40000000000UL))
+# define TASK_SIZE              TASK_SIZE_OF(current)
 # define TASK_UNMAPPED_BASE     (TASK_SIZE / 2)
 # define DEFAULT_TASK_SIZE      (0x40000000000UL)
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 483ea4e1accf..c30d174a02fa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2087,6 +2087,10 @@ static inline void migration_init(void)
 }
 #endif
 
+#ifndef TASK_SIZE_OF
+#define TASK_SIZE_OF(tsk)       TASK_SIZE
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif