[PATCH] powerpc: Merge thread_info.h

Merge ppc32 and ppc64 versions of thread_info.h.  They were pretty
similar already, the chief changes are:

	- Instead of inline asm to implement current_thread_info(),
which needs to be different for ppc32 and ppc64, we use C with an
asm("r1") register variable.  gcc turns it into the same asm as we
used to have for both platforms.
	- We replace ppc32's 'local_flags' with the ppc64
'syscall_noerror' field.  The noerror flag was in fact the only thing
in the local_flags field anyway, so the ppc64 approach is simpler, and
means we only need a load-immediate/store instead of load/mask/store
when clearing the flag.
	- In readiness for 64k pages, when THREAD_SIZE will be less
than a page, ppc64 used kmalloc() rather than get_free_pages() to
allocate the kernel stack.  With this patch we do the same for ppc32,
since there's no strong reason not to.
	- For ppc64, we no longer export THREAD_SHIFT and THREAD_SIZE
via asm-offsets, thread_info.h can now be safely included in asm, as
on ppc32.

Built and booted on G4 Powerbook (ARCH=ppc and ARCH=powerpc) and
Power5 (ARCH=ppc64 and ARCH=powerpc).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 23 insertions, 120 deletions

diff --git a/include/asm-ppc64/thread_info.h b/include/asm-powerpc/thread_info.h
index 71244d8a427d..0b4c24551c21 100644
--- a/include/asm-ppc64/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -1,15 +1,25 @@
-/* thread_info.h: PPC low-level thread information
+/* thread_info.h: PowerPC low-level thread information
  * adapted from the i386 version by Paul Mackerras
  *
  * Copyright (C) 2002  David Howells (dhowells@redhat.com)
  * - Incorporating suggestions made by Linus Torvalds and Dave Miller
  */
 
-#ifndef _ASM_THREAD_INFO_H
-#define _ASM_THREAD_INFO_H
+#ifndef _ASM_POWERPC_THREAD_INFO_H
+#define _ASM_POWERPC_THREAD_INFO_H
 
 #ifdef __KERNEL__
 
+/* We have 8k stacks on ppc32 and 16k on ppc64 */
+
+#ifdef CONFIG_PPC64
+#define THREAD_SHIFT            14
+#else
+#define THREAD_SHIFT            13
+#endif
+
+#define THREAD_SIZE             (1 << THREAD_SHIFT)
+
 #ifndef __ASSEMBLY__
 #include <linux/config.h>
 #include <linux/cache.h>
@@ -24,7 +34,8 @@ struct thread_info {
         struct task_struct *task;               /* main task structure */
         struct exec_domain *exec_domain;        /* execution domain */
         int             cpu;                    /* cpu we're on */
-        int             preempt_count;          /* 0 => preemptable, <0 => BUG */
+        int             preempt_count;          /* 0 => preemptable,
+                                                   <0 => BUG */
         struct restart_block restart_block;
         /* set by force_successful_syscall_return */
         unsigned char   syscall_noerror;
@@ -54,9 +65,6 @@ struct thread_info {
 
 /* thread information allocation */
 
-#define THREAD_SHIFT            14
-#define THREAD_ORDER            (THREAD_SHIFT - PAGE_SHIFT)
-#define THREAD_SIZE             (1 << THREAD_SHIFT)
 #ifdef CONFIG_DEBUG_STACK_USAGE
 #define alloc_thread_info(tsk)                                  \
         ({                                                      \
@@ -68,7 +76,7 @@ struct thread_info {
                 ret;                                            \
         })
 #else
-#define alloc_thread_info(tsk) kmalloc(THREAD_SIZE, GFP_KERNEL)
+#define alloc_thread_info(tsk)  kmalloc(THREAD_SIZE, GFP_KERNEL)
 #endif
 #define free_thread_info(ti)    kfree(ti)
 #define get_thread_info(ti)     get_task_struct((ti)->task)
@@ -77,9 +85,11 @@ struct thread_info {
 /* how to get the thread information struct from C */
 static inline struct thread_info *current_thread_info(void)
 {
-        struct thread_info *ti;
-        __asm__("clrrdi %0,1,%1" : "=r"(ti) : "i" (THREAD_SHIFT));
-        return ti;
+        register unsigned long sp asm("r1");
+
+        /* gcc4, at least, is smart enough to turn this into a single
+         * rlwinm for ppc32 and clrrdi for ppc64 */
+        return (struct thread_info *)(sp & ~(THREAD_SIZE-1));
 }
 
 #endif /* __ASSEMBLY__ */
@@ -122,4 +132,4 @@ static inline struct thread_info *current_thread_info(void)
 
 #endif /* __KERNEL__ */
 
-#endif /* _ASM_THREAD_INFO_H */
+#endif /* _ASM_POWERPC_THREAD_INFO_H */
diff --git a/include/asm-ppc/ptrace.h b/include/asm-ppc/ptrace.h
index 7043c164b537..c34fb4e37a97 100644
--- a/include/asm-ppc/ptrace.h
+++ b/include/asm-ppc/ptrace.h
@@ -57,7 +57,7 @@ extern unsigned long profile_pc(struct pt_regs *regs);
 
 #define force_successful_syscall_return()   \
         do { \
-                current_thread_info()->local_flags |= _TIFL_FORCE_NOERROR; \
+                current_thread_info()->syscall_noerror = 1; \
         } while(0)
 
 /*
diff --git a/include/asm-ppc/thread_info.h b/include/asm-ppc/thread_info.h
deleted file mode 100644
index 27903db42efc..000000000000
--- a/include/asm-ppc/thread_info.h
+++ /dev/null
@@ -1,107 +0,0 @@
-/* thread_info.h: PPC low-level thread information
- * adapted from the i386 version by Paul Mackerras
- *
- * Copyright (C) 2002  David Howells (dhowells@redhat.com)
- * - Incorporating suggestions made by Linus Torvalds and Dave Miller
- */
-
-#ifndef _ASM_THREAD_INFO_H
-#define _ASM_THREAD_INFO_H
-
-#ifdef __KERNEL__
-#ifndef __ASSEMBLY__
-/*
- * low level task data.
- * If you change this, change the TI_* offsets below to match.
- */
-struct thread_info {
-        struct task_struct      *task;          /* main task structure */
-        struct exec_domain      *exec_domain;   /* execution domain */
-        unsigned long           flags;          /* low level flags */
-        unsigned long           local_flags;    /* non-racy flags */
-        int                     cpu;            /* cpu we're on */
-        int                     preempt_count;  /* 0 => preemptable,
-                                                   <0 => BUG */
-        struct restart_block    restart_block;
-};
-
-#define INIT_THREAD_INFO(tsk)                   \
-{                                               \
-        .task =         &tsk,                   \
-        .exec_domain =  &default_exec_domain,   \
-        .flags =        0,                      \
-        .local_flags =  0,                      \
-        .cpu =          0,                      \
-        .preempt_count = 1,                     \
-        .restart_block = {                      \
-                .fn = do_no_restart_syscall,    \
-        },                                      \
-}
-
-#define init_thread_info        (init_thread_union.thread_info)
-#define init_stack              (init_thread_union.stack)
-
-/*
- * macros/functions for gaining access to the thread information structure
- */
-
-/* how to get the thread information struct from C */
-static inline struct thread_info *current_thread_info(void)
-{
-        struct thread_info *ti;
-        __asm__("rlwinm %0,1,0,0,18" : "=r"(ti));
-        return ti;
-}
-
-/* thread information allocation */
-#define alloc_thread_info(tsk) ((struct thread_info *) \
-                                __get_free_pages(GFP_KERNEL, 1))
-#define free_thread_info(ti)    free_pages((unsigned long) (ti), 1)
-#define get_thread_info(ti)     get_task_struct((ti)->task)
-#define put_thread_info(ti)     put_task_struct((ti)->task)
-#endif /* __ASSEMBLY__ */
-
-/*
- * Size of kernel stack for each process.
- */
-#define THREAD_SIZE             8192    /* 2 pages */
-
-#define PREEMPT_ACTIVE          0x10000000
-
-/*
- * thread information flag bit numbers
- */
-#define TIF_SYSCALL_TRACE       0       /* syscall trace active */
-#define TIF_NOTIFY_RESUME       1       /* resumption notification requested */