[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>

arch/powerpc/kernel/entry_32.S

@@ -199,10 +199,9 @@ _GLOBAL(DoSyscall)
 #ifdef SHOW_SYSCALLS
 	bl	do_show_syscall
 #endif /* SHOW_SYSCALLS */
-	rlwinm	r10,r1,0,0,18	/* current_thread_info() */
-	lwz	r11,TI_LOCAL_FLAGS(r10)
-	rlwinm	r11,r11,0,~_TIFL_FORCE_NOERROR
-	stw	r11,TI_LOCAL_FLAGS(r10)
+	rlwinm	r10,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
+	li	r11,0
+	stb	r11,TI_SC_NOERR(r10)
 	lwz	r11,TI_FLAGS(r10)
 	andi.	r11,r11,_TIF_SYSCALL_T_OR_A
 	bne-	syscall_dotrace
@@ -225,10 +224,10 @@ ret_from_syscall:
 	mr	r6,r3
 	li	r11,-_LAST_ERRNO
 	cmplw	0,r3,r11
-	rlwinm	r12,r1,0,0,18	/* current_thread_info() */
+	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
 	blt+	30f
-	lwz	r11,TI_LOCAL_FLAGS(r12)
-	andi.	r11,r11,_TIFL_FORCE_NOERROR
+	lbz	r11,TI_SC_NOERR(r12)
+	cmpwi	r11,0
 	bne	30f
 	neg	r3,r3
 	lwz	r10,_CCR(r1)	/* Set SO bit in CR */
@@ -315,7 +314,7 @@ syscall_exit_work:
 	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
 	SYNC
 	MTMSRD(r10)		/* disable interrupts again */
-	rlwinm	r12,r1,0,0,18	/* current_thread_info() */
+	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
 	lwz	r9,TI_FLAGS(r12)
 5:
 	andi.	r0,r9,_TIF_NEED_RESCHED
@@ -630,7 +629,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_601)
 	.globl	sigreturn_exit
 sigreturn_exit:
 	subi	r1,r3,STACK_FRAME_OVERHEAD
-	rlwinm	r12,r1,0,0,18	/* current_thread_info() */
+	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
 	lwz	r9,TI_FLAGS(r12)
 	andi.	r0,r9,_TIF_SYSCALL_T_OR_A
 	beq+	ret_from_except_full
@@ -657,7 +656,7 @@ ret_from_except:
 
 user_exc_return:		/* r10 contains MSR_KERNEL here */
 	/* Check current_thread_info()->flags */
-	rlwinm	r9,r1,0,0,18
+	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
 	lwz	r9,TI_FLAGS(r9)
 	andi.	r0,r9,(_TIF_SIGPENDING|_TIF_NEED_RESCHED)
 	bne	do_work
@@ -677,7 +676,7 @@ restore_user:
 /* N.B. the only way to get here is from the beq following ret_from_except. */
 resume_kernel:
 	/* check current_thread_info->preempt_count */
-	rlwinm	r9,r1,0,0,18
+	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
 	lwz	r0,TI_PREEMPT(r9)
 	cmpwi	0,r0,0		/* if non-zero, just restore regs and return */
 	bne	restore
@@ -687,7 +686,7 @@ resume_kernel:
 	andi.	r0,r3,MSR_EE	/* interrupts off? */
 	beq	restore		/* don't schedule if so */
 1:	bl	preempt_schedule_irq
-	rlwinm	r9,r1,0,0,18
+	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
 	lwz	r3,TI_FLAGS(r9)
 	andi.	r0,r3,_TIF_NEED_RESCHED
 	bne-	1b
@@ -889,7 +888,7 @@ recheck:
 	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
 	SYNC
 	MTMSRD(r10)		/* disable interrupts */
-	rlwinm	r9,r1,0,0,18
+	rlwinm	r9,r1,0,0,(31-THREAD_SHIFT)
 	lwz	r9,TI_FLAGS(r9)
 	andi.	r0,r9,_TIF_NEED_RESCHED
 	bne-	do_resched