powerpc: Move bad_stack() below the fwnmi_data_area

At the moment the allmodconfig build is failing because we run out of
space between altivec_assist() at 0x5700 and the fwnmi_data_area at
0x7000.

Fixing it permanently will take some more work, but a quick fix is to
move bad_stack() below the fwnmi_data_area. That gives us just enough
room with everything enabled.

bad_stack() is called from the common exception handlers, but it's a
non-conditional branch, so we have plenty of scope to move it further
way.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/exceptions-64s.S

@@ -952,66 +952,6 @@ system_call_entry:
 ppc64_runlatch_on_trampoline:
 	b	__ppc64_runlatch_on
 
-/*
- * Here we have detected that the kernel stack pointer is bad.
- * R9 contains the saved CR, r13 points to the paca,
- * r10 contains the (bad) kernel stack pointer,
- * r11 and r12 contain the saved SRR0 and SRR1.
- * We switch to using an emergency stack, save the registers there,
- * and call kernel_bad_stack(), which panics.
- */
-bad_stack:
-	ld	r1,PACAEMERGSP(r13)
-	subi	r1,r1,64+INT_FRAME_SIZE
-	std	r9,_CCR(r1)
-	std	r10,GPR1(r1)
-	std	r11,_NIP(r1)
-	std	r12,_MSR(r1)
-	mfspr	r11,SPRN_DAR
-	mfspr	r12,SPRN_DSISR
-	std	r11,_DAR(r1)
-	std	r12,_DSISR(r1)
-	mflr	r10
-	mfctr	r11
-	mfxer	r12
-	std	r10,_LINK(r1)
-	std	r11,_CTR(r1)
-	std	r12,_XER(r1)
-	SAVE_GPR(0,r1)
-	SAVE_GPR(2,r1)
-	ld	r10,EX_R3(r3)
-	std	r10,GPR3(r1)
-	SAVE_GPR(4,r1)
-	SAVE_4GPRS(5,r1)
-	ld	r9,EX_R9(r3)
-	ld	r10,EX_R10(r3)
-	SAVE_2GPRS(9,r1)
-	ld	r9,EX_R11(r3)
-	ld	r10,EX_R12(r3)
-	ld	r11,EX_R13(r3)
-	std	r9,GPR11(r1)
-	std	r10,GPR12(r1)
-	std	r11,GPR13(r1)
-BEGIN_FTR_SECTION
-	ld	r10,EX_CFAR(r3)
-	std	r10,ORIG_GPR3(r1)
-END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
-	SAVE_8GPRS(14,r1)
-	SAVE_10GPRS(22,r1)
-	lhz	r12,PACA_TRAP_SAVE(r13)
-	std	r12,_TRAP(r1)
-	addi	r11,r1,INT_FRAME_SIZE
-	std	r11,0(r1)
-	li	r12,0
-	std	r12,0(r11)
-	ld	r2,PACATOC(r13)
-	ld	r11,exception_marker@toc(r2)
-	std	r12,RESULT(r1)
-	std	r11,STACK_FRAME_OVERHEAD-16(r1)
-1:	addi	r3,r1,STACK_FRAME_OVERHEAD
-	bl	kernel_bad_stack
-	b	1b
-
 /*
  * Here r13 points to the paca, r9 contains the saved CR,
  * SRR0 and SRR1 are saved in r11 and r12,
@@ -1636,3 +1576,63 @@ handle_dabr_fault:
 	li	r5,SIGSEGV
 	bl	bad_page_fault
 	b	ret_from_except
+
+/*
+ * Here we have detected that the kernel stack pointer is bad.
+ * R9 contains the saved CR, r13 points to the paca,
+ * r10 contains the (bad) kernel stack pointer,
+ * r11 and r12 contain the saved SRR0 and SRR1.
+ * We switch to using an emergency stack, save the registers there,
+ * and call kernel_bad_stack(), which panics.
+ */
+bad_stack:
+	ld	r1,PACAEMERGSP(r13)
+	subi	r1,r1,64+INT_FRAME_SIZE
+	std	r9,_CCR(r1)
+	std	r10,GPR1(r1)
+	std	r11,_NIP(r1)
+	std	r12,_MSR(r1)
+	mfspr	r11,SPRN_DAR
+	mfspr	r12,SPRN_DSISR
+	std	r11,_DAR(r1)
+	std	r12,_DSISR(r1)
+	mflr	r10
+	mfctr	r11
+	mfxer	r12
+	std	r10,_LINK(r1)
+	std	r11,_CTR(r1)
+	std	r12,_XER(r1)
+	SAVE_GPR(0,r1)
+	SAVE_GPR(2,r1)
+	ld	r10,EX_R3(r3)
+	std	r10,GPR3(r1)
+	SAVE_GPR(4,r1)
+	SAVE_4GPRS(5,r1)
+	ld	r9,EX_R9(r3)
+	ld	r10,EX_R10(r3)
+	SAVE_2GPRS(9,r1)
+	ld	r9,EX_R11(r3)
+	ld	r10,EX_R12(r3)
+	ld	r11,EX_R13(r3)
+	std	r9,GPR11(r1)
+	std	r10,GPR12(r1)
+	std	r11,GPR13(r1)
+BEGIN_FTR_SECTION
+	ld	r10,EX_CFAR(r3)
+	std	r10,ORIG_GPR3(r1)
+END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
+	SAVE_8GPRS(14,r1)
+	SAVE_10GPRS(22,r1)
+	lhz	r12,PACA_TRAP_SAVE(r13)
+	std	r12,_TRAP(r1)
+	addi	r11,r1,INT_FRAME_SIZE
+	std	r11,0(r1)
+	li	r12,0
+	std	r12,0(r11)
+	ld	r2,PACATOC(r13)
+	ld	r11,exception_marker@toc(r2)
+	std	r12,RESULT(r1)
+	std	r11,STACK_FRAME_OVERHEAD-16(r1)
+1:	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	kernel_bad_stack
+	b	1b