[PARISC] Kill off broken irqstack code

It's been unfinished and broken long enough, and I have some ideas on how
to do it more cleanly.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/kernel/entry.S

@@ -98,7 +98,6 @@
 	 * The "get_stack" macros are responsible for determining the
 	 * kernel stack value.
 	 *
-	 * For Faults:
 	 *      If sr7 == 0
 	 *          Already using a kernel stack, so call the
 	 *          get_stack_use_r30 macro to push a pt_regs structure
@@ -110,26 +109,6 @@
 	 *          task pointer pointed to by cr30. Set the stack
 	 *          pointer to point to the end of the task structure.
 	 *
-	 * For Interrupts:
-	 *      If sr7 == 0
-	 *          Already using a kernel stack, check to see if r30
-	 *          is already pointing to the per processor interrupt
-	 *          stack. If it is, call the get_stack_use_r30 macro
-	 *          to push a pt_regs structure on the stack, and store
-	 *          registers there. Otherwise, call get_stack_use_cr31
-	 *          to get a pointer to the base of the interrupt stack
-	 *          and push a pt_regs structure on that stack.
-	 *      else
-	 *          Need to set up a kernel stack, so call the
-	 *          get_stack_use_cr30 macro to set up a pointer
-	 *          to the pt_regs structure contained within the
-	 *          task pointer pointed to by cr30. Set the stack
-	 *          pointer to point to the end of the task structure.
-	 *          N.B: We don't use the interrupt stack for the
-	 *          first interrupt from userland, because signals/
-	 *          resched's are processed when returning to userland,
-	 *          and we can sleep in those cases.
-	 *
 	 * Note that we use shadowed registers for temps until
 	 * we can save %r26 and %r29. %r26 is used to preserve
 	 * %r8 (a shadowed register) which temporarily contained
@@ -1086,23 +1065,13 @@ intr_do_preempt:
 
 intr_extint:
 	CMPIB=,n 0,%r16,1f
+
 	get_stack_use_cr30
-	b,n 3f
+	b,n 2f
 
 1:
-#if 0  /* Interrupt Stack support not working yet! */
-	mfctl	%cr31,%r1
-	copy	%r30,%r17
-	/* FIXME! depi below has hardcoded idea of interrupt stack size (32k)*/
-	DEPI	0,31,15,%r17
-	CMPB=,n	%r1,%r17,2f
-	get_stack_use_cr31
-	b,n 3f
-#endif
-2:
 	get_stack_use_r30
-
-3:
+2:
 	save_specials	%r29
 	virt_map
 	save_general	%r29

arch/parisc/kernel/head.S

@@ -128,10 +128,6 @@ $pgt_fill_loop:
 	/* And the stack pointer too */
 	ldo             THREAD_SZ_ALGN(%r6),%sp
 
-	/* And the interrupt stack */
-	load32		interrupt_stack,%r6
-	mtctl           %r6,%cr31
-
 #ifdef CONFIG_SMP
 	/* Set the smp rendevous address into page zero.
 	** It would be safer to do this in init_smp_config() but

arch/parisc/kernel/init_task.c

@@ -49,7 +49,6 @@ EXPORT_SYMBOL(init_mm);
  * way process stacks are handled. This is done by having a special
  * "init_task" linker map entry..
  */
-unsigned char interrupt_stack[ISTACK_SIZE] __attribute__ ((section("init_istack"), aligned(PAGE_SIZE)));
 union thread_union init_thread_union
 	__attribute__((aligned(128))) __attribute__((__section__(".data.init_task"))) =
 		{ INIT_THREAD_INFO(init_task) };

arch/parisc/kernel/smp.c

@@ -432,22 +432,10 @@ smp_cpu_init(int cpunum)
 void __init smp_callin(void)
 {
 	int slave_id = cpu_now_booting;
-#if 0
-	void *istack;
-#endif
 
 	smp_cpu_init(slave_id);
 	preempt_disable();
 
-#if 0	/* NOT WORKING YET - see entry.S */
-	istack = (void *)__get_free_pages(GFP_KERNEL,ISTACK_ORDER);
-	if (istack == NULL) {
-	    printk(KERN_CRIT "Failed to allocate interrupt stack for cpu %d\n",slave_id);
-	    BUG();
-	}
-	mtctl(istack,31);
-#endif
-
 	flush_cache_all_local(); /* start with known state */
 	flush_tlb_all_local(NULL);
 

arch/parisc/kernel/vmlinux.lds.S

@@ -153,14 +153,6 @@ SECTIONS
 		*(.data.init_task)
 	}
 
-	/* The interrupt stack is currently partially coded, but not yet
-	 * implemented
-	 */
-	. = ALIGN(16384);	
-	init_istack : {
-		*(init_istack)
-	}
-
 #ifdef CONFIG_64BIT
 	. = ALIGN(16);
 	/* Linkage tables */

include/asm-parisc/pgtable.h

@@ -49,14 +49,6 @@
 #define pgd_ERROR(e) \
 	printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, (unsigned long)pgd_val(e))
 
- /* Note: If you change ISTACK_SIZE, you need to change the corresponding
-  * values in vmlinux.lds and vmlinux64.lds (init_istack section). Also,
-  * the "order" and size need to agree.
-  */
-
-#define  ISTACK_SIZE  32768 /* Interrupt Stack Size */
-#define  ISTACK_ORDER 3
-
 /* This is the size of the initially mapped kernel memory */
 #ifdef CONFIG_64BIT
 #define KERNEL_INITIAL_ORDER	24	/* 0 to 1<<24 = 16MB */