[PATCH] cleanup patch that prepares for 4Kb stacks

From: Arjan van de Ven <arjanv@redhat.com>

I have 4Kb stacks + IRQ stacks working in my tree.  The biggest part of the
4K-stacks work is changing hardcoded 8Kb assumptions to the proper,
pre-existing define for this.  That part of the patch is appropriate in
general, even when 4Kb stacks might not be.

arch/i386/kernel/entry.S

@@ -515,8 +515,8 @@ ENTRY(nmi)
 	/* Do not access memory above the end of our stack page,
 	 * it might not exist.
 	 */
-	andl $0x1fff,%eax
-	cmpl $0x1fec,%eax
+	andl $(THREAD_SIZE-1),%eax
+	cmpl $(THREAD_SIZE-20),%eax
 	popl %eax
 	jae nmi_stack_correct
 	cmpl $sysenter_entry,12(%esp)

arch/i386/kernel/head.S

@@ -16,6 +16,8 @@
 #include <asm/pgtable.h>
 #include <asm/desc.h>
 #include <asm/cache.h>
+#include <asm/thread_info.h>
+
 
 #define OLD_CL_MAGIC_ADDR	0x90020
 #define OLD_CL_MAGIC		0xA33F
@@ -325,7 +327,7 @@ rp_sidt:
 	ret
 
 ENTRY(stack_start)
-	.long init_thread_union+8192
+	.long init_thread_union+THREAD_SIZE
 	.long __BOOT_DS
 
 /* This is the default interrupt "handler" :-) */

arch/i386/kernel/irq.c

@@ -435,7 +435,7 @@ asmlinkage unsigned int do_IRQ(struct pt_regs regs)
 		long esp;
 
 		__asm__ __volatile__("andl %%esp,%0" :
-					"=r" (esp) : "0" (8191));
+					"=r" (esp) : "0" (THREAD_SIZE - 1));
 		if (unlikely(esp < (sizeof(struct thread_info) + 1024))) {
 			printk("do_IRQ: stack overflow: %ld\n",
 				esp - sizeof(struct thread_info));

arch/i386/kernel/process.c

@@ -637,6 +637,8 @@ extern void scheduling_functions_start_here(void);
 extern void scheduling_functions_end_here(void);
 #define first_sched	((unsigned long) scheduling_functions_start_here)
 #define last_sched	((unsigned long) scheduling_functions_end_here)
+#define top_esp                (THREAD_SIZE - sizeof(unsigned long))
+#define top_ebp                (THREAD_SIZE - 2*sizeof(unsigned long))
 
 unsigned long get_wchan(struct task_struct *p)
 {
@@ -647,12 +649,12 @@ unsigned long get_wchan(struct task_struct *p)
 		return 0;
 	stack_page = (unsigned long)p->thread_info;
 	esp = p->thread.esp;
-	if (!stack_page || esp < stack_page || esp > 8188+stack_page)
+	if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
 		return 0;
 	/* include/asm-i386/system.h:switch_to() pushes ebp last. */
 	ebp = *(unsigned long *) esp;
 	do {
-		if (ebp < stack_page || ebp > 8184+stack_page)
+		if (ebp < stack_page || ebp > top_ebp+stack_page)
 			return 0;
 		eip = *(unsigned long *) (ebp+4);
 		if (eip < first_sched || eip >= last_sched)

arch/i386/kernel/traps.c

@@ -119,7 +119,7 @@ void show_trace_task(struct task_struct *tsk)
 	unsigned long esp = tsk->thread.esp;
 
 	/* User space on another CPU? */
-	if ((esp ^ (unsigned long)tsk->thread_info) & (PAGE_MASK<<1))
+	if ((esp ^ (unsigned long)tsk->thread_info) & ~(THREAD_SIZE - 1))
 		return;
 	show_trace(tsk, (unsigned long *)esp);
 }

include/asm-i386/thread_info.h

@@ -77,16 +77,17 @@ struct thread_info {
 #define init_thread_info	(init_thread_union.thread_info)
 #define init_stack		(init_thread_union.stack)
 
+#define THREAD_SIZE (2*PAGE_SIZE)
+
 /* how to get the thread information struct from C */
 static inline struct thread_info *current_thread_info(void)
 {
 	struct thread_info *ti;
-	__asm__("andl %%esp,%0; ":"=r" (ti) : "0" (~8191UL));
+	__asm__("andl %%esp,%0; ":"=r" (ti) : "0" (~(THREAD_SIZE - 1)));
 	return ti;
 }
 
 /* thread information allocation */
-#define THREAD_SIZE (2*PAGE_SIZE)
 #define alloc_thread_info(task) ((struct thread_info *)kmalloc(THREAD_SIZE, GFP_KERNEL))
 #define free_thread_info(info)	kfree(info)
 #define get_thread_info(ti) get_task_struct((ti)->task)
@@ -94,9 +95,11 @@ static inline struct thread_info *current_thread_info(void)
 
 #else /* !__ASSEMBLY__ */
 
+#define THREAD_SIZE	8192
+
 /* how to get the thread information struct from ASM */
 #define GET_THREAD_INFO(reg) \
-	movl $-8192, reg; \
+	movl $-THREAD_SIZE, reg; \
 	andl %esp, reg
 
 #endif