Merged the configurable kernel stack size changes from 2.4. This

paramerizes the kernel stack size and adds a config option to set
the order.

arch/um/Kconfig

@@ -164,6 +164,14 @@ config KERNEL_HALF_GIGS
 config HIGHMEM
 	bool "Highmem support"
 
+config KERNEL_STACK_ORDER
+	int "Kernel stack size order"
+	default 2
+	help
+	This option determines the size of UML kernel stacks.  They will
+	be 1 << order pages.  The default is OK unless you're running Valgrind
+	on UML, in which case, set this to 3.
+
 endmenu
 
 

arch/um/kernel/init_task.c

@@ -3,6 +3,7 @@
  * Licensed under the GPL
  */
 
+#include "linux/config.h"
 #include "linux/mm.h"
 #include "linux/sched.h"
 #include "linux/init_task.h"
@@ -37,17 +38,16 @@ union thread_union init_thread_union
 __attribute__((__section__(".data.init_task"))) = 
 { INIT_THREAD_INFO(init_task) };
 
-struct task_struct *alloc_task_struct(void){
-	struct task_struct *task;
-
-	task = (struct task_struct *) __get_free_pages(GFP_KERNEL, 2);
-	if(task == NULL) return(NULL);
-	return(task);
+struct task_struct *alloc_task_struct(void)
+{
+	return((struct task_struct *) 
+	       __get_free_pages(GFP_KERNEL, CONFIG_KERNEL_STACK_ORDER));
 }
 
 void unprotect_stack(unsigned long stack)
 {
-	protect_memory(stack, 4 * PAGE_SIZE, 1, 1, 0, 1);
+	protect_memory(stack, (1 << CONFIG_KERNEL_STACK_ORDER) * PAGE_SIZE, 
+		       1, 1, 0, 1);
 }
 
 void free_task_struct(struct task_struct *task)
@@ -55,7 +55,7 @@ void free_task_struct(struct task_struct *task)
 	/* free_pages decrements the page counter and only actually frees
 	 * the pages if they are now not accessed by anything.
 	 */
-	free_pages((unsigned long) task, 2);
+	free_pages((unsigned long) task, CONFIG_KERNEL_STACK_ORDER);
 }
 
 /*

arch/um/kernel/process.c

@@ -38,16 +38,17 @@
 #include "choose-mode.h"
 #include "mode.h"
 #ifdef CONFIG_MODE_SKAS
-#include "skas_ptrace.h"
 #include "skas.h"
+#include "skas_ptrace.h"
 #endif
 
 void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
 {
-	int flags = 0;
+	int flags = 0, pages;
 
 	if(sig_stack != NULL){
-		set_sigstack(sig_stack, 2 * page_size());
+		pages = (1 << CONFIG_KERNEL_STACK_ORDER) - 2;
+		set_sigstack(sig_stack, pages * page_size());
 		flags = SA_ONSTACK;
 	}
 	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);

arch/um/kernel/process_kern.c

@@ -306,7 +306,11 @@ EXPORT_SYMBOL(not_implemented);
 
 int user_context(unsigned long sp)
 {
-	return((sp & (PAGE_MASK << 1)) != current->thread.kernel_stack);
+	unsigned long stack;
+
+	stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
+	stack += 2 * PAGE_SIZE;
+	return(stack != current->thread.kernel_stack);
 }
 
 extern void remove_umid_dir(void);

arch/um/kernel/tt/process_kern.c

@@ -367,11 +367,14 @@ __uml_setup("jail", jail_setup,
 static void mprotect_kernel_mem(int w)
 {
 	unsigned long start, end;
+	int pages;
 
 	if(!jail || (current == &init_task)) return;
 
+	pages = (1 << CONFIG_KERNEL_STACK_ORDER);
+
 	start = (unsigned long) current->thread_info + PAGE_SIZE;
-	end = (unsigned long) current->thread_info + PAGE_SIZE * 4;
+	end = (unsigned long) current + PAGE_SIZE * pages;
 	protect_memory(uml_reserved, start - uml_reserved, 1, w, 1, 1);
 	protect_memory(end, high_physmem - end, 1, w, 1, 1);
 
@@ -470,8 +473,10 @@ void clear_singlestep(void *t)
 int start_uml_tt(void)
 {
 	void *sp;
+	int pages;
 
-	sp = (void *) init_task.thread.kernel_stack + 2 * PAGE_SIZE - 
+	pages = (1 << CONFIG_KERNEL_STACK_ORDER) - 2;
+	sp = (void *) init_task.thread.kernel_stack + pages * PAGE_SIZE - 
 		sizeof(unsigned long);
 	return(tracer(start_kernel_proc, sp));
 }

include/asm-um/current.h

@@ -13,7 +13,8 @@ struct thread_info;
 #include "linux/config.h"
 #include "asm/page.h"
 
-#define CURRENT_THREAD(dummy) (((unsigned long) &dummy) & (PAGE_MASK << 2))
+#define CURRENT_THREAD(dummy) (((unsigned long) &dummy) & \
+			        (PAGE_MASK << CONFIG_KERNEL_SACK_ORDER))
 
 #define current ({ int dummy; \
                    ((struct thread_info *) CURRENT_THREAD(dummy))->task; })

include/asm-um/processor-generic.h

@@ -80,21 +80,21 @@ struct thread_struct {
 
 #define INIT_THREAD \
 { \
-	forking:		0, \
-	kernel_stack:		0, \
-	nsyscalls:		0, \
-        regs:		   	EMPTY_REGS, \
-	cr2:			0, \
-	err:			0, \
-	fault_addr:		NULL, \
-	prev_sched:		NULL, \
-	temp_stack:		0, \
-	exec_buf:		NULL, \
-	arch:			INIT_ARCH_THREAD, \
-	request:		{ 0 } \
+	.forking		= 0, \
+	.kernel_stack		= 0, \
+	.nsyscalls		= 0, \
+        .regs		   	= EMPTY_REGS, \
+	.cr2			= 0, \
+	.err			= 0, \
+	.fault_addr		= NULL, \
+	.prev_sched		= NULL, \
+	.temp_stack		= 0, \
+	.exec_buf		= NULL, \
+	.arch			= INIT_ARCH_THREAD, \
+	.request		= { 0 } \
 }
 
-#define INIT_THREAD_SIZE (4 * PAGE_SIZE)
+#define THREAD_SIZE ((1 << CONFIG_KERNEL_STACK_ORDER) * PAGE_SIZE)
 
 typedef struct {
 	unsigned long seg;