Commit 7ba78053 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/process: Unify 32bit and 64bit implementations of get_wchan() 



The stack layout and the functionality is identical. Use the 64bit
version for all of x86.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav Petkov <bp@alien8.de>
Reviewed-by: default avatarDmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: kasan-dev <kasan-dev@googlegroups.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>
Link: http://lkml.kernel.org/r/20150930083302.779694618@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent eddd3826

arch/x86/kernel/process.c

+55 −0
Original line number Diff line number Diff line
@@ -506,3 +506,58 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) 
	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;

}



/*

 * Called from fs/proc with a reference on @p to find the function

 * which called into schedule(). This needs to be done carefully

 * because the task might wake up and we might look at a stack

 * changing under us.

 */

unsigned long get_wchan(struct task_struct *p)

{

	unsigned long start, bottom, top, sp, fp, ip;

	int count = 0;



	if (!p || p == current || p->state == TASK_RUNNING)

		return 0;



	start = (unsigned long)task_stack_page(p);

	if (!start)

		return 0;



	/*

	 * Layout of the stack page:

	 *

	 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)

	 * PADDING

	 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING

	 * stack

	 * ----------- bottom = start + sizeof(thread_info)

	 * thread_info

	 * ----------- start

	 *

	 * The tasks stack pointer points at the location where the

	 * framepointer is stored. The data on the stack is:

	 * ... IP FP ... IP FP

	 *

	 * We need to read FP and IP, so we need to adjust the upper

	 * bound by another unsigned long.

	 */

	top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;

	top -= 2 * sizeof(unsigned long);

	bottom = start + sizeof(struct thread_info);



	sp = READ_ONCE(p->thread.sp);

	if (sp < bottom || sp > top)

		return 0;



	fp = READ_ONCE(*(unsigned long *)sp);

	do {

		if (fp < bottom || fp > top)

			return 0;

		ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));

		if (!in_sched_functions(ip))

			return ip;

		fp = READ_ONCE(*(unsigned long *)fp);

	} while (count++ < 16 && p->state != TASK_RUNNING);

	return 0;

}

arch/x86/kernel/process_32.c

+0 −28
Original line number Diff line number Diff line
@@ -324,31 +324,3 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 


	return prev_p;

}
 


#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)

{

	unsigned long bp, sp, ip;

	unsigned long stack_page;

	int count = 0;

	if (!p || p == current || p->state == TASK_RUNNING)

		return 0;

	stack_page = (unsigned long)task_stack_page(p);

	sp = p->thread.sp;

	if (!stack_page || sp < stack_page || sp > top_esp+stack_page)

		return 0;

	/* include/asm-i386/system.h:switch_to() pushes bp last. */

	bp = *(unsigned long *) sp;

	do {

		if (bp < stack_page || bp > top_ebp+stack_page)

			return 0;

		ip = *(unsigned long *) (bp+4);

		if (!in_sched_functions(ip))

			return ip;

		bp = *(unsigned long *) bp;

	} while (count++ < 16);

	return 0;

}

arch/x86/kernel/process_64.c

+0 −56
Original line number Diff line number Diff line
@@ -499,62 +499,6 @@ void set_personality_ia32(bool x32) 
}

EXPORT_SYMBOL_GPL(set_personality_ia32);



/*

 * Called from fs/proc with a reference on @p to find the function

 * which called into schedule(). This needs to be done carefully

 * because the task might wake up and we might look at a stack

 * changing under us.

 */

unsigned long get_wchan(struct task_struct *p)

{

	unsigned long start, bottom, top, sp, fp, ip;

	int count = 0;



	if (!p || p == current || p->state == TASK_RUNNING)

		return 0;



	start = (unsigned long)task_stack_page(p);

	if (!start)

		return 0;



	/*

	 * Layout of the stack page:

	 *

	 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)

	 * PADDING

	 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING

	 * stack

	 * ----------- bottom = start + sizeof(thread_info)

	 * thread_info

	 * ----------- start

	 *

	 * The tasks stack pointer points at the location where the

	 * framepointer is stored. The data on the stack is:

	 * ... IP FP ... IP FP

	 *

	 * We need to read FP and IP, so we need to adjust the upper

	 * bound by another unsigned long.

	 */

	top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;

	top -= 2 * sizeof(unsigned long);

	bottom = start + sizeof(struct thread_info);



	sp = READ_ONCE(p->thread.sp);

	if (sp < bottom || sp > top)

		return 0;



	fp = READ_ONCE(*(unsigned long *)sp);

	do {

		if (fp < bottom || fp > top)

			return 0;

		ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));

		if (!in_sched_functions(ip))

			return ip;

		fp = READ_ONCE(*(unsigned long *)fp);

	} while (count++ < 16 && p->state != TASK_RUNNING);

	return 0;

}



long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)

{

	int ret = 0;

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