Commit ffcb043b authored by Brian Gerst's avatar Brian Gerst Committed by Ingo Molnar
Browse files

sched/x86: Fix thread_saved_pc() 



thread_saved_pc() was using a completely bogus method to get the return
address.  Since switch_to() was previously inlined, there was no sane way
to know where on the stack the return address was stored.  Now with the
frame of a sleeping thread well defined, this can be implemented correctly.

Signed-off-by: default avatarBrian Gerst <brgerst@gmail.com>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471106302-10159-7-git-send-email-brgerst@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 616d2483

arch/x86/include/asm/processor.h

+2 −8
Original line number Original line Diff line number Diff line
@@ -721,8 +721,6 @@ static inline void spin_lock_prefetch(const void *x) 
	.addr_limit		= KERNEL_DS,				  \

	.addr_limit		= KERNEL_DS,				  \

}

}





extern unsigned long thread_saved_pc(struct task_struct *tsk);



/*

/*

 * TOP_OF_KERNEL_STACK_PADDING reserves 8 bytes on top of the ring0 stack.

 * TOP_OF_KERNEL_STACK_PADDING reserves 8 bytes on top of the ring0 stack.

 * This is necessary to guarantee that the entire "struct pt_regs"

 * This is necessary to guarantee that the entire "struct pt_regs"
@@ -773,17 +771,13 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk); 
	.addr_limit		= KERNEL_DS,			\

	.addr_limit		= KERNEL_DS,			\

}

}





/*

 * Return saved PC of a blocked thread.

 * What is this good for? it will be always the scheduler or ret_from_fork.

 */

#define thread_saved_pc(t)	READ_ONCE_NOCHECK(*(unsigned long *)((t)->thread.sp - 8))



#define task_pt_regs(tsk)	((struct pt_regs *)(tsk)->thread.sp0 - 1)

#define task_pt_regs(tsk)	((struct pt_regs *)(tsk)->thread.sp0 - 1)

extern unsigned long KSTK_ESP(struct task_struct *task);

extern unsigned long KSTK_ESP(struct task_struct *task);





#endif /* CONFIG_X86_64 */

#endif /* CONFIG_X86_64 */





extern unsigned long thread_saved_pc(struct task_struct *tsk);



extern void start_thread(struct pt_regs *regs, unsigned long new_ip,

extern void start_thread(struct pt_regs *regs, unsigned long new_ip,

					       unsigned long new_sp);

					       unsigned long new_sp);

arch/x86/kernel/process.c

+11 −0
Original line number Original line Diff line number Diff line
@@ -513,6 +513,17 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) 
	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;

	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;

}

}





/*

 * Return saved PC of a blocked thread.

 * What is this good for? it will be always the scheduler or ret_from_fork.

 */

unsigned long thread_saved_pc(struct task_struct *tsk)

{

	struct inactive_task_frame *frame =

		(struct inactive_task_frame *) READ_ONCE(tsk->thread.sp);

	return READ_ONCE_NOCHECK(frame->ret_addr);

}



/*

/*

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

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

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

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

arch/x86/kernel/process_32.c

+0 −8
Original line number Original line Diff line number Diff line
@@ -55,14 +55,6 @@ 
#include <asm/switch_to.h>

#include <asm/switch_to.h>

#include <asm/vm86.h>

#include <asm/vm86.h>





/*

 * Return saved PC of a blocked thread.

 */

unsigned long thread_saved_pc(struct task_struct *tsk)

{

	return ((unsigned long *)tsk->thread.sp)[3];

}



void __show_regs(struct pt_regs *regs, int all)

void __show_regs(struct pt_regs *regs, int all)

{

{

	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;

	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;

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