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Commit 6bcdf9d5 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
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x86/unwind: Read stack return address in update_stack_state() 



Instead of reading the return address when unwind_get_return_address()
is called, read it from update_stack_state() and store it in the unwind
state.  This enables the next patch to check the return address from
unwind_next_frame() so it can detect an entry code frame.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dave Jones <davej@codemonkey.org.uk>
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>
Link: http://lkml.kernel.org/r/af0c5e4560c49c0343dca486ea26c4fa92bc4e35.1492020577.git.jpoimboe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5ed8d8bb

arch/x86/include/asm/unwind.h

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ struct unwind_state { 
#ifdef CONFIG_FRAME_POINTER

	unsigned long *bp, *orig_sp;

	struct pt_regs *regs;

	unsigned long ip;

#else

	unsigned long *sp;

#endif

arch/x86/kernel/unwind_frame.c

+13 −12
Original line number Diff line number Diff line
@@ -56,20 +56,10 @@ static void unwind_dump(struct unwind_state *state, unsigned long *sp) 


unsigned long unwind_get_return_address(struct unwind_state *state)

{

	unsigned long addr;

	unsigned long *addr_p = unwind_get_return_address_ptr(state);



	if (unwind_done(state))

		return 0;



	if (state->regs && user_mode(state->regs))

		return 0;



	addr = READ_ONCE_TASK_STACK(state->task, *addr_p);

	addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, addr,

				     addr_p);



	return __kernel_text_address(addr) ? addr : 0;

	return __kernel_text_address(state->ip) ? state->ip : 0;

}

EXPORT_SYMBOL_GPL(unwind_get_return_address);
@@ -141,7 +131,7 @@ static bool update_stack_state(struct unwind_state *state, 
	struct stack_info *info = &state->stack_info;

	enum stack_type prev_type = info->type;

	struct pt_regs *regs;

	unsigned long *frame, *prev_frame_end;

	unsigned long *frame, *prev_frame_end, *addr_p, addr;

	size_t len;



	if (state->regs)
@@ -185,6 +175,16 @@ static bool update_stack_state(struct unwind_state *state, 
		state->regs = NULL;

	}



	/* Save the return address: */

	if (state->regs && user_mode(state->regs))

		state->ip = 0;

	else {

		addr_p = unwind_get_return_address_ptr(state);

		addr = READ_ONCE_TASK_STACK(state->task, *addr_p);

		state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,

						  addr, addr_p);

	}



	/* Save the original stack pointer for unwind_dump(): */

	if (!state->orig_sp || info->type != prev_type)

		state->orig_sp = frame;
@@ -228,6 +228,7 @@ bool unwind_next_frame(struct unwind_state *state) 
		 */

		state->regs = regs;

		state->bp = NULL;

		state->ip = 0;

		return true;

	}