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Commit 3ae908c9 authored by Max Filippov's avatar Max Filippov Committed by Chris Zankel
Browse files

xtensa: provide custom CALLER_ADDR* implementations 



Definition of CALLER_ADDR* through __builtin_return_address makes
compiler insert calls to __xtensa_libgcc_window_spill, which in turn
makes fast_syscall_spill_registers syscall that clobbers registers when
called from the kernel mode, leading to invalid opcode exceptions on
return to userspace.

Provide definition for CALLER_ADDR0 as MAKE_PC_FROM_RA(a0, a1) and in
case CONFIG_FRAME_POINTER is enabled extract CALLER_ADDR{1-3} from
stack.

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: default avatarChris Zankel <chris@zankel.net>
parent 3e4196a5

arch/xtensa/include/asm/ftrace.h

+33 −1
Original line number Original line Diff line number Diff line 
/* empty */
 
/*

 * arch/xtensa/include/asm/ftrace.h

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 *

 * Copyright (C) 2013 Tensilica Inc.

 */

#ifndef _XTENSA_FTRACE_H

#define _XTENSA_FTRACE_H



#include <asm/processor.h>



#define HAVE_ARCH_CALLER_ADDR

#define CALLER_ADDR0 ({ unsigned long a0, a1; \

		__asm__ __volatile__ ( \

			"mov %0, a0\n" \

			"mov %1, a1\n" \

			: "=r"(a0), "=r"(a1) : : ); \

		MAKE_PC_FROM_RA(a0, a1); })

#ifdef CONFIG_FRAME_POINTER

extern unsigned long return_address(unsigned level);

#define CALLER_ADDR1 return_address(1)

#define CALLER_ADDR2 return_address(2)

#define CALLER_ADDR3 return_address(3)

#else

#define CALLER_ADDR1 (0)

#define CALLER_ADDR2 (0)

#define CALLER_ADDR3 (0)

#endif



#endif /* _XTENSA_FTRACE_H */

arch/xtensa/kernel/stacktrace.c

+33 −0
Original line number Original line Diff line number Diff line
@@ -85,3 +85,36 @@ void save_stack_trace(struct stack_trace *trace) 
EXPORT_SYMBOL_GPL(save_stack_trace);

EXPORT_SYMBOL_GPL(save_stack_trace);





#endif

#endif



#ifdef CONFIG_FRAME_POINTER



struct return_addr_data {

	unsigned long addr;

	unsigned skip;

};



static int return_address_cb(struct stackframe *frame, void *data)

{

	struct return_addr_data *r = data;



	if (r->skip) {

		--r->skip;

		return 0;

	}

	if (!kernel_text_address(frame->pc))

		return 0;

	r->addr = frame->pc;

	return 1;

}



unsigned long return_address(unsigned level)

{

	struct return_addr_data r = {

		.skip = level + 1,

	};

	walk_stackframe(stack_pointer(NULL), return_address_cb, &r);

	return r.addr;

}

EXPORT_SYMBOL(return_address);



#endif