01223f3650
This makes return_address() return a correct value for CALLER_ADDRn. To have a correct value from CALLER_ADDRn, we need to fix three points. * The unwind_frame() does not update frame->lr but frame->pc for backtrace. So frame->pc is meaningful for backtrace. * data.level should be adjusted by adding 2 additional iteration levels. With the current +1 level adjustment, the result of CALLER_ADDR1 will be the same return address with CALLER_ADDR0. * The initialization of data.addr to NULL is needed. When unwind_fame() fails right after data.level reaches zero, the routine returns data.addr which has uninitialized garbage value. Signed-off-by: Sahara <keun-o.park@windriver.com> Reviewed-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
/*
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* arch/arm/kernel/return_address.c
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*
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* Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
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* for Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <linux/ftrace.h>
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#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
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#include <linux/sched.h>
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#include <asm/stacktrace.h>
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struct return_address_data {
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unsigned int level;
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void *addr;
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};
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static int save_return_addr(struct stackframe *frame, void *d)
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{
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struct return_address_data *data = d;
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if (!data->level) {
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data->addr = (void *)frame->pc;
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return 1;
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} else {
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--data->level;
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return 0;
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}
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}
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void *return_address(unsigned int level)
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{
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struct return_address_data data;
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struct stackframe frame;
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register unsigned long current_sp asm ("sp");
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data.level = level + 2;
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data.addr = NULL;
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frame.fp = (unsigned long)__builtin_frame_address(0);
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frame.sp = current_sp;
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frame.lr = (unsigned long)__builtin_return_address(0);
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frame.pc = (unsigned long)return_address;
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walk_stackframe(&frame, save_return_addr, &data);
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if (!data.level)
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return data.addr;
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else
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return NULL;
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}
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#else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
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#if defined(CONFIG_ARM_UNWIND)
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#warning "TODO: return_address should use unwind tables"
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#endif
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void *return_address(unsigned int level)
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{
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return NULL;
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}
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#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */
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EXPORT_SYMBOL_GPL(return_address);
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