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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/xtensa/kernel/mcount.S
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/*

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 * arch/xtensa/kernel/mcount.S

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 *

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 * Xtensa specific mcount support

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 *

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

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

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 * for more details.

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 *

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 * Copyright (C) 2013 Tensilica Inc.

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 */

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#include <linux/linkage.h>

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#include <asm/asmmacro.h>

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#include <asm/ftrace.h>

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/*

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 * Entry condition:

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 *

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 *   a2:	a0 of the caller in windowed ABI

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 *   a10:	a0 of the caller in call0 ABI

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 *

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 * In call0 ABI the function _mcount is called with the special ABI:

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 * its argument is in a10 and all the usual argument registers (a2 - a7)

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 * must be preserved in addition to callee-saved a12 - a15.

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 */

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ENTRY(_mcount)

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#if defined(__XTENSA_WINDOWED_ABI__)

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	abi_entry_default

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	movi	a4, ftrace_trace_function

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	l32i	a4, a4, 0

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	movi	a3, ftrace_stub

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	bne	a3, a4, 1f

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	abi_ret_default

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1: 	xor	a7, a2, a1

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	movi	a3, 0x3fffffff

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	and	a7, a7, a3

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	xor	a7, a7, a1

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	xor	a6, a0, a1

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	and	a6, a6, a3

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	xor	a6, a6, a1

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	addi	a6, a6, -MCOUNT_INSN_SIZE

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	callx4	a4

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	abi_ret_default

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#elif defined(__XTENSA_CALL0_ABI__)

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	abi_entry_default

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	movi	a9, ftrace_trace_function

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	l32i	a9, a9, 0

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	movi	a11, ftrace_stub

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	bne	a9, a11, 1f

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	abi_ret_default

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1:	abi_entry(28)

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	s32i	a0, sp, 0

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	s32i	a2, sp, 4

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	s32i	a3, sp, 8

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	s32i	a4, sp, 12

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	s32i	a5, sp, 16

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	s32i	a6, sp, 20

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	s32i	a7, sp, 24

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	addi	a2, a10, -MCOUNT_INSN_SIZE

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	callx0	a9

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	l32i	a0, sp, 0

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	l32i	a2, sp, 4

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	l32i	a3, sp, 8

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	l32i	a4, sp, 12

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	l32i	a5, sp, 16

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	l32i	a6, sp, 20

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	l32i	a7, sp, 24

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	abi_ret(28)

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#else

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#error Unsupported Xtensa ABI

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#endif

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ENDPROC(_mcount)

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EXPORT_SYMBOL(_mcount)

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ENTRY(ftrace_stub)

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	abi_entry_default

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	abi_ret_default

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ENDPROC(ftrace_stub)

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