CoCalc -- fixed

GitHub Repository: awilliam/linux-vfio
Path: blob/master/arch/blackfin/kernel/fixed_code.S
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/*
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 * This file contains sequences of code that will be copied to a
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 * fixed location, defined in <asm/fixed_code.h>.  The interrupt
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 * handlers ensure that these sequences appear to be atomic when
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 * executed from userspace.
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 * These are aligned to 16 bytes, so that we have some space to replace
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 * these sequences with something else (e.g. kernel traps if we ever do
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 * BF561 SMP).
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 *
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 * Copyright 2007-2008 Analog Devices Inc.
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 *
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 * Licensed under the GPL-2 or later.
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 */
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <linux/unistd.h>
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#include <asm/entry.h>
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__INIT
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ENTRY(_fixed_code_start)
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.align 16
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ENTRY(_sigreturn_stub)
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	P0 = __NR_rt_sigreturn;
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	EXCPT 0;
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	/* Speculative execution paranoia.  */
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0:	JUMP.S 0b;
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ENDPROC (_sigreturn_stub)
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.align 16
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	/*
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	 * Atomic swap, 8 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R1: value to store
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	 * Output:	R0: old contents of the memory address, zero extended.
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	 */
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ENTRY(_atomic_xchg32)
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	R0 = [P0];
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	[P0] = R1;
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	rts;
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ENDPROC (_atomic_xchg32)
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.align 16
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	/*
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	 * Compare and swap, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R1: compare value
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	 *		R2: new value to store
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	 * The new value is stored if the contents of the memory
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	 * address is equal to the compare value.
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	 * Output:	R0: old contents of the memory address.
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	 */
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ENTRY(_atomic_cas32)
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	R0 = [P0];
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	CC = R0 == R1;
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	IF !CC JUMP 1f;
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	[P0] = R2;
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1:
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	rts;
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ENDPROC (_atomic_cas32)
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.align 16
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	/*
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	 * Atomic add, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R0: value to add
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	 * Outputs:	R0: new contents of the memory address.
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	 *		R1: previous contents of the memory address.
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	 */
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ENTRY(_atomic_add32)
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	R1 = [P0];
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	R0 = R1 + R0;
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	[P0] = R0;
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	rts;
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ENDPROC (_atomic_add32)
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.align 16
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	/*
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	 * Atomic sub, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R0: value to subtract
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	 * Outputs:	R0: new contents of the memory address.
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	 *		R1: previous contents of the memory address.
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	 */
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ENTRY(_atomic_sub32)
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	R1 = [P0];
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	R0 = R1 - R0;
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	[P0] = R0;
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	rts;
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ENDPROC (_atomic_sub32)
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.align 16
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	/*
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	 * Atomic ior, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R0: value to ior
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	 * Outputs:	R0: new contents of the memory address.
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	 *		R1: previous contents of the memory address.
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	 */
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ENTRY(_atomic_ior32)
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	R1 = [P0];
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	R0 = R1 | R0;
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	[P0] = R0;
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	rts;
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ENDPROC (_atomic_ior32)
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.align 16
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	/*
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	 * Atomic and, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R0: value to and
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	 * Outputs:	R0: new contents of the memory address.
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	 *		R1: previous contents of the memory address.
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	 */
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ENTRY(_atomic_and32)
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	R1 = [P0];
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	R0 = R1 & R0;
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	[P0] = R0;
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	rts;
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ENDPROC (_atomic_and32)
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.align 16
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	/*
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	 * Atomic xor, 32 bit.
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	 * Inputs:	P0: memory address to use
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	 *		R0: value to xor
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	 * Outputs:	R0: new contents of the memory address.
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	 *		R1: previous contents of the memory address.
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	 */
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ENTRY(_atomic_xor32)
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	R1 = [P0];
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	R0 = R1 ^ R0;
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	[P0] = R0;
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	rts;
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ENDPROC (_atomic_xor32)
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.align 16
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	/*
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	 * safe_user_instruction
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	 * Four NOPS are enough to allow the pipeline to speculativily load
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	 * execute anything it wants. After that, things have gone bad, and
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	 * we are stuck - so panic. Since we might be in user space, we can't
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	 * call panic, so just cause a unhandled exception, this should cause
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	 * a dump of the trace buffer so we can tell were we are, and a reboot
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	 */
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ENTRY(_safe_user_instruction)
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	NOP; NOP; NOP; NOP;
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	EXCPT 0x4;
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ENDPROC(_safe_user_instruction)
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ENTRY(_fixed_code_end)
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__FINIT
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