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      1 /*	$NetBSD: patch.c,v 1.8 2023/11/21 22:19:12 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2007, 2021 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Andrew Doran and Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Patch kernel code at boot time, depending on available CPU features
     34  * and configuration.
     35  */
     36 
     37 #include <sys/cdefs.h>
     38 __KERNEL_RCSID(0, "$NetBSD: patch.c,v 1.8 2023/11/21 22:19:12 thorpej Exp $");
     39 
     40 #include "opt_multiprocessor.h"
     41 
     42 #include <sys/types.h>
     43 #include <sys/systm.h>
     44 #include <sys/lwp.h>
     45 
     46 #include <machine/cpu.h>
     47 #include <machine/alpha.h>
     48 #include <machine/intr.h>
     49 
     50 #include <machine/alpha_instruction.h>
     51 
     52 void	_membar_producer(void);
     53 void	_membar_producer_end(void);
     54 void	_membar_producer_mp(void);
     55 void	_membar_producer_mp_end(void);
     56 
     57 void	_membar_sync(void);
     58 void	_membar_sync_end(void);
     59 void	_membar_sync_mp(void);
     60 void	_membar_sync_mp_end(void);
     61 
     62 extern char alpha_copystr_bwx[], alpha_copystr_bwx_end[];
     63 extern char alpha_copystr[], alpha_copystr_end[];
     64 
     65 #if defined(MULTIPROCESSOR)
     66 extern uint32_t *lock_stub_patch_table[];
     67 
     68 static void
     69 patch_lock_stubs(void)
     70 {
     71 	alpha_instruction insn = {
     72 		.mem_format = {
     73 			.opcode = op_special,
     74 			.displacement = op_mb,
     75 		},
     76 	};
     77 	int i, s;
     78 
     79 	s = splhigh();
     80 
     81 	for (i = 0; lock_stub_patch_table[i] != NULL; i++) {
     82 		*lock_stub_patch_table[i] = insn.bits;
     83 	}
     84 	alpha_pal_imb();
     85 
     86 	splx(s);
     87 }
     88 #endif /* MULTIPROCESSOR */
     89 
     90 static void
     91 patchfunc(void *from_s, void *from_e, void *to_s, void *to_e)
     92 {
     93 	int s;
     94 
     95 	s = splhigh();
     96 
     97 	if ((uintptr_t)from_e - (uintptr_t)from_s !=
     98 	    (uintptr_t)to_e - (uintptr_t)to_s)
     99 	    	panic("patchfunc: sizes do not match (from=%p)", from_s);
    100 
    101 	memcpy(to_s, from_s, (uintptr_t)to_e - (uintptr_t)to_s);
    102 	alpha_pal_imb();
    103 
    104 	splx(s);
    105 }
    106 
    107 void
    108 alpha_patch(bool is_mp)
    109 {
    110 
    111 	/*
    112 	 * We allow this function to be called multiple times
    113 	 * (there is no harm in doing so), so long as other
    114 	 * CPUs have not yet actually hatched to start running
    115 	 * kernel code.
    116 	 */
    117 
    118 	if (cpu_amask & ALPHA_AMASK_BWX) {
    119 		patchfunc(alpha_copystr_bwx, alpha_copystr_bwx_end,
    120 		    alpha_copystr, alpha_copystr_end);
    121 	}
    122 
    123 #if defined(MULTIPROCESSOR)
    124 	if (is_mp) {
    125 		KASSERT(curcpu()->ci_flags & CPUF_PRIMARY);
    126 		KASSERT((cpus_running & ~(1UL << cpu_number())) == 0);
    127 
    128 		patch_lock_stubs();
    129 
    130 		patchfunc(_membar_producer_mp, _membar_producer_mp_end,
    131 			  _membar_producer, _membar_producer_end);
    132 		patchfunc(_membar_sync_mp, _membar_sync_mp_end,
    133 			  _membar_sync, _membar_sync_end);
    134 	}
    135 #else
    136 	KASSERT(is_mp == false);
    137 #endif /* MULTIPROCESSOR */
    138 }
    139