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      1 /*
      2  * Copyright (c) 2002-2004 Roland McGrath <roland (at) redhat.com>
      3  * Copyright (c) 2009-2016 Dmitry V. Levin <ldv (at) altlinux.org>
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include "defs.h"
     30 #include <sched.h>
     31 
     32 static unsigned int
     33 get_cpuset_size(void)
     34 {
     35 	static unsigned int cpuset_size;
     36 
     37 	if (!cpuset_size) {
     38 		/*
     39 		 * If the cpuset size passed to sched_getaffinity is less
     40 		 * than necessary to store the bitmask, the kernel does not
     41 		 * look at the mask pointer and fails with EINVAL.
     42 		 *
     43 		 * If the cpuset size is large enough, the kernel fails with
     44 		 * EFAULT on inaccessible mask pointers.
     45 		 *
     46 		 * This undocumented kernel feature can be used to probe
     47 		 * the kernel and find out the minimal valid cpuset size
     48 		 * without allocating any memory for the CPU affinity mask.
     49 		 */
     50 		cpuset_size = 128;
     51 		while (cpuset_size &&
     52 		       sched_getaffinity(0, cpuset_size, NULL) == -1 &&
     53 		       EINVAL == errno) {
     54 			cpuset_size <<= 1;
     55 		}
     56 		if (!cpuset_size)
     57 			cpuset_size = 128;
     58 	}
     59 
     60 	return cpuset_size;
     61 }
     62 
     63 static void
     64 print_affinitylist(struct tcb *const tcp, const kernel_ulong_t addr,
     65 		   const unsigned int len)
     66 {
     67 	const unsigned int max_size = get_cpuset_size();
     68 	const unsigned int umove_size = len < max_size ? len : max_size;
     69 	const unsigned int size =
     70 		(umove_size + current_wordsize - 1) & -current_wordsize;
     71 	const unsigned int ncpu = size * 8;
     72 	void *cpu;
     73 
     74 	if (!verbose(tcp) || (exiting(tcp) && syserror(tcp)) ||
     75 	    !addr || !len || !(cpu = calloc(size, 1))) {
     76 		printaddr(addr);
     77 		return;
     78 	}
     79 
     80 	if (!umoven_or_printaddr(tcp, addr, umove_size, cpu)) {
     81 		int i = 0;
     82 		const char *sep = "";
     83 
     84 		tprints("[");
     85 		for (;; i++) {
     86 			i = next_set_bit(cpu, i, ncpu);
     87 			if (i < 0)
     88 				break;
     89 			tprintf("%s%d", sep, i);
     90 			sep = ", ";
     91 		}
     92 		if (size < len)
     93 			tprintf("%s...", sep);
     94 		tprints("]");
     95 	}
     96 
     97 	free(cpu);
     98 }
     99 
    100 SYS_FUNC(sched_setaffinity)
    101 {
    102 	const int pid = tcp->u_arg[0];
    103 	const unsigned int len = tcp->u_arg[1];
    104 
    105 	tprintf("%d, %u, ", pid, len);
    106 	print_affinitylist(tcp, tcp->u_arg[2], len);
    107 
    108 	return RVAL_DECODED;
    109 }
    110 
    111 SYS_FUNC(sched_getaffinity)
    112 {
    113 	const int pid = tcp->u_arg[0];
    114 	const unsigned int len = tcp->u_arg[1];
    115 
    116 	if (entering(tcp)) {
    117 		tprintf("%d, %u, ", pid, len);
    118 	} else {
    119 		print_affinitylist(tcp, tcp->u_arg[2], tcp->u_rval);
    120 	}
    121 	return 0;
    122 }
    123