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      1 /*
      2  * Copyright (c) 2015   Author: Oleg Nesterov <oleg (at) redhat.com>
      3  *                      Modify: Li Wang <liwang (at) redhat.com>
      4  *
      5  * This program is free software; you can redistribute it and/or modify it
      6  * under the terms of version 2 of the GNU General Public License as
      7  * published by the Free Software Foundation.
      8  *
      9  * This program is distributed in the hope that it would be useful, but
     10  * WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     12  *
     13  * you should have received a copy of the GNU General Public License along
     14  * with this program; if not, write the Free Software Foundation, Inc.,
     15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
     16  */
     17 
     18 /*
     19  * Description:
     20  *
     21  *      save_xstate_sig()->drop_init_fpu() doesn't look right. setup_rt_frame()
     22  *      can fail after that, in this case the next setup_rt_frame() triggered
     23  *      by SIGSEGV won't save fpu simply because the old state was lost. This
     24  *      obviously mean that fpu won't be restored after sys_rt_sigreturn() from
     25  *      SIGSEGV handler.
     26  *
     27  *      These commits fix the issue on v3.17-rc3-3 stable kernel:
     28  *
     29  *      commit df24fb859a4e200d9324e2974229fbb7adf00aef
     30  * 		Author: Oleg Nesterov <oleg (at) redhat.com>
     31  * 		Date:   Tue Sep 2 19:57:17 2014 +0200
     32  *
     33  *      commit 66463db4fc5605d51c7bb81d009d5bf30a783a2c
     34  *              Author: Oleg Nesterov <oleg (at) redhat.com>
     35  *              Date:   Tue Sep 2 19:57:13 2014 +0200
     36  *
     37  * Reproduce:
     38  *	Test-case (needs -O2).
     39  */
     40 
     41 #include <stdio.h>
     42 #include <signal.h>
     43 #include <unistd.h>
     44 #include <sys/syscall.h>
     45 #include <sys/mman.h>
     46 #include <pthread.h>
     47 #include <assert.h>
     48 #include <errno.h>
     49 
     50 #include "test.h"
     51 #include "lapi/syscalls.h"
     52 
     53 char *TCID = "signal06";
     54 int TST_TOTAL = 5;
     55 
     56 #if __x86_64__
     57 
     58 #define LOOPS 30000
     59 #define VALUE 123.456
     60 
     61 volatile double D;
     62 volatile int FLAGE;
     63 
     64 char altstack[4096 * 10] __attribute__((aligned(4096)));
     65 
     66 void test(void)
     67 {
     68 	int loop = 0;
     69 	int pid = getpid();
     70 
     71 	D = VALUE;
     72 	while (D == VALUE && loop < LOOPS) {
     73 		/* sys_tkill(pid, SIGHUP); asm to avoid save/reload
     74 		 * fp regs around c call */
     75 		asm ("" : : "a"(__NR_tkill), "D"(pid), "S"(SIGHUP));
     76 		asm ("syscall" : : : "ax");
     77 
     78 		loop++;
     79 	}
     80 
     81 	FLAGE = 1;
     82 	tst_resm(TINFO, "loop = %d", loop);
     83 
     84 	if (loop == LOOPS) {
     85 		tst_resm(TPASS, "%s call succeeded", TCID);
     86 	} else {
     87 		tst_resm(TFAIL, "Bug Reproduced!");
     88 		tst_exit();
     89 	}
     90 }
     91 
     92 void sigh(int sig LTP_ATTRIBUTE_UNUSED)
     93 {
     94 }
     95 
     96 void *tfunc(void *arg LTP_ATTRIBUTE_UNUSED)
     97 {
     98 	int i;
     99 
    100 	for (i = -1; ; i *= -1) {
    101 		if (i == -1) {
    102 			TEST(mprotect(altstack, sizeof(altstack), PROT_READ));
    103 			if (TEST_RETURN == -1)
    104 				tst_brkm(TBROK | TTERRNO, NULL, "mprotect failed");
    105 		}
    106 
    107 		TEST(mprotect(altstack, sizeof(altstack), PROT_READ | PROT_WRITE));
    108 		if (TEST_RETURN == -1)
    109 			tst_brkm(TBROK | TTERRNO, NULL, "mprotect failed");
    110 
    111 		if (FLAGE == 1)
    112 			return NULL;
    113 	}
    114 }
    115 
    116 int main(int ac, char **av)
    117 {
    118 	int i, lc;
    119 	pthread_t pt;
    120 
    121 	tst_parse_opts(ac, av, NULL, NULL);
    122 
    123 	stack_t st = {
    124 		.ss_sp = altstack,
    125 		.ss_size = sizeof(altstack),
    126 		.ss_flags = SS_ONSTACK,
    127 	};
    128 
    129 	struct sigaction sa = {
    130 		.sa_handler = sigh,
    131 	};
    132 
    133 	TEST(sigaction(SIGSEGV, &sa, NULL));
    134 	if (TEST_RETURN == -1)
    135 		tst_brkm(TBROK | TTERRNO, NULL,
    136 				"SIGSEGV signal setup failed");
    137 	sigaltstack(&st, NULL);
    138 	sa.sa_flags = SA_ONSTACK;
    139 
    140 	TEST(sigaction(SIGHUP, &sa, NULL));
    141 	if (TEST_RETURN == -1)
    142 		tst_brkm(TBROK | TTERRNO, NULL,
    143 				"SIGHUP signal setup failed");
    144 
    145 	for (lc = 0; TEST_LOOPING(lc); lc++) {
    146 		tst_count = 0;
    147 
    148 		for (i = 0; i < TST_TOTAL; i++) {
    149 			FLAGE = 0;
    150 
    151 			TEST(pthread_create(&pt, NULL, tfunc, NULL));
    152 			if (TEST_RETURN)
    153 				tst_brkm(TBROK | TRERRNO, NULL,
    154 						"pthread_create failed");
    155 
    156 			test();
    157 
    158 			TEST(pthread_join(pt, NULL));
    159 			if (TEST_RETURN)
    160 				tst_brkm(TBROK | TRERRNO, NULL,
    161 						"pthread_join failed");
    162 		}
    163 	}
    164 
    165 	tst_exit();
    166 }
    167 
    168 #else
    169 int main(void)
    170 {
    171 	tst_brkm(TCONF, NULL, "Only test on x86_64.");
    172 }
    173 #endif
    174