1 /*
2 * Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved.
3 * Portions Copyright (c) 2000 Ulrich Drepper
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 * Further, this software is distributed without any warranty that it is
14 * free of the rightful claim of any third person regarding infringement
15 * or the like. Any license provided herein, whether implied or
16 * otherwise, applies only to this software file. Patent licenses, if
17 * any, provided herein do not apply to combinations of this program with
18 * other software, or any other product whatsoever.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write the Free Software Foundation, Inc.,
22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 *
24 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
25 * Mountain View, CA 94043, or:
26 *
27 * http://www.sgi.com$
28 *
29 * For further information regarding this notice, see:$
30 *
31 * http://oss.sgi.com/projects/GenInfo/NoticeExplan/
32 *
33 *
34 * Linux Test Project - Silicon Graphics, Inc.
35 * TEST IDENTIFIER : fork05
36 * EXECUTED BY : anyone
37 * TEST TITLE : Make sure LDT is propagated correctly
38 * TEST CASE TOTAL : 1
39 * CPU TYPES : i386
40 * AUTHORS : Ulrich Drepper
41 * Nate Straz
42 *
43 *On Friday, May 2, 2003 at 09:47:00AM MST, Ulrich Drepper wrote:
44 *>Robert Williamson wrote:
45 *>
46 *>> I'm getting a SIGSEGV with one of our tests, fork05.c, that apparently
47 *>> you wrote (attached below). The test passes on my 2.5.68 machine running
48 *>> SuSE 8.0 (glibc 2.2.5 and Linuxthreads), however it segmentation faults on
49 *>> RedHat 9 running 2.5.68. The test seems to "break" when it attempts to run
50 *>> the assembly code....could you take a look at it?
51 *>
52 *>There is no need to look at it, I know it cannot work anymore on recent
53 *>systems. Either change all uses of %gs to %fs or skip the entire patch
54 *>if %gs has a nonzero value.
55 *>
56 *>- --
57 *>- --------------. ,-. 444 Castro Street
58 *>Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
59 *>Red Hat `--' drepper at redhat.com `---------------------------
60 *
61 *
62 *
63 *On Sat, Aug 12, 2000 at 12:47:31PM -0700, Ulrich Drepper wrote:
64 *> Ever since the %gs handling was fixed in the 2.3.99 series the
65 *> appended test program worked. Now with 2.4.0-test6 it's not working
66 *> again. Looking briefly over the patch from test5 to test6 I haven't
67 *> seen an immediate candidate for the breakage. It could be missing
68 *> propagation of the LDT to the new process (and therefore an invalid
69 *> segment descriptor) or simply clearing %gs.
70 *>
71 *> Anyway, this is what you should see and what you get with test5:
72 *>
73 *> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
74 *> a = 42
75 *> %gs = 0x0007
76 *> %gs = 0x0007
77 *> a = 99
78 *> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
79 *>
80 *> This is what you get with test6:
81 *>
82 *> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
83 *> a = 42
84 *> %gs = 0x0007
85 *> %gs = 0x0000
86 *> <SEGFAULT>
87 *> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
88 *>
89 *> If somebody is actually creating a test suite for the kernel, please
90 *> add this program. It's mostly self-contained. The correct handling
91 *> of %gs is really important since glibc 2.2 will make heavy use of it.
92 *>
93 *> - --
94 *> - ---------------. ,-. 1325 Chesapeake Terrace
95 *> Ulrich Drepper \ ,-------------------' \ Sunnyvale, CA 94089 USA
96 *> Red Hat `--' drepper at redhat.com `------------------------
97 *>
98 *> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
99 *
100 */
101
102 #include <stdio.h>
103 #include <fcntl.h>
104 #include <unistd.h>
105 #include <stdlib.h>
106 #include <sys/wait.h>
107 #include "test.h"
108
109 char *TCID = "fork05";
110
111 static char *environ_list[] = { "TERM", "NoTSetzWq", "TESTPROG" };
112
113 #define NUMBER_OF_ENVIRON (sizeof(environ_list)/sizeof(char *))
114 int TST_TOTAL = NUMBER_OF_ENVIRON;
115
116 #if defined(linux) && defined(__i386__)
117
118 struct modify_ldt_ldt_s {
119 unsigned int entry_number;
120 unsigned long int base_addr;
121 unsigned int limit;
122 unsigned int seg_32bit:1;
123 unsigned int contents:2;
124 unsigned int read_exec_only:1;
125 unsigned int limit_in_pages:1;
126 unsigned int seg_not_present:1;
127 unsigned int useable:1;
128 unsigned int empty:25;
129 };
130
131 static int a = 42;
132
133 static void modify_ldt(int, struct modify_ldt_ldt_s *, int);
134 asm(" .text\n\
135 .type modify_ldt,@function \n\
136 modify_ldt: \n\
137 push %ebx \n\
138 mov 0x10(%esp,1),%edx \n\
139 mov 0xc(%esp,1),%ecx \n\
140 mov 0x8(%esp,1),%ebx \n\
141 mov $0x7b,%eax \n\
142 int $0x80 \n\
143 pop %ebx \n\
144 ret");
145
main(void)146 int main(void)
147 {
148 struct modify_ldt_ldt_s ldt0;
149 int lo;
150 pid_t pid;
151 int res;
152
153 ldt0.entry_number = 0;
154 ldt0.base_addr = (long)&a;
155 ldt0.limit = 4;
156 ldt0.seg_32bit = 1;
157 ldt0.contents = 0;
158 ldt0.read_exec_only = 0;
159 ldt0.limit_in_pages = 0;
160 ldt0.seg_not_present = 0;
161 ldt0.useable = 1;
162 ldt0.empty = 0;
163
164 modify_ldt(1, &ldt0, sizeof(ldt0));
165
166 asm volatile ("movw %w0, %%fs"::"q" (7));
167
168 asm volatile ("movl %%fs:0, %0":"=r" (lo));
169 tst_resm(TINFO, "a = %d", lo);
170
171 asm volatile ("pushl %%fs; popl %0":"=q" (lo));
172 tst_resm(TINFO, "%%fs = %#06hx", lo);
173
174 asm volatile ("movl %0, %%fs:0"::"r" (99));
175
176 pid = fork();
177
178 if (pid == 0) {
179 asm volatile ("pushl %%fs; popl %0":"=q" (lo));
180 tst_resm(TINFO, "%%fs = %#06hx", lo);
181
182 asm volatile ("movl %%fs:0, %0":"=r" (lo));
183 tst_resm(TINFO, "a = %d", lo);
184
185 if (lo != 99)
186 tst_resm(TFAIL, "Test failed");
187 else
188 tst_resm(TPASS, "Test passed");
189 exit(lo != 99);
190 } else {
191 waitpid(pid, &res, 0);
192 }
193
194 return WIFSIGNALED(res);
195 }
196
197 #else /* if defined(linux) && defined(__i386__) */
198
main(void)199 int main(void)
200 {
201 tst_resm(TINFO, "%%fs test only for ix86");
202
203 /*
204 * should be successful on all non-ix86 platforms.
205 */
206 tst_exit();
207 }
208
209 #endif /* if defined(linux) && defined(__i386__) */
210