Trying to run the tests and need a bit of direction... #4
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I'd build an uClibc x86_64 toolchain using buildroot for that purpose ... but if you want to test your build system of uClibc ... then I don't know. |
mikpe
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Dec 13, 2021
- use the provided __res_state() method instead of direct access to struct __res_state pointer &_res/*__resp - change the __UCLIBC_HAS_TLS__ protected __res_state() implementation to the one where the comment 'When threaded, _res may be a per-thread variable.' indicates this should be used with threads/TLS enabled Fixes the following segfaults with buildroot raspberrypi3_64_defconfig (uclibc, -Os, Note: runs fine using the raspberrypi3_defconfig): $ /usr/sbin/ntpd -n -d 1970-01-01T00:01:49 ntpd[249]: INIT: ntpd ntpsec-1.2.0 2021-11-03T20:39:50Z: Starting 1970-01-01T00:01:49 ntpd[249]: INIT: Command line: /usr/sbin/ntpd -n -d 1970-01-01T00:01:49 ntpd[249]: INIT: precision = 7.240 usec (-17) 1970-01-01T00:01:49 ntpd[249]: INIT: successfully locked into RAM 1970-01-01T00:01:49 ntpd[249]: CONFIG: readconfig: parsing file: /etc/ntp.conf 1970-01-01T00:01:49 ntpd[249]: CONFIG: restrict nopeer ignored 1970-01-01T00:01:49 ntpd[249]: INIT: Using SO_TIMESTAMPNS 1970-01-01T00:01:49 ntpd[249]: IO: Listen and drop on 0 v6wildcard [::]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen and drop on 1 v4wildcard 0.0.0.0:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 2 lo 127.0.0.1:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 3 eth0 172.16.0.30:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 4 lo [::1]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listen normally on 5 eth0 [fe80::ba27:ebff:fea6:340%2]:123 1970-01-01T00:01:49 ntpd[249]: IO: Listening on routing socket on fd #22 for interface updates 1970-01-01T00:01:50 ntpd[249]: SYNC: Found 10 servers, suggest minsane at least 3 1970-01-01T00:01:50 ntpd[249]: INIT: MRU 10922 entries, 13 hash bits, 65536 bytes 1970-01-01T00:01:50 ntpd[249]: statistics directory /var/NTP/ does not exist or is unwriteable, error No such file or directory 1970-01-01T00:01:51 ntpd[249]: DNS: dns_probe: 0.pool.ntp.org, cast_flags:8, flags:101 Segmentation fault (core dumped) $ ./host/bin/aarch64-buildroot-linux-uclibc-gdb ./build/ntpsec-1_2_0/build/main/ntpd/ntpd core Core was generated by `/usr/sbin/ntpd -n -d'. Program terminated with signal SIGSEGV, Segmentation fault. (gdb) where #0 0x0000007f8ff1f150 in res_sync_func () at libc/inet/resolv.c:3356 wbx-github#1 0x0000007f8ff1c468 in __open_nameservers () at libc/inet/resolv.c:949 wbx-github#2 0x0000007f8ff1b498 in __dns_lookup (name=0x55943c67f0 "0.pool.ntp.org", type=1, outpacket=0x7f8fe91c48, a=0x7f8fe91c08) at libc/inet/resolv.c:1134 wbx-github#3 0x0000007f8ff1d744 in __GI_gethostbyname_r ( name=0x55943c67f0 "0.pool.ntp.org", result_buf=0x7f8fe92628, buf=0x7f8fe91d90 "", buflen=992, result=0x7f8fe92670, h_errnop=0x7f8fe92668) at libc/inet/resolv.c:1966 wbx-github#4 0x0000007f8ff1d9a0 in __GI_gethostbyname2_r ( name=0x55943c67f0 "0.pool.ntp.org", family=2, result_buf=0x7f8fe92628, buf=0x7f8fe91d70 "0.pool.ntp.org", buflen=1024, result=0x7f8fe92670, h_errnop=0x7f8fe92668) at libc/inet/resolv.c:2065 wbx-github#5 0x0000007f8ff16924 in gaih_inet (name=0x55943c67f0 "0.pool.ntp.org", service=0x7f8fe92828, req=0x7f8fe92890, pai=0x7f8fe92838) at libc/inet/getaddrinfo.c:596 wbx-github#6 0x0000007f8ff17624 in __GI_getaddrinfo ( name=0x55943c67f0 "0.pool.ntp.org", service=0x5582eb8acd "\377H\213D$\bL\211\367H\213\260\270", hints=0x7f8fe92890, pai=0x5582ee1bf8) at libc/inet/getaddrinfo.c:957 wbx-github#7 0x0000005582ea60f4 in _start () (gdb) p _res $1 = {options = 0, nsaddr_list = {{sin_family = 0, sin_port = 0, sin_addr = { s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, { sin_family = 0, sin_port = 0, sin_addr = {s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, {sin_family = 0, sin_port = 0, sin_addr = {s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}}, dnsrch = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, nscount = 0 '\000', ndots = 0 '\000', retrans = 0 '\000', retry = 0 '\000', defdname = '\000' <repeats 255 times>, nsort = 0 '\000', pfcode = 0, id = 0, res_h_errno = 0, sort_list = {{addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}, {addr = { s_addr = 0}, mask = 0}, {addr = {s_addr = 0}, mask = 0}}, _u = { _ext = {nsaddrs = {0x0, 0x0, 0x0}, nscount = 0 '\000', nstimes = {0, 0, 0}, nssocks = {0, 0, 0}, nscount6 = 0, nsinit = 0}}} (gdb) p &_res $2 = (struct __res_state *) 0x7f8ff8fd98 <_res> (gdb) p rp $3 = (struct __res_state *) 0x7fffffffff And the following uclibc code at libc/inet/resolv.c:3356: 3345 static void res_sync_func(void) 3346 { 3347 struct __res_state *rp = &(_res); 3348 int n; 3349 3350 /* If we didn't get malloc failure earlier... */ 3351 if (__nameserver != (void*) &__local_nameserver) { 3352 /* TODO: 3353 * if (__nameservers < rp->nscount) - try to grow __nameserver[]? 3354 */ 3355 #ifdef __UCLIBC_HAS_IPV6__ 3356 if (__nameservers > rp->_u._ext.nscount) 3357 __nameservers = rp->_u._ext.nscount; 3358 n = __nameservers; The special thing about ntpsec is the DNS lookup in an extra thread and/or the call to res_init(), see ntpsec-1_2_0/ntpd/ntp_dns.c: 69 msyslog(LOG_INFO, "DNS: dns_probe: %s, cast_flags:%x, flags:%x%s", 70 hostname, pp->cast_flags, pp->cfg.flags, busy); 71 if (NULL != active) /* normally redundant */ 72 return false; 73 74 active = pp; 75 76 sigfillset(&block_mask); 77 pthread_sigmask(SIG_BLOCK, &block_mask, &saved_sig_mask); 78 rc = pthread_create(&worker, NULL, dns_lookup, pp); and 165 static void* dns_lookup(void* arg) 166 { 167 struct peer *pp = (struct peer *) arg; 168 struct addrinfo hints; 169 170 #ifdef HAVE_SECCOMP_H 171 setup_SIGSYS_trap(); /* enable trap for this thread */ 172 #endif 173 174 #ifdef HAVE_RES_INIT 175 /* Reload DNS servers from /etc/resolv.conf in case DHCP has updated it. 176 * We only need to do this occasionally, but it's not expensive 177 * and simpler to do it every time than it is to figure out when 178 * to do it. 179 * This res_init() covers NTS too. 180 */ 181 res_init(); 182 #endif 183 184 if (pp->cfg.flags & FLAG_NTS) { 185 #ifndef DISABLE_NTS 186 nts_probe(pp); 187 #endif 188 } else { 189 ZERO(hints); 190 hints.ai_protocol = IPPROTO_UDP; 191 hints.ai_socktype = SOCK_DGRAM; 192 hints.ai_family = AF(&pp->srcadr); 193 gai_rc = getaddrinfo(pp->hostname, NTP_PORTA, &hints, &answer); 194 } $ /usr/lib/uclibc-ng-test/test/inet/tst-res Segmentation fault (core dumped) $ ./host/bin/aarch64-buildroot-linux-uclibc-gdb ./build/uclibc-ng-test-0844445e7358eb10e716155b55b0fb23e88d644a/test/inet/tst-res core Core was generated by `/usr/lib/uclibc-ng-test/test/inet/tst-res'. Program terminated with signal SIGSEGV, Segmentation fault. (gdb) where #0 __GI___res_init () at libc/inet/resolv.c:3514 wbx-github#1 0x0000005591e507e4 in main (argc=<optimized out>, argv=<optimized out>) at tst-res.c:20 First reported here: https://lore.kernel.org/buildroot/[email protected]/ https://www.mail-archive.com/[email protected]/msg01085.html Signed-off-by: Peter Seiderer <[email protected]>
mikpe
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that referenced
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Sep 8, 2022
O0 build result in the following codegen
00000000 <ldrex>:
0: b480 push {r7}
2: b085 sub sp, #20
4: af00 add r7, sp, #0
6: 6078 str r0, [r7, wbx-github#4]
8: 687b ldr r3, [r7, wbx-github#4]
a: e853 3f00 ldrex r3, [r3]
e: 60fb str r3, [r7, wbx-github#12]
10: 68fb ldr r3, [r7, wbx-github#12]
12: 4618 mov r0, r3
14: 3714 adds r7, #20
16: 46bd mov sp, r7
18: f85d 7b04 ldr.w r7, [sp], wbx-github#4
1c: 4770 bx lr
0000001e <strex>:
1e: b480 push {r7}
20: b085 sub sp, #20
22: af00 add r7, sp, #0
24: 6078 str r0, [r7, wbx-github#4]
26: 6039 str r1, [r7, #0]
28: 687b ldr r3, [r7, wbx-github#4]
2a: 683a ldr r2, [r7, #0]
2c: e842 3300 strex r3, r3, [r2]
30: 60fb str r3, [r7, wbx-github#12]
32: 68fb ldr r3, [r7, wbx-github#12]
34: 4618 mov r0, r3
36: 3714 adds r7, #20
38: 46bd mov sp, r7
3a: f85d 7b04 ldr.w r7, [sp], wbx-github#4
3e: 4770 bx lr
00000040 <testandset>:
40: b590 push {r4, r7, lr}
42: b083 sub sp, wbx-github#12
44: af00 add r7, sp, #0
46: 6078 str r0, [r7, wbx-github#4]
48: 6878 ldr r0, [r7, wbx-github#4]
4a: f7ff fffe bl 0 <ldrex>
4e: 4603 mov r3, r0
50: 461c mov r4, r3
52: 6879 ldr r1, [r7, wbx-github#4]
54: 2001 movs r0, wbx-github#1
56: f7ff fffe bl 1e <strex>
5a: 4603 mov r3, r0
5c: 2b00 cmp r3, #0
5e: d1f3 bne.n 48 <testandset+0x8>
60: 4623 mov r3, r4
62: 4618 mov r0, r3
64: 370c adds r7, wbx-github#12
66: 46bd mov sp, r7
68: bd90 pop {r4, r7, pc}
ARM ARM suggests that LoadExcl/StoreExcl loops are guaranteed to make
forward progress only if, for any LoadExcl/StoreExcl loop within a
single thread of execution, the software meets all of the following
conditions:
1 Between the Load-Exclusive and the Store-Exclusive, there are no
explicit memory accesses, preloads, direct or indirect System
register writes, address translation instructions, cache or TLB
maintenance instructions, exception generating instructions,
exception returns, or indirect branches.
...
Obviously condition is not met for O0 builds.
O2 build (which is highly likely the most common setting) able to do
the right thing resulting in
00000000 <ldrex>:
0: e850 0f00 ldrex r0, [r0]
4: 4770 bx lr
6: bf00 nop
00000008 <strex>:
8: e841 0000 strex r0, r0, [r1]
c: 4770 bx lr
e: bf00 nop
00000010 <testandset>:
10: 2101 movs r1, wbx-github#1
12: 4603 mov r3, r0
14: e853 0f00 ldrex r0, [r3]
18: e843 1200 strex r2, r1, [r3]
1c: 2a00 cmp r2, #0
1e: d1f9 bne.n 14 <testandset+0x4>
20: 4770 bx lr
22: bf00 nop
Rather than depending on level of optimisation implement whole
ldrex/strex loop in inline assembly.
Signed-off-by: Vladimir Murzin <[email protected]>
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I'm attempting to build uClibc from scratch using a combination of CMake and clang and/or gcc. I'd like to test my builds and have the uclibc-ng-test respository. I'd prefer not to actually install the libraries, but I want the build for the test code to use the code from the directory where I built it. I've tried using LD_LIBRARY_PATH, but want to see what would be the best way to do this and not use the libraries that are actually installed. Any direction someone can give me would be greatly appreciated.
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