Re: Resolution (Re: [uml-devel] 2.4.22-[67] problems)

[Matt Zimmerman <mdz@debian.org>]

On Tue, Jan 06, 2004 at 09:20:06AM +0000, Nuno Silva wrote:

> Nuno Silva wrote:
> 
> [...]
> 
> >
> >I've been doing some tests and I'd say that the problem is something 
> >regarding the NPTL+TLS+__thread features of recent libc6 (2.3.2 and 
> >2.3.3cvs)... But I'm clueless about the fix :-)
> >
> >I'll setup a chroot where I can play around with glibc setups.
> >
> 
> OK, just finished the chroot: debian unstable with glibc-2.3.3cvs 
> hand-compiled (../libc/configure --with-tls --with-__thread 
> --enable-add-ons=nptl --prefix=/ --enable-kernel=2.6.0) and removed the 
> debian's libc.
> 
> Everything runs OK with the new glibc, tested: bash, apt-get, perl, mc, 
> strace, gcc, etc.
> 
> However linux (UML's executable) doesn't run:
> puma:/uml# ls -la /proc/mm
> --w--w--w-    1 root     root            0 Jan  6 08:33 /proc/mm
> puma:/uml# uname -a
> Linux puma 2.6.0 #2 Mon Jan 5 09:25:45 WET 2004 i686 unknown unknown 
> GNU/Linux
> puma:/uml# ./linux
> Checking for the skas3 patch in the host...found
> Checking for /proc/mm...found
> 
> [1]+  Stopped                 ./linux
> puma:/uml# fg
> ./linux
> Segmentation fault
> puma:/uml#

This looks quite different from what I and others were seeing in #224431,
which was random ENOSYS errors because the system call number in the regs
struct was being mysteriously cleared during a context switch on the cost.

> Now with strace:
> (see attached file)
> 
> Now with gdb:
> puma:/uml# gdb ./linux
> GNU gdb 6.0-debian
> Copyright 2003 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain 
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i386-linux"...
> (gdb) run
> Starting program: /uml/linux
> Detaching after fork from child process 26378.
> Checking for the skas3 patch in the host...found
> Checking for /proc/mm...found
> Detaching after fork from child process 26379.
> 
> Program received signal SIGSTOP, Stopped (signal).
> 0x400f18dc in clone () from /lib/libc.so.6
> (gdb) bt
> #0  0x400f18dc in clone () from /lib/libc.so.6
> #1  0x4014f000 in ?? ()
> #2  0x00000007 in ?? ()
> #3  0x00001000 in ?? ()
> #4  0xa00a7b7f in start_userspace (cpu=26379) at process.c:113
> #5  0xa00a88e2 in start_uml_skas () at process_kern.c:162
> #6  0xa00a6bcb in linux_main (argc=0, argv=0xa0000000) at um_arch.c:387
> #7  0xa000de0e in main (argc=1, argv=0xbffffa44, envp=0xbffffa4c) at 
> arch/um/main.c:146
> (gdb) cont
> Continuing.
> 
> Program received signal SIGSTOP, Stopped (signal).
> 0x400f18dc in clone () from /lib/libc.so.6
> (gdb) bt
> #0  0x400f18dc in clone () from /lib/libc.so.6
> #1  0x4014f000 in ?? ()
> #2  0x00000007 in ?? ()
> #3  0x00001000 in ?? ()
> #4  0xa00a7b7f in start_userspace (cpu=26379) at process.c:113
> #5  0xa00a88e2 in start_uml_skas () at process_kern.c:162
> #6  0xa00a6bcb in linux_main (argc=0, argv=0xa0000000) at um_arch.c:387
> #7  0xa000de0e in main (argc=1, argv=0xbffffa44, envp=0xbffffa4c) at 
> arch/um/main.c:146
> (gdb) cont
> Continuing.
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0xa001305a in panic (fmt=0xbfffc000 "") at panic.c:67
> 67      panic.c: No such file or directory.
>         in panic.c
> (gdb) bt
> #0  0xa001305a in panic (fmt=0xbfffc000 "") at panic.c:67
> #1  0xa00a7bdd in start_userspace (cpu=-1073758208) at process.c:127
> #2  0xa00a88e2 in start_uml_skas () at process_kern.c:162
> #3  0xa00a6bcb in linux_main (argc=0, argv=0xa0000000) at um_arch.c:387
> #4  0xa000de0e in main (argc=1, argv=0xbffffa44, envp=0xbffffa4c) at 
> arch/um/main.c:146
> (gdb) cont
> Continuing.
> 
> Program terminated with signal SIGSEGV, Segmentation fault.
> The program no longer exists.
> (gdb) quit
> puma:/uml#
> 
> In my tree, arch/um/kernel/skas/process.c:113 is the pid=clone(..., in
> 
> void start_userspace(int cpu)
> {
>         void *stack;
>         unsigned long sp;
>         int pid, status, n;
> 
>         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
>                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>         if(stack == MAP_FAILED)
>                 panic("start_userspace : mmap failed, errno = %d", errno);
>         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
> 
>         pid = clone(userspace_tramp, (void *) sp,
>                     CLONE_FILES | CLONE_VM | SIGCHLD, NULL);
> 
> 
> I hope this makes sense to someone because I'm off to sleep a few hours :-)
> 
> Regards,
> Nuno Silva
> 
> 
> 
> 

> execve("./linux", ["./linux"], [/* 25 vars */]) = 0
> uname({sys="Linux", node="puma", ...})  = 0
> brk(0)                                  = 0xa01f6000
> open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40017000
> open("/lib/tls/i686/mmx/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/tls/i686/mmx", 0xbffff16c) = -1 ENOENT (No such file or directory)
> open("/lib/tls/i686/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/tls/i686", 0xbffff16c)     = -1 ENOENT (No such file or directory)
> open("/lib/tls/mmx/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/tls/mmx", 0xbffff16c)      = -1 ENOENT (No such file or directory)
> open("/lib/tls/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/tls", 0xbffff16c)          = -1 ENOENT (No such file or directory)
> open("/lib/i686/mmx/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/i686/mmx", 0xbffff16c)     = -1 ENOENT (No such file or directory)
> open("/lib/i686/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/i686", 0xbffff16c)         = -1 ENOENT (No such file or directory)
> open("/lib/mmx/libutil.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
> stat64("/lib/mmx", 0xbffff16c)          = -1 ENOENT (No such file or directory)
> open("/lib/libutil.so.1", O_RDONLY)     = 3
> read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@\16\0\000"..., 512) = 512
> fstat64(3, {st_mode=S_IFREG|0755, st_size=92994, ...}) = 0
> mmap2(NULL, 10672, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40018000
> mmap2(0x4001a000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x1) = 0x4001a000
> close(3)                                = 0
> open("/lib/libc.so.6", O_RDONLY)        = 3
> read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0PZ\1\000"..., 512) = 512
> fstat64(3, {st_mode=S_IFREG|0755, st_size=19666162, ...}) = 0
> mmap2(NULL, 1252652, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4001b000
> mmap2(0x40142000, 36864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x127) = 0x40142000
> mmap2(0x4014b000, 7468, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4014b000
> close(3)                                = 0
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4014d000
> set_thread_area({entry_number:-1 -> 6, base_addr:0x4014d070, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
> rt_sigprocmask(SIG_SETMASK, [IO], NULL, 8) = 0
> getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
> brk(0)                                  = 0xa01f6000
> brk(0xa0217000)                         = 0xa0217000
> brk(0)                                  = 0xa0217000
> rt_sigaction(SIGINT, {0xa000dc90, [], SA_NOMASK|SA_ONESHOT}, NULL, 8) = 0
> rt_sigaction(SIGTERM, {0xa000dc90, [], SA_NOMASK|SA_ONESHOT}, NULL, 8) = 0
> rt_sigaction(SIGHUP, {0xa000dc90, [], SA_NOMASK|SA_ONESHOT}, NULL, 8) = 0
> fstat64(1, {st_mode=S_IFREG|0644, st_size=3126, ...}) = 0
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4014e000
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4014f000
> clone(child_stack=0x4014ffd8, flags=0|SIGCHLD) = 26355
> --- SIGCHLD (Child exited) @ 0 (0) ---
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> waitpid(26355, [WIFSTOPPED(s) && WSTOPSIG(s) == SIGSTOP], WUNTRACED) = 26355
> ptrace(0x34 /* PTRACE_??? */, 26355, 0, 0xbffff8a0) = 0
> ptrace(PTRACE_GETREGS, 26355, 0, 0xa01d8c60) = 0
> ptrace(PTRACE_GETFPXREGS, 26355, 0, 0xa01d8d40) = 0
> ptrace(PTRACE_CONT, 26355, 0, SIG_0)    = 0
> waitpid(26355, [WIFEXITED(s) && WEXITSTATUS(s) == 1], 0) = 26355
> --- SIGCHLD (Child exited) @ 0 (0) ---
> munmap(0x4014f000, 4096)                = 0
> access("/proc/mm", W_OK)                = 0
> brk(0)                                  = 0xa0217000
> uname({sys="Linux", node="puma", ...})  = 0
> gettimeofday({1073378804, 532883}, NULL) = 0
> getpid()                                = 26354
> open("/tmp/vm_file-AukWKw", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
> unlink("/tmp/vm_file-AukWKw")           = 0
> fchmod(3, 0777)                         = 0
> _llseek(3, 33554432, [33554432], SEEK_SET) = 0
> write(3, "\0", 1)                       = 1
> fcntl64(3, F_SETFD, FD_CLOEXEC)         = 0
> mmap2(0xa0800000, 25165824, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 3, 0x800) = 0xa0800000
> mkdir("/root/.uml/", 0777)              = -1 EEXIST (File exists)
> open("/root/.uml/uPjYnh", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
> close(4)                                = 0
> unlink("/root/.uml/uPjYnh")             = 0
> mkdir("/root/.uml/uPjYnh", 0777)        = 0
> open("/root/.uml/uPjYnh/pid", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0644) = 4
> write(4, "26354\n", 6)                  = 6
> close(4)                                = 0
> mprotect(0xa0196000, 8192, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
> write(1, "Checking for the skas3 patch in "..., 79Checking for the skas3 patch in the host...found
> Checking for /proc/mm...found
> ) = 79
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4014f000
> clone(child_stack=0x4014ffd8, flags=CLONE_VM|CLONE_FILES|SIGCHLD) = 26356
> --- SIGCHLD (Child exited) @ 0 (0) ---
> --- SIGSTOP (Stopped (signal)) @ 0 (0) ---
> --- SIGSTOP (Stopped (signal)) @ 0 (0) ---
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> waitpid(26356, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WUNTRACED) = 26356
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [], [IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [ALRM VTALRM IO], NULL, 8) = 0
> rt_sigprocmask(SIG_UNBLOCK, [ALRM VTALRM], [ALRM VTALRM IO], 8) = 0
> rt_sigprocmask(SIG_BLOCK, [IO], NULL, 8) = 0
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> +++ killed by SIGSEGV +++


-- 
 - mdz


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