Package: emacs;
Reported by: Thomas Fitzsimmons <fitzsim <at> fitzsim.org>
Date: Sat, 27 Oct 2018 10:31:02 UTC
Severity: normal
Found in version 27.0.50
Done: Paul Eggert <eggert <at> cs.ucla.edu>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: Thomas Fitzsimmons <fitzsim <at> fitzsim.org> To: Paul Eggert <eggert <at> cs.ucla.edu> Cc: 33174 <at> debbugs.gnu.org Subject: bug#33174: 27.0.50; Dump fails on GNU/Linux ppc64le Date: Sun, 28 Oct 2018 21:47:06 -0400
Paul Eggert <eggert <at> cs.ucla.edu> writes:
> Wonderful. Yet another reason we need to get the pdumper branch working. Anyway:
>
> 1. Can you use strace and/or GDB to investigate how ./temacs is
> disabling address randomization? In the emacs-26 branch, if you run
> this command in src:
>
> strace -f -o /tmp/tr ./temacs --batch --load loadup bootstrap
>
> the output file /tmp/tr should contain something like this:
>
> 18406 personality(0xffffffff) = 0 (PER_LINUX)
> 18406 personality(PER_LINUX|ADDR_NO_RANDOMIZE) = 0 (PER_LINUX)
> 18406 personality(0xffffffff) = 0x40000 (PER_LINUX|ADDR_NO_RANDOMIZE)
I see the above personality calls exactly as you've shown them.
strace never gets to the next execve; the crash happens before the next
execve is run, see below.
> 18406 execve("./temacs", ["./temacs", "--batch", "--load", "loadup",
> "bootstrap"], 0xc521b0 /* 80 vars */) = 0
>
> and later on there should be one more call to 'personality', like this:
>
> 18406 personality(0xffffffff) = 0x40000 (PER_LINUX|ADDR_NO_RANDOMIZE)
>
> If it doesn't look like this, please investigate why, by using GDB.
When I run the command under gdb, it succeeds, so I had to enable core
dumps to get the backtrace:
$ gdb ./temacs core
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "powerpc64le-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
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For help, type "help".
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Reading symbols from ./temacs...done.
[New LWP 26831]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/powerpc64le-linux-gnu/libthread_db.so.1".
Core was generated by `./temacs --batch --load loadup bootstrap '.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 __memcpy_power7 () at ../sysdeps/powerpc/powerpc64/power7/memcpy.S:111
111 ../sysdeps/powerpc/powerpc64/power7/memcpy.S: No such file or directory.
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not from terminal]
DISPLAY = :0
TERM = dumb
Breakpoint 1 at 0x10118108: file emacs.c, line 363.
Temporary breakpoint 2 at 0x10137aa8: init_sys_modes. (3 locations)
(gdb) thread apply all bt
Thread 1 (Thread 0x7fff940a7be0 (LWP 26831)):
#0 __memcpy_power7 () at ../sysdeps/powerpc/powerpc64/power7/memcpy.S:111
#1 0x00000000101ec188 in memcpy (__len=383855080, __src=0x105cd618, __dest=<optimized out>) at /usr/include/powerpc64le-linux-gnu/bits/string3.h:53
#2 unexec (new_name=0x11b934f8 <bss_sbrk_buffer+22229000> "/build/emacs/src/emacs",
old_name=0x11b93528 <bss_sbrk_buffer+22229048> "/build/emacs/src/temacs") at unexelf.c:411
#3 0x0000000010110bec in Fdump_emacs (filename=XIL(0x11b945a4), symfile=XIL(0x11b94584)) at emacs.c:2224
#4 0x00000000101a7cb8 in eval_sub (form=...) at eval.c:2244
#5 0x00000000101a8194 in Fprogn (body=XIL(0x107360d3)) at eval.c:459
#6 0x00000000101a7d6c in eval_sub (form=...) at eval.c:2193
#7 0x00000000101ab8bc in Fif (args=...) at eval.c:414
#8 0x00000000101a7d6c in eval_sub (form=...) at eval.c:2193
#9 0x00000000101d8a98 in readevalloop (readcharfun=XIL(0x68d0), infile0=0x7fffc3cef950, sourcename=XIL(0x107216a4), printflag=false, unibyte=...,
readfun=XIL(0), start=XIL(0), end=XIL(0)) at lread.c:2048
#10 0x00000000101d90bc in Fload (file=XIL(0x107215a4), noerror=..., nomessage=XIL(0), nosuffix=..., must_suffix=...) at lread.c:1435
#11 0x00000000101a7c34 in eval_sub (form=...) at eval.c:2255
#12 0x00000000101acd18 in Feval (form=XIL(0x10727f03), lexical=...) at eval.c:2061
#13 0x00000000101188f8 in top_level_2 () at keyboard.c:1119
#14 0x00000000101a6410 in internal_condition_case (bfun=0x101188d0 <top_level_2>, handlers=..., hfun=0x1011f030 <cmd_error>) at eval.c:1336
#15 0x00000000101188a8 in top_level_1 (ignore=...) at keyboard.c:1127
#16 0x00000000101a6364 in internal_catch (tag=..., func=0x10118800 <top_level_1>, arg=XIL(0)) at eval.c:1101
#17 0x000000001011873c in command_loop () at keyboard.c:1088
#18 0x000000001011e89c in recursive_edit_1 () at keyboard.c:695
#19 0x000000001011eeb4 in Frecursive_edit () at keyboard.c:766
#20 0x0000000010017804 in main (argc=<optimized out>, argv=0x7fffc3cf0308) at emacs.c:1717
You can't do that without a process to debug.
(gdb)
> 2. What filesystem are you building in,
ext4
> and does it support xattrs?
Yes.
> What is the output of the following in your build directory?
>
> touch x
> setfattr -n user.variable -v value x
> getfattr -n user.variable x
I bootstrapped Debian from a minimal root file system, so I didn't have
the attr package installed (i.e., the setfattr and getfattr commands
were not found). After I installed it, the output of the above commands
is:
$ touch x
$ setfattr -n user.variable -v value x
$ getfattr -n user.variable x
# file: x
user.variable="value"
> 3. What is the output of "getfattr -d src/temacs"? It should be something like this:
>
> # file: src/temacs
> user.pax.flags="er"
>
> If not, we need to figure out why not.
Yes, after I re-ran configure and make after having installed the attr
package:
$ getfattr -d src/temacs
# file: src/temacs
user.pax.flags="er"
> 4. The output of 'make V=1' should contain something like the
> following. If not, please investigate why not.
>
> setfattr -n user.pax.flags -v er temacs
When setfattr is not installed, configure shows:
[...]
checking for setfattr... no
[...]
and that command is not run. After I installed the attr package,
configure shows:
checking for setfattr... yes
and the above command shows up in make V=1 output.
Thomas
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