svn commit: r338930 - head/libexec/rtld-elf/powerpc

[Andreas Tobler]

On 27.09.18 20:48, Michael Tuexen wrote:
>> On 25. Sep 2018, at 21:29, Andreas Tobler <andreast at FreeBSD.org> wrote:
>>
>> Author: andreast
>> Date: Tue Sep 25 19:29:35 2018
>> New Revision: 338930
>> URL: https://svnweb.freebsd.org/changeset/base/338930
>>
>> Log:
>>   Bring the 32-bit powerpc (PowerMac) back to live. The commit 338486 reworked
>>   some TLS bits. This broke operation on the PowerMac. Namely one could not login.
>>   At login the screen/shell was giving back lots of backslashes and the login
>>   shell dumped core.
>>
>>   The fix to this issue is to revert the powerpc commit from 338486 and to
>>   increase the TLS_TCB_SIZE to 16.
>>   Reverting only did not help, login was possible but userland applications
>>   aborted with strange messages.
>>
>>   I tested this patch with world/kernel builds and with port upgrades.
>>   Additionally a full gcc8 bootstrap was successfully completed.
>>
>>   Reviewed by: jhibbits@
>>   Approved by: re (Glen)
>>
>> Modified:
>>   head/libexec/rtld-elf/powerpc/rtld_machdep.h
>>
>> Modified: head/libexec/rtld-elf/powerpc/rtld_machdep.h
>> ==============================================================================
>> --- head/libexec/rtld-elf/powerpc/rtld_machdep.h	Tue Sep 25 18:54:18 2018	(r338929)
>> +++ head/libexec/rtld-elf/powerpc/rtld_machdep.h	Tue Sep 25 19:29:35 2018	(r338930)
>> @@ -69,12 +69,12 @@ void _rtld_powerpc_pltcall(void);
>>
>> #define TLS_TP_OFFSET	0x7000
>> #define TLS_DTV_OFFSET	0x8000
>> -#define TLS_TCB_SIZE	8
>> +#define TLS_TCB_SIZE	16
>>
>> #define round(size, align) \
>>      (((size) + (align) - 1) & ~((align) - 1))
>> #define calculate_first_tls_offset(size, align) \
>> -    TLS_TCB_SIZE
>> +    round(8, align)
>> #define calculate_tls_offset(prev_offset, prev_size, size, align) \
>>      round(prev_offset + prev_size, align)
>> #define calculate_tls_end(off, size)    ((off) + (size))
>>
> After performing a buildworld/buildkernel and running r338956 on a 32-bit powerpc machine (G4 Mac Mini),
> the following program:
> 
> #include <pthread.h>
> #include <stdio.h>
> #include <string.h>
> 
> void *
> f(void * arg)
> {
> 	return (arg);
> }
> 
> int
> main(void)
> {
> 	void *res;
> 	pthread_t tid;
> 	int err;
> 
> 	if ((err = pthread_create(&tid, NULL, f, NULL)) != 0) {
> 		fprintf(stderr, "pthread_create: %s\n", strerror(err));
> 	}
> 	if ((err = pthread_join(tid, &res)) != 0) {
> 		fprintf(stderr, "pthread_join: %s\n", strerror(err));
> 	}
> 	return (0);
> }
> 
> is killed:
> 
> tuexen at bsd5:~ % ./test
> ld-elf.so.1: assert failed: /usr/home/tuexen/head/libexec/rtld-elf/rtld.c:4753
> Abort (core dumped)
> 
> gdb shows:
> 
> tuexen at bsd5:~ % gdb -c test.core test
> GNU gdb (GDB) 8.1 [GDB v8.1 for FreeBSD]
> Copyright (C) 2018 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "powerpc-portbld-freebsd12.0".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
> Find the GDB manual and other documentation resources online at:
> <http://www.gnu.org/software/gdb/documentation/>.
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from test...done.
> [New LWP 100112]
> Core was generated by `./test'.
> Program terminated with signal SIGABRT, Aborted.
> #0  0x41829a58 in thr_kill () at thr_kill.S:3
> 3	RSYSCALL(thr_kill)
> (gdb) bt
> #0  0x41829a58 in thr_kill () at thr_kill.S:3
> #1  0x41829378 in __raise (s=6)
>      at /usr/home/tuexen/head/lib/libc/gen/raise.c:52
> #2  0x41823b84 in abort () at /usr/home/tuexen/head/lib/libc/stdlib/abort.c:67
> #3  0x41813f58 in allocate_tls (objs=0x41843000, oldtcb=<optimized out>,
>      tcbsize=8, tcbalign=<optimized out>)
>      at /usr/home/tuexen/head/libexec/rtld-elf/rtld.c:4753
> #4  0x41813fc0 in _rtld_allocate_tls (oldtls=0x0, tcbsize=8, tcbalign=16)
>      at /usr/home/tuexen/head/libexec/rtld-elf/rtld.c:5030
> #5  0x41877438 in _tcb_ctor (thread=0x41a8d300, initial=<optimized out>)
>      at /usr/home/tuexen/head/lib/libthr/thread/thr_ctrdtr.c:45
> #6  0x41876ebc in _thr_alloc (curthread=0x41a8d000)
>      at /usr/home/tuexen/head/lib/libthr/thread/thr_list.c:172
> #7  0x41867118 in _pthread_create (thread=0xffffdc10, attr=0x0,
>      start_routine=0x180073c <f>, arg=0x0)
>      at /usr/home/tuexen/head/lib/libthr/thread/thr_create.c:81
> #8  0x01800798 in main ()
> (gdb) quit
> 
> Any idea what is wrong?

TLS is broken on powerpc ;)

I see the same.

Would you mind reverting my commit and see if it is better/different and 
how different?

For me the commit was an improvement, but I agree this is not enough.

I try to analyze what is going on. Any help is appreciated.

Thanks for the report.
Andreas