Subject: [Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain

From: [email-masked]
Date: Thu, 11 Jun 2020 06:43:44 +0000

https://bugzilla.kernel.org/show_bug.cgi?id=205183

--- Comment #4 from Daniel Black ([email-masked]) ---
Still broken.

danielgb@talos2:~$ gcc -g -Wall -O stacktest.c
danielgb@talos2:~$  ./a.out 1240000 &
[1] 494618
danielgb@talos2:~$ cat /proc/$(pidof a.out)/maps | grep stack
7fffcde80000-7fffcdfb0000 rw-p 00000000 00:00 0                         
[stack]
danielgb@talos2:~$ kill -USR1 %1
danielgb@talos2:~$ signal delivered, stack base 0x7fffcdfb0000 top
0x7fffcde81427 (1240025 used)

[1]+  Done                    ./a.out 1240000
danielgb@talos2:~$ ./a.out 1241000 &
[1] 494677
danielgb@talos2:~$ kill -USR1 %1
danielgb@talos2:~$ 
[1]+  Segmentation fault      ./a.out 1241000
danielgb@talos2:~$ 
danielgb@talos2:~$ dmesg | grep a.out
[10617.616145] a.out[494587]: bad frame in setup_rt_frame: 00007fffdea30010 nip
000000011a0a09fc lr 00007fffa1c404c8
[10865.752876] a.out[494677]: bad frame in setup_rt_frame: 00007fffcc420030 nip
0000000135a70a3c lr 00007fff952604c8
danielgb@talos2:~$ uname -a
Linux talos2 5.7.0-rc5-77151-gfea086b627a0 #1 SMP Mon May 11 16:00:00 AEST 2020
ppc64le ppc64le ppc64le GNU/Linux

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