[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 Michael Ellerman (mich...@ellerman.id.au) changed: What|Removed |Added Status|RESOLVED|CLOSED -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183
--- Comment #6 from Michael Ellerman (mich...@ellerman.id.au) ---
Fixed in 63dee5df43a3 ("powerpc: Allow 4224 bytes of stack expansion for the
signal frame")
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[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 Michael Ellerman (mich...@ellerman.id.au) changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |CODE_FIX -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 Michael Ellerman (mich...@ellerman.id.au) changed: What|Removed |Added Status|NEW |ASSIGNED CC||mich...@ellerman.id.au --- Comment #5 from Michael Ellerman (mich...@ellerman.id.au) --- Patches posted: https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=192046 -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 --- Comment #4 from Daniel Black (dan...@linux.ibm.com) --- Still broken. danielgb@talos2:~$ gcc -g -Wall -O stacktest.c danielgb@talos2:~$ ./a.out 124 & [1] 494618 danielgb@talos2:~$ cat /proc/$(pidof a.out)/maps | grep stack 7fffcde8-7fffcdfb rw-p 00:00 0 [stack] danielgb@talos2:~$ kill -USR1 %1 danielgb@talos2:~$ signal delivered, stack base 0x7fffcdfb top 0x7fffcde81427 (1240025 used) [1]+ Done./a.out 124 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: 7fffdea30010 nip 00011a0a09fc lr 7fffa1c404c8 [10865.752876] a.out[494677]: bad frame in setup_rt_frame: 7fffcc420030 nip 000135a70a3c lr 7fff952604c8 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 -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 --- Comment #3 from Daniel Axtens (d...@axtens.net) --- I have a proposed patch at https://lore.kernel.org/linuxppc-dev/20191211014337.28128-1-...@axtens.net/T/#u -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 Daniel Axtens (d...@axtens.net) changed: What|Removed |Added CC||d...@axtens.net --- Comment #2 from Daniel Axtens (d...@axtens.net) --- Hi, I'm starting to have a look at this for Daniel B. So looking at the fault that fails, I see that it's a fault with the NIP in the _kernel_ that fails, rather than in userspace. Dumping stack we see: [ 118.917679] Call Trace: [ 118.917715] [c0007b457820] [c0b71538] dump_stack+0xbc/0x104 (unreliable) [ 118.917719] [c0007b457860] [c006e8f0] __do_page_fault+0x860/0xf90 [ 118.917721] [c0007b457940] [c000af68] handle_page_fault+0x10/0x30 [ 118.917725] --- interrupt: 301 at handle_rt_signal64+0x180/0x13a0 LR = handle_rt_signal64+0x148/0x13a0 [ 118.917726] [c0007b457d30] [c0023d30] do_notify_resume+0x2e0/0x410 [ 118.917728] [c0007b457e20] [c000e4c4] ret_from_except_lite+0x70/0x74 I'm still debugging, but it looks like handle_rt_signal64 attempts to reserve a stack frame for the signal, but computes a stack address that sits outside valid stack space. Then when writing to it, it pagefaults, and because it's not a userland NIP, it refuses to expand the stack. I'll keep you up to date. Regards, Daniel A -- You are receiving this mail because: You are watching the assignee of the bug.
[Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain
https://bugzilla.kernel.org/show_bug.cgi?id=205183 Daniel Black (dan...@linux.ibm.com) changed: What|Removed |Added CC||dan...@linux.ibm.com --- Comment #1 from Daniel Black (dan...@linux.ibm.com) --- Tom, Thanks for the bug report. Appreciate it. Feel free to use the linuxppc-dev@lists.ozlabs.org list. Reproduced in 5.4.0-rc8 danielgb@talos2:~$ uname -a Linux talos2 5.4.0-rc8 #5 SMP Mon Nov 18 13:27:11 AEDT 2019 ppc64le ppc64le ppc64le GNU/Linux danielgb@talos2:~$ gcc -g -Wall -O stacktest.c danielgb@talos2:~$ ./a.out 124 & [1] 2944 danielgb@talos2:~$ cat /proc/$(pidof a.out)/maps | grep stack 7fffc62f-7fffc642 rw-p 00:00 0 [stack] danielgb@talos2:~$ kill -USR1 %1 danielgb@talos2:~$ signal delivered, stack base 0x7fffc642 top 0x7fffc62f1427 (1240025 used) [1]+ Done./a.out 124 danielgb@talos2:~$ ./a.out 1241000 & [1] 2948 danielgb@talos2:~$ kill -USR1 %1 danielgb@talos2:~$ [1]+ Segmentation fault ./a.out 1241000 [ 6415.077590] a.out[2948]: bad frame in setup_rt_frame: 7fffe4fb0010 nip 06a185d909fc lr 77ecda3c04e8 I'll get someone to look at this soon. -- You are receiving this mail because: You are watching the assignee of the bug.
