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[222.152.189.137]) by smtp.gmail.com with ESMTPSA id x2sm9275150pfp.155.2021.06.18.19.17.20 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Jun 2021 19:17:24 -0700 (PDT) Subject: Re: [PATCH v2] m68k: save extra registers on more syscall entry points To: Linus Torvalds References: <1623979642-14983-1-git-send-email-schmitzmic@gmail.com> <91865b90-c597-6119-5e14-dfe521a33489@gmail.com> <2b2ba866-104c-afea-9c29-145e9d80c2d5@gmail.com> Cc: Geert Uytterhoeven , linux-arch , linux-m68k , "Eric W. Biederman" , Andreas Schwab From: Michael Schmitz Message-ID: <596b6fa5-a533-7c80-0138-5d0de756e707@gmail.com> Date: Sat, 19 Jun 2021 14:17:18 +1200 User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Hi Linus, Am 19.06.2021 um 13:54 schrieb Linus Torvalds: > On Fri, Jun 18, 2021 at 6:32 PM Michael Schmitz wrote: >> >> *** FORMAT ERROR *** FORMAT=0 >> Current process id is 1 >> BAD KERNEL TRAP: 00000000 >> Modules linked in: >> PC: [<00002af0>] resume_userspace+0x14/0x16 >> SR: 2204 SP: (ptrval) a2: 00000000 >> d0: 00000000 d1: 00000000 d2: 00000000 d3: 00000000 >> d4: 00000000 d5: 00000000 a0: 00000000 a1: 00000000 > > Yeah, so that's presumably the rte that causes an exception due to > garbage on the stack. > > The registers being zero at that point is actually expected, so that's > not much of a hint. But yeah, clearly I got some stack initialization > offset or something wrong there, and I don't know modern m68k nearly > well enough to even guess where I screwed up. It might have been me screwing up - I hand applied the patch on top of my last one and fat fingered one bit (forgot to remove the addql #4,sp@ I had added before the switch stack save). With the patch correctly applied, I get this dump: Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b CPU: 0 PID: 1 Comm: init Not tainted 5.13.0-rc1-atari-fpuemu-exitfix+ #1126 Stack from 0081be08: 0081be08 003363d8 003363d8 002aebaa 000000ff 00000001 0002fa64 00818a90 0081a000 0000000b 0081be70 00028610 0032df62 0000000b 0000000b 0002e0d2 0002fa64 00000001 001a978c 0000000b 0081bf30 0081daf8 0081bf44 00000000 00000000 00000000 0081ec40 00029458 0000000b 0081a007 00030504 0000000b 00000000 00000000 00000000 00000000 00818550 00000000 0081bf90 0081bf30 00000000 0081bf68 00030066 0081da30 000042c4 0081bf30 00000000 00000000 Call Trace: [<002aebaa>] panic+0xc0/0x282 [<0002fa64>] do_signal_stop+0x0/0x14a [<00028610>] do_exit+0x152/0x6f4 [<0002e0d2>] recalc_sigpending+0x0/0x1e [<0002fa64>] do_signal_stop+0x0/0x14a [<001a978c>] memcpy+0x0/0x88 [<00029458>] do_group_exit+0x40/0x7e [<00030504>] get_signal+0x22c/0x510 [<00030066>] force_sig_info_to_task+0x7e/0x8a [<000042c4>] do_notify_resume+0x3c/0x484 [<000302b2>] force_sig_fault_to_task+0x30/0x3c [<000302d2>] force_sig_fault+0x14/0x1a [<00005eb8>] send_fault_sig+0x24/0x86 [<00002b14>] do_signal_return+0x10/0x1a [<00007008>] atari_reset+0x90/0xbc [<0000c000>] clr_mant+0x8/0x14 No registers dumped at all - no idea how that happened. I'll try your latest patch next ... bear with me, got a 9-year old chewing my ear off to entertain in between tests. Cheers, Michael > > Linus >