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[222.152.189.137]) by smtp.gmail.com with ESMTPSA id v6sm10522032pgk.33.2021.06.18.18.32.26 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Jun 2021 18:32:31 -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> Cc: Geert Uytterhoeven , linux-arch , linux-m68k , "Eric W. Biederman" , Andreas Schwab From: Michael Schmitz Message-ID: <2b2ba866-104c-afea-9c29-145e9d80c2d5@gmail.com> Date: Sat, 19 Jun 2021 13:32:23 +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=windows-1252; 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 11:38 schrieb Linus Torvalds: > On Fri, Jun 18, 2021 at 3:34 PM Michael Schmitz wrote: >> >> Is your patch to copy_thread() to add the extra stack frame still needed? > > So it's been a long time since I did any m68k assembly, but I think > the m68k patch for the PF_IO_WORKER thread case should look something > like the attached. > > Note: my only m68k work was ever on the 68008, and used the Motorola > syntax, not the odd Sun assembler syntax, so my m68k asm skills really > aren't good. > > Put another way: I'd be surprised if the attached patch actually > works, but I think it's fairly close. I tried to add comments to > explain the code at least a bit. That went well: *** 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 Process init (pid: 1, task=(ptrval)) Frame format=0 Stack from 0081bffc: 19bc0000 Call Trace: Code: 1029 0007 660c 4cdf 073e 201f 588f dfdf <4e73> 254f 03ec e308 660a 487a ffe0 60ff 002a f6ba 598f 48e7 031e 486f 001c 61ff Disabling lock debugging due to kernel taint Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b Looks like the zeroed frame was restored where we'd have expected an actual save frame? I'll next try and apply your solution to IO worker threads only ... Cheers, Michael > > Hmm? > > Linus >