From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3ssmvs1Rj5zDrL1 for ; Mon, 10 Oct 2016 15:13:45 +1100 (AEDT) From: Michael Ellerman To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin Subject: Re: [PATCH] powerpc: build time sort extable In-Reply-To: <20161007112941.20073-1-npiggin@gmail.com> References: <20161007112941.20073-1-npiggin@gmail.com> Date: Mon, 10 Oct 2016 15:13:44 +1100 Message-ID: <87eg3o7sef.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Nicholas Piggin writes: > Can we just switch this on? Powerpc does not use relative extables > (that's a nice exercise left for the reader), so it should just use > the standard sort. > > This patch seems to work, famous last words... Would be nice but ... > Sorting probably only takes a few ms on any real hardware, but on on > very large kernel configs, extable sorting can take several seconds in > simulators and be a noticable cost to booting. (We even carried a patch for years to speed it up.) Blows up for me at boot: [ OK ] Started LSB: Control pmcd (the collection daemon for PCP). Unable to handle kernel paging request for data at address 0x00000000 Faulting instruction address: 0xc000000000062d60 cpu 0x1: Vector: 300 (Data Access) at [c0000001d6687aa0] pc: c000000000062d60: __copy_tofrom_user_base+0x54/0x5b4 lr: c0000000000633d8: copy_from_user+0x78/0xe0 sp: c0000001d6687d20 msr: 8000000000009033 dar: 0 dsisr: 40000000 current = 0xc0000001d6601880 paca = 0xc000000007e00400 softe: 0 irq_happened: 0x01 pid = 7101, comm = docker Linux version 4.8.0-compiler_gcc-6.2.0-11418-g4011878e4cd3 (michael@ka3.ozlabs.ibm.com) (gcc version 6.2.0 (GCC) ) #219 SMP Mon Oct 10 14:48:04 AEDT 2016 enter ? for help [link register ] c0000000000633d8 copy_from_user+0x78/0xe0 [c0000001d6687d20] c0000001d6687d90 (unreliable) [c0000001d6687d60] c0000000001c7358 do_seccomp+0x78/0x6d0 [c0000001d6687dd0] c0000000000dc08c SyS_prctl+0x27c/0x670 [c0000001d6687e30] c00000000000bde4 system_call+0x38/0xfc --- Exception: c01 (System Call) at 000000001025634c SP (c8208d6cd8) is in userspace cheers