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Violators will be prosecuted for from ; Sun, 7 Oct 2012 01:16:45 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q96FJOdj19595300 for ; Sun, 7 Oct 2012 01:19:25 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q96FJO9u011903 for ; Sun, 7 Oct 2012 01:19:24 +1000 Date: Sat, 6 Oct 2012 20:49:14 +0530 From: Vaidyanathan Srinivasan To: Nishanth Aravamudan Subject: Re: [PATCH] powerpc: fix VMX fix for memcpy case Message-ID: <20121006151914.GA3927@dirshya.in.ibm.com> References: <20121002005912.GA27768@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <20121002005912.GA27768@linux.vnet.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, paulus@samba.org, Anton Blanchard Reply-To: svaidy@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , * Nishanth Aravamudan [2012-10-01 17:59:13]: > [urgh, sorry Anton, Ben & Paul, inadvertently hit send before adding > linuxppc-dev to the cc!] > > Hi Anton, > > In 2fae7cdb60240e2e2d9b378afbf6d9fcce8a3890 ("powerpc: Fix VMX in > interrupt check in POWER7 copy loops"), I think you inadvertently > introduced a regression for memcpy on POWER7 machines. copyuer and > memcpy diverge slightly in their use of cr1 (copyuser doesn't use it, > but memcpy does) and you end up clobbering that register with your fix. > That results in (taken from an FC18 kernel): > > [ 18.824604] Unrecoverable VMX/Altivec Unavailable Exception f20 at c000000000052f40 > [ 18.824618] Oops: Unrecoverable VMX/Altivec Unavailable Exception, sig: 6 [#1] > [ 18.824623] SMP NR_CPUS=1024 NUMA pSeries > [ 18.824633] Modules linked in: tg3(+) be2net(+) cxgb4(+) ipr(+) sunrpc xts lrw gf128mul dm_crypt dm_round_robin dm_multipath linear raid10 raid456 async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx raid1 raid0 scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc scsi_dh_alua squashfs cramfs > [ 18.824705] NIP: c000000000052f40 LR: c00000000020b874 CTR: 0000000000000512 > [ 18.824709] REGS: c000001f1fef7790 TRAP: 0f20 Not tainted (3.6.0-0.rc6.git0.2.fc18.ppc64) > [ 18.824713] MSR: 8000000000009032 CR: 4802802e XER: 20000010 > [ 18.824726] SOFTE: 0 > [ 18.824728] CFAR: 0000000000000f20 > [ 18.824731] TASK = c000000fa7128400[0] 'swapper/24' THREAD: c000000fa7480000 CPU: 24 > GPR00: 00000000ffffffc0 c000001f1fef7a10 c00000000164edc0 c000000f9b9a8120 > GPR04: c000000f9b9a8124 0000000000001438 0000000000000060 03ffffff064657ee > GPR08: 0000000080000000 0000000000000010 0000000000000020 0000000000000030 > GPR12: 0000000028028022 c00000000ff25400 0000000000000001 0000000000000000 > GPR16: 0000000000000000 7fffffffffffffff c0000000016b2180 c00000000156a500 > GPR20: c000000f968c7a90 c0000000131c31d8 c000001f1fef4000 c000000001561d00 > GPR24: 000000000000000a 0000000000000000 0000000000000001 0000000000000012 > GPR28: c000000fa5c04f80 00000000000008bc c0000000015c0a28 000000000000022e > [ 18.824792] NIP [c000000000052f40] .memcpy_power7+0x5a0/0x7c4 > [ 18.824797] LR [c00000000020b874] .pcpu_free_area+0x174/0x2d0 > [ 18.824800] Call Trace: > [ 18.824803] [c000001f1fef7a10] [c000000000052c14] .memcpy_power7+0x274/0x7c4 (unreliable) > [ 18.824809] [c000001f1fef7b10] [c00000000020b874] .pcpu_free_area+0x174/0x2d0 > [ 18.824813] [c000001f1fef7bb0] [c00000000020ba88] .free_percpu+0xb8/0x1b0 > [ 18.824819] [c000001f1fef7c50] [c00000000043d144] .throtl_pd_exit+0x94/0xd0 > [ 18.824824] [c000001f1fef7cf0] [c00000000043acf8] .blkg_free+0x88/0xe0 > [ 18.824829] [c000001f1fef7d90] [c00000000018c048] .rcu_process_callbacks+0x2e8/0x8a0 > [ 18.824835] [c000001f1fef7e90] [c0000000000a8ce8] .__do_softirq+0x158/0x4d0 > [ 18.824840] [c000001f1fef7f90] [c000000000025ecc] .call_do_softirq+0x14/0x24 > [ 18.824845] [c000000fa7483650] [c000000000010e80] .do_softirq+0x160/0x1a0 > [ 18.824850] [c000000fa74836f0] [c0000000000a94a4] .irq_exit+0xf4/0x120 > [ 18.824854] [c000000fa7483780] [c000000000020c44] .timer_interrupt+0x154/0x4d0 > [ 18.824859] [c000000fa7483830] [c000000000003be0] decrementer_common+0x160/0x180 > [ 18.824866] --- Exception: 901 at .plpar_hcall_norets+0x84/0xd4 > [ 18.824866] LR = .check_and_cede_processor+0x48/0x80 > [ 18.824871] [c000000fa7483b20] [c00000000007f018] .check_and_cede_processor+0x18/0x80 (unreliable) > [ 18.824877] [c000000fa7483b90] [c00000000007f104] .dedicated_cede_loop+0x84/0x150 > [ 18.824883] [c000000fa7483c50] [c0000000006bc030] .cpuidle_enter+0x30/0x50 > [ 18.824887] [c000000fa7483cc0] [c0000000006bc9f4] .cpuidle_idle_call+0x104/0x720 > [ 18.824892] [c000000fa7483d80] [c000000000070af8] .pSeries_idle+0x18/0x40 > [ 18.824897] [c000000fa7483df0] [c000000000019084] .cpu_idle+0x1a4/0x380 > [ 18.824902] [c000000fa7483ec0] [c0000000008a4c18] .start_secondary+0x520/0x528 > [ 18.824907] [c000000fa7483f90] [c0000000000093f0] .start_secondary_prolog+0x10/0x14 > [ 18.824911] Instruction dump: > [ 18.824914] 38840008 90030000 90e30004 38630008 7ca62850 7cc300d0 78c7e102 7cf01120 > [ 18.824923] 78c60660 39200010 39400020 39600030 <7e00200c> 7c0020ce 38840010 409f001c > [ 18.824935] ---[ end trace 0bb95124affaaa45 ]--- > [ 18.825046] Unrecoverable VMX/Altivec Unavailable Exception f20 at c000000000052d08 > > I believe the right fix is to make memcpy match usercopy and not use > cr1. > > Signed-off-by: Nishanth Aravamudan Tested-by: Vaidyanathan Srinivasan > --- > I've not tested this fix yet, but I think it's logically correct. > Probably needs to go to 3.6-stable as well. > > diff --git a/arch/powerpc/lib/memcpy_power7.S b/arch/powerpc/lib/memcpy_power7.S > index 7ba6c96..0663630 100644 > --- a/arch/powerpc/lib/memcpy_power7.S > +++ b/arch/powerpc/lib/memcpy_power7.S > @@ -239,8 +239,8 @@ _GLOBAL(memcpy_power7) > ori r9,r9,1 /* stream=1 */ > > srdi r7,r5,7 /* length in cachelines, capped at 0x3FF */ > - cmpldi cr1,r7,0x3FF > - ble cr1,1f > + cmpldi r7,0x3FF > + ble 1f > li r7,0x3FF > 1: lis r0,0x0E00 /* depth=7 */ > sldi r7,r7,7 This change on v3.6 mainline tree allows kernel to boot without exception. --Vaidy