| Message ID | 20121002005912.GA27768@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
* Nishanth Aravamudan <nacc@linux.vnet.ibm.com> [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 <SF,EE,ME,IR,DR,RI> 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 <nacc@us.ibm.com> Tested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> > --- > 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
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
[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 <SF,EE,ME,IR,DR,RI> 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 <nacc@us.ibm.com> --- I've not tested this fix yet, but I think it's logically correct. Probably needs to go to 3.6-stable as well.