| Message ID | 20220724010221.17371-1-zhouzhouyi@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [linux-next] powerpc: init jump label early in ppc 64 | expand |
zhouzhouyi@gmail.com writes: > From: Zhouyi Zhou <zhouzhouyi@gmail.com> > > In ppc 64, invoke jump_label_init in setup_feature_keys is too late > because static key will be used in subroutine of early_init_devtree. > > So we can invoke jump_label_init earlier in early_setup. > We can not move setup_feature_keys backward because its subroutine > cpu_feature_keys_init depend on data structures initialized in > early_init_devtree. > > Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> > --- > Dear PPC developers > > I found this bug when trying to do rcutorture tests in ppc VM of > Open Source Lab of Oregon State University. > > qemu-system-ppc64 -nographic -smp cores=8,threads=1 -net none -M pseries -nodefaults -device spapr-vscsi -serial file:/home/ubuntu/linux-next/tools/testing/selftests/rcutorture/res/2022.07.19-01.18.42-torture/results-rcutorture/TREE03/console.log -m 512 -kernel /home/ubuntu/linux-next/tools/testing/selftests/rcutorture/res/2022.07.19-01.18.42-torture/results-rcutorture/TREE03/vmlinux -append "debug_boot_weak_hash panic=-1 console=ttyS0 rcupdate.rcu_cpu_stall_suppress_at_boot=1 torture.disable_onoff_at_boot rcupdate.rcu_task_stall_timeout=30000 rcutorture.onoff_interval=200 rcutorture.onoff_holdoff=30 rcutree.gp_preinit_delay=12 rcutree.gp_init_delay=3 rcutree.gp_cleanup_delay=3 rcutree.kthread_prio=2 threadirqs tree.use_softirq=0 rcutorture.n_barrier_cbs=4 rcutorture.stat_interval=15 rcutorture.shutdown_secs=420 rcutorture.test_no_idle_hz=1 rcutorture.verbose=1" > > console.log report following WARN: > [ 0.000000][ T0] static_key_enable_cpuslocked(): static key '0xc000000002953260' used before call to jump_label_init()^M > [ 0.000000][ T0] WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166 static_key_enable_cpuslocked+0xfc/0x120^M > [ 0.000000][ T0] Modules linked in:^M > [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 5.19.0-rc5-next-20220708-dirty #131^M > [ 0.000000][ T0] NIP: c00000000038068c LR: c000000000380688 CTR: c000000000186ac0^M > [ 0.000000][ T0] REGS: c000000002867930 TRAP: 0700 Not tainted (5.19.0-rc5-next-20220708-dirty)^M > [ 0.000000][ T0] MSR: 8000000000022003 <SF,FP,RI,LE> CR: 24282224 XER: 20040000^M > [ 0.000000][ T0] CFAR: 0000000000000730 IRQMASK: 1 ^M > [ 0.000000][ T0] GPR00: c000000000380688 c000000002867bd0 c000000002868d00 0000000000000065 ^M > [ 0.000000][ T0] GPR04: 0000000000000001 0000000000000000 0000000000000080 000000000000000d ^M > [ 0.000000][ T0] GPR08: 0000000000000000 0000000000000000 c0000000027fd000 000000000000000f ^M > [ 0.000000][ T0] GPR12: c000000000186ac0 c000000002082280 0000000000000003 000000000000000d ^M > [ 0.000000][ T0] GPR16: 0000000002cc00d0 0000000000000000 c000000002082280 0000000000000001 ^M > [ 0.000000][ T0] GPR20: c000000002080942 0000000000000000 0000000000000000 0000000000000000 ^M > [ 0.000000][ T0] GPR24: 0000000000000000 c0000000010d6168 0000000000000000 c0000000020034c8 ^M > [ 0.000000][ T0] GPR28: 0000002800000000 0000000000000000 c000000002080942 c000000002953260 ^M > [ 0.000000][ T0] NIP [c00000000038068c] static_key_enable_cpuslocked+0xfc/0x120^M > [ 0.000000][ T0] LR [c000000000380688] static_key_enable_cpuslocked+0xf8/0x120^M > [ 0.000000][ T0] Call Trace:^M > [ 0.000000][ T0] [c000000002867bd0] [c000000000380688] static_key_enable_cpuslocked+0xf8/0x120 (unreliable)^M > [ 0.000000][ T0] [c000000002867c40] [c000000000380810] static_key_enable+0x30/0x50^M > [ 0.000000][ T0] [c000000002867c70] [c000000002030314] setup_forced_irqthreads+0x28/0x40^M > [ 0.000000][ T0] [c000000002867c90] [c000000002003568] do_early_param+0xa0/0x108^M > [ 0.000000][ T0] [c000000002867d10] [c000000000175340] parse_args+0x290/0x4e0^M > [ 0.000000][ T0] [c000000002867e10] [c000000002003c74] parse_early_options+0x48/0x5c^M > [ 0.000000][ T0] [c000000002867e30] [c000000002003ce0] parse_early_param+0x58/0x84^M > [ 0.000000][ T0] [c000000002867e60] [c000000002009878] early_init_devtree+0xd4/0x518^M > [ 0.000000][ T0] [c000000002867f10] [c00000000200aee0] early_setup+0xb4/0x214^M > > After this fix, the WARN does not show again. Hi Zhouyi, We have hit something like this previously, see the stack trace in commit e7eb919057c3 ("powerpc/64s: Handle program checks in wrong endian during early boot"). That was fixed incidentally/accidentally by the page_poison code changing to not use static keys so early. There was a similar case recently in the random code too, see 60e5b2886b92 ("random: do not use jump labels before they are initialized"). But I guess this will keep happening, as generic code authors expect to be able to use static keys in early_param() handlers. I think the ideal solution would be to move most early param parsing later. There's only a few parameters that need to be parsed that early in early_init_devtree(). That would be a complex and error-prone change though, so I won't ask you to do that :) But I think it would be better if you moved the call to jump_label_init() into early_init_devtree(), just before we call parse_early_param(), with a comment saying that it's required to call it before parsing early params. And ... > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > index 2b2d0b0fbb30..bf2fb76221da 100644 > --- a/arch/powerpc/kernel/setup_64.c > +++ b/arch/powerpc/kernel/setup_64.c > @@ -365,6 +365,9 @@ void __init early_setup(unsigned long dt_ptr) > > udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr); > > + /* Initialise jump label because subsequent calls need it */ > + jump_label_init(); > + > /* > * Do early initialization using the flattened device > * tree, such as retrieving the physical memory map or > @@ -394,8 +397,15 @@ void __init early_setup(unsigned long dt_ptr) > > /* Apply all the dynamic patching */ > apply_feature_fixups(); > - setup_feature_keys(); I think you can just leave this as-is, it's fine to call jump_label_init() more than once. > + > + /* > + * All the cpu/mmu_has_feature() checks take on their correct polarity > + * based on the current set of CPU/MMU features. These should be done > + * only after early_init_devtree. > + */ > + cpu_feature_keys_init(); > + mmu_feature_keys_init(); > + > > /* Initialize the hash table or TLB handling */ > early_init_mmu(); > -- > 2.25.1 cheers
On Mon, Jul 25, 2022 at 3:55 PM Michael Ellerman <mpe@ellerman.id.au> wrote: > > zhouzhouyi@gmail.com writes: > > From: Zhouyi Zhou <zhouzhouyi@gmail.com> > > > > In ppc 64, invoke jump_label_init in setup_feature_keys is too late > > because static key will be used in subroutine of early_init_devtree. > > > > So we can invoke jump_label_init earlier in early_setup. > > We can not move setup_feature_keys backward because its subroutine > > cpu_feature_keys_init depend on data structures initialized in > > early_init_devtree. > > > > Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> > > --- > > Dear PPC developers > > > > I found this bug when trying to do rcutorture tests in ppc VM of > > Open Source Lab of Oregon State University. > > > > qemu-system-ppc64 -nographic -smp cores=8,threads=1 -net none -M pseries -nodefaults -device spapr-vscsi -serial file:/home/ubuntu/linux-next/tools/testing/selftests/rcutorture/res/2022.07.19-01.18.42-torture/results-rcutorture/TREE03/console.log -m 512 -kernel /home/ubuntu/linux-next/tools/testing/selftests/rcutorture/res/2022.07.19-01.18.42-torture/results-rcutorture/TREE03/vmlinux -append "debug_boot_weak_hash panic=-1 console=ttyS0 rcupdate.rcu_cpu_stall_suppress_at_boot=1 torture.disable_onoff_at_boot rcupdate.rcu_task_stall_timeout=30000 rcutorture.onoff_interval=200 rcutorture.onoff_holdoff=30 rcutree.gp_preinit_delay=12 rcutree.gp_init_delay=3 rcutree.gp_cleanup_delay=3 rcutree.kthread_prio=2 threadirqs tree.use_softirq=0 rcutorture.n_barrier_cbs=4 rcutorture.stat_interval=15 rcutorture.shutdown_secs=420 rcutorture.test_no_idle_hz=1 rcutorture.verbose=1" > > > > console.log report following WARN: > > [ 0.000000][ T0] static_key_enable_cpuslocked(): static key '0xc000000002953260' used before call to jump_label_init()^M > > [ 0.000000][ T0] WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166 static_key_enable_cpuslocked+0xfc/0x120^M > > [ 0.000000][ T0] Modules linked in:^M > > [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 5.19.0-rc5-next-20220708-dirty #131^M > > [ 0.000000][ T0] NIP: c00000000038068c LR: c000000000380688 CTR: c000000000186ac0^M > > [ 0.000000][ T0] REGS: c000000002867930 TRAP: 0700 Not tainted (5.19.0-rc5-next-20220708-dirty)^M > > [ 0.000000][ T0] MSR: 8000000000022003 <SF,FP,RI,LE> CR: 24282224 XER: 20040000^M > > [ 0.000000][ T0] CFAR: 0000000000000730 IRQMASK: 1 ^M > > [ 0.000000][ T0] GPR00: c000000000380688 c000000002867bd0 c000000002868d00 0000000000000065 ^M > > [ 0.000000][ T0] GPR04: 0000000000000001 0000000000000000 0000000000000080 000000000000000d ^M > > [ 0.000000][ T0] GPR08: 0000000000000000 0000000000000000 c0000000027fd000 000000000000000f ^M > > [ 0.000000][ T0] GPR12: c000000000186ac0 c000000002082280 0000000000000003 000000000000000d ^M > > [ 0.000000][ T0] GPR16: 0000000002cc00d0 0000000000000000 c000000002082280 0000000000000001 ^M > > [ 0.000000][ T0] GPR20: c000000002080942 0000000000000000 0000000000000000 0000000000000000 ^M > > [ 0.000000][ T0] GPR24: 0000000000000000 c0000000010d6168 0000000000000000 c0000000020034c8 ^M > > [ 0.000000][ T0] GPR28: 0000002800000000 0000000000000000 c000000002080942 c000000002953260 ^M > > [ 0.000000][ T0] NIP [c00000000038068c] static_key_enable_cpuslocked+0xfc/0x120^M > > [ 0.000000][ T0] LR [c000000000380688] static_key_enable_cpuslocked+0xf8/0x120^M > > [ 0.000000][ T0] Call Trace:^M > > [ 0.000000][ T0] [c000000002867bd0] [c000000000380688] static_key_enable_cpuslocked+0xf8/0x120 (unreliable)^M > > [ 0.000000][ T0] [c000000002867c40] [c000000000380810] static_key_enable+0x30/0x50^M > > [ 0.000000][ T0] [c000000002867c70] [c000000002030314] setup_forced_irqthreads+0x28/0x40^M > > [ 0.000000][ T0] [c000000002867c90] [c000000002003568] do_early_param+0xa0/0x108^M > > [ 0.000000][ T0] [c000000002867d10] [c000000000175340] parse_args+0x290/0x4e0^M > > [ 0.000000][ T0] [c000000002867e10] [c000000002003c74] parse_early_options+0x48/0x5c^M > > [ 0.000000][ T0] [c000000002867e30] [c000000002003ce0] parse_early_param+0x58/0x84^M > > [ 0.000000][ T0] [c000000002867e60] [c000000002009878] early_init_devtree+0xd4/0x518^M > > [ 0.000000][ T0] [c000000002867f10] [c00000000200aee0] early_setup+0xb4/0x214^M > > > > After this fix, the WARN does not show again. > > Hi Zhouyi, Thank Michael for your guidance. > > We have hit something like this previously, see the stack trace in > commit e7eb919057c3 ("powerpc/64s: Handle program checks in wrong endian > during early boot"). I am learning the fantastic work by you (git log -p e7eb919057c3), e7eb919057c3 provides a trampoline to detect and correct the wrong endian when handling the exception caused by the WARN (static key used before call to jump_label_init) > > That was fixed incidentally/accidentally by the page_poison code > changing to not use static keys so early. > > There was a similar case recently in the random code too, see > 60e5b2886b92 ("random: do not use jump labels before they are > initialized"). I am also studying 60e5b2886b92, this commit delays the use of the static key after jump_label_init is called. > > But I guess this will keep happening, as generic code authors expect to > be able to use static keys in early_param() handlers. > > I think the ideal solution would be to move most early param parsing > later. There's only a few parameters that need to be parsed that early > in early_init_devtree(). That would be a complex and error-prone change > though, so I won't ask you to do that :) Yes, as a beginner, I like to study technologies, but I am not able to do such a complex job ;-) > > But I think it would be better if you moved the call to > jump_label_init() into early_init_devtree(), just before we call > parse_early_param(), with a comment saying that it's required to call it > before parsing early params. OK, I will do that. > > And ... > > > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > > index 2b2d0b0fbb30..bf2fb76221da 100644 > > --- a/arch/powerpc/kernel/setup_64.c > > +++ b/arch/powerpc/kernel/setup_64.c > > @@ -365,6 +365,9 @@ void __init early_setup(unsigned long dt_ptr) > > > > udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr); > > > > + /* Initialise jump label because subsequent calls need it */ > > + jump_label_init(); > > + > > /* > > * Do early initialization using the flattened device > > * tree, such as retrieving the physical memory map or > > @@ -394,8 +397,15 @@ void __init early_setup(unsigned long dt_ptr) > > > > /* Apply all the dynamic patching */ > > apply_feature_fixups(); > > - setup_feature_keys(); > > I think you can just leave this as-is, it's fine to call > jump_label_init() more than once. Thanks again for your guidance ;-) I will try to make a second version of the PATCH tomorrow. Anyhow, this is a valuable learning process for me ;-) Many Thank Best Regards Zhouyi > > > + > > + /* > > + * All the cpu/mmu_has_feature() checks take on their correct polarity > > + * based on the current set of CPU/MMU features. These should be done > > + * only after early_init_devtree. > > + */ > > + cpu_feature_keys_init(); > > + mmu_feature_keys_init(); > > + > > > > /* Initialize the hash table or TLB handling */ > > early_init_mmu(); > > -- > > 2.25.1 > > cheers
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 2b2d0b0fbb30..bf2fb76221da 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -365,6 +365,9 @@ void __init early_setup(unsigned long dt_ptr) udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr); + /* Initialise jump label because subsequent calls need it */ + jump_label_init(); + /* * Do early initialization using the flattened device * tree, such as retrieving the physical memory map or @@ -394,8 +397,15 @@ void __init early_setup(unsigned long dt_ptr) /* Apply all the dynamic patching */ apply_feature_fixups(); - setup_feature_keys(); + + /* + * All the cpu/mmu_has_feature() checks take on their correct polarity + * based on the current set of CPU/MMU features. These should be done + * only after early_init_devtree. + */ + cpu_feature_keys_init(); + mmu_feature_keys_init(); + /* Initialize the hash table or TLB handling */ early_init_mmu(); --