- 02 Dec, 2021 3 commits
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Nicholas Piggin authored
The pseries platform does not use the native hash code but the PAPR virtualised hash interfaces, so remove PPC_HASH_MMU_NATIVE. This requires moving tlbiel code from hash_native.c to hash_utils.c. Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-4-npiggin@gmail.com
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Nicholas Piggin authored
PPC_NATIVE now only controls the native HPT code, so rename it to be more descriptive. Restrict it to Book3S only. Signed-off-by:
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Nicholas Piggin authored
FW_FEATURE_NATIVE_ALWAYS and FW_FEATURE_NATIVE_POSSIBLE are always zero and never do anything. Remove them. Signed-off-by:
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- 01 Dec, 2021 2 commits
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Cédric Le Goater authored
The automatic "save & restore" of interrupt context is a POWER10/XIVE2 feature exploited by KVM under the PowerNV platform. It is not available under pSeries and the associated toggle should not be exposed under the XIVE debugfs directory. Introduce a platform handler for debugfs initialization and move the 'save-restore' entry under the native (PowerNV) backend to fix compile when !CONFIG_PPC_POWERNV. Fixes: 1e7684dc ("powerpc/xive: Add a debugfs toggle for save-restore") Reported-by:
kernel test robot <lkp@intel.com> Signed-off-by:
Cédric Le Goater <clg@kaod.org> Signed-off-by:
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Kees Cook authored
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Add a struct_group() for the spe registers so that memset() can correctly reason about the size: In function 'fortify_memset_chk', inlined from 'restore_user_regs.part.0' at arch/powerpc/kernel/signal_32.c:539:3: >> include/linux/fortify-string.h:195:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 195 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ Reported-by:Kees Cook <keescook@chromium.org> Reviewed-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by:
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- 30 Nov, 2021 8 commits
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Christophe Leroy authored
================================================================================ UBSAN: shift-out-of-bounds in arch/powerpc/mm/kasan/book3s_32.c:22:23 shift exponent -1 is negative CPU: 0 PID: 0 Comm: swapper Not tainted 5.15.5-gentoo-PowerMacG4 #9 Call Trace: [c214be60] [c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable) [c214be80] [c0b99288] ubsan_epilogue+0x10/0x5c [c214be90] [c0b98fe0] __ubsan_handle_shift_out_of_bounds+0x94/0x138 [c214bf00] [c1c0f010] kasan_init_region+0xd8/0x26c [c214bf30] [c1c0ed84] kasan_init+0xc0/0x198 [c214bf70] [c1c08024] setup_arch+0x18/0x54c [c214bfc0] [c1c037f0] start_kernel+0x90/0x33c [c214bff0] [00003610] 0x3610 ================================================================================ This happens when the directly mapped memory is a power of 2. Fix it by checking the shift and set the result to 0 when shift is -1 Fixes: 7974c473 ("powerpc/32s: Implement dedicated kasan_init_region()") Reported-by:
Erhard Furtner <erhard_f@mailbox.org> Signed-off-by:
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Christophe Leroy authored
KeyWest i2c @0xf8001003 irq 42 /uni-n@f8000000/i2c@f8001000 BUG: key c2d00cbc has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:4801 lockdep_init_map_type+0x4c0/0xb4c Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.5-gentoo-PowerMacG4 #9 NIP: c01a9428 LR: c01a9428 CTR: 00000000 REGS: e1033cf0 TRAP: 0700 Not tainted (5.15.5-gentoo-PowerMacG4) MSR: 00029032 <EE,ME,IR,DR,RI> CR: 24002002 XER: 00000000 GPR00: c01a9428 e1033db0 c2d1cf20 00000016 00000004 00000001 c01c0630 e1033a73 GPR08: 00000000 00000000 00000000 e1033db0 24002004 00000000 f8729377 00000003 GPR16: c1829a9c 00000000 18305357 c1416fc0 c1416f80 c006ac60 c2d00ca8 c1416f00 GPR24: 00000000 c21586f0 c2160000 00000000 c2d00cbc c2170000 c216e1a0 c2160000 NIP [c01a9428] lockdep_init_map_type+0x4c0/0xb4c LR [c01a9428] lockdep_init_map_type+0x4c0/0xb4c Call Trace: [e1033db0] [c01a9428] lockdep_init_map_type+0x4c0/0xb4c (unreliable) [e1033df0] [c1c177b8] kw_i2c_add+0x334/0x424 [e1033e20] [c1c18294] pmac_i2c_init+0x9ec/0xa9c [e1033e80] [c1c1a790] smp_core99_probe+0xbc/0x35c [e1033eb0] [c1c03cb0] kernel_init_freeable+0x190/0x5a4 [e1033f10] [c000946c] kernel_init+0x28/0x154 [e1033f30] [c0035148] ret_from_kernel_thread+0x14/0x1c Add missing lockdep_register_key() Reported-by:
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Christophe Leroy authored
module_alloc() first tries to allocate module text within 24 bits direct jump from kernel text, and tries a wider allocation if first one fails. When first allocation fails the following is observed in kernel logs: vmap allocation for size 2400256 failed: use vmalloc=<size> to increase size systemd-udevd: vmalloc error: size 2395133b, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null) CPU: 0 PID: 127 Comm: systemd-udevd Tainted: G W 5.15.5-gentoo-PowerMacG4 #9 Call Trace: [e2a53a50] [c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable) [e2a53a70] [c0540128] warn_alloc+0x11c/0x2b4 [e2a53b50] [c0531be8] __vmalloc_node_range+0xd8/0x64c [e2a53c10] [c00338c0] module_alloc+0xa0/0xac [e2a53c40] [c027a368] load_module+0x2ae0/0x8148 [e2a53e30] [c027fc78] sys_finit_module+0xfc/0x130 [e2a53f30] [c0035098] ret_from_syscall+0x0/0x28 ... Add __GFP_NOWARN flag to first allocation so that no warning appears when it fails. Reported-by:
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Nicholas Piggin authored
Allow the LPID bit width and partition table size to be set at runtime from the device tree. Move the PID bit width detection into the same place. KVM does not support using the extra bits yet, this is mainly required to get the PTCR register values correct (so KVM will run but it will not allocate > 4096 LPIDs). OPAL firmware provides this property for POWER10 CPUs since skiboot commit 9b85f7d961f2 ("hdata: add mmu-pid-bits and mmu-lpid-bits for POWER10 CPUs"). Signed-off-by:Fabiano Rosas <farosas@linux.ibm.com> Signed-off-by:
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Athira Rajeev authored
Running perf fuzzer showed below in dmesg logs: "Can't find PMC that caused IRQ" This means a PMU exception happened, but none of the PMC's (Performance Monitor Counter) were found to be overflown. There are some corner cases that clears the PMCs after PMI gets masked. In such cases, the perf interrupt handler will not find the active PMC values that had caused the overflow and thus leads to this message while replaying. Case 1: PMU Interrupt happens during replay of other interrupts and counter values gets cleared by PMU callbacks before replay: During replay of interrupts like timer, __do_irq() and doorbell exception, we conditionally enable interrupts via may_hard_irq_enable(). This could potentially create a window to generate a PMI. Since irq soft mask is set to ALL_DISABLED, the PMI will get masked here. We could get IPIs run before perf interrupt is replayed and the PMU events could be deleted or stopped. This will change the PMU SPR values and resets the counters. Snippet of ftrace log showing PMU callbacks invoked in __do_irq(): <idle>-0 [051] dns. 132025441306354: __do_irq <-call_do_irq <idle>-0 [051] dns. 132025441306430: irq_enter <-__do_irq <idle>-0 [051] dns. 132025441306503: irq_enter_rcu <-__do_irq <idle>-0 [051] dnH. 132025441306599: xive_get_irq <-__do_irq <<>> <idle>-0 [051] dnH. 132025441307770: generic_smp_call_function_single_interrupt <-smp_ipi_demux_relaxed <idle>-0 [051] dnH. 132025441307839: flush_smp_call_function_queue <-smp_ipi_demux_relaxed <idle>-0 [051] dnH. 132025441308057: _raw_spin_lock <-event_function <idle>-0 [051] dnH. 132025441308206: power_pmu_disable <-perf_pmu_disable <idle>-0 [051] dnH. 132025441308337: power_pmu_del <-event_sched_out <idle>-0 [051] dnH. 132025441308407: power_pmu_read <-power_pmu_del <idle>-0 [051] dnH. 132025441308477: read_pmc <-power_pmu_read <idle>-0 [051] dnH. 132025441308590: isa207_disable_pmc <-power_pmu_del <idle>-0 [051] dnH. 132025441308663: write_pmc <-power_pmu_del <idle>-0 [051] dnH. 132025441308787: power_pmu_event_idx <-perf_event_update_userpage <idle>-0 [051] dnH. 132025441308859: rcu_read_unlock_strict <-perf_event_update_userpage <idle>-0 [051] dnH. 132025441308975: power_pmu_enable <-perf_pmu_enable <<>> <idle>-0 [051] dnH. 132025441311108: irq_exit <-__do_irq <idle>-0 [051] dns. 132025441311319: performance_monitor_exception <-replay_soft_interrupts Case 2: PMI's masked during local_* operations, example local_add(). If the local_add() operation happens within a local_irq_save(), replay of PMI will be during local_irq_restore(). Similar to case 1, this could also create a window before replay where PMU events gets deleted or stopped. Fix it by updating the PMU callback function power_pmu_disable() to check for pending perf interrupt. If there is an overflown PMC and pending perf interrupt indicated in paca, clear the PMI bit in paca to drop that sample. Clearing of PMI bit is done in power_pmu_disable() since disable is invoked before any event gets deleted/stopped. With this fix, if there are more than one event running in the PMU, there is a chance that we clear the PMI bit for the event which is not getting deleted/stopped. The other events may still remain active. Hence to make sure we don't drop valid sample in such cases, another check is added in power_pmu_enable. This checks if there is an overflown PMC found among the active events and if so enable back the PMI bit. Two new helper functions are introduced to clear/set the PMI, ie clear_pmi_irq_pending() and set_pmi_irq_pending(). Helper function pmi_irq_pending() is introduced to give a warning if there is pending PMI bit in paca, but no PMC is overflown. Also there are corner cases which result in performance monitor interrupts being triggered during power_pmu_disable(). This happens since PMXE bit is not cleared along with disabling of other MMCR0 bits in the pmu_disable. Such PMI's could leave the PMU running and could trigger PMI again which will set MMCR0 PMAO bit. This could lead to spurious interrupts in some corner cases. Example, a timer after power_pmu_del() which will re-enable interrupts and triggers a PMI again since PMAO bit is still set. But fails to find valid overflow since PMC was cleared in power_pmu_del(). Fix that by disabling PMXE along with disabling of other MMCR0 bits in power_pmu_disable(). We can't just replay PMI any time. Hence this approach is preferred rather than replaying PMI before resetting overflown PMC. Patch also documents core-book3s on a race condition which can trigger these PMC messages during idle path in PowerNV. Fixes: f442d004 ("powerpc/64s: Add support to mask perf interrupts and replay them") Reported-by:
Nageswara R Sastry <nasastry@in.ibm.com> Suggested-by:
Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by:
Athira Rajeev <atrajeev@linux.vnet.ibm.com> Tested-by:
Nageswara R Sastry <rnsastry@linux.ibm.com> Reviewed-by:
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Christophe Leroy authored
Now that atomic_add() and atomic_sub() handle immediate operands, atomic_inc() and atomic_dec() have no added value compared to the generic fallback which calls atomic_add(1) and atomic_sub(1). Also remove atomic_inc_not_zero() which fallsback to atomic_add_unless() which itself fallsback to atomic_fetch_add_unless() which now handles immediate operands. Signed-off-by:
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Christophe Leroy authored
Today we get the following code generation for atomic operations: c001bb2c: 39 20 00 01 li r9,1 c001bb30: 7d 40 18 28 lwarx r10,0,r3 c001bb34: 7d 09 50 50 subf r8,r9,r10 c001bb38: 7d 00 19 2d stwcx. r8,0,r3 c001c7a8: 39 40 00 01 li r10,1 c001c7ac: 7d 00 18 28 lwarx r8,0,r3 c001c7b0: 7c ea 42 14 add r7,r10,r8 c001c7b4: 7c e0 19 2d stwcx. r7,0,r3 By allowing GCC to choose between immediate or regular operation, we get: c001bb2c: 7d 20 18 28 lwarx r9,0,r3 c001bb30: 39 49 ff ff addi r10,r9,-1 c001bb34: 7d 40 19 2d stwcx. r10,0,r3 -- c001c7a4: 7d 40 18 28 lwarx r10,0,r3 c001c7a8: 39 0a 00 01 addi r8,r10,1 c001c7ac: 7d 00 19 2d stwcx. r8,0,r3 For "and", the dot form has to be used because "andi" doesn't exist. For logical operations we use unsigned 16 bits immediate. For arithmetic operations we use signed 16 bits immediate. On pmac32_defconfig, it reduces the text by approx another 8 kbytes. Signed-off-by:
Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by:
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Christophe Leroy authored
Today we get the following code generation for bitops like set or clear bit: c0009fe0: 39 40 08 00 li r10,2048 c0009fe4: 7c e0 40 28 lwarx r7,0,r8 c0009fe8: 7c e7 53 78 or r7,r7,r10 c0009fec: 7c e0 41 2d stwcx. r7,0,r8 c000d568: 39 00 18 00 li r8,6144 c000d56c: 7c c0 38 28 lwarx r6,0,r7 c000d570: 7c c6 40 78 andc r6,r6,r8 c000d574: 7c c0 39 2d stwcx. r6,0,r7 Most set bits are constant on lower 16 bits, so it can easily be replaced by the "immediate" version of the operation. Allow GCC to choose between the normal or immediate form. For clear bits, on 32 bits 'rlwinm' can be used instead of 'andc' for when all bits to be cleared are consecutive. On 64 bits we don't have any equivalent single operation for clearing, single bits or a few bits, we'd need two 'rldicl' so it is not worth it, the li/andc sequence is doing the same. With this patch we get: c0009fe0: 7d 00 50 28 lwarx r8,0,r10 c0009fe4: 61 08 08 00 ori r8,r8,2048 c0009fe8: 7d 00 51 2d stwcx. r8,0,r10 c000d558: 7c e0 40 28 lwarx r7,0,r8 c000d55c: 54 e7 05 64 rlwinm r7,r7,0,21,18 c000d560: 7c e0 41 2d stwcx. r7,0,r8 On pmac32_defconfig, it reduces the text by approx 10 kbytes. Signed-off-by:
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- 29 Nov, 2021 16 commits
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Nicholas Piggin authored
Introduce macros that operate on a (start, end) range of GPRs, which reduces lines of code and need to do mental arithmetic while reading the code. Signed-off-by:
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Nicholas Piggin authored
The printk layer at the moment does not seem to have a good way to force flush printk messages that are created in NMI context, except in the panic path. NMI-context printk messages normally get to the console with irq_work, but that won't help if the CPU is stuck with irqs disabled, as can be the case for hard lockup watchdog messages. The watchdog currently flushes the printk buffers after detecting a lockup on remote CPUs, but they may not have processed their NMI IPI yet by that stage, or they may have self-detected a lockup in which case they won't go via this NMI IPI path. Improve the situation by having NMI-context mark a flag if it called printk, and have watchdog timer interrupts check if that flag was set and try to flush if it was. Latency is not a big problem because we were already stuck for a while, just need to try to make sure the messages eventually make it out. Depends-on: 5d5e4522 ("printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces") Signed-off-by:
Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by:
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Christophe Leroy authored
Since commit 9a427556 ("vmlinux.lds.h: catch compound literals into data and BSS") .data..Lubsan sections are taken into account in DATA_MAIN which is included in DATA_DATA macro. No need to take care of them anymore in powerpc vmlinux.lds.S Signed-off-by:
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Christophe Leroy authored
We have wrong units on BAT's sizes (G instead of M, M instead of ...) ---[ Instruction Block Address Translation ]--- 0: 0xc0000000-0xc03fffff 0x00000000 4G Kernel x m 1: 0xc0400000-0xc05fffff 0x00400000 2G Kernel x m 2: 0xc0600000-0xc06fffff 0x00600000 1G Kernel x m 3: 0xc0700000-0xc077ffff 0x00700000 512M Kernel x m 4: 0xc0780000-0xc079ffff 0x00780000 128M Kernel x m 5: 0xc07a0000-0xc07bffff 0x007a0000 128M Kernel x m 6: - 7: - This is because pt_dump_size() expects a size in Kbytes but bat_show_603() gives the size in bytes. To avoid risk of confusion, change pt_dump_size() to take bytes. Signed-off-by:
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Christophe Leroy authored
Unlike PPC64, PPC32 doesn't require any special compiler option to get _mcount() call not clobbering registers. Provide ftrace_regs_caller() and ftrace_regs_call() and activate HAVE_DYNAMIC_FTRACE_WITH_REGS. That's heavily copied from ftrace_64_mprofile.S For the time being leave livepatching aside, it will come with following patch. Signed-off-by:
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Christophe Leroy authored
module_trampoline_target() is used by __ftrace_modify_call(). Implement it for PPC32 so that CONFIG_DYNAMIC_FTRACE_WITH_REGS can be activated on PPC32 as well. Signed-off-by:
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Christophe Leroy authored
All functions calling _mcount do it exactly the same way, with the following sequence of instructions: c07de788: 7c 08 02 a6 mflr r0 c07de78c: 90 01 00 04 stw r0,4(r1) c07de790: 4b 84 13 65 bl c001faf4 <_mcount> Allthough LR is pushed on stack, it is still in r0 while entering _mcount(). Function arguments are in r3-r10, so r11 and r12 are still available at that point. Do like PPC64 and use r12 to move LR into CTR, so that r0 is preserved and doesn't need to be restored from the stack. While at it, bring back the EXPORT_SYMBOL at the end of _mcount. Signed-off-by:
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Michael Ellerman authored
Prior to commit b1923caa ("powerpc: Merge 32-bit and 64-bit setup_arch()") probe_machine() was called from setup_32/64.c and lived in setup-common.c. But now it's only called from setup-common.c so it can be static and __init, and we don't need the declaration in machdep.h either. Signed-off-by:
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Michael Ellerman authored
setup_profiling_timer() is only needed when CONFIG_PROFILING is enabled. Fixes the following W=1 warning when CONFIG_PROFILING=n: linux/arch/powerpc/kernel/smp.c:1638:5: error: no previous prototype for ‘setup_profiling_timer’ Signed-off-by:
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Michael Ellerman authored
Building with W=1 we see a warning: linux/arch/powerpc/mm/nohash/fsl_book3e.c:63:15: error: no previous prototype for ‘tlbcam_sz’ tlbcam_sz() is not used outside this file, so we can make it static. However it's only used inside #ifdef CONFIG_PPC32, so move it within that ifdef, otherwise we would get a defined but not used error. Signed-off-by:
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Michael Ellerman authored
To fix the W=1 warning: linux/arch/powerpc/platforms/85xx/c293pcie.c:22:13: error: no previous prototype for ‘c293_pcie_pic_init’ Signed-off-by:
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Michael Ellerman authored
To fix the W=1 warning: arch/powerpc/platforms/85xx/smp.c:369:6: error: no previous prototype for ‘mpc85xx_smp_kexec_cpu_down’ Signed-off-by:
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Michael Ellerman authored
Fixes the following W=1 warning: arch/powerpc/platforms/85xx/mpc85xx_pm_ops.c:89:12: warning: no previous prototype for 'mpc85xx_setup_pmc' Reported-by:
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Nicholas Piggin authored
Some core kernel code starts to go beyond the 2048 byte stack size warning at NR_CPUS=8192, so select CPUMASK_OFFSTACK in that case. x86 does similarly for very large NR_CPUS. Signed-off-by:
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Nicholas Piggin authored
This function builds the cores online map with on-stack cpumasks which can cause high stack usage with large NR_CPUS. It is not used in any performance sensitive paths, so instead just check for first thread sibling. Signed-off-by:
Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by:
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Michael Ellerman authored
This reverts commit 8b8a8f0a. As reported[1] by Sachin this causes problems with ftrace, and it also causes the code patching selftests to fail as reported[2] by Stephen. So revert it for now. 1: https://lore.kernel.org/linuxppc-dev/3668743C-09DF-4673-B15C-2FFE2A57F7D7@linux.vnet.ibm.com/ 2: https://lore.kernel.org/linuxppc-dev/20211126161747.1f7795b0@canb.auug.org.au/Signed-off-by:
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- 25 Nov, 2021 11 commits
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Nicholas Piggin authored
wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of marking CPUs stuck and removing them from the pending mask before it begins any printing. This causes last reset times reported to be off. Fix this by reading it into a local variable before it gets reset. Fixes: 76521c4b ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi") Signed-off-by:
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Michael Ellerman authored
Make microwatt_get_random_darn() static, because it can be. Reported-by:
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Nicholas Piggin authored
When taking watchdog actions, printing messages, comparing and re-setting wd_smp_last_reset_tb, etc., read TB close to the point of use and under wd_smp_lock or printing lock (if applicable). This should keep timebase mostly monotonic with kernel log messages, and could prevent (in theory) a laggy CPU updating wd_smp_last_reset_tb to something a long way in the past, and causing other CPUs to appear to be stuck. These additional TB reads are all slowpath (lockup has been detected), so performance does not matter. Signed-off-by:
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Nicholas Piggin authored
There is a deadlock with the console_owner lock and the wd_smp_lock: CPU x takes the console_owner lock CPU y takes a watchdog timer interrupt and takes __wd_smp_lock CPU x takes a soft-NMI interrupt, detects deadlock, spins on __wd_smp_lock CPU y detects deadlock, tries to print something and spins on console_owner -> deadlock Change the watchdog locking scheme so wd_smp_lock protects the watchdog internal data, but "reporting" (printing, issuing NMI IPIs, taking any action outside of watchdog) uses a non-waiting exclusion. If a CPU detects a problem but can not take the reporting lock, it just returns because something else is already reporting. It will try again at some point. Typically hard lockup watchdog report usefulness is not impacted due to failure to spewing a large enough amount of data in as short a time as possible, but by messages getting garbled. Laurent debugged this and found the deadlock, and this patch is based on his general approach to avoid expensive operations while holding the lock. With the addition of the reporting exclusion. Signed-off-by:
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Nicholas Piggin authored
Most updates to wd_smp_cpus_pending are under lock except the watchdog interrupt bit clear. This can race with non-atomic RMW updates to the mask under lock, which can happen in two instances: Firstly, if another CPU detects this one is stuck, removes it from the mask, mask becomes empty and is re-filled with non-atomic stores. This is okay because it would re-fill the mask with this CPU's bit clear anyway (because this CPU is now stuck), so it doesn't matter that the bit clear update got "lost". Add a comment for this. Secondly, if another CPU detects a different CPU is stuck and removes it from the pending mask with a non-atomic store to bytes which also include the bit of this CPU. This case can result in the bit clear being lost and the end result being the bit is set. This should be so rare it hardly matters, but to make things simpler to reason about just avoid the non-atomic access for that case. Signed-off-by:
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Nicholas Piggin authored
It is possible for all CPUs to miss the pending cpumask becoming clear, and then nobody resetting it, which will cause the lockup detector to stop working. It will eventually expire, but watchdog_smp_panic will avoid doing anything if the pending mask is clear and it will never be reset. Order the cpumask clear vs the subsequent test to close this race. Add an extra check for an empty pending mask when the watchdog fires and finds its bit still clear, to try to catch any other possible races or bugs here and keep the watchdog working. The extra test in arch_touch_nmi_watchdog is required to prevent the new warning from firing off. Signed-off-by:
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Peiwei Hu authored
prom_getprop() can return PROM_ERROR. Binary operator can not identify it. Fixes: 94d2dde7 ("[POWERPC] Efika: prune fixups and make them more carefull") Signed-off-by:
Peiwei Hu <jlu.hpw@foxmail.com> Signed-off-by:
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Nathan Lynch authored
Provide API documentation for rtas_busy_delay_time(), explaining why we return the same value for 9900 and -2. Signed-off-by:
Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by:
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Nathan Lynch authored
Generally RTAS cannot block, and in PAPR it is required to return control to the OS within a few tens of microseconds. In order to support operations which may take longer to complete, many RTAS primitives can return intermediate -2 ("busy") or 990x ("extended delay") values, which indicate that the OS should reattempt the same call with the same arguments at some point in the future. Current versions of PAPR are less than clear about this, but the intended meanings of these values in more detail are: RTAS_BUSY (-2): RTAS has suspended a potentially long-running operation in order to meet its latency obligation and give the OS the opportunity to perform other work. RTAS can resume making progress as soon as the OS reattempts the call. RTAS_EXTENDED_DELAY_{MIN...MAX} (9900-9905): RTAS must wait for an external event to occur or for internal contention to resolve before it can complete the requested operation. The value encodes a non-binding hint as to roughly how long the OS should wait before calling again, but the OS is allowed to reattempt the call sooner or even immediately. Linux of course must take its own CPU scheduling obligations into account when handling these statuses; e.g. a task which receives an RTAS_BUSY status should check whether to reschedule before it attempts the RTAS call again to avoid starving other tasks. rtas_busy_delay() is a helper function that "consumes" a busy or extended delay status. Common usage: int rc; do { rc = rtas_call(rtas_token("some-function"), ...); } while (rtas_busy_delay(rc)); /* convert rc to Linux error value, etc */ If rc is a busy or extended delay status, the caller can rely on rtas_busy_delay() to perform an appropriate sleep or reschedule and return nonzero. Other statuses are handled normally by the caller. The current implementation of rtas_busy_delay() both oversleeps and overuses the CPU: * It performs msleep() for all 990x and even when no delay is suggested (-2), but this is understood to actually sleep for two jiffies minimum in practice (20ms with HZ=100). 9900 (1ms) and 9901 (10ms) appear to be the most common extended delay statuses, and the oversleeping measurably lengthens DLPAR operations, which perform many RTAS calls. * It does not sleep on 990x unless need_resched() is true, causing code like the loop above to needlessly retry, wasting CPU time. Alter the logic to align better with the intended meanings: * When passed RTAS_BUSY, perform cond_resched() and return without sleeping. The caller should reattempt immediately * Always sleep when passed an extended delay status, using usleep_range() for precise shorter sleeps. Limit the sleep time to one second even though there are higher architected values. Change rtas_busy_delay()'s return type to bool to better reflect its usage, and add kernel-doc. rtas_busy_delay_time() is unchanged, even though it "incorrectly" returns 1 for RTAS_BUSY. There are users of that API with open-coded delay loops in sensitive contexts that will have to be taken on an individual basis. Brief results for addition and removal of 5GB memory on a small P9 PowerVM partition follow. Load was generated with stress-ng --cpu N. For add, elapsed time is greatly reduced without significant change in the number of RTAS calls or time spent on CPU. For remove, elapsed time is modestly reduced, with significant reductions in RTAS calls and time spent on CPU. With no competing workload (- before, + after): Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs): - 1,935 probe:rtas_call # 0.003 M/sec ( +- 0.22% ) - 609.99 msec task-clock # 0.183 CPUs utilized ( +- 0.19% ) + 1,956 probe:rtas_call # 0.003 M/sec ( +- 0.17% ) + 618.56 msec task-clock # 0.278 CPUs utilized ( +- 0.11% ) - 3.3322 +- 0.0670 seconds time elapsed ( +- 2.01% ) + 2.2222 +- 0.0416 seconds time elapsed ( +- 1.87% ) Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs): - 6,224 probe:rtas_call # 0.008 M/sec ( +- 2.57% ) - 750.36 msec task-clock # 0.190 CPUs utilized ( +- 2.01% ) + 843 probe:rtas_call # 0.003 M/sec ( +- 0.12% ) + 250.66 msec task-clock # 0.068 CPUs utilized ( +- 0.17% ) - 3.9394 +- 0.0890 seconds time elapsed ( +- 2.26% ) + 3.678 +- 0.113 seconds time elapsed ( +- 3.07% ) With all CPUs 100% busy (- before, + after): Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs): - 2,979 probe:rtas_call # 0.003 M/sec ( +- 0.12% ) - 1,096.62 msec task-clock # 0.105 CPUs utilized ( +- 0.10% ) + 2,981 probe:rtas_call # 0.003 M/sec ( +- 0.22% ) + 1,095.26 msec task-clock # 0.154 CPUs utilized ( +- 0.21% ) - 10.476 +- 0.104 seconds time elapsed ( +- 1.00% ) + 7.1124 +- 0.0865 seconds time elapsed ( +- 1.22% ) Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs): - 2,702 probe:rtas_call # 0.004 M/sec ( +- 4.00% ) - 722.71 msec task-clock # 0.067 CPUs utilized ( +- 2.41% ) + 1,246 probe:rtas_call # 0.003 M/sec ( +- 0.25% ) + 487.73 msec task-clock # 0.049 CPUs utilized ( +- 0.20% ) - 10.829 +- 0.163 seconds time elapsed ( +- 1.51% ) + 9.9887 +- 0.0866 seconds time elapsed ( +- 0.87% ) Signed-off-by: -
Nathan Lynch authored
Remove the pseries scanlog driver. This code supports functions from Power4-era servers that are not present on targets currently supported by arch/powerpc. System manuals from this time have this description: Scan Dump data is a set of chip data that the service processor gathers after a system malfunction. It consists of chip scan rings, chip trace arrays, and Scan COM (SCOM) registers. This data is stored in the scan-log partition of the system’s Nonvolatile Random Access Memory (NVRAM). PowerVM partition firmware development doesn't recognize the associated function call or property, and they don't see any references to them in their codebase. It seems to have been specific to non-virtualized pseries. References: Historical Linux commit from February 2003 (interesting to note this seems to be the source of non-GPL exports for rtas_call etc): https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=f92e361842d5251e50562b09664082dcbd0548bb IntelliStation and pSeries docs which refer to the feature: http://ps-2.retropc.se/basil.holloway/ALL%20PDF/380635.pdf http://ps-2.kev009.com/rs6000/manuals/p/p615-6C3-6E3/6C3_and_6E3_Users_Guide_SA38-0629.pdfSigned-off-by:
Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by:
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Nathan Lynch authored
Fix the following issues reported by kernel-doc: $ scripts/kernel-doc -v -none arch/powerpc/kernel/rtas.c arch/powerpc/kernel/rtas.c:810: info: Scanning doc for function rtas_activate_firmware arch/powerpc/kernel/rtas.c:818: warning: contents before sections arch/powerpc/kernel/rtas.c:841: info: Scanning doc for function rtas_call_reentrant arch/powerpc/kernel/rtas.c:893: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst * Find a specific pseries error log in an RTAS extended event log. Signed-off-by:
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