kernel.git/arch/arm64/kernel, branch linux-5.9.y

sched/idle: Fix arch_cpu_idle() vs tracing

2020-12-16T09:58:32Z

[ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ] We call arch_cpu_idle() with RCU disabled, but then use local_irq_{en,dis}able(), which invokes tracing, which relies on RCU. Switch all arch_cpu_idle() implementations to use raw_local_irq_{en,dis}able() and carefully manage the lockdep,rcu,tracing state like we do in entry. (XXX: we really should change arch_cpu_idle() to not return with interrupts enabled) Reported-by: Sven Schnelle Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mark Rutland Tested-by: Mark Rutland Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org Signed-off-by: Sasha Levin

arm64: cpu_errata: Apply Erratum 845719 to KRYO2XX Silver

2020-11-24T12:38:54Z

[ Upstream commit 23c216416056148136bdaf0cdd18caf4904bb6e1 ] QCOM KRYO2XX Silver cores are Cortex-A53 based and are susceptible to the 845719 erratum. Add them to the lookup list to apply the erratum. Signed-off-by: Konrad Dybcio Link: https://lore.kernel.org/r/20201104232218.198800-5-konrad.dybcio@somainline.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: kpti: Add KRYO2XX gold/silver CPU cores to kpti safelist

2020-11-24T12:38:54Z

[ Upstream commit e3dd11a9f2521cecbcf30c2fd17ecc5a445dfb94 ] QCOM KRYO2XX gold (big) silver (LITTLE) CPU cores are based on Cortex-A73 and Cortex-A53 respectively and are meltdown safe, hence add them to kpti_safe_list[]. Signed-off-by: Konrad Dybcio Link: https://lore.kernel.org/r/20201104232218.198800-3-konrad.dybcio@somainline.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: smp: Tell RCU about CPUs that fail to come online

2020-11-24T12:38:53Z

[ Upstream commit 04e613ded8c26489b3e0f9101b44462f780d1a35 ] Commit ce3d31ad3cac ("arm64/smp: Move rcu_cpu_starting() earlier") ensured that RCU is informed early about incoming CPUs that might end up calling into printk() before they are online. However, if such a CPU fails the early CPU feature compatibility checks in check_local_cpu_capabilities(), then it will be powered off or parked without informing RCU, leading to an endless stream of stalls: | rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: | rcu: 2-O...: (0 ticks this GP) idle=002/1/0x4000000000000000 softirq=0/0 fqs=2593 | (detected by 0, t=5252 jiffies, g=9317, q=136) | Task dump for CPU 2: | task:swapper/2 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x00000028 | Call trace: | ret_from_fork+0x0/0x30 Ensure that the dying CPU invokes rcu_report_dead() prior to being powered off or parked. Cc: Qian Cai Cc: "Paul E. McKenney" Reviewed-by: Paul E. McKenney Suggested-by: Qian Cai Link: https://lore.kernel.org/r/20201105222242.GA8842@willie-the-truck Link: https://lore.kernel.org/r/20201106103602.9849-3-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: psci: Avoid printing in cpu_psci_cpu_die()

2020-11-24T12:38:53Z

[ Upstream commit 891deb87585017d526b67b59c15d38755b900fea ] cpu_psci_cpu_die() is called in the context of the dying CPU, which will no longer be online or tracked by RCU. It is therefore not generally safe to call printk() if the PSCI "cpu off" request fails, so remove the pr_crit() invocation. Cc: Qian Cai Cc: "Paul E. McKenney" Cc: Catalin Marinas Link: https://lore.kernel.org/r/20201106103602.9849-2-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: errata: Fix handling of 1418040 with late CPU onlining

2020-11-24T12:38:53Z

[ Upstream commit f969f03888b9438fdb227b6460d99ede5737326d ] In a surprising turn of events, it transpires that CPU capabilities configured as ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE are never set as the result of late-onlining. Therefore our handling of erratum 1418040 does not get activated if it is not required by any of the boot CPUs, even though we allow late-onlining of an affected CPU. In order to get things working again, replace the cpus_have_const_cap() invocation with an explicit check for the current CPU using this_cpu_has_cap(). Cc: Sai Prakash Ranjan Cc: Stephen Boyd Cc: Catalin Marinas Cc: Mark Rutland Reviewed-by: Suzuki K Poulose Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20201106114952.10032-1-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: kexec_file: try more regions if loading segments fails

2020-11-18T18:22:14Z

[ Upstream commit 108aa503657ee2fe8aa071dc620d96372c252ecd ] It's possible that the first region picked for the new kernel will make it impossible to fit the other segments in the required 32GB window, especially if we have a very large initrd. Instead of giving up, we can keep testing other regions for the kernel until we find one that works. Suggested-by: Ryan O'Leary Signed-off-by: Benjamin Gwin Link: https://lore.kernel.org/r/20201103201106.2397844-1-bgwin@google.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

kbuild: explicitly specify the build id style

2020-11-18T18:22:07Z

[ Upstream commit a968433723310f35898b4a2f635a7991aeef66b1 ] ld's --build-id defaults to "sha1" style, while lld defaults to "fast". The build IDs are very different between the two, which may confuse programs that reference them. Signed-off-by: Bill Wendling Acked-by: David S. Miller Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

arm64/smp: Move rcu_cpu_starting() earlier

2020-11-10T11:39:07Z

[ Upstream commit ce3d31ad3cac765484463b4f5a0b6b1f8f1a963e ] The call to rcu_cpu_starting() in secondary_start_kernel() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: WARNING: suspicious RCU usage ----------------------------- kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. Call trace: dump_backtrace+0x0/0x3c8 show_stack+0x14/0x60 dump_stack+0x14c/0x1c4 lockdep_rcu_suspicious+0x134/0x14c __lock_acquire+0x1c30/0x2600 lock_acquire+0x274/0xc48 _raw_spin_lock+0xc8/0x140 vprintk_emit+0x90/0x3d0 vprintk_default+0x34/0x40 vprintk_func+0x378/0x590 printk+0xa8/0xd4 __cpuinfo_store_cpu+0x71c/0x868 cpuinfo_store_cpu+0x2c/0xc8 secondary_start_kernel+0x244/0x318 This is avoided by moving the call to rcu_cpu_starting up near the beginning of the secondary_start_kernel() function. Signed-off-by: Qian Cai Acked-by: Paul E. McKenney Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/ Link: https://lore.kernel.org/r/20201028182614.13655-1-cai@redhat.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

arm64: topology: Stop using MPIDR for topology information

2020-11-05T10:51:19Z

[ Upstream commit 3102bc0e6ac752cc5df896acb557d779af4d82a1 ] In the absence of ACPI or DT topology data, we fallback to haphazardly decoding *something* out of MPIDR. Sadly, the contents of that register are mostly unusable due to the implementation leniancy and things like Aff0 having to be capped to 15 (despite being encoded on 8 bits). Consider a simple system with a single package of 32 cores, all under the same LLC. We ought to be shoving them in the same core_sibling mask, but MPIDR is going to look like: | CPU | 0 | ... | 15 | 16 | ... | 31 | |------+---+-----+----+----+-----+----+ | Aff0 | 0 | ... | 15 | 0 | ... | 15 | | Aff1 | 0 | ... | 0 | 1 | ... | 1 | | Aff2 | 0 | ... | 0 | 0 | ... | 0 | Which will eventually yield core_sibling(0-15) == 0-15 core_sibling(16-31) == 16-31 NUMA woes ========= If we try to play games with this and set up NUMA boundaries within those groups of 16 cores via e.g. QEMU: # Node0: 0-9; Node1: 10-19 $ qemu-system-aarch64 \ -smp 20 -numa node,cpus=0-9,nodeid=0 -numa node,cpus=10-19,nodeid=1 The scheduler's MC domain (all CPUs with same LLC) is going to be built via arch_topology.c::cpu_coregroup_mask() In there we try to figure out a sensible mask out of the topology information we have. In short, here we'll pick the smallest of NUMA or core sibling mask. node_mask(CPU9) == 0-9 core_sibling(CPU9) == 0-15 MC mask for CPU9 will thus be 0-9, not a problem. node_mask(CPU10) == 10-19 core_sibling(CPU10) == 0-15 MC mask for CPU10 will thus be 10-19, not a problem. node_mask(CPU16) == 10-19 core_sibling(CPU16) == 16-19 MC mask for CPU16 will thus be 16-19... Uh oh. CPUs 16-19 are in two different unique MC spans, and the scheduler has no idea what to make of that. That triggers the WARN_ON() added by commit ccf74128d66c ("sched/topology: Assert non-NUMA topology masks don't (partially) overlap") Fixing MPIDR-derived topology ============================= We could try to come up with some cleverer scheme to figure out which of the available masks to pick, but really if one of those masks resulted from MPIDR then it should be discarded because it's bound to be bogus. I was hoping to give MPIDR a chance for SMT, to figure out which threads are in the same core using Aff1-3 as core ID, but Sudeep and Robin pointed out to me that there are systems out there where *all* cores have non-zero values in their higher affinity fields (e.g. RK3288 has "5" in all of its cores' MPIDR.Aff1), which would expose a bogus core ID to userspace. Stop using MPIDR for topology information. When no other source of topology information is available, mark each CPU as its own core and its NUMA node as its LLC domain. Signed-off-by: Valentin Schneider Reviewed-by: Sudeep Holla Link: https://lore.kernel.org/r/20200829130016.26106-1-valentin.schneider@arm.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin