From: Wander Lairson Costa wander@redhat.com

[ Upstream commit d243b34459cea30cfe5f3a9b2feb44e7daff9938 ]

Under PREEMPT_RT, __put_task_struct() indirectly acquires sleeping locks. Therefore, it can't be called from an non-preemptible context.

One practical example is splat inside inactive_task_timer(), which is called in a interrupt context:

CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W --------- Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012 Call Trace: dump_stack_lvl+0x57/0x7d mark_lock_irq.cold+0x33/0xba mark_lock+0x1e7/0x400 mark_usage+0x11d/0x140 __lock_acquire+0x30d/0x930 lock_acquire.part.0+0x9c/0x210 rt_spin_lock+0x27/0xe0 refill_obj_stock+0x3d/0x3a0 kmem_cache_free+0x357/0x560 inactive_task_timer+0x1ad/0x340 __run_hrtimer+0x8a/0x1a0 __hrtimer_run_queues+0x91/0x130 hrtimer_interrupt+0x10f/0x220 __sysvec_apic_timer_interrupt+0x7b/0xd0 sysvec_apic_timer_interrupt+0x4f/0xd0 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0033:0x7fff196bf6f5

Instead of calling __put_task_struct() directly, we defer it using call_rcu(). A more natural approach would use a workqueue, but since in PREEMPT_RT, we can't allocate dynamic memory from atomic context, the code would become more complex because we would need to put the work_struct instance in the task_struct and initialize it when we allocate a new task_struct.

The issue is reproducible with stress-ng:

while true; do stress-ng --sched deadline --sched-period 1000000000 \ --sched-runtime 800000000 --sched-deadline \ 1000000000 --mmapfork 23 -t 20 done

Reported-by: Hu Chunyu chuhu@redhat.com Suggested-by: Oleg Nesterov oleg@redhat.com Suggested-by: Valentin Schneider vschneid@redhat.com Suggested-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Wander Lairson Costa wander@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lore.kernel.org/r/20230614122323.37957-2-wander@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/sched/task.h | 28 +++++++++++++++++++++++++++- kernel/fork.c | 8 ++++++++ 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index d23977e9035d4..0c2d008099151 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -108,10 +108,36 @@ static inline struct task_struct *get_task_struct(struct task_struct *t) }

extern void __put_task_struct(struct task_struct *t); +extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);

static inline void put_task_struct(struct task_struct *t) { - if (refcount_dec_and_test(&t->usage)) + if (!refcount_dec_and_test(&t->usage)) + return; + + /* + * under PREEMPT_RT, we can't call put_task_struct + * in atomic context because it will indirectly + * acquire sleeping locks. + * + * call_rcu() will schedule delayed_put_task_struct_rcu() + * to be called in process context. + * + * __put_task_struct() is called when + * refcount_dec_and_test(&t->usage) succeeds. + * + * This means that it can't "conflict" with + * put_task_struct_rcu_user() which abuses ->rcu the same + * way; rcu_users has a reference so task->usage can't be + * zero after rcu_users 1 -> 0 transition. + * + * delayed_free_task() also uses ->rcu, but it is only called + * when it fails to fork a process. Therefore, there is no + * way it can conflict with put_task_struct(). + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) && !preemptible()) + call_rcu(&t->rcu, __put_task_struct_rcu_cb); + else __put_task_struct(t); }

diff --git a/kernel/fork.c b/kernel/fork.c index ace0717c71e27..753e641f617bd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -764,6 +764,14 @@ void __put_task_struct(struct task_struct *tsk) } EXPORT_SYMBOL_GPL(__put_task_struct);

+void __put_task_struct_rcu_cb(struct rcu_head *rhp) +{ + struct task_struct *task = container_of(rhp, struct task_struct, rcu); + + __put_task_struct(task); +} +EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb); + void __init __weak arch_task_cache_init(void) { }

/*

From: "Paul E. McKenney" paulmck@kernel.org

[ Upstream commit 013608cd0812bdb21fc26d39ed8fdd2fc76e8b9b ]

Kernels built with CONFIG_KASAN=y quarantine newly freed memory in order to better detect use-after-free errors. However, this can exhaust memory more quickly in allocator-heavy tests, which can result in spurious scftorture failure. This commit therefore forgives memory-allocation failure in kernels built with CONFIG_KASAN=y, but continues counting the errors for use in detailed test-result analyses.

Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/scftorture.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/scftorture.c b/kernel/scftorture.c index 27286d99e0c28..41006eef003f6 100644 --- a/kernel/scftorture.c +++ b/kernel/scftorture.c @@ -175,7 +175,8 @@ static void scf_torture_stats_print(void) scfs.n_all_wait += scf_stats_p[i].n_all_wait; } if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || - atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs)) + atomic_read(&n_mb_out_errs) || + (!IS_ENABLED(CONFIG_KASAN) && atomic_read(&n_alloc_errs))) bangstr = "!!! "; pr_alert("%s %sscf_invoked_count %s: %lld resched: %lld single: %lld/%lld single_ofl: %lld/%lld single_rpc: %lld single_rpc_ofl: %lld many: %lld/%lld all: %lld/%lld ", SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count, scfs.n_resched, @@ -327,7 +328,8 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra preempt_disable(); if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) { scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); - if (WARN_ON_ONCE(!scfcp)) { + if (!scfcp) { + WARN_ON_ONCE(!IS_ENABLED(CONFIG_KASAN)); atomic_inc(&n_alloc_errs); } else { scfcp->scfc_cpu = -1;

From: Yicong Yang yangyicong@hisilicon.com

[ Upstream commit 0242737dc4eb9f6e9a5ea594b3f93efa0b12f28d ]

Some HiSilicon SMMU PMCG suffers the erratum 162001900 that the PMU disable control sometimes fail to disable the counters. This will lead to error or inaccurate data since before we enable the counters the counter's still counting for the event used in last perf session.

This patch tries to fix this by hardening the global disable process. Before disable the PMU, writing an invalid event type (0xffff) to focibly stop the counters. Correspondingly restore each events on pmu::pmu_enable().

Signed-off-by: Yicong Yang yangyicong@hisilicon.com Link: https://lore.kernel.org/r/20230814124012.58013-1-yangyicong@huawei.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/arm64/silicon-errata.rst | 3 ++ drivers/acpi/arm64/iort.c | 5 ++- drivers/perf/arm_smmuv3_pmu.c | 46 +++++++++++++++++++++++++- include/linux/acpi_iort.h | 1 + 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 83a75e16e54de..d2f90ecc426f9 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -172,6 +172,9 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | Hisilicon | Hip08 SMMU PMCG | #162001800 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +| Hisilicon | Hip08 SMMU PMCG | #162001900 | N/A | +| | Hip09 SMMU PMCG | | | ++----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ | Qualcomm Tech. | Kryo/Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 | +----------------+-----------------+-----------------+-----------------------------+ diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c index f2f8f05662deb..3dd74ad95d01b 100644 --- a/drivers/acpi/arm64/iort.c +++ b/drivers/acpi/arm64/iort.c @@ -1381,7 +1381,10 @@ static void __init arm_smmu_v3_pmcg_init_resources(struct resource *res, static struct acpi_platform_list pmcg_plat_info[] __initdata = { /* HiSilicon Hip08 Platform */ {"HISI ", "HIP08 ", 0, ACPI_SIG_IORT, greater_than_or_equal, - "Erratum #162001800", IORT_SMMU_V3_PMCG_HISI_HIP08}, + "Erratum #162001800, Erratum #162001900", IORT_SMMU_V3_PMCG_HISI_HIP08}, + /* HiSilicon Hip09 Platform */ + {"HISI ", "HIP09 ", 0, ACPI_SIG_IORT, greater_than_or_equal, + "Erratum #162001900", IORT_SMMU_V3_PMCG_HISI_HIP09}, { } };

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c index 5933ad151f869..1ef683bb40b64 100644 --- a/drivers/perf/arm_smmuv3_pmu.c +++ b/drivers/perf/arm_smmuv3_pmu.c @@ -96,6 +96,7 @@ #define SMMU_PMCG_PA_SHIFT 12

#define SMMU_PMCG_EVCNTR_RDONLY BIT(0) +#define SMMU_PMCG_HARDEN_DISABLE BIT(1)

static int cpuhp_state_num;

@@ -140,6 +141,20 @@ static inline void smmu_pmu_enable(struct pmu *pmu) writel(SMMU_PMCG_CR_ENABLE, smmu_pmu->reg_base + SMMU_PMCG_CR); }

+static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu, + struct perf_event *event, int idx); + +static inline void smmu_pmu_enable_quirk_hip08_09(struct pmu *pmu) +{ + struct smmu_pmu *smmu_pmu = to_smmu_pmu(pmu); + unsigned int idx; + + for_each_set_bit(idx, smmu_pmu->used_counters, smmu_pmu->num_counters) + smmu_pmu_apply_event_filter(smmu_pmu, smmu_pmu->events[idx], idx); + + smmu_pmu_enable(pmu); +} + static inline void smmu_pmu_disable(struct pmu *pmu) { struct smmu_pmu *smmu_pmu = to_smmu_pmu(pmu); @@ -148,6 +163,22 @@ static inline void smmu_pmu_disable(struct pmu *pmu) writel(0, smmu_pmu->reg_base + SMMU_PMCG_IRQ_CTRL); }

+static inline void smmu_pmu_disable_quirk_hip08_09(struct pmu *pmu) +{ + struct smmu_pmu *smmu_pmu = to_smmu_pmu(pmu); + unsigned int idx; + + /* + * The global disable of PMU sometimes fail to stop the counting. + * Harden this by writing an invalid event type to each used counter + * to forcibly stop counting. + */ + for_each_set_bit(idx, smmu_pmu->used_counters, smmu_pmu->num_counters) + writel(0xffff, smmu_pmu->reg_base + SMMU_PMCG_EVTYPER(idx)); + + smmu_pmu_disable(pmu); +} + static inline void smmu_pmu_counter_set_value(struct smmu_pmu *smmu_pmu, u32 idx, u64 value) { @@ -747,7 +778,10 @@ static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu) switch (model) { case IORT_SMMU_V3_PMCG_HISI_HIP08: /* HiSilicon Erratum 162001800 */ - smmu_pmu->options |= SMMU_PMCG_EVCNTR_RDONLY; + smmu_pmu->options |= SMMU_PMCG_EVCNTR_RDONLY | SMMU_PMCG_HARDEN_DISABLE; + break; + case IORT_SMMU_V3_PMCG_HISI_HIP09: + smmu_pmu->options |= SMMU_PMCG_HARDEN_DISABLE; break; }

@@ -836,6 +870,16 @@ static int smmu_pmu_probe(struct platform_device *pdev)

smmu_pmu_get_acpi_options(smmu_pmu);

+ /* + * For platforms suffer this quirk, the PMU disable sometimes fails to + * stop the counters. This will leads to inaccurate or error counting. + * Forcibly disable the counters with these quirk handler. + */ + if (smmu_pmu->options & SMMU_PMCG_HARDEN_DISABLE) { + smmu_pmu->pmu.pmu_enable = smmu_pmu_enable_quirk_hip08_09; + smmu_pmu->pmu.pmu_disable = smmu_pmu_disable_quirk_hip08_09; + } + /* Pick one CPU to be the preferred one to use */ smmu_pmu->on_cpu = raw_smp_processor_id(); WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu))); diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h index f1f0842a2cb2b..43082bd44a999 100644 --- a/include/linux/acpi_iort.h +++ b/include/linux/acpi_iort.h @@ -21,6 +21,7 @@ */ #define IORT_SMMU_V3_PMCG_GENERIC 0x00000000 /* Generic SMMUv3 PMCG */ #define IORT_SMMU_V3_PMCG_HISI_HIP08 0x00000001 /* HiSilicon HIP08 PMCG */ +#define IORT_SMMU_V3_PMCG_HISI_HIP09 0x00000002 /* HiSilicon HIP09 PMCG */

int iort_register_domain_token(int trans_id, phys_addr_t base, struct fwnode_handle *fw_node);

From: Tomislav Novak tnovak@meta.com

[ Upstream commit d11a69873d9a7435fe6a48531e165ab80a8b1221 ]

Arm platforms use is_default_overflow_handler() to determine if the hw_breakpoint code should single-step over the breakpoint trigger or let the custom handler deal with it.

Since bpf_overflow_handler() currently isn't recognized as a default handler, attaching a BPF program to a PERF_TYPE_BREAKPOINT event causes it to keep firing (the instruction triggering the data abort exception is never skipped). For example:

# bpftrace -e 'watchpoint:0x10000:4:w { print("hit") }' -c ./test Attaching 1 probe... hit hit [...] ^C

(./test performs a single 4-byte store to 0x10000)

This patch replaces the check with uses_default_overflow_handler(), which accounts for the bpf_overflow_handler() case by also testing if one of the perf_event_output functions gets invoked indirectly, via orig_default_handler.

Signed-off-by: Tomislav Novak tnovak@meta.com Tested-by: Samuel Gosselin sgosselin@google.com # arm64 Reviewed-by: Catalin Marinas catalin.marinas@arm.com Acked-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/linux-arm-kernel/20220923203644.2731604-1-tnovak@fb.... Link: https://lore.kernel.org/r/20230605191923.1219974-1-tnovak@meta.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/kernel/hw_breakpoint.c | 8 ++++---- arch/arm64/kernel/hw_breakpoint.c | 4 ++-- include/linux/perf_event.h | 22 +++++++++++++++++++--- 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index b1423fb130ea4..8f1fa7aac31fb 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -626,7 +626,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, hw->address &= ~alignment_mask; hw->ctrl.len <<= offset;

- if (is_default_overflow_handler(bp)) { + if (uses_default_overflow_handler(bp)) { /* * Mismatch breakpoints are required for single-stepping * breakpoints. @@ -798,7 +798,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, * Otherwise, insert a temporary mismatch breakpoint so that * we can single-step over the watchpoint trigger. */ - if (!is_default_overflow_handler(wp)) + if (!uses_default_overflow_handler(wp)) continue; step: enable_single_step(wp, instruction_pointer(regs)); @@ -811,7 +811,7 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, info->trigger = addr; pr_debug("watchpoint fired: address = 0x%x\n", info->trigger); perf_bp_event(wp, regs); - if (is_default_overflow_handler(wp)) + if (uses_default_overflow_handler(wp)) enable_single_step(wp, instruction_pointer(regs)); }

@@ -886,7 +886,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) info->trigger = addr; pr_debug("breakpoint fired: address = 0x%x\n", addr); perf_bp_event(bp, regs); - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) enable_single_step(bp, addr); goto unlock; } diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index 2a7f21314cde6..c30fa24458328 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -654,7 +654,7 @@ static int breakpoint_handler(unsigned long unused, unsigned long esr, perf_bp_event(bp, regs);

/* Do we need to handle the stepping? */ - if (is_default_overflow_handler(bp)) + if (uses_default_overflow_handler(bp)) step = 1; unlock: rcu_read_unlock(); @@ -733,7 +733,7 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val, static int watchpoint_report(struct perf_event *wp, unsigned long addr, struct pt_regs *regs) { - int step = is_default_overflow_handler(wp); + int step = uses_default_overflow_handler(wp); struct arch_hw_breakpoint *info = counter_arch_bp(wp);

info->trigger = addr; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 014eb0a963fcb..5806fc4dc7e59 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1084,15 +1084,31 @@ extern int perf_event_output(struct perf_event *event, struct pt_regs *regs);

static inline bool -is_default_overflow_handler(struct perf_event *event) +__is_default_overflow_handler(perf_overflow_handler_t overflow_handler) { - if (likely(event->overflow_handler == perf_event_output_forward)) + if (likely(overflow_handler == perf_event_output_forward)) return true; - if (unlikely(event->overflow_handler == perf_event_output_backward)) + if (unlikely(overflow_handler == perf_event_output_backward)) return true; return false; }

+#define is_default_overflow_handler(event) \ + __is_default_overflow_handler((event)->overflow_handler) + +#ifdef CONFIG_BPF_SYSCALL +static inline bool uses_default_overflow_handler(struct perf_event *event) +{ + if (likely(is_default_overflow_handler(event))) + return true; + + return __is_default_overflow_handler(event->orig_overflow_handler); +} +#else +#define uses_default_overflow_handler(event) \ + is_default_overflow_handler(event) +#endif + extern void perf_event_header__init_id(struct perf_event_header *header, struct perf_sample_data *data,