// SPDX-License-Identifier: GPL-2.0-only/* Copyright (c) 2016 Facebook */#include <linux/bpf.h>#include <linux/jhash.h>#include <linux/filter.h>#include <linux/kernel.h>#include <linux/stacktrace.h>#include <linux/perf_event.h>#include <linux/irq_work.h>#include <linux/btf_ids.h>#include <linux/buildid.h>#include "percpu_freelist.h" #define STACK_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ BPF_F_STACK_BUILD_ID) struct stack_map_bucket { struct pcpu_freelist_node fnode; u32 hash; u32 nr; u64 data[];}; struct bpf_stack_map { struct bpf_map map; void *elems; struct pcpu_freelist freelist; u32 n_buckets; struct stack_map_bucket *buckets[];}; /* irq_work to run up_read() for build_id lookup in nmi context */struct stack_map_irq_work { struct irq_work irq_work; struct mm_struct *mm;}; static void do_up_read(struct irq_work *entry){ struct stack_map_irq_work *work; if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT))) return; work = container_of(entry, struct stack_map_irq_work, irq_work); mmap_read_unlock_non_owner(work->mm);} static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work); static inline bool stack_map_use_build_id(struct bpf_map *map){ return (map->map_flags & BPF_F_STACK_BUILD_ID);} static inline int stack_map_data_size(struct bpf_map *map){ return stack_map_use_build_id(map) ? sizeof(struct bpf_stack_build_id) : sizeof(u64);} static int prealloc_elems_and_freelist(struct bpf_stack_map *smap){ u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; int err; smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, smap->map.numa_node); if (!smap->elems) return -ENOMEM; err = pcpu_freelist_init(&smap->freelist); if (err) goto free_elems; pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, smap->map.max_entries); return 0; free_elems: bpf_map_area_free(smap->elems); return err;} /* Called from syscall */static struct bpf_map *stack_map_alloc(union bpf_attr *attr){ u32 value_size = attr->value_size; struct bpf_stack_map *smap; u64 cost, n_buckets; int err; if (!bpf_capable()) return ERR_PTR(-EPERM); if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) return ERR_PTR(-EINVAL); /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || value_size < 8 || value_size % 8) return ERR_PTR(-EINVAL); BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); if (attr->map_flags & BPF_F_STACK_BUILD_ID) { if (value_size % sizeof(struct bpf_stack_build_id) || value_size / sizeof(struct bpf_stack_build_id) > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); } else if (value_size / 8 > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); /* hash table size must be power of 2 */ n_buckets = roundup_pow_of_two(attr->max_entries); if (!n_buckets) return ERR_PTR(-E2BIG); cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); cost += n_buckets * (value_size + sizeof(struct stack_map_bucket)); smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); if (!smap) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&smap->map, attr); smap->map.value_size = value_size; smap->n_buckets = n_buckets; err = get_callchain_buffers(sysctl_perf_event_max_stack); if (err) goto free_smap; err = prealloc_elems_and_freelist(smap); if (err) goto put_buffers; return &smap->map; put_buffers: put_callchain_buffers();free_smap: bpf_map_area_free(smap); return ERR_PTR(err);} static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u64 *ips, u32 trace_nr, bool user){ int i; struct vm_area_struct *vma; bool irq_work_busy = false; struct stack_map_irq_work *work = NULL; if (irqs_disabled()) { if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { work = this_cpu_ptr(&up_read_work); if (irq_work_is_busy(&work->irq_work)) { /* cannot queue more up_read, fallback */ irq_work_busy = true; } } else { /* * PREEMPT_RT does not allow to trylock mmap sem in * interrupt disabled context. Force the fallback code. */ irq_work_busy = true; } } /* * We cannot do up_read() when the irq is disabled, because of * risk to deadlock with rq_lock. To do build_id lookup when the * irqs are disabled, we need to run up_read() in irq_work. We use * a percpu variable to do the irq_work. If the irq_work is * already used by another lookup, we fall back to report ips. * * Same fallback is used for kernel stack (!user) on a stackmap * with build_id. */ if (!user || !current || !current->mm || irq_work_busy || !mmap_read_trylock_non_owner(current->mm)) { /* cannot access current->mm, fall back to ips */ for (i = 0; i < trace_nr; i++) { id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); } return; } for (i = 0; i < trace_nr; i++) { vma = find_vma(current->mm, ips[i]); if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); continue; } id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] - vma->vm_start; id_offs[i].status = BPF_STACK_BUILD_ID_VALID; } if (!work) { mmap_read_unlock_non_owner(current->mm); } else { work->mm = current->mm; irq_work_queue(&work->irq_work); }} static struct perf_callchain_entry *get_callchain_entry_for_task(struct task_struct *task, u32 init_nr){#ifdef CONFIG_STACKTRACE struct perf_callchain_entry *entry; int rctx; entry = get_callchain_entry(&rctx); if (!entry) return NULL; entry->nr = init_nr + stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr), sysctl_perf_event_max_stack - init_nr, 0); /* stack_trace_save_tsk() works on unsigned long array, while * perf_callchain_entry uses u64 array. For 32-bit systems, it is * necessary to fix this mismatch. */ if (__BITS_PER_LONG != 64) { unsigned long *from = (unsigned long *) entry->ip; u64 *to = entry->ip; int i; /* copy data from the end to avoid using extra buffer */ for (i = entry->nr - 1; i >= (int)init_nr; i--) to[i] = (u64)(from[i]); } put_callchain_entry(rctx); return entry;#else /* CONFIG_STACKTRACE */ return NULL;#endif} static long __bpf_get_stackid(struct bpf_map *map, struct perf_callchain_entry *trace, u64 flags){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; u32 max_depth = map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ u32 init_nr = sysctl_perf_event_max_stack - max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; u32 hash, id, trace_nr, trace_len; bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; /* get_perf_callchain() guarantees that trace->nr >= init_nr * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth */ trace_nr = trace->nr - init_nr; if (trace_nr <= skip) /* skipping more than usable stack trace */ return -EFAULT; trace_nr -= skip; trace_len = trace_nr * sizeof(u64); ips = trace->ip + skip + init_nr; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); bucket = READ_ONCE(smap->buckets[id]); hash_matches = bucket && bucket->hash == hash; /* fast cmp */ if (hash_matches && flags & BPF_F_FAST_STACK_CMP) return id; if (stack_map_use_build_id(map)) { /* for build_id+offset, pop a bucket before slow cmp */ new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; new_bucket->nr = trace_nr; stack_map_get_build_id_offset( (struct bpf_stack_build_id *)new_bucket->data, ips, trace_nr, user); trace_len = trace_nr * sizeof(struct bpf_stack_build_id); if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, new_bucket->data, trace_len) == 0) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return id; } if (bucket && !(flags & BPF_F_REUSE_STACKID)) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return -EEXIST; } } else { if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, ips, trace_len) == 0) return id; if (bucket && !(flags & BPF_F_REUSE_STACKID)) return -EEXIST; new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; memcpy(new_bucket->data, ips, trace_len); } new_bucket->hash = hash; new_bucket->nr = trace_nr; old_bucket = xchg(&smap->buckets[id], new_bucket); if (old_bucket) pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return id;} BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags){ u32 max_depth = map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ u32 init_nr = sysctl_perf_event_max_stack - max_depth; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; trace = get_perf_callchain(regs, init_nr, kernel, user, sysctl_perf_event_max_stack, false, false); if (unlikely(!trace)) /* couldn't fetch the stack trace */ return -EFAULT; return __bpf_get_stackid(map, trace, flags);} const struct bpf_func_proto bpf_get_stackid_proto = { .func = bpf_get_stackid, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING,}; static __u64 count_kernel_ip(struct perf_callchain_entry *trace){ __u64 nr_kernel = 0; while (nr_kernel < trace->nr) { if (trace->ip[nr_kernel] == PERF_CONTEXT_USER) break; nr_kernel++; } return nr_kernel;} BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, struct bpf_map *, map, u64, flags){ struct perf_event *event = ctx->event; struct perf_callchain_entry *trace; bool kernel, user; __u64 nr_kernel; int ret; /* perf_sample_data doesn't have callchain, use bpf_get_stackid */ if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY)) return bpf_get_stackid((unsigned long)(ctx->regs), (unsigned long) map, flags, 0, 0); if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; user = flags & BPF_F_USER_STACK; kernel = !user; trace = ctx->data->callchain; if (unlikely(!trace)) return -EFAULT; nr_kernel = count_kernel_ip(trace); if (kernel) { __u64 nr = trace->nr; trace->nr = nr_kernel; ret = __bpf_get_stackid(map, trace, flags); /* restore nr */ trace->nr = nr; } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK; skip += nr_kernel; if (skip > BPF_F_SKIP_FIELD_MASK) return -EFAULT; flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; ret = __bpf_get_stackid(map, trace, flags); } return ret;} const struct bpf_func_proto bpf_get_stackid_proto_pe = { .func = bpf_get_stackid_pe, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING,}; static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags){ u32 init_nr, trace_nr, copy_len, elem_size, num_elem; bool user_build_id = flags & BPF_F_USER_BUILD_ID; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; int err = -EINVAL; u64 *ips; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_USER_BUILD_ID))) goto clear; if (kernel && user_build_id) goto clear; elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) : sizeof(u64); if (unlikely(size % elem_size)) goto clear; /* cannot get valid user stack for task without user_mode regs */ if (task && user && !user_mode(regs)) goto err_fault; num_elem = size / elem_size; if (sysctl_perf_event_max_stack < num_elem) init_nr = 0; else init_nr = sysctl_perf_event_max_stack - num_elem; if (trace_in) trace = trace_in; else if (kernel && task) trace = get_callchain_entry_for_task(task, init_nr); else trace = get_perf_callchain(regs, init_nr, kernel, user, sysctl_perf_event_max_stack, false, false); if (unlikely(!trace)) goto err_fault; trace_nr = trace->nr - init_nr; if (trace_nr < skip) goto err_fault; trace_nr -= skip; trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; copy_len = trace_nr * elem_size; ips = trace->ip + skip + init_nr; if (user && user_build_id) stack_map_get_build_id_offset(buf, ips, trace_nr, user); else memcpy(buf, ips, copy_len); if (size > copy_len) memset(buf + copy_len, 0, size - copy_len); return copy_len; err_fault: err = -EFAULT;clear: memset(buf, 0, size); return err;} Lines 1–500 of 727. 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// SPDX-License-Identifier: GPL-2.0-only /* Copyright (c) 2016 Facebook */ #include <linux/bpf.h> #include <linux/jhash.h> #include <linux/filter.h> #include <linux/kernel.h> #include <linux/stacktrace.h> #include <linux/perf_event.h> #include <linux/irq_work.h> #include <linux/btf_ids.h> #include <linux/buildid.h> #include "percpu_freelist.h" #define STACK_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ BPF_F_STACK_BUILD_ID) struct stack_map_bucket { struct pcpu_freelist_node fnode; u32 hash; u32 nr; u64 data[]; }; struct bpf_stack_map { struct bpf_map map; void *elems; struct pcpu_freelist freelist; u32 n_buckets; struct stack_map_bucket *buckets[]; }; /* irq_work to run up_read() for build_id lookup in nmi context */ struct stack_map_irq_work { struct irq_work irq_work; struct mm_struct *mm; }; static void do_up_read(struct irq_work *entry) { struct stack_map_irq_work *work; if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT))) return; work = container_of(entry, struct stack_map_irq_work, irq_work); mmap_read_unlock_non_owner(work->mm); } static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work); static inline bool stack_map_use_build_id(struct bpf_map *map) { return (map->map_flags & BPF_F_STACK_BUILD_ID); } static inline int stack_map_data_size(struct bpf_map *map) { return stack_map_use_build_id(map) ? sizeof(struct bpf_stack_build_id) : sizeof(u64); } static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) { u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; int err; smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, smap->map.numa_node); if (!smap->elems) return -ENOMEM; err = pcpu_freelist_init(&smap->freelist); if (err) goto free_elems; pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, smap->map.max_entries); return 0; free_elems: bpf_map_area_free(smap->elems); return err; } /* Called from syscall */ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) { u32 value_size = attr->value_size; struct bpf_stack_map *smap; u64 cost, n_buckets; int err; if (!bpf_capable()) return ERR_PTR(-EPERM); if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) return ERR_PTR(-EINVAL); /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || value_size < 8 || value_size % 8) return ERR_PTR(-EINVAL); BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); if (attr->map_flags & BPF_F_STACK_BUILD_ID) { if (value_size % sizeof(struct bpf_stack_build_id) || value_size / sizeof(struct bpf_stack_build_id) > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); } else if (value_size / 8 > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); /* hash table size must be power of 2 */ n_buckets = roundup_pow_of_two(attr->max_entries); if (!n_buckets) return ERR_PTR(-E2BIG); cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); cost += n_buckets * (value_size + sizeof(struct stack_map_bucket)); smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); if (!smap) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&smap->map, attr); smap->map.value_size = value_size; smap->n_buckets = n_buckets; err = get_callchain_buffers(sysctl_perf_event_max_stack); if (err) goto free_smap; err = prealloc_elems_and_freelist(smap); if (err) goto put_buffers; return &smap->map; put_buffers: put_callchain_buffers(); free_smap: bpf_map_area_free(smap); return ERR_PTR(err); } static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u64 *ips, u32 trace_nr, bool user) { int i; struct vm_area_struct *vma; bool irq_work_busy = false; struct stack_map_irq_work *work = NULL; if (irqs_disabled()) { if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { work = this_cpu_ptr(&up_read_work); if (irq_work_is_busy(&work->irq_work)) { /* cannot queue more up_read, fallback */ irq_work_busy = true; } } else { /* * PREEMPT_RT does not allow to trylock mmap sem in * interrupt disabled context. Force the fallback code. */ irq_work_busy = true; } } /* * We cannot do up_read() when the irq is disabled, because of * risk to deadlock with rq_lock. To do build_id lookup when the * irqs are disabled, we need to run up_read() in irq_work. We use * a percpu variable to do the irq_work. If the irq_work is * already used by another lookup, we fall back to report ips. * * Same fallback is used for kernel stack (!user) on a stackmap * with build_id. */ if (!user || !current || !current->mm || irq_work_busy || !mmap_read_trylock_non_owner(current->mm)) { /* cannot access current->mm, fall back to ips */ for (i = 0; i < trace_nr; i++) { id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); } return; } for (i = 0; i < trace_nr; i++) { vma = find_vma(current->mm, ips[i]); if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); continue; } id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] - vma->vm_start; id_offs[i].status = BPF_STACK_BUILD_ID_VALID; } if (!work) { mmap_read_unlock_non_owner(current->mm); } else { work->mm = current->mm; irq_work_queue(&work->irq_work); } } static struct perf_callchain_entry * get_callchain_entry_for_task(struct task_struct *task, u32 init_nr) { #ifdef CONFIG_STACKTRACE struct perf_callchain_entry *entry; int rctx; entry = get_callchain_entry(&rctx); if (!entry) return NULL; entry->nr = init_nr + stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr), sysctl_perf_event_max_stack - init_nr, 0); /* stack_trace_save_tsk() works on unsigned long array, while * perf_callchain_entry uses u64 array. For 32-bit systems, it is * necessary to fix this mismatch. */ if (__BITS_PER_LONG != 64) { unsigned long *from = (unsigned long *) entry->ip; u64 *to = entry->ip; int i; /* copy data from the end to avoid using extra buffer */ for (i = entry->nr - 1; i >= (int)init_nr; i--) to[i] = (u64)(from[i]); } put_callchain_entry(rctx); return entry; #else /* CONFIG_STACKTRACE */ return NULL; #endif } static long __bpf_get_stackid(struct bpf_map *map, struct perf_callchain_entry *trace, u64 flags) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; u32 max_depth = map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ u32 init_nr = sysctl_perf_event_max_stack - max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; u32 hash, id, trace_nr, trace_len; bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches; /* get_perf_callchain() guarantees that trace->nr >= init_nr * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth */ trace_nr = trace->nr - init_nr; if (trace_nr <= skip) /* skipping more than usable stack trace */ return -EFAULT; trace_nr -= skip; trace_len = trace_nr * sizeof(u64); ips = trace->ip + skip + init_nr; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); bucket = READ_ONCE(smap->buckets[id]); hash_matches = bucket && bucket->hash == hash; /* fast cmp */ if (hash_matches && flags & BPF_F_FAST_STACK_CMP) return id; if (stack_map_use_build_id(map)) { /* for build_id+offset, pop a bucket before slow cmp */ new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; new_bucket->nr = trace_nr; stack_map_get_build_id_offset( (struct bpf_stack_build_id *)new_bucket->data, ips, trace_nr, user); trace_len = trace_nr * sizeof(struct bpf_stack_build_id); if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, new_bucket->data, trace_len) == 0) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return id; } if (bucket && !(flags & BPF_F_REUSE_STACKID)) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return -EEXIST; } } else { if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, ips, trace_len) == 0) return id; if (bucket && !(flags & BPF_F_REUSE_STACKID)) return -EEXIST; new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; memcpy(new_bucket->data, ips, trace_len); } new_bucket->hash = hash; new_bucket->nr = trace_nr; old_bucket = xchg(&smap->buckets[id], new_bucket); if (old_bucket) pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return id; } BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags) { u32 max_depth = map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ u32 init_nr = sysctl_perf_event_max_stack - max_depth; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; trace = get_perf_callchain(regs, init_nr, kernel, user, sysctl_perf_event_max_stack, false, false); if (unlikely(!trace)) /* couldn't fetch the stack trace */ return -EFAULT; return __bpf_get_stackid(map, trace, flags); } const struct bpf_func_proto bpf_get_stackid_proto = { .func = bpf_get_stackid, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING, }; static __u64 count_kernel_ip(struct perf_callchain_entry *trace) { __u64 nr_kernel = 0; while (nr_kernel < trace->nr) { if (trace->ip[nr_kernel] == PERF_CONTEXT_USER) break; nr_kernel++; } return nr_kernel; } BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, struct bpf_map *, map, u64, flags) { struct perf_event *event = ctx->event; struct perf_callchain_entry *trace; bool kernel, user; __u64 nr_kernel; int ret; /* perf_sample_data doesn't have callchain, use bpf_get_stackid */ if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY)) return bpf_get_stackid((unsigned long)(ctx->regs), (unsigned long) map, flags, 0, 0); if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL; user = flags & BPF_F_USER_STACK; kernel = !user; trace = ctx->data->callchain; if (unlikely(!trace)) return -EFAULT; nr_kernel = count_kernel_ip(trace); if (kernel) { __u64 nr = trace->nr; trace->nr = nr_kernel; ret = __bpf_get_stackid(map, trace, flags); /* restore nr */ trace->nr = nr; } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK; skip += nr_kernel; if (skip > BPF_F_SKIP_FIELD_MASK) return -EFAULT; flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; ret = __bpf_get_stackid(map, trace, flags); } return ret; } const struct bpf_func_proto bpf_get_stackid_proto_pe = { .func = bpf_get_stackid_pe, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING, }; static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags) { u32 init_nr, trace_nr, copy_len, elem_size, num_elem; bool user_build_id = flags & BPF_F_USER_BUILD_ID; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; int err = -EINVAL; u64 *ips; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_USER_BUILD_ID))) goto clear; if (kernel && user_build_id) goto clear; elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) : sizeof(u64); if (unlikely(size % elem_size)) goto clear; /* cannot get valid user stack for task without user_mode regs */ if (task && user && !user_mode(regs)) goto err_fault; num_elem = size / elem_size; if (sysctl_perf_event_max_stack < num_elem) init_nr = 0; else init_nr = sysctl_perf_event_max_stack - num_elem; if (trace_in) trace = trace_in; else if (kernel && task) trace = get_callchain_entry_for_task(task, init_nr); else trace = get_perf_callchain(regs, init_nr, kernel, user, sysctl_perf_event_max_stack, false, false); if (unlikely(!trace)) goto err_fault; trace_nr = trace->nr - init_nr; if (trace_nr < skip) goto err_fault; trace_nr -= skip; trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; copy_len = trace_nr * elem_size; ips = trace->ip + skip + init_nr; if (user && user_build_id) stack_map_get_build_id_offset(buf, ips, trace_nr, user); else memcpy(buf, ips, copy_len); if (size > copy_len) memset(buf + copy_len, 0, size - copy_len); return copy_len; err_fault: err = -EFAULT; clear: memset(buf, 0, size); return err; }