683 lines
17 KiB
C
683 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2016 Facebook
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*/
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#include <linux/bpf.h>
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#include <linux/jhash.h>
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#include <linux/filter.h>
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#include <linux/kernel.h>
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#include <linux/stacktrace.h>
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#include <linux/perf_event.h>
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#include <linux/btf_ids.h>
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#include <linux/buildid.h>
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#include "percpu_freelist.h"
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#include "mmap_unlock_work.h"
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#define STACK_CREATE_FLAG_MASK \
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(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \
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BPF_F_STACK_BUILD_ID)
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struct stack_map_bucket {
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struct pcpu_freelist_node fnode;
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u32 hash;
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u32 nr;
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u64 data[];
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};
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struct bpf_stack_map {
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struct bpf_map map;
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void *elems;
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struct pcpu_freelist freelist;
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u32 n_buckets;
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struct stack_map_bucket *buckets[];
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};
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static inline bool stack_map_use_build_id(struct bpf_map *map)
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{
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return (map->map_flags & BPF_F_STACK_BUILD_ID);
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}
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static inline int stack_map_data_size(struct bpf_map *map)
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{
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return stack_map_use_build_id(map) ?
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sizeof(struct bpf_stack_build_id) : sizeof(u64);
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}
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static int prealloc_elems_and_freelist(struct bpf_stack_map *smap)
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{
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u64 elem_size = sizeof(struct stack_map_bucket) +
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(u64)smap->map.value_size;
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int err;
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smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries,
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smap->map.numa_node);
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if (!smap->elems)
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return -ENOMEM;
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err = pcpu_freelist_init(&smap->freelist);
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if (err)
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goto free_elems;
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pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size,
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smap->map.max_entries);
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return 0;
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free_elems:
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bpf_map_area_free(smap->elems);
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return err;
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}
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/* Called from syscall */
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static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
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{
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u32 value_size = attr->value_size;
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struct bpf_stack_map *smap;
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u64 cost, n_buckets;
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int err;
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if (!bpf_capable())
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return ERR_PTR(-EPERM);
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if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
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return ERR_PTR(-EINVAL);
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/* check sanity of attributes */
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if (attr->max_entries == 0 || attr->key_size != 4 ||
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value_size < 8 || value_size % 8)
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return ERR_PTR(-EINVAL);
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BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64));
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if (attr->map_flags & BPF_F_STACK_BUILD_ID) {
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if (value_size % sizeof(struct bpf_stack_build_id) ||
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value_size / sizeof(struct bpf_stack_build_id)
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> sysctl_perf_event_max_stack)
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return ERR_PTR(-EINVAL);
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} else if (value_size / 8 > sysctl_perf_event_max_stack)
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return ERR_PTR(-EINVAL);
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/* hash table size must be power of 2 */
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n_buckets = roundup_pow_of_two(attr->max_entries);
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if (!n_buckets)
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return ERR_PTR(-E2BIG);
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cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
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smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
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if (!smap)
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return ERR_PTR(-ENOMEM);
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bpf_map_init_from_attr(&smap->map, attr);
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smap->n_buckets = n_buckets;
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err = get_callchain_buffers(sysctl_perf_event_max_stack);
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if (err)
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goto free_smap;
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err = prealloc_elems_and_freelist(smap);
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if (err)
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goto put_buffers;
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return &smap->map;
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put_buffers:
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put_callchain_buffers();
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free_smap:
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bpf_map_area_free(smap);
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return ERR_PTR(err);
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}
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static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
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u64 *ips, u32 trace_nr, bool user)
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{
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int i;
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struct mmap_unlock_irq_work *work = NULL;
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bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
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struct vm_area_struct *vma, *prev_vma = NULL;
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const char *prev_build_id;
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/* If the irq_work is in use, fall back to report ips. Same
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* fallback is used for kernel stack (!user) on a stackmap with
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* build_id.
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*/
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if (!user || !current || !current->mm || irq_work_busy ||
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!mmap_read_trylock(current->mm)) {
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/* cannot access current->mm, fall back to ips */
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for (i = 0; i < trace_nr; i++) {
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id_offs[i].status = BPF_STACK_BUILD_ID_IP;
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id_offs[i].ip = ips[i];
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memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
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}
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return;
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}
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for (i = 0; i < trace_nr; i++) {
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if (range_in_vma(prev_vma, ips[i], ips[i])) {
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vma = prev_vma;
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memcpy(id_offs[i].build_id, prev_build_id,
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BUILD_ID_SIZE_MAX);
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goto build_id_valid;
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}
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vma = find_vma(current->mm, ips[i]);
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if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
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/* per entry fall back to ips */
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id_offs[i].status = BPF_STACK_BUILD_ID_IP;
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id_offs[i].ip = ips[i];
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memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
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continue;
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}
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build_id_valid:
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id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
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- vma->vm_start;
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id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
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prev_vma = vma;
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prev_build_id = id_offs[i].build_id;
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}
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bpf_mmap_unlock_mm(work, current->mm);
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}
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static struct perf_callchain_entry *
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get_callchain_entry_for_task(struct task_struct *task, u32 max_depth)
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{
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#ifdef CONFIG_STACKTRACE
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struct perf_callchain_entry *entry;
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int rctx;
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entry = get_callchain_entry(&rctx);
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if (!entry)
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return NULL;
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entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip,
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max_depth, 0);
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/* stack_trace_save_tsk() works on unsigned long array, while
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* perf_callchain_entry uses u64 array. For 32-bit systems, it is
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* necessary to fix this mismatch.
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*/
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if (__BITS_PER_LONG != 64) {
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unsigned long *from = (unsigned long *) entry->ip;
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u64 *to = entry->ip;
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int i;
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/* copy data from the end to avoid using extra buffer */
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for (i = entry->nr - 1; i >= 0; i--)
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to[i] = (u64)(from[i]);
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}
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put_callchain_entry(rctx);
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return entry;
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#else /* CONFIG_STACKTRACE */
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return NULL;
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#endif
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}
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static long __bpf_get_stackid(struct bpf_map *map,
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struct perf_callchain_entry *trace, u64 flags)
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{
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struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
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struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
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u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
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u32 hash, id, trace_nr, trace_len;
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bool user = flags & BPF_F_USER_STACK;
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u64 *ips;
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bool hash_matches;
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if (trace->nr <= skip)
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/* skipping more than usable stack trace */
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return -EFAULT;
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trace_nr = trace->nr - skip;
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trace_len = trace_nr * sizeof(u64);
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ips = trace->ip + skip;
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hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
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id = hash & (smap->n_buckets - 1);
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bucket = READ_ONCE(smap->buckets[id]);
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hash_matches = bucket && bucket->hash == hash;
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/* fast cmp */
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if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
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return id;
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if (stack_map_use_build_id(map)) {
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/* for build_id+offset, pop a bucket before slow cmp */
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new_bucket = (struct stack_map_bucket *)
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pcpu_freelist_pop(&smap->freelist);
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if (unlikely(!new_bucket))
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return -ENOMEM;
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new_bucket->nr = trace_nr;
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stack_map_get_build_id_offset(
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(struct bpf_stack_build_id *)new_bucket->data,
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ips, trace_nr, user);
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trace_len = trace_nr * sizeof(struct bpf_stack_build_id);
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if (hash_matches && bucket->nr == trace_nr &&
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memcmp(bucket->data, new_bucket->data, trace_len) == 0) {
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pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
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return id;
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}
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if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
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pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
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return -EEXIST;
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}
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} else {
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if (hash_matches && bucket->nr == trace_nr &&
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memcmp(bucket->data, ips, trace_len) == 0)
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return id;
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if (bucket && !(flags & BPF_F_REUSE_STACKID))
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return -EEXIST;
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new_bucket = (struct stack_map_bucket *)
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pcpu_freelist_pop(&smap->freelist);
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if (unlikely(!new_bucket))
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return -ENOMEM;
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memcpy(new_bucket->data, ips, trace_len);
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}
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new_bucket->hash = hash;
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new_bucket->nr = trace_nr;
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old_bucket = xchg(&smap->buckets[id], new_bucket);
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if (old_bucket)
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pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
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return id;
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}
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BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
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u64, flags)
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{
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u32 max_depth = map->value_size / stack_map_data_size(map);
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u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
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bool user = flags & BPF_F_USER_STACK;
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struct perf_callchain_entry *trace;
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bool kernel = !user;
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if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
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BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
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return -EINVAL;
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max_depth += skip;
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if (max_depth > sysctl_perf_event_max_stack)
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max_depth = sysctl_perf_event_max_stack;
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trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
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false, false);
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if (unlikely(!trace))
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/* couldn't fetch the stack trace */
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return -EFAULT;
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return __bpf_get_stackid(map, trace, flags);
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}
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const struct bpf_func_proto bpf_get_stackid_proto = {
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.func = bpf_get_stackid,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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.arg2_type = ARG_CONST_MAP_PTR,
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.arg3_type = ARG_ANYTHING,
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};
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static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
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{
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__u64 nr_kernel = 0;
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while (nr_kernel < trace->nr) {
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if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
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break;
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nr_kernel++;
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}
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return nr_kernel;
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}
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BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
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struct bpf_map *, map, u64, flags)
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{
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struct perf_event *event = ctx->event;
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struct perf_callchain_entry *trace;
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bool kernel, user;
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__u64 nr_kernel;
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int ret;
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/* perf_sample_data doesn't have callchain, use bpf_get_stackid */
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if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
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return bpf_get_stackid((unsigned long)(ctx->regs),
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(unsigned long) map, flags, 0, 0);
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if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
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BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
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return -EINVAL;
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user = flags & BPF_F_USER_STACK;
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kernel = !user;
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trace = ctx->data->callchain;
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if (unlikely(!trace))
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return -EFAULT;
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nr_kernel = count_kernel_ip(trace);
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if (kernel) {
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__u64 nr = trace->nr;
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trace->nr = nr_kernel;
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ret = __bpf_get_stackid(map, trace, flags);
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/* restore nr */
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trace->nr = nr;
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} else { /* user */
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u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
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skip += nr_kernel;
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if (skip > BPF_F_SKIP_FIELD_MASK)
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return -EFAULT;
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flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
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ret = __bpf_get_stackid(map, trace, flags);
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}
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return ret;
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}
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const struct bpf_func_proto bpf_get_stackid_proto_pe = {
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.func = bpf_get_stackid_pe,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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.arg2_type = ARG_CONST_MAP_PTR,
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.arg3_type = ARG_ANYTHING,
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};
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static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
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struct perf_callchain_entry *trace_in,
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void *buf, u32 size, u64 flags)
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{
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u32 trace_nr, copy_len, elem_size, num_elem, max_depth;
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bool user_build_id = flags & BPF_F_USER_BUILD_ID;
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u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
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bool user = flags & BPF_F_USER_STACK;
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struct perf_callchain_entry *trace;
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bool kernel = !user;
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int err = -EINVAL;
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u64 *ips;
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if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
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BPF_F_USER_BUILD_ID)))
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goto clear;
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if (kernel && user_build_id)
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goto clear;
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elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
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: sizeof(u64);
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if (unlikely(size % elem_size))
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goto clear;
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/* cannot get valid user stack for task without user_mode regs */
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if (task && user && !user_mode(regs))
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goto err_fault;
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num_elem = size / elem_size;
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max_depth = num_elem + skip;
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if (sysctl_perf_event_max_stack < max_depth)
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max_depth = sysctl_perf_event_max_stack;
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if (trace_in)
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trace = trace_in;
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else if (kernel && task)
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trace = get_callchain_entry_for_task(task, max_depth);
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else
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trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
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false, false);
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if (unlikely(!trace))
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goto err_fault;
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if (trace->nr < skip)
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goto err_fault;
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trace_nr = trace->nr - skip;
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trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
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copy_len = trace_nr * elem_size;
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ips = trace->ip + skip;
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if (user && user_build_id)
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stack_map_get_build_id_offset(buf, ips, trace_nr, user);
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else
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memcpy(buf, ips, copy_len);
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if (size > copy_len)
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memset(buf + copy_len, 0, size - copy_len);
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return copy_len;
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err_fault:
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err = -EFAULT;
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clear:
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memset(buf, 0, size);
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return err;
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}
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BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
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u64, flags)
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{
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return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
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}
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const struct bpf_func_proto bpf_get_stack_proto = {
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.func = bpf_get_stack,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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.arg2_type = ARG_PTR_TO_UNINIT_MEM,
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.arg3_type = ARG_CONST_SIZE_OR_ZERO,
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.arg4_type = ARG_ANYTHING,
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};
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BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
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u32, size, u64, flags)
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{
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struct pt_regs *regs;
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long res = -EINVAL;
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if (!try_get_task_stack(task))
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return -EFAULT;
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regs = task_pt_regs(task);
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if (regs)
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res = __bpf_get_stack(regs, task, NULL, buf, size, flags);
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put_task_stack(task);
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return res;
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}
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const struct bpf_func_proto bpf_get_task_stack_proto = {
|
|
.func = bpf_get_task_stack,
|
|
.gpl_only = false,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_BTF_ID,
|
|
.arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
|
|
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
|
|
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
|
|
.arg4_type = ARG_ANYTHING,
|
|
};
|
|
|
|
BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
|
|
void *, buf, u32, size, u64, flags)
|
|
{
|
|
struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
|
|
struct perf_event *event = ctx->event;
|
|
struct perf_callchain_entry *trace;
|
|
bool kernel, user;
|
|
int err = -EINVAL;
|
|
__u64 nr_kernel;
|
|
|
|
if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
|
|
return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
|
|
|
|
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
|
|
BPF_F_USER_BUILD_ID)))
|
|
goto clear;
|
|
|
|
user = flags & BPF_F_USER_STACK;
|
|
kernel = !user;
|
|
|
|
err = -EFAULT;
|
|
trace = ctx->data->callchain;
|
|
if (unlikely(!trace))
|
|
goto clear;
|
|
|
|
nr_kernel = count_kernel_ip(trace);
|
|
|
|
if (kernel) {
|
|
__u64 nr = trace->nr;
|
|
|
|
trace->nr = nr_kernel;
|
|
err = __bpf_get_stack(regs, NULL, trace, buf, size, 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)
|
|
goto clear;
|
|
|
|
flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
|
|
err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
|
|
}
|
|
return err;
|
|
|
|
clear:
|
|
memset(buf, 0, size);
|
|
return err;
|
|
|
|
}
|
|
|
|
const struct bpf_func_proto bpf_get_stack_proto_pe = {
|
|
.func = bpf_get_stack_pe,
|
|
.gpl_only = true,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_PTR_TO_UNINIT_MEM,
|
|
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
|
|
.arg4_type = ARG_ANYTHING,
|
|
};
|
|
|
|
/* Called from eBPF program */
|
|
static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
return ERR_PTR(-EOPNOTSUPP);
|
|
}
|
|
|
|
/* Called from syscall */
|
|
int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
|
|
{
|
|
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
|
|
struct stack_map_bucket *bucket, *old_bucket;
|
|
u32 id = *(u32 *)key, trace_len;
|
|
|
|
if (unlikely(id >= smap->n_buckets))
|
|
return -ENOENT;
|
|
|
|
bucket = xchg(&smap->buckets[id], NULL);
|
|
if (!bucket)
|
|
return -ENOENT;
|
|
|
|
trace_len = bucket->nr * stack_map_data_size(map);
|
|
memcpy(value, bucket->data, trace_len);
|
|
memset(value + trace_len, 0, map->value_size - trace_len);
|
|
|
|
old_bucket = xchg(&smap->buckets[id], bucket);
|
|
if (old_bucket)
|
|
pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
|
|
return 0;
|
|
}
|
|
|
|
static int stack_map_get_next_key(struct bpf_map *map, void *key,
|
|
void *next_key)
|
|
{
|
|
struct bpf_stack_map *smap = container_of(map,
|
|
struct bpf_stack_map, map);
|
|
u32 id;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
if (!key) {
|
|
id = 0;
|
|
} else {
|
|
id = *(u32 *)key;
|
|
if (id >= smap->n_buckets || !smap->buckets[id])
|
|
id = 0;
|
|
else
|
|
id++;
|
|
}
|
|
|
|
while (id < smap->n_buckets && !smap->buckets[id])
|
|
id++;
|
|
|
|
if (id >= smap->n_buckets)
|
|
return -ENOENT;
|
|
|
|
*(u32 *)next_key = id;
|
|
return 0;
|
|
}
|
|
|
|
static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Called from syscall or from eBPF program */
|
|
static int stack_map_delete_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
|
|
struct stack_map_bucket *old_bucket;
|
|
u32 id = *(u32 *)key;
|
|
|
|
if (unlikely(id >= smap->n_buckets))
|
|
return -E2BIG;
|
|
|
|
old_bucket = xchg(&smap->buckets[id], NULL);
|
|
if (old_bucket) {
|
|
pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
|
|
return 0;
|
|
} else {
|
|
return -ENOENT;
|
|
}
|
|
}
|
|
|
|
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
|
|
static void stack_map_free(struct bpf_map *map)
|
|
{
|
|
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
|
|
|
|
bpf_map_area_free(smap->elems);
|
|
pcpu_freelist_destroy(&smap->freelist);
|
|
bpf_map_area_free(smap);
|
|
put_callchain_buffers();
|
|
}
|
|
|
|
static u64 stack_map_mem_usage(const struct bpf_map *map)
|
|
{
|
|
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
|
|
u64 value_size = map->value_size;
|
|
u64 n_buckets = smap->n_buckets;
|
|
u64 enties = map->max_entries;
|
|
u64 usage = sizeof(*smap);
|
|
|
|
usage += n_buckets * sizeof(struct stack_map_bucket *);
|
|
usage += enties * (sizeof(struct stack_map_bucket) + value_size);
|
|
return usage;
|
|
}
|
|
|
|
BTF_ID_LIST_SINGLE(stack_trace_map_btf_ids, struct, bpf_stack_map)
|
|
const struct bpf_map_ops stack_trace_map_ops = {
|
|
.map_meta_equal = bpf_map_meta_equal,
|
|
.map_alloc = stack_map_alloc,
|
|
.map_free = stack_map_free,
|
|
.map_get_next_key = stack_map_get_next_key,
|
|
.map_lookup_elem = stack_map_lookup_elem,
|
|
.map_update_elem = stack_map_update_elem,
|
|
.map_delete_elem = stack_map_delete_elem,
|
|
.map_check_btf = map_check_no_btf,
|
|
.map_mem_usage = stack_map_mem_usage,
|
|
.map_btf_id = &stack_trace_map_btf_ids[0],
|
|
};
|