// SPDX-License-Identifier: GPL-2.0-only
|
/* Copyright (c) 2016 Facebook
|
*/
|
#include <linux/bpf.h>
|
#include <linux/jhash.h>
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#include <linux/filter.h>
|
#include <linux/kernel.h>
|
#include <linux/stacktrace.h>
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#include <linux/perf_event.h>
|
#include <linux/elf.h>
|
#include <linux/pagemap.h>
|
#include <linux/irq_work.h>
|
#include <linux/btf_ids.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)
|
{
|
u64 elem_size = sizeof(struct stack_map_bucket) +
|
(u64)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;
|
struct bpf_map_memory mem;
|
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 */
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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);
|
err = bpf_map_charge_init(&mem, cost + attr->max_entries *
|
(sizeof(struct stack_map_bucket) + (u64)value_size));
|
if (err)
|
return ERR_PTR(err);
|
|
smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
|
if (!smap) {
|
bpf_map_charge_finish(&mem);
|
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_charge;
|
|
err = prealloc_elems_and_freelist(smap);
|
if (err)
|
goto put_buffers;
|
|
bpf_map_charge_move(&smap->map.memory, &mem);
|
|
return &smap->map;
|
|
put_buffers:
|
put_callchain_buffers();
|
free_charge:
|
bpf_map_charge_finish(&mem);
|
bpf_map_area_free(smap);
|
return ERR_PTR(err);
|
}
|
|
#define BPF_BUILD_ID 3
|
/*
|
* Parse build id from the note segment. This logic can be shared between
|
* 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
|
* identical.
|
*/
|
static inline int stack_map_parse_build_id(void *page_addr,
|
unsigned char *build_id,
|
void *note_start,
|
Elf32_Word note_size)
|
{
|
Elf32_Word note_offs = 0, new_offs;
|
|
/* check for overflow */
|
if (note_start < page_addr || note_start + note_size < note_start)
|
return -EINVAL;
|
|
/* only supports note that fits in the first page */
|
if (note_start + note_size > page_addr + PAGE_SIZE)
|
return -EINVAL;
|
|
while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
|
Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
|
|
if (nhdr->n_type == BPF_BUILD_ID &&
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nhdr->n_namesz == sizeof("GNU") &&
|
nhdr->n_descsz > 0 &&
|
nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
|
memcpy(build_id,
|
note_start + note_offs +
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ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
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nhdr->n_descsz);
|
memset(build_id + nhdr->n_descsz, 0,
|
BPF_BUILD_ID_SIZE - nhdr->n_descsz);
|
return 0;
|
}
|
new_offs = note_offs + sizeof(Elf32_Nhdr) +
|
ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
|
if (new_offs <= note_offs) /* overflow */
|
break;
|
note_offs = new_offs;
|
}
|
return -EINVAL;
|
}
|
|
/* Parse build ID from 32-bit ELF */
|
static int stack_map_get_build_id_32(void *page_addr,
|
unsigned char *build_id)
|
{
|
Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
|
Elf32_Phdr *phdr;
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int i;
|
|
/* only supports phdr that fits in one page */
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if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
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return -EINVAL;
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phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr));
|
|
for (i = 0; i < ehdr->e_phnum; ++i) {
|
if (phdr[i].p_type == PT_NOTE &&
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!stack_map_parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
|
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/* Parse build ID from 64-bit ELF */
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static int stack_map_get_build_id_64(void *page_addr,
|
unsigned char *build_id)
|
{
|
Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
|
Elf64_Phdr *phdr;
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int i;
|
|
/* only supports phdr that fits in one page */
|
if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
|
return -EINVAL;
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phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr));
|
|
for (i = 0; i < ehdr->e_phnum; ++i) {
|
if (phdr[i].p_type == PT_NOTE &&
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!stack_map_parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
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/* Parse build ID of ELF file mapped to vma */
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static int stack_map_get_build_id(struct vm_area_struct *vma,
|
unsigned char *build_id)
|
{
|
Elf32_Ehdr *ehdr;
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struct page *page;
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void *page_addr;
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int ret;
|
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/* only works for page backed storage */
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if (!vma->vm_file)
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return -EINVAL;
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page = find_get_page(vma->vm_file->f_mapping, 0);
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if (!page)
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return -EFAULT; /* page not mapped */
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ret = -EINVAL;
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page_addr = kmap_atomic(page);
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ehdr = (Elf32_Ehdr *)page_addr;
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|
/* compare magic x7f "ELF" */
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if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
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goto out;
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|
/* only support executable file and shared object file */
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if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
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goto out;
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if (ehdr->e_ident[EI_CLASS] == ELFCLASS32)
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ret = stack_map_get_build_id_32(page_addr, build_id);
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else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64)
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ret = stack_map_get_build_id_64(page_addr, build_id);
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out:
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kunmap_atomic(page_addr);
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put_page(page);
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return ret;
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}
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|
static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
|
u64 *ips, u32 trace_nr, bool user)
|
{
|
int i;
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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 (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY) {
|
/* 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, BPF_BUILD_ID_SIZE);
|
}
|
return;
|
}
|
|
for (i = 0; i < trace_nr; i++) {
|
vma = find_vma(current->mm, ips[i]);
|
if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) {
|
/* 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, BPF_BUILD_ID_SIZE);
|
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 max_depth)
|
{
|
#ifdef CONFIG_STACKTRACE
|
struct perf_callchain_entry *entry;
|
int rctx;
|
|
entry = get_callchain_entry(&rctx);
|
|
if (!entry)
|
return NULL;
|
|
entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip,
|
max_depth, 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 >= 0; 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 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;
|
|
if (trace->nr <= skip)
|
/* skipping more than usable stack trace */
|
return -EFAULT;
|
|
trace_nr = trace->nr - skip;
|
trace_len = trace_nr * sizeof(u64);
|
ips = trace->ip + skip;
|
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);
|
u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
|
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;
|
|
max_depth += skip;
|
if (max_depth > sysctl_perf_event_max_stack)
|
max_depth = sysctl_perf_event_max_stack;
|
|
trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
|
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 trace_nr, copy_len, elem_size, num_elem, max_depth;
|
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;
|
max_depth = num_elem + skip;
|
if (sysctl_perf_event_max_stack < max_depth)
|
max_depth = sysctl_perf_event_max_stack;
|
|
if (trace_in)
|
trace = trace_in;
|
else if (kernel && task)
|
trace = get_callchain_entry_for_task(task, max_depth);
|
else
|
trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
|
false, false);
|
if (unlikely(!trace))
|
goto err_fault;
|
|
if (trace->nr < skip)
|
goto err_fault;
|
|
trace_nr = trace->nr - skip;
|
trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
|
copy_len = trace_nr * elem_size;
|
|
ips = trace->ip + skip;
|
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;
|
}
|
|
BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
|
u64, flags)
|
{
|
return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
|
}
|
|
const struct bpf_func_proto bpf_get_stack_proto = {
|
.func = bpf_get_stack,
|
.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,
|
};
|
|
BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
|
u32, size, u64, flags)
|
{
|
struct pt_regs *regs;
|
long res = -EINVAL;
|
|
if (!try_get_task_stack(task))
|
return -EFAULT;
|
|
regs = task_pt_regs(task);
|
if (regs)
|
res = __bpf_get_stack(regs, task, NULL, buf, size, flags);
|
put_task_stack(task);
|
|
return res;
|
}
|
|
BTF_ID_LIST_SINGLE(bpf_get_task_stack_btf_ids, struct, task_struct)
|
|
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 = &bpf_get_task_stack_btf_ids[0],
|
.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_EARLY))
|
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 int stack_trace_map_btf_id;
|
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_btf_name = "bpf_stack_map",
|
.map_btf_id = &stack_trace_map_btf_id,
|
};
|
|
static int __init stack_map_init(void)
|
{
|
int cpu;
|
struct stack_map_irq_work *work;
|
|
for_each_possible_cpu(cpu) {
|
work = per_cpu_ptr(&up_read_work, cpu);
|
init_irq_work(&work->irq_work, do_up_read);
|
}
|
return 0;
|
}
|
subsys_initcall(stack_map_init);
|
