| // 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/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) |
| { |
| 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); |
| } |
| |
| #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 && |
| nhdr->n_namesz == sizeof("GNU") && |
| nhdr->n_descsz > 0 && |
| nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { |
| memcpy(build_id, |
| note_start + note_offs + |
| ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), |
| 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; |
| int i; |
| |
| /* only supports phdr that fits in one page */ |
| if (ehdr->e_phnum > |
| (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) |
| return -EINVAL; |
| |
| phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); |
| |
| for (i = 0; i < ehdr->e_phnum; ++i) { |
| if (phdr[i].p_type == PT_NOTE && |
| !stack_map_parse_build_id(page_addr, build_id, |
| page_addr + phdr[i].p_offset, |
| phdr[i].p_filesz)) |
| return 0; |
| } |
| return -EINVAL; |
| } |
| |
| /* Parse build ID from 64-bit ELF */ |
| 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; |
| int i; |
| |
| /* only supports phdr that fits in one page */ |
| if (ehdr->e_phnum > |
| (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) |
| return -EINVAL; |
| |
| phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); |
| |
| for (i = 0; i < ehdr->e_phnum; ++i) { |
| if (phdr[i].p_type == PT_NOTE && |
| !stack_map_parse_build_id(page_addr, build_id, |
| page_addr + phdr[i].p_offset, |
| phdr[i].p_filesz)) |
| return 0; |
| } |
| return -EINVAL; |
| } |
| |
| /* Parse build ID of ELF file mapped to vma */ |
| static int stack_map_get_build_id(struct vm_area_struct *vma, |
| unsigned char *build_id) |
| { |
| Elf32_Ehdr *ehdr; |
| struct page *page; |
| void *page_addr; |
| int ret; |
| |
| /* only works for page backed storage */ |
| if (!vma->vm_file) |
| return -EINVAL; |
| |
| page = find_get_page(vma->vm_file->f_mapping, 0); |
| if (!page) |
| return -EFAULT; /* page not mapped */ |
| |
| ret = -EINVAL; |
| page_addr = kmap_atomic(page); |
| ehdr = (Elf32_Ehdr *)page_addr; |
| |
| /* compare magic x7f "ELF" */ |
| if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) |
| goto out; |
| |
| /* only support executable file and shared object file */ |
| if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) |
| goto out; |
| |
| if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) |
| ret = stack_map_get_build_id_32(page_addr, build_id); |
| else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) |
| ret = stack_map_get_build_id_64(page_addr, build_id); |
| out: |
| kunmap_atomic(page_addr); |
| put_page(page); |
| return ret; |
| } |
| |
| 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, 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 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; |
| } |
| |
| 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 = task_pt_regs(task); |
| |
| return __bpf_get_stack(regs, task, NULL, buf, size, flags); |
| } |
| |
| 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); |