diff options
Diffstat (limited to 'kernel/bpf/stackmap.c')
| -rw-r--r-- | kernel/bpf/stackmap.c | 877 |
1 files changed, 877 insertions, 0 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c new file mode 100644 index 000000000..b8afea2ce --- /dev/null +++ b/kernel/bpf/stackmap.c @@ -0,0 +1,877 @@ +// 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) +{ + 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 */ + 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 && + 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 (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; + bool crosstask = task && task != current; + 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; + + /* get_perf_callchain does not support crosstask user stack walking + * but returns an empty stack instead of NULL. + */ + if (crosstask && user) { + err = -EOPNOTSUPP; + goto clear; + } + + 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, + crosstask, 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); |