/* Copyright (c) 2016 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */#include <linux/bpf.h>#include <linux/jhash.h>#include <linux/filter.h>#include <linux/vmalloc.h>#include <linux/stacktrace.h>#include <linux/perf_event.h>#include "percpu_freelist.h" struct stack_map_bucket {	struct pcpu_freelist_node fnode;	u32 hash;	u32 nr;	u64 ip[];}; struct bpf_stack_map {	struct bpf_map map;	void *elems;	struct pcpu_freelist freelist;	u32 n_buckets;	struct stack_map_bucket *buckets[];}; 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 = vzalloc(elem_size * smap->map.max_entries);	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:	vfree(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 (!capable(CAP_SYS_ADMIN))		return ERR_PTR(-EPERM); 	if (attr->map_flags)		return ERR_PTR(-EINVAL); 	/* check sanity of attributes */	if (attr->max_entries == 0 || attr->key_size != 4 ||	    value_size < 8 || value_size % 8 ||	    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); 	cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);	if (cost >= U32_MAX - PAGE_SIZE)		return ERR_PTR(-E2BIG); 	smap = kzalloc(cost, GFP_USER | __GFP_NOWARN);	if (!smap) {		smap = vzalloc(cost);		if (!smap)			return ERR_PTR(-ENOMEM);	} 	err = -E2BIG;	cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));	if (cost >= U32_MAX - PAGE_SIZE)		goto free_smap; 	smap->map.map_type = attr->map_type;	smap->map.key_size = attr->key_size;	smap->map.value_size = value_size;	smap->map.max_entries = attr->max_entries;	smap->n_buckets = n_buckets;	smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; 	err = bpf_map_precharge_memlock(smap->map.pages);	if (err)		goto free_smap; 	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:	kvfree(smap);	return ERR_PTR(err);} u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5){	struct pt_regs *regs = (struct pt_regs *) (long) r1;	struct bpf_map *map = (struct bpf_map *) (long) r2;	struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);	struct perf_callchain_entry *trace;	struct stack_map_bucket *bucket, *new_bucket, *old_bucket;	u32 max_depth = map->value_size / 8;	/* 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;	bool kernel = !user;	u64 *ips; 	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; 	/* 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]); 	if (bucket && bucket->hash == hash) {		if (flags & BPF_F_FAST_STACK_CMP)			return id;		if (bucket->nr == trace_nr &&		    memcmp(bucket->ip, ips, trace_len) == 0)			return id;	} 	/* this call stack is not in the map, try to add it */	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->ip, 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;} 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,}; /* Called from eBPF program */static void *stack_map_lookup_elem(struct bpf_map *map, void *key){	return NULL;} /* 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 * sizeof(u64);	memcpy(value, bucket->ip, 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){	return -EINVAL;} 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); 	/* wait for bpf programs to complete before freeing stack map */	synchronize_rcu(); 	vfree(smap->elems);	pcpu_freelist_destroy(&smap->freelist);	kvfree(smap);	put_callchain_buffers();} static const struct bpf_map_ops stack_map_ops = {	.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,}; static struct bpf_map_type_list stack_map_type __read_mostly = {	.ops = &stack_map_ops,	.type = BPF_MAP_TYPE_STACK_TRACE,}; static int __init register_stack_map(void){	bpf_register_map_type(&stack_map_type);	return 0;}late_initcall(register_stack_map);