blob: 937bfc7db41e751f27c55f5092c2ed9687ca010e [file] [log] [blame]
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2021 Facebook */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <linux/filter.h>
#include <sys/param.h>
#include "btf.h"
#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"
#include "hashmap.h"
#include "bpf_gen_internal.h"
#include "skel_internal.h"
#define MAX_USED_MAPS 64
#define MAX_USED_PROGS 32
#define MAX_KFUNC_DESCS 256
#define MAX_FD_ARRAY_SZ (MAX_USED_PROGS + MAX_KFUNC_DESCS)
/* The following structure describes the stack layout of the loader program.
* In addition R6 contains the pointer to context.
* R7 contains the result of the last sys_bpf command (typically error or FD).
* R9 contains the result of the last sys_close command.
*
* Naming convention:
* ctx - bpf program context
* stack - bpf program stack
* blob - bpf_attr-s, strings, insns, map data.
* All the bytes that loader prog will use for read/write.
*/
struct loader_stack {
__u32 btf_fd;
__u32 prog_fd[MAX_USED_PROGS];
__u32 inner_map_fd;
};
#define stack_off(field) \
(__s16)(-sizeof(struct loader_stack) + offsetof(struct loader_stack, field))
#define attr_field(attr, field) (attr + offsetof(union bpf_attr, field))
static int realloc_insn_buf(struct bpf_gen *gen, __u32 size)
{
size_t off = gen->insn_cur - gen->insn_start;
void *insn_start;
if (gen->error)
return gen->error;
if (size > INT32_MAX || off + size > INT32_MAX) {
gen->error = -ERANGE;
return -ERANGE;
}
insn_start = realloc(gen->insn_start, off + size);
if (!insn_start) {
gen->error = -ENOMEM;
free(gen->insn_start);
gen->insn_start = NULL;
return -ENOMEM;
}
gen->insn_start = insn_start;
gen->insn_cur = insn_start + off;
return 0;
}
static int realloc_data_buf(struct bpf_gen *gen, __u32 size)
{
size_t off = gen->data_cur - gen->data_start;
void *data_start;
if (gen->error)
return gen->error;
if (size > INT32_MAX || off + size > INT32_MAX) {
gen->error = -ERANGE;
return -ERANGE;
}
data_start = realloc(gen->data_start, off + size);
if (!data_start) {
gen->error = -ENOMEM;
free(gen->data_start);
gen->data_start = NULL;
return -ENOMEM;
}
gen->data_start = data_start;
gen->data_cur = data_start + off;
return 0;
}
static void emit(struct bpf_gen *gen, struct bpf_insn insn)
{
if (realloc_insn_buf(gen, sizeof(insn)))
return;
memcpy(gen->insn_cur, &insn, sizeof(insn));
gen->insn_cur += sizeof(insn);
}
static void emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bpf_insn insn2)
{
emit(gen, insn1);
emit(gen, insn2);
}
void bpf_gen__init(struct bpf_gen *gen, int log_level)
{
size_t stack_sz = sizeof(struct loader_stack);
int i;
gen->log_level = log_level;
/* save ctx pointer into R6 */
emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1));
/* bzero stack */
emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz));
emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));
/* jump over cleanup code */
emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0,
/* size of cleanup code below */
(stack_sz / 4) * 3 + 2));
/* remember the label where all error branches will jump to */
gen->cleanup_label = gen->insn_cur - gen->insn_start;
/* emit cleanup code: close all temp FDs */
for (i = 0; i < stack_sz; i += 4) {
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i));
emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
}
/* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */
emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
emit(gen, BPF_EXIT_INSN());
}
static int add_data(struct bpf_gen *gen, const void *data, __u32 size)
{
__u32 size8 = roundup(size, 8);
__u64 zero = 0;
void *prev;
if (realloc_data_buf(gen, size8))
return 0;
prev = gen->data_cur;
if (data) {
memcpy(gen->data_cur, data, size);
memcpy(gen->data_cur + size, &zero, size8 - size);
} else {
memset(gen->data_cur, 0, size8);
}
gen->data_cur += size8;
return prev - gen->data_start;
}
/* Get index for map_fd/btf_fd slot in reserved fd_array, or in data relative
* to start of fd_array. Caller can decide if it is usable or not.
*/
static int add_map_fd(struct bpf_gen *gen)
{
if (!gen->fd_array)
gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
if (gen->nr_maps == MAX_USED_MAPS) {
pr_warn("Total maps exceeds %d\n", MAX_USED_MAPS);
gen->error = -E2BIG;
return 0;
}
return gen->nr_maps++;
}
static int add_kfunc_btf_fd(struct bpf_gen *gen)
{
int cur;
if (!gen->fd_array)
gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
if (gen->nr_fd_array == MAX_KFUNC_DESCS) {
cur = add_data(gen, NULL, sizeof(int));
return (cur - gen->fd_array) / sizeof(int);
}
return MAX_USED_MAPS + gen->nr_fd_array++;
}
static int blob_fd_array_off(struct bpf_gen *gen, int index)
{
return gen->fd_array + index * sizeof(int);
}
static int insn_bytes_to_bpf_size(__u32 sz)
{
switch (sz) {
case 8: return BPF_DW;
case 4: return BPF_W;
case 2: return BPF_H;
case 1: return BPF_B;
default: return -1;
}
}
/* *(u64 *)(blob + off) = (u64)(void *)(blob + data) */
static void emit_rel_store(struct bpf_gen *gen, int off, int data)
{
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, data));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, off));
emit(gen, BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0));
}
static void move_blob2blob(struct bpf_gen *gen, int off, int size, int blob_off)
{
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_off));
emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_2, 0));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, off));
emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}
static void move_blob2ctx(struct bpf_gen *gen, int ctx_off, int size, int blob_off)
{
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_off));
emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_1, 0));
emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
}
static void move_ctx2blob(struct bpf_gen *gen, int off, int size, int ctx_off,
bool check_non_zero)
{
emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_6, ctx_off));
if (check_non_zero)
/* If value in ctx is zero don't update the blob.
* For example: when ctx->map.max_entries == 0, keep default max_entries from bpf.c
*/
emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, off));
emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}
static void move_stack2blob(struct bpf_gen *gen, int off, int size, int stack_off)
{
emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, off));
emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}
static void move_stack2ctx(struct bpf_gen *gen, int ctx_off, int size, int stack_off)
{
emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
}
static void emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int attr_size)
{
emit(gen, BPF_MOV64_IMM(BPF_REG_1, cmd));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, attr));
emit(gen, BPF_MOV64_IMM(BPF_REG_3, attr_size));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_bpf));
/* remember the result in R7 */
emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
}
static bool is_simm16(__s64 value)
{
return value == (__s64)(__s16)value;
}
static void emit_check_err(struct bpf_gen *gen)
{
__s64 off = -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1;
/* R7 contains result of last sys_bpf command.
* if (R7 < 0) goto cleanup;
*/
if (is_simm16(off)) {
emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, off));
} else {
gen->error = -ERANGE;
emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, -1));
}
}
/* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */
static void emit_debug(struct bpf_gen *gen, int reg1, int reg2,
const char *fmt, va_list args)
{
char buf[1024];
int addr, len, ret;
if (!gen->log_level)
return;
ret = vsnprintf(buf, sizeof(buf), fmt, args);
if (ret < 1024 - 7 && reg1 >= 0 && reg2 < 0)
/* The special case to accommodate common debug_ret():
* to avoid specifying BPF_REG_7 and adding " r=%%d" to
* prints explicitly.
*/
strcat(buf, " r=%d");
len = strlen(buf) + 1;
addr = add_data(gen, buf, len);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, addr));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
if (reg1 >= 0)
emit(gen, BPF_MOV64_REG(BPF_REG_3, reg1));
if (reg2 >= 0)
emit(gen, BPF_MOV64_REG(BPF_REG_4, reg2));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_trace_printk));
}
static void debug_regs(struct bpf_gen *gen, int reg1, int reg2, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
emit_debug(gen, reg1, reg2, fmt, args);
va_end(args);
}
static void debug_ret(struct bpf_gen *gen, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
emit_debug(gen, BPF_REG_7, -1, fmt, args);
va_end(args);
}
static void __emit_sys_close(struct bpf_gen *gen)
{
emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0,
/* 2 is the number of the following insns
* * 6 is additional insns in debug_regs
*/
2 + (gen->log_level ? 6 : 0)));
emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_1));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
debug_regs(gen, BPF_REG_9, BPF_REG_0, "close(%%d) = %%d");
}
static void emit_sys_close_stack(struct bpf_gen *gen, int stack_off)
{
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, stack_off));
__emit_sys_close(gen);
}
static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off)
{
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_off));
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 0));
__emit_sys_close(gen);
}
int bpf_gen__finish(struct bpf_gen *gen)
{
int i;
emit_sys_close_stack(gen, stack_off(btf_fd));
for (i = 0; i < gen->nr_progs; i++)
move_stack2ctx(gen,
sizeof(struct bpf_loader_ctx) +
sizeof(struct bpf_map_desc) * gen->nr_maps +
sizeof(struct bpf_prog_desc) * i +
offsetof(struct bpf_prog_desc, prog_fd), 4,
stack_off(prog_fd[i]));
for (i = 0; i < gen->nr_maps; i++)
move_blob2ctx(gen,
sizeof(struct bpf_loader_ctx) +
sizeof(struct bpf_map_desc) * i +
offsetof(struct bpf_map_desc, map_fd), 4,
blob_fd_array_off(gen, i));
emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0));
emit(gen, BPF_EXIT_INSN());
pr_debug("gen: finish %d\n", gen->error);
if (!gen->error) {
struct gen_loader_opts *opts = gen->opts;
opts->insns = gen->insn_start;
opts->insns_sz = gen->insn_cur - gen->insn_start;
opts->data = gen->data_start;
opts->data_sz = gen->data_cur - gen->data_start;
}
return gen->error;
}
void bpf_gen__free(struct bpf_gen *gen)
{
if (!gen)
return;
free(gen->data_start);
free(gen->insn_start);
free(gen);
}
void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data,
__u32 btf_raw_size)
{
int attr_size = offsetofend(union bpf_attr, btf_log_level);
int btf_data, btf_load_attr;
union bpf_attr attr;
memset(&attr, 0, attr_size);
pr_debug("gen: load_btf: size %d\n", btf_raw_size);
btf_data = add_data(gen, btf_raw_data, btf_raw_size);
attr.btf_size = btf_raw_size;
btf_load_attr = add_data(gen, &attr, attr_size);
/* populate union bpf_attr with user provided log details */
move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_level), 4,
offsetof(struct bpf_loader_ctx, log_level), false);
move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_size), 4,
offsetof(struct bpf_loader_ctx, log_size), false);
move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_buf), 8,
offsetof(struct bpf_loader_ctx, log_buf), false);
/* populate union bpf_attr with a pointer to the BTF data */
emit_rel_store(gen, attr_field(btf_load_attr, btf), btf_data);
/* emit BTF_LOAD command */
emit_sys_bpf(gen, BPF_BTF_LOAD, btf_load_attr, attr_size);
debug_ret(gen, "btf_load size %d", btf_raw_size);
emit_check_err(gen);
/* remember btf_fd in the stack, if successful */
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7, stack_off(btf_fd)));
}
void bpf_gen__map_create(struct bpf_gen *gen,
struct bpf_create_map_attr *map_attr, int map_idx)
{
int attr_size = offsetofend(union bpf_attr, btf_vmlinux_value_type_id);
bool close_inner_map_fd = false;
int map_create_attr, idx;
union bpf_attr attr;
memset(&attr, 0, attr_size);
attr.map_type = map_attr->map_type;
attr.key_size = map_attr->key_size;
attr.value_size = map_attr->value_size;
attr.map_flags = map_attr->map_flags;
memcpy(attr.map_name, map_attr->name,
min((unsigned)strlen(map_attr->name), BPF_OBJ_NAME_LEN - 1));
attr.numa_node = map_attr->numa_node;
attr.map_ifindex = map_attr->map_ifindex;
attr.max_entries = map_attr->max_entries;
switch (attr.map_type) {
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
case BPF_MAP_TYPE_CGROUP_ARRAY:
case BPF_MAP_TYPE_STACK_TRACE:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
case BPF_MAP_TYPE_CPUMAP:
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
case BPF_MAP_TYPE_RINGBUF:
break;
default:
attr.btf_key_type_id = map_attr->btf_key_type_id;
attr.btf_value_type_id = map_attr->btf_value_type_id;
}
pr_debug("gen: map_create: %s idx %d type %d value_type_id %d\n",
attr.map_name, map_idx, map_attr->map_type, attr.btf_value_type_id);
map_create_attr = add_data(gen, &attr, attr_size);
if (attr.btf_value_type_id)
/* populate union bpf_attr with btf_fd saved in the stack earlier */
move_stack2blob(gen, attr_field(map_create_attr, btf_fd), 4,
stack_off(btf_fd));
switch (attr.map_type) {
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
move_stack2blob(gen, attr_field(map_create_attr, inner_map_fd), 4,
stack_off(inner_map_fd));
close_inner_map_fd = true;
break;
default:
break;
}
/* conditionally update max_entries */
if (map_idx >= 0)
move_ctx2blob(gen, attr_field(map_create_attr, max_entries), 4,
sizeof(struct bpf_loader_ctx) +
sizeof(struct bpf_map_desc) * map_idx +
offsetof(struct bpf_map_desc, max_entries),
true /* check that max_entries != 0 */);
/* emit MAP_CREATE command */
emit_sys_bpf(gen, BPF_MAP_CREATE, map_create_attr, attr_size);
debug_ret(gen, "map_create %s idx %d type %d value_size %d value_btf_id %d",
attr.map_name, map_idx, map_attr->map_type, attr.value_size,
attr.btf_value_type_id);
emit_check_err(gen);
/* remember map_fd in the stack, if successful */
if (map_idx < 0) {
/* This bpf_gen__map_create() function is called with map_idx >= 0
* for all maps that libbpf loading logic tracks.
* It's called with -1 to create an inner map.
*/
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
stack_off(inner_map_fd)));
} else if (map_idx != gen->nr_maps) {
gen->error = -EDOM; /* internal bug */
return;
} else {
/* add_map_fd does gen->nr_maps++ */
idx = add_map_fd(gen);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_fd_array_off(gen, idx)));
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7, 0));
}
if (close_inner_map_fd)
emit_sys_close_stack(gen, stack_off(inner_map_fd));
}
void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *attach_name,
enum bpf_attach_type type)
{
const char *prefix;
int kind, ret;
btf_get_kernel_prefix_kind(type, &prefix, &kind);
gen->attach_kind = kind;
ret = snprintf(gen->attach_target, sizeof(gen->attach_target), "%s%s",
prefix, attach_name);
if (ret == sizeof(gen->attach_target))
gen->error = -ENOSPC;
}
static void emit_find_attach_target(struct bpf_gen *gen)
{
int name, len = strlen(gen->attach_target) + 1;
pr_debug("gen: find_attach_tgt %s %d\n", gen->attach_target, gen->attach_kind);
name = add_data(gen, gen->attach_target, len);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, name));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
emit(gen, BPF_MOV64_IMM(BPF_REG_3, gen->attach_kind));
emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
debug_ret(gen, "find_by_name_kind(%s,%d)",
gen->attach_target, gen->attach_kind);
emit_check_err(gen);
/* if successful, btf_id is in lower 32-bit of R7 and
* btf_obj_fd is in upper 32-bit
*/
}
void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
int kind, int insn_idx)
{
struct ksym_relo_desc *relo;
relo = libbpf_reallocarray(gen->relos, gen->relo_cnt + 1, sizeof(*relo));
if (!relo) {
gen->error = -ENOMEM;
return;
}
gen->relos = relo;
relo += gen->relo_cnt;
relo->name = name;
relo->is_weak = is_weak;
relo->kind = kind;
relo->insn_idx = insn_idx;
gen->relo_cnt++;
}
/* returns existing ksym_desc with ref incremented, or inserts a new one */
static struct ksym_desc *get_ksym_desc(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
struct ksym_desc *kdesc;
for (int i = 0; i < gen->nr_ksyms; i++) {
if (!strcmp(gen->ksyms[i].name, relo->name)) {
gen->ksyms[i].ref++;
return &gen->ksyms[i];
}
}
kdesc = libbpf_reallocarray(gen->ksyms, gen->nr_ksyms + 1, sizeof(*kdesc));
if (!kdesc) {
gen->error = -ENOMEM;
return NULL;
}
gen->ksyms = kdesc;
kdesc = &gen->ksyms[gen->nr_ksyms++];
kdesc->name = relo->name;
kdesc->kind = relo->kind;
kdesc->ref = 1;
kdesc->off = 0;
kdesc->insn = 0;
return kdesc;
}
/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
* Returns result in BPF_REG_7
*/
static void emit_bpf_find_by_name_kind(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
int name_off, len = strlen(relo->name) + 1;
name_off = add_data(gen, relo->name, len);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, name_off));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
emit(gen, BPF_MOV64_IMM(BPF_REG_3, relo->kind));
emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
debug_ret(gen, "find_by_name_kind(%s,%d)", relo->name, relo->kind);
}
/* Expects:
* BPF_REG_8 - pointer to instruction
*
* We need to reuse BTF fd for same symbol otherwise each relocation takes a new
* index, while kernel limits total kfunc BTFs to 256. For duplicate symbols,
* this would mean a new BTF fd index for each entry. By pairing symbol name
* with index, we get the insn->imm, insn->off pairing that kernel uses for
* kfunc_tab, which becomes the effective limit even though all of them may
* share same index in fd_array (such that kfunc_btf_tab has 1 element).
*/
static void emit_relo_kfunc_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
{
struct ksym_desc *kdesc;
int btf_fd_idx;
kdesc = get_ksym_desc(gen, relo);
if (!kdesc)
return;
/* try to copy from existing bpf_insn */
if (kdesc->ref > 1) {
move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
kdesc->insn + offsetof(struct bpf_insn, imm));
move_blob2blob(gen, insn + offsetof(struct bpf_insn, off), 2,
kdesc->insn + offsetof(struct bpf_insn, off));
goto log;
}
/* remember insn offset, so we can copy BTF ID and FD later */
kdesc->insn = insn;
emit_bpf_find_by_name_kind(gen, relo);
if (!relo->is_weak)
emit_check_err(gen);
/* get index in fd_array to store BTF FD at */
btf_fd_idx = add_kfunc_btf_fd(gen);
if (btf_fd_idx > INT16_MAX) {
pr_warn("BTF fd off %d for kfunc %s exceeds INT16_MAX, cannot process relocation\n",
btf_fd_idx, relo->name);
gen->error = -E2BIG;
return;
}
kdesc->off = btf_fd_idx;
/* set a default value for imm */
emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
/* skip success case store if ret < 0 */
emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 1));
/* store btf_id into insn[insn_idx].imm */
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
/* load fd_array slot pointer */
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_fd_array_off(gen, btf_fd_idx)));
/* skip store of BTF fd if ret < 0 */
emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 3));
/* store BTF fd in slot */
emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));
emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_9, 0));
/* set a default value for off */
emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
/* skip insn->off store if ret < 0 */
emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 2));
/* skip if vmlinux BTF */
emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_9, 0, 1));
/* store index into insn[insn_idx].off */
emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), btf_fd_idx));
log:
if (!gen->log_level)
return;
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
offsetof(struct bpf_insn, imm)));
emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8,
offsetof(struct bpf_insn, off)));
debug_regs(gen, BPF_REG_7, BPF_REG_9, " func (%s:count=%d): imm: %%d, off: %%d",
relo->name, kdesc->ref);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, blob_fd_array_off(gen, kdesc->off)));
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_0, 0));
debug_regs(gen, BPF_REG_9, -1, " func (%s:count=%d): btf_fd",
relo->name, kdesc->ref);
}
/* Expects:
* BPF_REG_8 - pointer to instruction
*/
static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
{
struct ksym_desc *kdesc;
kdesc = get_ksym_desc(gen, relo);
if (!kdesc)
return;
/* try to copy from existing ldimm64 insn */
if (kdesc->ref > 1) {
move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
kdesc->insn + offsetof(struct bpf_insn, imm));
move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
goto log;
}
/* remember insn offset, so we can copy BTF ID and FD later */
kdesc->insn = insn;
emit_bpf_find_by_name_kind(gen, relo);
emit_check_err(gen);
/* store btf_id into insn[insn_idx].imm */
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
/* store btf_obj_fd into insn[insn_idx + 1].imm */
emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7,
sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
log:
if (!gen->log_level)
return;
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
offsetof(struct bpf_insn, imm)));
emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8, sizeof(struct bpf_insn) +
offsetof(struct bpf_insn, imm)));
debug_regs(gen, BPF_REG_7, BPF_REG_9, " var (%s:count=%d): imm: %%d, fd: %%d",
relo->name, kdesc->ref);
}
static void emit_relo(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insns)
{
int insn;
pr_debug("gen: emit_relo (%d): %s at %d\n", relo->kind, relo->name, relo->insn_idx);
insn = insns + sizeof(struct bpf_insn) * relo->insn_idx;
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_8, BPF_PSEUDO_MAP_IDX_VALUE, 0, 0, 0, insn));
switch (relo->kind) {
case BTF_KIND_VAR:
emit_relo_ksym_btf(gen, relo, insn);
break;
case BTF_KIND_FUNC:
emit_relo_kfunc_btf(gen, relo, insn);
break;
default:
pr_warn("Unknown relocation kind '%d'\n", relo->kind);
gen->error = -EDOM;
return;
}
}
static void emit_relos(struct bpf_gen *gen, int insns)
{
int i;
for (i = 0; i < gen->relo_cnt; i++)
emit_relo(gen, gen->relos + i, insns);
}
static void cleanup_relos(struct bpf_gen *gen, int insns)
{
int i, insn;
for (i = 0; i < gen->nr_ksyms; i++) {
if (gen->ksyms[i].kind == BTF_KIND_VAR) {
/* close fd recorded in insn[insn_idx + 1].imm */
insn = gen->ksyms[i].insn;
insn += sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm);
emit_sys_close_blob(gen, insn);
} else { /* BTF_KIND_FUNC */
emit_sys_close_blob(gen, blob_fd_array_off(gen, gen->ksyms[i].off));
if (gen->ksyms[i].off < MAX_FD_ARRAY_SZ)
gen->nr_fd_array--;
}
}
if (gen->nr_ksyms) {
free(gen->ksyms);
gen->nr_ksyms = 0;
gen->ksyms = NULL;
}
if (gen->relo_cnt) {
free(gen->relos);
gen->relo_cnt = 0;
gen->relos = NULL;
}
}
void bpf_gen__prog_load(struct bpf_gen *gen,
struct bpf_prog_load_params *load_attr, int prog_idx)
{
int attr_size = offsetofend(union bpf_attr, fd_array);
int prog_load_attr, license, insns, func_info, line_info;
union bpf_attr attr;
memset(&attr, 0, attr_size);
pr_debug("gen: prog_load: type %d insns_cnt %zd\n",
load_attr->prog_type, load_attr->insn_cnt);
/* add license string to blob of bytes */
license = add_data(gen, load_attr->license, strlen(load_attr->license) + 1);
/* add insns to blob of bytes */
insns = add_data(gen, load_attr->insns,
load_attr->insn_cnt * sizeof(struct bpf_insn));
attr.prog_type = load_attr->prog_type;
attr.expected_attach_type = load_attr->expected_attach_type;
attr.attach_btf_id = load_attr->attach_btf_id;
attr.prog_ifindex = load_attr->prog_ifindex;
attr.kern_version = 0;
attr.insn_cnt = (__u32)load_attr->insn_cnt;
attr.prog_flags = load_attr->prog_flags;
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
func_info = add_data(gen, load_attr->func_info,
attr.func_info_cnt * attr.func_info_rec_size);
attr.line_info_rec_size = load_attr->line_info_rec_size;
attr.line_info_cnt = load_attr->line_info_cnt;
line_info = add_data(gen, load_attr->line_info,
attr.line_info_cnt * attr.line_info_rec_size);
memcpy(attr.prog_name, load_attr->name,
min((unsigned)strlen(load_attr->name), BPF_OBJ_NAME_LEN - 1));
prog_load_attr = add_data(gen, &attr, attr_size);
/* populate union bpf_attr with a pointer to license */
emit_rel_store(gen, attr_field(prog_load_attr, license), license);
/* populate union bpf_attr with a pointer to instructions */
emit_rel_store(gen, attr_field(prog_load_attr, insns), insns);
/* populate union bpf_attr with a pointer to func_info */
emit_rel_store(gen, attr_field(prog_load_attr, func_info), func_info);
/* populate union bpf_attr with a pointer to line_info */
emit_rel_store(gen, attr_field(prog_load_attr, line_info), line_info);
/* populate union bpf_attr fd_array with a pointer to data where map_fds are saved */
emit_rel_store(gen, attr_field(prog_load_attr, fd_array), gen->fd_array);
/* populate union bpf_attr with user provided log details */
move_ctx2blob(gen, attr_field(prog_load_attr, log_level), 4,
offsetof(struct bpf_loader_ctx, log_level), false);
move_ctx2blob(gen, attr_field(prog_load_attr, log_size), 4,
offsetof(struct bpf_loader_ctx, log_size), false);
move_ctx2blob(gen, attr_field(prog_load_attr, log_buf), 8,
offsetof(struct bpf_loader_ctx, log_buf), false);
/* populate union bpf_attr with btf_fd saved in the stack earlier */
move_stack2blob(gen, attr_field(prog_load_attr, prog_btf_fd), 4,
stack_off(btf_fd));
if (gen->attach_kind) {
emit_find_attach_target(gen);
/* populate union bpf_attr with btf_id and btf_obj_fd found by helper */
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, prog_load_attr));
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
offsetof(union bpf_attr, attach_btf_id)));
emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
offsetof(union bpf_attr, attach_btf_obj_fd)));
}
emit_relos(gen, insns);
/* emit PROG_LOAD command */
emit_sys_bpf(gen, BPF_PROG_LOAD, prog_load_attr, attr_size);
debug_ret(gen, "prog_load %s insn_cnt %d", attr.prog_name, attr.insn_cnt);
/* successful or not, close btf module FDs used in extern ksyms and attach_btf_obj_fd */
cleanup_relos(gen, insns);
if (gen->attach_kind)
emit_sys_close_blob(gen,
attr_field(prog_load_attr, attach_btf_obj_fd));
emit_check_err(gen);
/* remember prog_fd in the stack, if successful */
emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
stack_off(prog_fd[gen->nr_progs])));
gen->nr_progs++;
}
void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue,
__u32 value_size)
{
int attr_size = offsetofend(union bpf_attr, flags);
int map_update_attr, value, key;
union bpf_attr attr;
int zero = 0;
memset(&attr, 0, attr_size);
pr_debug("gen: map_update_elem: idx %d\n", map_idx);
value = add_data(gen, pvalue, value_size);
key = add_data(gen, &zero, sizeof(zero));
/* if (map_desc[map_idx].initial_value)
* copy_from_user(value, initial_value, value_size);
*/
emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6,
sizeof(struct bpf_loader_ctx) +
sizeof(struct bpf_map_desc) * map_idx +
offsetof(struct bpf_map_desc, initial_value)));
emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 4));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, value));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user));
map_update_attr = add_data(gen, &attr, attr_size);
move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
blob_fd_array_off(gen, map_idx));
emit_rel_store(gen, attr_field(map_update_attr, key), key);
emit_rel_store(gen, attr_field(map_update_attr, value), value);
/* emit MAP_UPDATE_ELEM command */
emit_sys_bpf(gen, BPF_MAP_UPDATE_ELEM, map_update_attr, attr_size);
debug_ret(gen, "update_elem idx %d value_size %d", map_idx, value_size);
emit_check_err(gen);
}
void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx)
{
int attr_size = offsetofend(union bpf_attr, map_fd);
int map_freeze_attr;
union bpf_attr attr;
memset(&attr, 0, attr_size);
pr_debug("gen: map_freeze: idx %d\n", map_idx);
map_freeze_attr = add_data(gen, &attr, attr_size);
move_blob2blob(gen, attr_field(map_freeze_attr, map_fd), 4,
blob_fd_array_off(gen, map_idx));
/* emit MAP_FREEZE command */
emit_sys_bpf(gen, BPF_MAP_FREEZE, map_freeze_attr, attr_size);
debug_ret(gen, "map_freeze");
emit_check_err(gen);
}