korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-12-04 01:24:12 +08:00
Code Issues Packages Projects Releases Wiki Activity

bpf: allow for tailcalls in BPF subprograms for x64 JIT

Browse Source 
Relax verifier's restriction that was meant to forbid tailcall usage
when subprog count was higher than 1.

Also, do not max out the stack depth of program that utilizes tailcalls.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Maciej Fijalkowski 2020-09-16 23:10:09 +02:00 committed by Alexei Starovoitov
parent ebf7d1f508
commit e411901c0b
1 changed files with 17 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/bpf/verifier.c
View File

@ -4268,6 +4268,11 @@ static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
return false;
}
static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64);
}
static int check_map_func_compatibility(struct bpf_verifier_env *env,
struct bpf_map *map, int func_id)
{
@ -4383,8 +4388,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_FUNC_tail_call:
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
goto error;
if (env->subprog_cnt > 1) {
verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
return -EINVAL;
}
break;
@ -10469,6 +10474,13 @@ static int fixup_call_args(struct bpf_verifier_env *env)
return err;
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
/* When JIT fails the progs with bpf2bpf calls and tail_calls
* have to be rejected, since interpreter doesn't support them yet.
*/
verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
return -EINVAL;
}
for (i = 0; i < prog->len; i++, insn++) {
if (insn->code != (BPF_JMP | BPF_CALL) ||
insn->src_reg != BPF_PSEUDO_CALL)
@ -10632,8 +10644,9 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
* the program array.
*/
prog->cb_access = 1;
env->prog->aux->stack_depth = MAX_BPF_STACK;
env->prog->aux->max_pkt_offset = MAX_PACKET_OFF;
if (!allow_tail_call_in_subprogs(env))
prog->aux->stack_depth = MAX_BPF_STACK;
prog->aux->max_pkt_offset = MAX_PACKET_OFF;
/* mark bpf_tail_call as different opcode to avoid
* conditional branch in the interpeter for every normal