From: Tony Ambardar Date: Fri, 17 Jun 2022 10:57:34 +0000 (+0200) Subject: bpf, x64: Add predicate for bpf2bpf with tailcalls support in JIT X-Git-Tag: v5.18.18~642 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b8b5bef0062da686482fc34397e7fce6336819e4;p=thirdparty%2Fkernel%2Fstable.git bpf, x64: Add predicate for bpf2bpf with tailcalls support in JIT [ Upstream commit 95acd8817e66d031d2e6ee7def3f1e1874819317 ] The BPF core/verifier is hard-coded to permit mixing bpf2bpf and tail calls for only x86-64. Change the logic to instead rely on a new weak function 'bool bpf_jit_supports_subprog_tailcalls(void)', which a capable JIT backend can override. Update the x86-64 eBPF JIT to reflect this. Signed-off-by: Tony Ambardar [jakub: drop MIPS bits and tweak patch subject] Signed-off-by: Jakub Sitnicki Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220617105735.733938-2-jakub@cloudflare.com Signed-off-by: Sasha Levin --- diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 9ec96d5a82397..124456bb23b92 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2477,3 +2477,9 @@ void *bpf_arch_text_copy(void *dst, void *src, size_t len) return ERR_PTR(-EINVAL); return dst; } + +/* Indicate the JIT backend supports mixing bpf2bpf and tailcalls. */ +bool bpf_jit_supports_subprog_tailcalls(void) +{ + return true; +} diff --git a/include/linux/filter.h b/include/linux/filter.h index ed0c0ff42ad5b..d9a0db845b508 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -948,6 +948,7 @@ u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog); void bpf_jit_compile(struct bpf_prog *prog); bool bpf_jit_needs_zext(void); +bool bpf_jit_supports_subprog_tailcalls(void); bool bpf_jit_supports_kfunc_call(void); bool bpf_helper_changes_pkt_data(void *func); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 3adff3831c047..7a1ce697689b9 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2712,6 +2712,12 @@ bool __weak bpf_jit_needs_zext(void) return false; } +/* Return TRUE if the JIT backend supports mixing bpf2bpf and tailcalls. */ +bool __weak bpf_jit_supports_subprog_tailcalls(void) +{ + return false; +} + bool __weak bpf_jit_supports_kfunc_call(void) { return false; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d04147a5efa55..a6d3a89723555 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5696,7 +5696,8 @@ static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env) { - return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64); + return env->prog->jit_requested && + bpf_jit_supports_subprog_tailcalls(); } static int check_map_func_compatibility(struct bpf_verifier_env *env,