From 18acb7fac22ff7b36c7ea5a76b12996e7b7dbaba Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 3 Nov 2022 13:00:13 +0100 Subject: [PATCH] bpf: Revert ("Fix dispatcher patchable function entry to 5 bytes nop") MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Because __attribute__((patchable_function_entry)) is only available since GCC-8 this solution fails to build on the minimum required GCC version. Undo these changes so we might try again -- without cluttering up the patches with too many changes. This is an almost complete revert of: dbe69b299884 ("bpf: Fix dispatcher patchable function entry to 5 bytes nop") ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations") (notably the arch/x86/Kconfig hunk is kept). Reported-by: David Laight Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Daniel Borkmann Tested-by: Björn Töpel Tested-by: Jiri Olsa Acked-by: Björn Töpel Acked-by: Jiri Olsa Link: https://lkml.kernel.org/r/439d8dc735bb4858875377df67f1b29a@AcuMS.aculab.com Link: https://lore.kernel.org/bpf/20221103120647.728830733@infradead.org --- arch/x86/net/bpf_jit_comp.c | 13 ------------- include/linux/bpf.h | 21 +-------------------- kernel/bpf/dispatcher.c | 6 ------ 3 files changed, 1 insertion(+), 39 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 00127ab..9962042 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -11,7 +11,6 @@ #include #include #include -#include #include #include #include @@ -389,18 +388,6 @@ out: return ret; } -int __init bpf_arch_init_dispatcher_early(void *ip) -{ - const u8 *nop_insn = x86_nops[5]; - - if (is_endbr(*(u32 *)ip)) - ip += ENDBR_INSN_SIZE; - - if (memcmp(ip, nop_insn, X86_PATCH_SIZE)) - text_poke_early(ip, nop_insn, X86_PATCH_SIZE); - return 0; -} - int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *old_addr, void *new_addr) { diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0566705..5cd9571 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -27,7 +27,6 @@ #include #include #include -#include struct bpf_verifier_env; struct bpf_verifier_log; @@ -971,8 +970,6 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key, struct bpf_attach_target_info *tgt_info); void bpf_trampoline_put(struct bpf_trampoline *tr); int arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int num_funcs); -int __init bpf_arch_init_dispatcher_early(void *ip); - #define BPF_DISPATCHER_INIT(_name) { \ .mutex = __MUTEX_INITIALIZER(_name.mutex), \ .func = &_name##_func, \ @@ -986,21 +983,7 @@ int __init bpf_arch_init_dispatcher_early(void *ip); }, \ } -#define BPF_DISPATCHER_INIT_CALL(_name) \ - static int __init _name##_init(void) \ - { \ - return bpf_arch_init_dispatcher_early(_name##_func); \ - } \ - early_initcall(_name##_init) - -#ifdef CONFIG_X86_64 -#define BPF_DISPATCHER_ATTRIBUTES __attribute__((patchable_function_entry(5))) -#else -#define BPF_DISPATCHER_ATTRIBUTES -#endif - #define DEFINE_BPF_DISPATCHER(name) \ - notrace BPF_DISPATCHER_ATTRIBUTES \ noinline __nocfi unsigned int bpf_dispatcher_##name##_func( \ const void *ctx, \ const struct bpf_insn *insnsi, \ @@ -1010,9 +993,7 @@ int __init bpf_arch_init_dispatcher_early(void *ip); } \ EXPORT_SYMBOL(bpf_dispatcher_##name##_func); \ struct bpf_dispatcher bpf_dispatcher_##name = \ - BPF_DISPATCHER_INIT(bpf_dispatcher_##name); \ - BPF_DISPATCHER_INIT_CALL(bpf_dispatcher_##name); - + BPF_DISPATCHER_INIT(bpf_dispatcher_##name); #define DECLARE_BPF_DISPATCHER(name) \ unsigned int bpf_dispatcher_##name##_func( \ const void *ctx, \ diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index 04f0a04..fa64b80 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -4,7 +4,6 @@ #include #include #include -#include /* The BPF dispatcher is a multiway branch code generator. The * dispatcher is a mechanism to avoid the performance penalty of an @@ -91,11 +90,6 @@ int __weak arch_prepare_bpf_dispatcher(void *image, void *buf, s64 *funcs, int n return -ENOTSUPP; } -int __weak __init bpf_arch_init_dispatcher_early(void *ip) -{ - return -ENOTSUPP; -} - static int bpf_dispatcher_prepare(struct bpf_dispatcher *d, void *image, void *buf) { s64 ips[BPF_DISPATCHER_MAX] = {}, *ipsp = &ips[0]; -- 2.7.4