From: Peter Zijlstra <peterz@infradead.org>
To: olsajiri@gmail.com, ast@kernel.org, daniel@iogearbox.net
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org, peterz@infradead.org, bjorn@kernel.org,
toke@redhat.com, David.Laight@aculab.com, rostedt@goodmis.org
Subject: [PATCH 1/2] bpf: Revert ("Fix dispatcher patchable function entry to 5 bytes nop")
Date: Thu, 03 Nov 2022 13:00:13 +0100 [thread overview]
Message-ID: <20221103120647.728830733@infradead.org> (raw)
In-Reply-To: 20221103120012.717020618@infradead.org
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 <David.Laight@aculab.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/439d8dc735bb4858875377df67f1b29a@AcuMS.aculab.com
---
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(-)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -11,7 +11,6 @@
#include <linux/bpf.h>
#include <linux/memory.h>
#include <linux/sort.h>
-#include <linux/init.h>
#include <asm/extable.h>
#include <asm/set_memory.h>
#include <asm/nospec-branch.h>
@@ -389,18 +388,6 @@ static int __bpf_arch_text_poke(void *ip
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)
{
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -27,7 +27,6 @@
#include <linux/bpfptr.h>
#include <linux/btf.h>
#include <linux/rcupdate_trace.h>
-#include <linux/init.h>
struct bpf_verifier_env;
struct bpf_verifier_log;
@@ -971,8 +970,6 @@ struct bpf_trampoline *bpf_trampoline_ge
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_earl
}, \
}
-#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_earl
} \
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, \
--- a/kernel/bpf/dispatcher.c
+++ b/kernel/bpf/dispatcher.c
@@ -4,7 +4,6 @@
#include <linux/hash.h>
#include <linux/bpf.h>
#include <linux/filter.h>
-#include <linux/init.h>
/* The BPF dispatcher is a multiway branch code generator. The
* dispatcher is a mechanism to avoid the performance penalty of an
@@ -90,11 +89,6 @@ int __weak arch_prepare_bpf_dispatcher(v
{
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)
{
next prev parent reply other threads:[~2022-11-03 12:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-03 12:00 [PATCH 0/2] bpf: Yet another approach to fix the BPF dispatcher thing Peter Zijlstra
2022-11-03 12:00 ` Peter Zijlstra [this message]
2022-11-03 12:00 ` [PATCH 2/2] bpf: Convert BPF_DISPATCHER to use static_call() (not ftrace) Peter Zijlstra
2022-11-14 17:36 ` Steven Rostedt
2022-11-03 13:42 ` [PATCH 0/2] bpf: Yet another approach to fix the BPF dispatcher thing Björn Töpel
2022-11-03 14:48 ` Jiri Olsa
2022-11-04 22:20 ` patchwork-bot+netdevbpf
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