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Date: Mon, 3 Feb 2020 21:27:39 +0100
From: Björn Töpel <bjorn.topel@...el.com>
To: Jiri Olsa <jolsa@...hat.com>
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>,
Jiri Olsa <jolsa@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
bpf@...r.kernel.org, Andrii Nakryiko <andriin@...com>,
Yonghong Song <yhs@...com>, Martin KaFai Lau <kafai@...com>,
Jakub Kicinski <jakub.kicinski@...ronome.com>,
David Miller <davem@...hat.com>
Subject: Re: [PATCH 5/5] bpf: Allow to resolve bpf trampoline in unwind
On 2020-02-03 20:58, Jiri Olsa wrote:
[...]
>>> ...and FWIW, it would be nice with bpf_dispatcher_<...> entries in kallsyms
>>
>> ok so it'd be 'bpf_dispatcher_<name>'
>
> hi,
> so the only dispatcher is currently defined as:
> DEFINE_BPF_DISPATCHER(bpf_dispatcher_xdp)
>
> with the bpf_dispatcher_<name> logic it shows in kallsyms as:
> ffffffffa0450000 t bpf_dispatcher_bpf_dispatcher_xdp [bpf]
>
Ick! :-P
> to fix that, would you guys preffer having:
> DEFINE_BPF_DISPATCHER(xdp)
>
> or using the full dispatcher name as kallsyms name?
> which would require some discipline for future dispatcher names ;-)
>
I'd prefer the latter, i.e. name "xdp" is shown as bpf_dispatcher_xdp in
kallsyms.
...and if this route is taken, the macros can be changed, so that the
trampoline functions are prefixed with "bpf_dispatcher_". Something like
this (and also a small '_' cleanup):
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8e9ad3943cd9..15c5f351f837 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -512,7 +512,7 @@ struct bpf_dispatcher {
u32 image_off;
};
-static __always_inline unsigned int bpf_dispatcher_nopfunc(
+static __always_inline unsigned int bpf_dispatcher_nop_func(
const void *ctx,
const struct bpf_insn *insnsi,
unsigned int (*bpf_func)(const void *,
@@ -527,7 +527,7 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog);
void bpf_trampoline_put(struct bpf_trampoline *tr);
#define BPF_DISPATCHER_INIT(name) { \
.mutex = __MUTEX_INITIALIZER(name.mutex), \
- .func = &name##func, \
+ .func = &name##_func, \
.progs = {}, \
.num_progs = 0, \
.image = NULL, \
@@ -535,7 +535,7 @@ void bpf_trampoline_put(struct bpf_trampoline *tr);
}
#define DEFINE_BPF_DISPATCHER(name) \
- noinline unsigned int name##func( \
+ noinline unsigned int bpf_dispatcher_##name##_func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
unsigned int (*bpf_func)(const void *, \
@@ -543,17 +543,18 @@ void bpf_trampoline_put(struct bpf_trampoline *tr);
{ \
return bpf_func(ctx, insnsi); \
} \
- EXPORT_SYMBOL(name##func); \
- struct bpf_dispatcher name = BPF_DISPATCHER_INIT(name);
+ EXPORT_SYMBOL(bpf_dispatcher_##name##_func); \
+ struct bpf_dispatcher bpf_dispatcher_##name = \
+ BPF_DISPATCHER_INIT(bpf_dispatcher_##name);
#define DECLARE_BPF_DISPATCHER(name) \
- unsigned int name##func( \
+ unsigned int bpf_dispatcher_##name##_func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
unsigned int (*bpf_func)(const void *, \
const struct bpf_insn *)); \
- extern struct bpf_dispatcher name;
-#define BPF_DISPATCHER_FUNC(name) name##func
-#define BPF_DISPATCHER_PTR(name) (&name)
+ extern struct bpf_dispatcher bpf_dispatcher_##name;
+#define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_##name##_func
+#define BPF_DISPATCHER_PTR(name) (&bpf_dispatcher_##name)
void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct
bpf_prog *from,
struct bpf_prog *to);
struct bpf_image {
@@ -579,7 +580,7 @@ static inline int bpf_trampoline_unlink_prog(struct
bpf_prog *prog)
static inline void bpf_trampoline_put(struct bpf_trampoline *tr) {}
#define DEFINE_BPF_DISPATCHER(name)
#define DECLARE_BPF_DISPATCHER(name)
-#define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_nopfunc
+#define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_nop_func
#define BPF_DISPATCHER_PTR(name) NULL
static inline void bpf_dispatcher_change_prog(struct bpf_dispatcher *d,
struct bpf_prog *from,
diff --git a/include/linux/filter.h b/include/linux/filter.h
index f349e2c0884c..eafe72644282 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -577,7 +577,7 @@ DECLARE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
ret; })
#define BPF_PROG_RUN(prog, ctx) __BPF_PROG_RUN(prog, ctx, \
- bpf_dispatcher_nopfunc)
+ bpf_dispatcher_nop_func)
#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
@@ -701,7 +701,7 @@ static inline u32 bpf_prog_run_clear_cb(const struct
bpf_prog *prog,
return res;
}
-DECLARE_BPF_DISPATCHER(bpf_dispatcher_xdp)
+DECLARE_BPF_DISPATCHER(xdp)
static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
struct xdp_buff *xdp)
@@ -712,8 +712,7 @@ static __always_inline u32 bpf_prog_run_xdp(const
struct bpf_prog *prog,
* already takes rcu_read_lock() when fetching the program, so
* it's not necessary here anymore.
*/
- return __BPF_PROG_RUN(prog, xdp,
- BPF_DISPATCHER_FUNC(bpf_dispatcher_xdp));
+ return __BPF_PROG_RUN(prog, xdp, BPF_DISPATCHER_FUNC(xdp));
}
void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog
*prog);
diff --git a/net/core/filter.c b/net/core/filter.c
index 792e3744b915..5db435141e16 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8835,10 +8835,9 @@ const struct bpf_prog_ops sk_reuseport_prog_ops = {
};
#endif /* CONFIG_INET */
-DEFINE_BPF_DISPATCHER(bpf_dispatcher_xdp)
+DEFINE_BPF_DISPATCHER(xdp)
void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog
*prog)
{
- bpf_dispatcher_change_prog(BPF_DISPATCHER_PTR(bpf_dispatcher_xdp),
- prev_prog, prog);
+ bpf_dispatcher_change_prog(BPF_DISPATCHER_PTR(xdp), prev_prog, prog);
}
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