Re: [PATCH 5/5] bpf: Allow to resolve bpf trampoline in unwind
From: Björn Töpel <hidden>
Date: 2020-02-03 20:27:44
Also in:
bpf
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Martin KaFai Lau, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On 2020-02-03 20:58, Jiri Olsa wrote: [...]
quoted
quoted
...and FWIW, it would be nice with bpf_dispatcher_<...> entries in kallsymsok 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);
}