Merge branch 'generalize-bpf-ksym'

Jiri Olsa says:

====================
this patchset adds trampoline and dispatcher objects
to be visible in /proc/kallsyms.

  $ sudo cat /proc/kallsyms | tail -20
  ...
  ffffffffa050f000 t bpf_prog_5a2b06eab81b8f51    [bpf]
  ffffffffa0511000 t bpf_prog_6deef7357e7b4530    [bpf]
  ffffffffa0542000 t bpf_trampoline_13832 [bpf]
  ffffffffa0548000 t bpf_prog_96f1b5bf4e4cc6dc_mutex_lock [bpf]
  ffffffffa0572000 t bpf_prog_d1c63e29ad82c4ab_bpf_prog1  [bpf]
  ffffffffa0585000 t bpf_prog_e314084d332a5338__dissect   [bpf]
  ffffffffa0587000 t bpf_prog_59785a79eac7e5d2_mutex_unlock       [bpf]
  ffffffffa0589000 t bpf_prog_d0db6e0cac050163_mutex_lock [bpf]
  ffffffffa058d000 t bpf_prog_d8f047721e4d8321_bpf_prog2  [bpf]
  ffffffffa05df000 t bpf_trampoline_25637 [bpf]
  ffffffffa05e3000 t bpf_prog_d8f047721e4d8321_bpf_prog2  [bpf]
  ffffffffa05e5000 t bpf_prog_3b185187f1855c4c    [bpf]
  ffffffffa05e7000 t bpf_prog_d8f047721e4d8321_bpf_prog2  [bpf]
  ffffffffa05eb000 t bpf_prog_93cebb259dd5c4b2_do_sys_open        [bpf]
  ffffffffa0677000 t bpf_dispatcher_xdp   [bpf]

v5 changes:
  - keeping just 1 bpf_tree for all the objects and adding flag
    to recognize bpf_objects when searching for exception tables [Alexei]
  - no need for is_bpf_image_address call in kernel_text_address [Alexei]
  - removed the bpf_image tree, because it's no longer needed

v4 changes:
  - add trampoline and dispatcher to kallsyms once the it's allocated [Alexei]
  - omit the symbols sorting for kallsyms [Alexei]
  - small title change in one patch [Song]
  - some function renames:
     bpf_get_prog_name to bpf_prog_ksym_set_name
     bpf_get_prog_addr_region to bpf_prog_ksym_set_addr
  - added acks to changelogs
  - I checked and there'll be conflict on perftool side with
    upcoming changes from Adrian Hunter (text poke events),
    so I think it's better if Arnaldo takes the perf changes
    via perf tree and we will solve all conflicts there

v3 changes:
  - use container_of directly in bpf_get_ksym_start  [Daniel]
  - add more changelog explanations for ksym addresses [Daniel]

v2 changes:
  - omit extra condition in __bpf_ksym_add for sorting code (Andrii)
  - rename bpf_kallsyms_tree_ops to bpf_ksym_tree (Andrii)
  - expose only executable code in kallsyms (Andrii)
  - use full trampoline key as its kallsyms id (Andrii)
  - explained the BPF_TRAMP_REPLACE case (Andrii)
  - small format changes in bpf_trampoline_link_prog/bpf_trampoline_unlink_prog (Andrii)
  - propagate error value in bpf_dispatcher_update and update kallsym if it's successful (Andrii)
  - get rid of __always_inline for bpf_ksym_tree callbacks (Andrii)
  - added KSYMBOL notification for bpf_image add/removal
  - added perf tools changes to properly display trampoline/dispatcher
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 44 insertions, 36 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c2f815e9f7d0..bdb981c204fa 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -18,6 +18,7 @@
 #include <linux/refcount.h>
 #include <linux/mutex.h>
 #include <linux/module.h>
+#include <linux/kallsyms.h>
 
 struct bpf_verifier_env;
 struct bpf_verifier_log;
@@ -471,6 +472,15 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end,
 u64 notrace __bpf_prog_enter(void);
 void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start);
 
+struct bpf_ksym {
+	unsigned long		 start;
+	unsigned long		 end;
+	char			 name[KSYM_NAME_LEN];
+	struct list_head	 lnode;
+	struct latch_tree_node	 tnode;
+	bool			 prog;
+};
+
 enum bpf_tramp_prog_type {
 	BPF_TRAMP_FENTRY,
 	BPF_TRAMP_FEXIT,
@@ -503,6 +513,7 @@ struct bpf_trampoline {
 	/* Executable image of trampoline */
 	void *image;
 	u64 selector;
+	struct bpf_ksym ksym;
 };
 
 #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */
@@ -520,9 +531,10 @@ struct bpf_dispatcher {
 	int num_progs;
 	void *image;
 	u32 image_off;
+	struct bpf_ksym ksym;
 };
 
-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 *,
@@ -535,17 +547,21 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key);
 int bpf_trampoline_link_prog(struct bpf_prog *prog);
 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,				\
-	.progs = {},					\
-	.num_progs = 0,					\
-	.image = NULL,					\
-	.image_off = 0					\
+#define BPF_DISPATCHER_INIT(_name) {				\
+	.mutex = __MUTEX_INITIALIZER(_name.mutex),		\
+	.func = &_name##_func,					\
+	.progs = {},						\
+	.num_progs = 0,						\
+	.image = NULL,						\
+	.image_off = 0,						\
+	.ksym = {						\
+		.name  = #_name,				\
+		.lnode = LIST_HEAD_INIT(_name.ksym.lnode),	\
+	},							\
 }
 
 #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 *,			\
@@ -553,26 +569,26 @@ 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 {
-	struct latch_tree_node tnode;
-	unsigned char data[];
-};
-#define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image))
-bool is_bpf_image_address(unsigned long address);
-void *bpf_image_alloc(void);
+/* Called only from JIT-enabled code, so there's no need for stubs. */
+void *bpf_jit_alloc_exec_page(void);
+void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym);
+void bpf_image_ksym_del(struct bpf_ksym *ksym);
+void bpf_ksym_add(struct bpf_ksym *ksym);
+void bpf_ksym_del(struct bpf_ksym *ksym);
 #else
 static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
@@ -589,7 +605,7 @@ 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,
@@ -650,8 +666,7 @@ struct bpf_prog_aux {
 	void *jit_data; /* JIT specific data. arch dependent */
 	struct bpf_jit_poke_descriptor *poke_tab;
 	u32 size_poke_tab;
-	struct latch_tree_node ksym_tnode;
-	struct list_head ksym_lnode;
+	struct bpf_ksym ksym;
 	const struct bpf_prog_ops *ops;
 	struct bpf_map **used_maps;
 	struct bpf_prog *prog;
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 43b5e455d2f5..9b5aa5c483cc 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_PROG_RUN(prog, ctx, bpf_dispatcher_nop_func)
 
 /*
  * Use in preemptible and therefore migratable context to make sure that
@@ -596,7 +596,7 @@ static inline u32 bpf_prog_run_pin_on_cpu(const struct bpf_prog *prog,
 	u32 ret;
 
 	migrate_disable();
-	ret = __BPF_PROG_RUN(prog, ctx, bpf_dispatcher_nopfunc);
+	ret = __BPF_PROG_RUN(prog, ctx, bpf_dispatcher_nop_func);
 	migrate_enable();
 	return ret;
 }
@@ -722,7 +722,7 @@ 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)
@@ -733,8 +733,7 @@ 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);
@@ -1084,7 +1083,6 @@ bpf_address_lookup(unsigned long addr, unsigned long *size,
 
 void bpf_prog_kallsyms_add(struct bpf_prog *fp);
 void bpf_prog_kallsyms_del(struct bpf_prog *fp);
-void bpf_get_prog_name(const struct bpf_prog *prog, char *sym);
 
 #else /* CONFIG_BPF_JIT */
 
@@ -1153,11 +1151,6 @@ static inline void bpf_prog_kallsyms_del(struct bpf_prog *fp)
 {
 }
 
-static inline void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
-{
-	sym[0] = '\0';
-}
-
 #endif /* CONFIG_BPF_JIT */
 
 void bpf_prog_kallsyms_del_all(struct bpf_prog *fp);