Commit 535911c8 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

bpf: Add struct bpf_ksym 



Adding 'struct bpf_ksym' object that will carry the
kallsym information for bpf symbol. Adding the start
and end address to begin with. It will be used by
bpf_prog, bpf_trampoline, bpf_dispatcher objects.

The symbol_start/symbol_end values were originally used
to sort bpf_prog objects. For the address displayed in
/proc/kallsyms we are using prog->bpf_func value.

I'm using the bpf_func value for program symbol start
instead of the symbol_start, because it makes no difference
for sorting bpf_prog objects and we can use it directly as
an address to display it in /proc/kallsyms.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200312195610.346362-4-jolsa@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 6a64037d

include/linux/bpf.h

+6 −0
Original line number Diff line number Diff line
@@ -471,6 +471,11 @@ 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;

};



enum bpf_tramp_prog_type {

	BPF_TRAMP_FENTRY,

	BPF_TRAMP_FEXIT,
@@ -653,6 +658,7 @@ struct bpf_prog_aux { 
	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;

kernel/bpf/core.c

+12 −16
Original line number Diff line number Diff line
@@ -523,18 +523,16 @@ int bpf_jit_kallsyms __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_DEFAULT_ON); 
int bpf_jit_harden   __read_mostly;

long bpf_jit_limit   __read_mostly;



static __always_inline void

bpf_get_prog_addr_region(const struct bpf_prog *prog,

			 unsigned long *symbol_start,

			 unsigned long *symbol_end)

static void

bpf_prog_ksym_set_addr(struct bpf_prog *prog)

{

	const struct bpf_binary_header *hdr = bpf_jit_binary_hdr(prog);

	unsigned long addr = (unsigned long)hdr;



	WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog));



	*symbol_start = addr;

	*symbol_end   = addr + hdr->pages * PAGE_SIZE;

	prog->aux->ksym.start = (unsigned long) prog->bpf_func;

	prog->aux->ksym.end   = addr + hdr->pages * PAGE_SIZE;

}



void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
@@ -575,13 +573,10 @@ void bpf_get_prog_name(const struct bpf_prog *prog, char *sym) 
static __always_inline unsigned long

bpf_get_prog_addr_start(struct latch_tree_node *n)

{

	unsigned long symbol_start, symbol_end;

	const struct bpf_prog_aux *aux;



	aux = container_of(n, struct bpf_prog_aux, ksym_tnode);

	bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end);



	return symbol_start;

	return aux->ksym.start;

}



static __always_inline bool bpf_tree_less(struct latch_tree_node *a,
@@ -593,15 +588,13 @@ static __always_inline bool bpf_tree_less(struct latch_tree_node *a, 
static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n)

{

	unsigned long val = (unsigned long)key;

	unsigned long symbol_start, symbol_end;

	const struct bpf_prog_aux *aux;



	aux = container_of(n, struct bpf_prog_aux, ksym_tnode);

	bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end);



	if (val < symbol_start)

	if (val < aux->ksym.start)

		return -1;

	if (val >= symbol_end)

	if (val >= aux->ksym.end)

		return  1;



	return 0;
@@ -649,6 +642,8 @@ void bpf_prog_kallsyms_add(struct bpf_prog *fp) 
	    !capable(CAP_SYS_ADMIN))

		return;



	bpf_prog_ksym_set_addr(fp);



	spin_lock_bh(&bpf_lock);

	bpf_prog_ksym_node_add(fp->aux);

	spin_unlock_bh(&bpf_lock);
@@ -677,14 +672,15 @@ static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr) 
const char *__bpf_address_lookup(unsigned long addr, unsigned long *size,

				 unsigned long *off, char *sym)

{

	unsigned long symbol_start, symbol_end;

	struct bpf_prog *prog;

	char *ret = NULL;



	rcu_read_lock();

	prog = bpf_prog_kallsyms_find(addr);

	if (prog) {

		bpf_get_prog_addr_region(prog, &symbol_start, &symbol_end);

		unsigned long symbol_start = prog->aux->ksym.start;

		unsigned long symbol_end = prog->aux->ksym.end;



		bpf_get_prog_name(prog, sym);



		ret = sym;

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