Commit 5576b991 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpf: Add BPF_FUNC_jiffies64 



This patch adds a helper to read the 64bit jiffies.  It will be used
in a later patch to implement the bpf_cubic.c.

The helper is inlined for jit_requested and 64 BITS_PER_LONG
as the map_gen_lookup().  Other cases could be considered together
with map_gen_lookup() if needed.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200122233646.903260-1-kafai@fb.com
parent 1b2fd38d

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -1414,6 +1414,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto; 
extern const struct bpf_func_proto bpf_strtol_proto;

extern const struct bpf_func_proto bpf_strtoul_proto;

extern const struct bpf_func_proto bpf_tcp_sock_proto;

extern const struct bpf_func_proto bpf_jiffies64_proto;



/* Shared helpers among cBPF and eBPF. */

void bpf_user_rnd_init_once(void);

include/uapi/linux/bpf.h

+8 −1
Original line number Diff line number Diff line
@@ -2886,6 +2886,12 @@ union bpf_attr { 
 *		**-EPERM** if no permission to send the *sig*.

 *

 *		**-EAGAIN** if bpf program can try again.

 *

 * u64 bpf_jiffies64(void)

 *	Description

 *		Obtain the 64bit jiffies

 *	Return

 *		The 64 bit jiffies

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -3005,7 +3011,8 @@ union bpf_attr { 
	FN(probe_read_user_str),	\

	FN(probe_read_kernel_str),	\

	FN(tcp_send_ack),		\

	FN(send_signal_thread),

	FN(send_signal_thread),		\

	FN(jiffies64),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

kernel/bpf/core.c

+1 −0
Original line number Diff line number Diff line
@@ -2137,6 +2137,7 @@ const struct bpf_func_proto bpf_map_pop_elem_proto __weak; 
const struct bpf_func_proto bpf_map_peek_elem_proto __weak;

const struct bpf_func_proto bpf_spin_lock_proto __weak;

const struct bpf_func_proto bpf_spin_unlock_proto __weak;

const struct bpf_func_proto bpf_jiffies64_proto __weak;



const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;

const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;

kernel/bpf/helpers.c

+12 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/uidgid.h>

#include <linux/filter.h>

#include <linux/ctype.h>

#include <linux/jiffies.h>



#include "../../lib/kstrtox.h"
@@ -312,6 +313,17 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src, 
	preempt_enable();

}



BPF_CALL_0(bpf_jiffies64)

{

	return get_jiffies_64();

}



const struct bpf_func_proto bpf_jiffies64_proto = {

	.func		= bpf_jiffies64,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

};



#ifdef CONFIG_CGROUPS

BPF_CALL_0(bpf_get_current_cgroup_id)

{

kernel/bpf/verifier.c

+24 −0
Original line number Diff line number Diff line
@@ -9445,6 +9445,30 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) 
			goto patch_call_imm;

		}



		if (prog->jit_requested && BITS_PER_LONG == 64 &&

		    insn->imm == BPF_FUNC_jiffies64) {

			struct bpf_insn ld_jiffies_addr[2] = {

				BPF_LD_IMM64(BPF_REG_0,

					     (unsigned long)&jiffies),

			};



			insn_buf[0] = ld_jiffies_addr[0];

			insn_buf[1] = ld_jiffies_addr[1];

			insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,

						  BPF_REG_0, 0);

			cnt = 3;



			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,

						       cnt);

			if (!new_prog)

				return -ENOMEM;



			delta    += cnt - 1;

			env->prog = prog = new_prog;

			insn      = new_prog->insnsi + i + delta;

			continue;

		}



patch_call_imm:

		fn = env->ops->get_func_proto(insn->imm, env->prog);

		/* all functions that have prototype and verifier allowed

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