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Message-ID: <20200121195414.3757563-1-kafai@fb.com>
Date: Tue, 21 Jan 2020 11:54:14 -0800
From: Martin KaFai Lau <kafai@...com>
To: <bpf@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
David Miller <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, <kernel-team@...com>,
<netdev@...r.kernel.org>
Subject: [PATCH bpf-next 1/3] 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. "gen_inline" is added to "struct bpf_func_proto"
to do that. This helper is available to CAP_SYS_ADMIN.
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
include/linux/bpf.h | 2 ++
include/uapi/linux/bpf.h | 9 ++++++++-
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 27 +++++++++++++++++++++++++++
kernel/bpf/verifier.c | 18 ++++++++++++++++++
net/core/filter.c | 2 ++
6 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8e3b8f4ad183..3d85ef44b247 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -258,6 +258,7 @@ enum bpf_return_type {
*/
struct bpf_func_proto {
u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+ u32 (*gen_inline)(struct bpf_insn *insn_buf);
bool gpl_only;
bool pkt_access;
enum bpf_return_type ret_type;
@@ -1406,6 +1407,7 @@ 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);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 033d90a2282d..d17c6bcd50cd 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2885,6 +2885,12 @@ 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), \
@@ -3004,7 +3010,8 @@ 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
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 29d47aae0dd1..973a20d49749 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -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;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index cada974c9f4e..b241cfd350c4 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -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 +313,32 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
preempt_enable();
}
+static u32 bpf_jiffies64_gen_inline(struct bpf_insn *insn_buf)
+{
+ struct bpf_insn *insn = insn_buf;
+#if BITS_PER_LONG == 64
+ struct bpf_insn ld_jiffies_addr[2] = {
+ BPF_LD_IMM64(BPF_REG_0, (unsigned long)&jiffies),
+ };
+
+ BUILD_BUG_ON(sizeof(jiffies) != sizeof(unsigned long));
+
+ *insn++ = ld_jiffies_addr[0];
+ *insn++ = ld_jiffies_addr[1];
+ *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
+#else
+ *insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(get_jiffies_64));
+#endif
+
+ return insn - insn_buf;
+}
+
+const struct bpf_func_proto bpf_jiffies64_proto = {
+ .gen_inline = bpf_jiffies64_gen_inline,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+};
+
#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ca17dccc17ba..91818aad2f80 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9447,6 +9447,24 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog);
+ if (fn->gen_inline) {
+ cnt = fn->gen_inline(insn_buf);
+ if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
+ verbose(env, "bpf verifier is misconfigured\n");
+ return -EINVAL;
+ }
+
+ 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;
+ }
+
/* all functions that have prototype and verifier allowed
* programs to call them, must be real in-kernel functions
*/
diff --git a/net/core/filter.c b/net/core/filter.c
index 17de6747d9e3..4bf3e4aa8a7a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5923,6 +5923,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_spin_unlock_proto;
case BPF_FUNC_trace_printk:
return bpf_get_trace_printk_proto();
+ case BPF_FUNC_jiffies64:
+ return &bpf_jiffies64_proto;
default:
return NULL;
}
--
2.17.1
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