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: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200122233646.903260-1-kafai@fb.com

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 05d1661..a968786 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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);

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e81628e..f1d74a2 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 29d47aa..973a20d 100644 (file)
--- 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 cada974..d8b7b11 100644 (file)
--- 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 +313,17 @@ 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)
 {

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9fe94f6..734abaa 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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

diff --git a/net/core/filter.c b/net/core/filter.c
index 17de674..4bf3e4a 100644 (file)
--- 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;
        }