diff mbox series

[bpf-next,RFC,v1,7/8] bpf: enable TCP congestion control kfunc from modules

Message ID 20210830173424.1385796-8-memxor@gmail.com
State Superseded
Headers show
Series [bpf-next,RFC,v1,1/8] bpf: Introduce BPF support for kernel module function calls | expand

Commit Message

Kumar Kartikeya Dwivedi Aug. 30, 2021, 5:34 p.m. UTC 
This commit moves BTF ID lookup into the newly added registration
helper, in a way that the bbr, cubic, and dctcp implementation set up
their sets in the bpf_tcp_ca kfunc_btf_set list, while the ones not
dependent on modules are looked up from the wrapper function.

This lifts the restriction for them to be compiled as built in objects,
and can be loaded as modules if required. Also modify link-vmlinux.sh to
resolve_btfids in TCP congestion control modules if the config option is
set, using the base BTF support added in the previous commit.

See following commits for background on use of:

 CONFIG_X86 ifdef:
 569c484f9995 (bpf: Limit static tcp-cc functions in the .BTF_ids list to x86)

 CONFIG_DYNAMIC_FTRACE ifdef:
 7aae231ac93b (bpf: tcp: Limit calling some tcp cc functions to CONFIG_DYNAMIC_FTRACE)

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 include/linux/btf.h       |  2 ++
 kernel/bpf/btf.c          |  2 ++
 net/ipv4/bpf_tcp_ca.c     | 34 +++-------------------------------
 net/ipv4/tcp_bbr.c        | 28 +++++++++++++++++++++++++++-
 net/ipv4/tcp_cubic.c      | 26 +++++++++++++++++++++++++-
 net/ipv4/tcp_dctcp.c      | 26 +++++++++++++++++++++++++-
 scripts/Makefile.modfinal |  1 +
 7 files changed, 85 insertions(+), 34 deletions(-)

Comments

Andrii Nakryiko Sept. 1, 2021, 12:48 a.m. UTC | #1 
On Mon, Aug 30, 2021 at 10:34 AM Kumar Kartikeya Dwivedi
<memxor@gmail.com> wrote:
>

> This commit moves BTF ID lookup into the newly added registration

> helper, in a way that the bbr, cubic, and dctcp implementation set up

> their sets in the bpf_tcp_ca kfunc_btf_set list, while the ones not

> dependent on modules are looked up from the wrapper function.

>

> This lifts the restriction for them to be compiled as built in objects,

> and can be loaded as modules if required. Also modify link-vmlinux.sh to

> resolve_btfids in TCP congestion control modules if the config option is

> set, using the base BTF support added in the previous commit.

>

> See following commits for background on use of:

>

>  CONFIG_X86 ifdef:

>  569c484f9995 (bpf: Limit static tcp-cc functions in the .BTF_ids list to x86)

>

>  CONFIG_DYNAMIC_FTRACE ifdef:

>  7aae231ac93b (bpf: tcp: Limit calling some tcp cc functions to CONFIG_DYNAMIC_FTRACE)

>

> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

> ---

>  include/linux/btf.h       |  2 ++

>  kernel/bpf/btf.c          |  2 ++

>  net/ipv4/bpf_tcp_ca.c     | 34 +++-------------------------------

>  net/ipv4/tcp_bbr.c        | 28 +++++++++++++++++++++++++++-

>  net/ipv4/tcp_cubic.c      | 26 +++++++++++++++++++++++++-

>  net/ipv4/tcp_dctcp.c      | 26 +++++++++++++++++++++++++-

>  scripts/Makefile.modfinal |  1 +

>  7 files changed, 85 insertions(+), 34 deletions(-)

>


[...]

> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal

> index 5e9b8057fb24..0755d4b8b74a 100644

> --- a/scripts/Makefile.modfinal

> +++ b/scripts/Makefile.modfinal

> @@ -58,6 +58,7 @@ quiet_cmd_btf_ko = BTF [M] $@

>        cmd_btf_ko =                                                     \

>         if [ -f vmlinux ]; then                                         \

>                 LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \

> +               $(RESOLVE_BTFIDS) --no-fail -s vmlinux $@;              \


why is this --no-fail?


>         else                                                            \

>                 printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \

>         fi;

> --

> 2.33.0

>
diff mbox series

Patch

diff --git a/include/linux/btf.h b/include/linux/btf.h
index d024b0eb43f9..8c0f29ed2af9 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -253,4 +253,6 @@  struct kfunc_btf_set {
 #define DEFINE_KFUNC_BTF_SET(set, name)                                        \
 	struct kfunc_btf_set name = { LIST_HEAD_INIT(name.list), (set) }
 
+DECLARE_KFUNC_BTF_SET_REG(bpf_tcp_ca);
+
 #endif
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 35873495761d..cc12470a55f9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6249,3 +6249,5 @@  BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct)
 		mutex_unlock(&type##_kfunc_btf_set_mutex);                     \
 	}                                                                      \
 	EXPORT_SYMBOL_GPL(unregister_##type##_kfunc_btf_set)
+
+DEFINE_KFUNC_BTF_SET_REG(bpf_tcp_ca);
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 0dcee9df1326..804f2f912fe9 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -223,41 +223,13 @@  BTF_ID(func, tcp_reno_cong_avoid)
 BTF_ID(func, tcp_reno_undo_cwnd)
 BTF_ID(func, tcp_slow_start)
 BTF_ID(func, tcp_cong_avoid_ai)
-#ifdef CONFIG_X86
-#ifdef CONFIG_DYNAMIC_FTRACE
-#if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC)
-BTF_ID(func, cubictcp_init)
-BTF_ID(func, cubictcp_recalc_ssthresh)
-BTF_ID(func, cubictcp_cong_avoid)
-BTF_ID(func, cubictcp_state)
-BTF_ID(func, cubictcp_cwnd_event)
-BTF_ID(func, cubictcp_acked)
-#endif
-#if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP)
-BTF_ID(func, dctcp_init)
-BTF_ID(func, dctcp_update_alpha)
-BTF_ID(func, dctcp_cwnd_event)
-BTF_ID(func, dctcp_ssthresh)
-BTF_ID(func, dctcp_cwnd_undo)
-BTF_ID(func, dctcp_state)
-#endif
-#if IS_BUILTIN(CONFIG_TCP_CONG_BBR)
-BTF_ID(func, bbr_init)
-BTF_ID(func, bbr_main)
-BTF_ID(func, bbr_sndbuf_expand)
-BTF_ID(func, bbr_undo_cwnd)
-BTF_ID(func, bbr_cwnd_event)
-BTF_ID(func, bbr_ssthresh)
-BTF_ID(func, bbr_min_tso_segs)
-BTF_ID(func, bbr_set_state)
-#endif
-#endif  /* CONFIG_DYNAMIC_FTRACE */
-#endif	/* CONFIG_X86 */
 BTF_SET_END(bpf_tcp_ca_kfunc_ids)
 
 static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id)
 {
-	return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id);
+	if (btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id))
+		return true;
+	return __bpf_check_bpf_tcp_ca_kfunc_call(kfunc_btf_id);
 }
 
 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 6274462b86b4..1fea15dd0e05 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -56,6 +56,8 @@ 
  * otherwise TCP stack falls back to an internal pacing using one high
  * resolution timer per TCP socket and may use more resources.
  */
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
 #include <linux/module.h>
 #include <net/tcp.h>
 #include <linux/inet_diag.h>
@@ -1152,14 +1154,38 @@  static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = {
 	.set_state	= bbr_set_state,
 };
 
+BTF_SET_START(tcp_bbr_kfunc_ids)
+#ifdef CONFIG_X86
+#ifdef CONFIG_DYNAMIC_FTRACE
+BTF_ID(func, bbr_init)
+BTF_ID(func, bbr_main)
+BTF_ID(func, bbr_sndbuf_expand)
+BTF_ID(func, bbr_undo_cwnd)
+BTF_ID(func, bbr_cwnd_event)
+BTF_ID(func, bbr_ssthresh)
+BTF_ID(func, bbr_min_tso_segs)
+BTF_ID(func, bbr_set_state)
+#endif
+#endif
+BTF_SET_END(tcp_bbr_kfunc_ids)
+
+static DEFINE_KFUNC_BTF_SET(&tcp_bbr_kfunc_ids, tcp_bbr_kfunc_btf_set);
+
 static int __init bbr_register(void)
 {
+	int ret;
+
 	BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE);
-	return tcp_register_congestion_control(&tcp_bbr_cong_ops);
+	ret = tcp_register_congestion_control(&tcp_bbr_cong_ops);
+	if (ret)
+		return ret;
+	register_bpf_tcp_ca_kfunc_btf_set(&tcp_bbr_kfunc_btf_set);
+	return 0;
 }
 
 static void __exit bbr_unregister(void)
 {
+	unregister_bpf_tcp_ca_kfunc_btf_set(&tcp_bbr_kfunc_btf_set);
 	tcp_unregister_congestion_control(&tcp_bbr_cong_ops);
 }
 
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 4a30deaa9a37..5b36b9442797 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -25,6 +25,8 @@ 
  */
 
 #include <linux/mm.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
 #include <linux/module.h>
 #include <linux/math64.h>
 #include <net/tcp.h>
@@ -482,8 +484,25 @@  static struct tcp_congestion_ops cubictcp __read_mostly = {
 	.name		= "cubic",
 };
 
+BTF_SET_START(tcp_cubic_kfunc_ids)
+#ifdef CONFIG_X86
+#ifdef CONFIG_DYNAMIC_FTRACE
+BTF_ID(func, cubictcp_init)
+BTF_ID(func, cubictcp_recalc_ssthresh)
+BTF_ID(func, cubictcp_cong_avoid)
+BTF_ID(func, cubictcp_state)
+BTF_ID(func, cubictcp_cwnd_event)
+BTF_ID(func, cubictcp_acked)
+#endif
+#endif
+BTF_SET_END(tcp_cubic_kfunc_ids)
+
+static DEFINE_KFUNC_BTF_SET(&tcp_cubic_kfunc_ids, tcp_cubic_kfunc_btf_set);
+
 static int __init cubictcp_register(void)
 {
+	int ret;
+
 	BUILD_BUG_ON(sizeof(struct bictcp) > ICSK_CA_PRIV_SIZE);
 
 	/* Precompute a bunch of the scaling factors that are used per-packet
@@ -514,11 +533,16 @@  static int __init cubictcp_register(void)
 	/* divide by bic_scale and by constant Srtt (100ms) */
 	do_div(cube_factor, bic_scale * 10);
 
-	return tcp_register_congestion_control(&cubictcp);
+	ret = tcp_register_congestion_control(&cubictcp);
+	if (ret)
+		return ret;
+	register_bpf_tcp_ca_kfunc_btf_set(&tcp_cubic_kfunc_btf_set);
+	return 0;
 }
 
 static void __exit cubictcp_unregister(void)
 {
+	unregister_bpf_tcp_ca_kfunc_btf_set(&tcp_cubic_kfunc_btf_set);
 	tcp_unregister_congestion_control(&cubictcp);
 }
 
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index 79f705450c16..efc47b4c7a11 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -36,6 +36,8 @@ 
  *	Glenn Judd <glenn.judd@morganstanley.com>
  */
 
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <net/tcp.h>
@@ -236,14 +238,36 @@  static struct tcp_congestion_ops dctcp_reno __read_mostly = {
 	.name		= "dctcp-reno",
 };
 
+BTF_SET_START(tcp_dctcp_kfunc_ids)
+#ifdef CONFIG_X86
+#ifdef CONFIG_DYNAMIC_FTRACE
+BTF_ID(func, dctcp_init)
+BTF_ID(func, dctcp_update_alpha)
+BTF_ID(func, dctcp_cwnd_event)
+BTF_ID(func, dctcp_ssthresh)
+BTF_ID(func, dctcp_cwnd_undo)
+BTF_ID(func, dctcp_state)
+#endif
+#endif
+BTF_SET_END(tcp_dctcp_kfunc_ids)
+
+static DEFINE_KFUNC_BTF_SET(&tcp_dctcp_kfunc_ids, tcp_dctcp_kfunc_btf_set);
+
 static int __init dctcp_register(void)
 {
+	int ret;
+
 	BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);
-	return tcp_register_congestion_control(&dctcp);
+	ret = tcp_register_congestion_control(&dctcp);
+	if (ret)
+		return ret;
+	register_bpf_tcp_ca_kfunc_btf_set(&tcp_dctcp_kfunc_btf_set);
+	return 0;
 }
 
 static void __exit dctcp_unregister(void)
 {
+	unregister_bpf_tcp_ca_kfunc_btf_set(&tcp_dctcp_kfunc_btf_set);
 	tcp_unregister_congestion_control(&dctcp);
 }
 
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 5e9b8057fb24..0755d4b8b74a 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -58,6 +58,7 @@  quiet_cmd_btf_ko = BTF [M] $@
       cmd_btf_ko = 							\
 	if [ -f vmlinux ]; then						\
 		LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \
+		$(RESOLVE_BTFIDS) --no-fail -s vmlinux $@; 		\
 	else								\
 		printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
 	fi;