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authorDaniel Borkmann <daniel@iogearbox.net>2015-03-14 02:27:17 +0100
committerDavid S. Miller <davem@davemloft.net>2015-03-15 21:57:25 -0400
commitc04167ce2ca0ecaeaafef006cb0d65cf01b68e42 (patch)
treeef0c4dc4642696d84bd56c4f409dd32507981bb0 /kernel
parent03e69b508b6f7c51743055c9f61d1dfeadf4b635 (diff)
downloadlinux-sh-c04167ce2ca0ecaeaafef006cb0d65cf01b68e42.tar.gz
ebpf: add helper for obtaining current processor id
This patch adds the possibility to obtain raw_smp_processor_id() in eBPF. Currently, this is only possible in classic BPF where commit da2033c28226 ("filter: add SKF_AD_RXHASH and SKF_AD_CPU") has added facilities for this. Perhaps most importantly, this would also allow us to track per CPU statistics with eBPF maps, or to implement a poor-man's per CPU data structure through eBPF maps. Example function proto-type looks like: u32 (*smp_processor_id)(void) = (void *)BPF_FUNC_get_smp_processor_id; Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/core.c1
-rw-r--r--kernel/bpf/helpers.c12
2 files changed, 13 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index c1dbbb5d289b..4139a0f8b558 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -662,6 +662,7 @@ const struct bpf_func_proto bpf_map_update_elem_proto __weak;
const struct bpf_func_proto bpf_map_delete_elem_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;
/* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call
* skb_copy_bits(), so provide a weak definition of it for NET-less config.
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 95eb59a045ea..bd7f5988ed9c 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -12,6 +12,7 @@
#include <linux/bpf.h>
#include <linux/rcupdate.h>
#include <linux/random.h>
+#include <linux/smp.h>
/* If kernel subsystem is allowing eBPF programs to call this function,
* inside its own verifier_ops->get_func_proto() callback it should return
@@ -99,3 +100,14 @@ const struct bpf_func_proto bpf_get_prandom_u32_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
};
+
+static u64 bpf_get_smp_processor_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ return raw_smp_processor_id();
+}
+
+const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
+ .func = bpf_get_smp_processor_id,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+};