From: Alexei Starovoitov <ast@xxxxxxxxxx>
LLVM generates rX = bpf_cast_kern/_user(rY, address_space) instructions
when pointers in non-zero address space are used by the bpf program.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
include/uapi/linux/bpf.h | 5 +++++
kernel/bpf/disasm.c | 11 +++++++++++
tools/include/uapi/linux/bpf.h | 5 +++++
3 files changed, 21 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f6648851eae6..3de1581379d4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1313,6 +1313,11 @@ enum {
*/
#define BPF_PSEUDO_KFUNC_CALL 2
+enum bpf_arena_cast_kinds {
+ BPF_ARENA_CAST_KERN = 1,
+ BPF_ARENA_CAST_USER = 2,
+};
+
/* flags for BPF_MAP_UPDATE_ELEM command */
enum {
BPF_ANY = 0, /* create new element or update existing */
diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c
index 49940c26a227..37d9b37b34f7 100644
--- a/kernel/bpf/disasm.c
+++ b/kernel/bpf/disasm.c
@@ -166,6 +166,12 @@ static bool is_movsx(const struct bpf_insn *insn)
(insn->off == 8 || insn->off == 16 || insn->off == 32);
}
+static bool is_arena_cast(const struct bpf_insn *insn)
+{
+ return insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) &&
+ (insn->off == BPF_ARENA_CAST_KERN || insn->off == BPF_ARENA_CAST_USER);
+}
+
void print_bpf_insn(const struct bpf_insn_cbs *cbs,
const struct bpf_insn *insn,
bool allow_ptr_leaks)
@@ -184,6 +190,11 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
insn->code, class == BPF_ALU ? 'w' : 'r',
insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
insn->dst_reg);
+ } else if (is_arena_cast(insn)) {
+ verbose(cbs->private_data, "(%02x) r%d = cast_%s(r%d, %d)\n",
+ insn->code, insn->dst_reg,
+ insn->off == BPF_ARENA_CAST_KERN ? "kern" : "user",
+ insn->src_reg, insn->imm);
} else if (BPF_SRC(insn->code) == BPF_X) {
verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n",
insn->code, class == BPF_ALU ? 'w' : 'r',
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index f6648851eae6..3de1581379d4 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1313,6 +1313,11 @@ enum {
*/
#define BPF_PSEUDO_KFUNC_CALL 2
+enum bpf_arena_cast_kinds {
+ BPF_ARENA_CAST_KERN = 1,
+ BPF_ARENA_CAST_USER = 2,
+};
+
/* flags for BPF_MAP_UPDATE_ELEM command */
enum {
BPF_ANY = 0, /* create new element or update existing */
--
2.34.1
