This patch update kernel BPF documents for JMP32 encoding.
Two macros are added for JMP32 to easy programming.
Signed-off-by: Jiong Wang <jiong.w...@netronome.com>
---
Documentation/networking/filter.txt | 10 ++++++++++
include/uapi/linux/bpf.h | 4 ++++
tools/include/uapi/linux/bpf.h | 4 ++++
3 files changed, 18 insertions(+)
diff --git a/Documentation/networking/filter.txt
b/Documentation/networking/filter.txt
index 2196b82..5f6fafa 100644
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -939,6 +939,16 @@ in eBPF means function exit only. The eBPF program needs
to store return
value into register R0 before doing a BPF_EXIT. Class 6 in eBPF is currently
unused and reserved for future use.
+And BPF_JMP has sub-opcode. When BPF_SRC(code) == BPF_X, the encoding is at
+insn->imm, starting from LSB. When BPF_SRC(code) == BPF_K, the encoding is at
+insn->src_reg, starting from LSB as well. Only one bit is used for sub-opcode
at
+the moment, all other bits in imm and src_reg are still reserved and should be
+zeroed. The BPF_JMP sub-opcode is:
+
+ BPF_JMP_SUBOP_32BIT 0x1
+
+It means jump insn use 32-bit sub-register when doing comparison.
+
For load and store instructions the 8-bit 'code' field is divided as:
+--------+--------+-------------------+
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e7d57e89..f30d646 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -42,6 +42,10 @@
#define BPF_CALL 0x80 /* function call */
#define BPF_EXIT 0x90 /* function return */
+/* jmp has sub-opcode */
+#define BPF_JMP_SUBOP_MASK 0x1
+#define BPF_JMP_SUBOP_32BIT 0x1
+
/* Register numbers */
enum {
BPF_REG_0 = 0,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index e7d57e89..f30d646 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -42,6 +42,10 @@
#define BPF_CALL 0x80 /* function call */
#define BPF_EXIT 0x90 /* function return */
+/* jmp has sub-opcode */
+#define BPF_JMP_SUBOP_MASK 0x1
+#define BPF_JMP_SUBOP_32BIT 0x1
+
/* Register numbers */
enum {
BPF_REG_0 = 0,
--
2.7.4
