[RFC PATCH bpf-next 04/13] bpf: Support new unconditional bswap instruction

[Yonghong Song <yhs@fb.com>]

The existing 'be' and 'le' insns will do conditional bswap
depends on host endianness. This patch implements
unconditional bswap insns.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 arch/x86/net/bpf_jit_comp.c |  1 +
 kernel/bpf/core.c           | 14 ++++++++++++++
 kernel/bpf/verifier.c       |  2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 7c85d1b01931..6385a8d740b0 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1322,6 +1322,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
 			break;
 
 		case BPF_ALU | BPF_END | BPF_FROM_BE:
+		case BPF_ALU64 | BPF_END | BPF_FROM_LE:
 			switch (imm32) {
 			case 16:
 				/* Emit 'ror %ax, 8' to swap lower 2 bytes */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 72ee246ac3af..b59b41a3d07c 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1524,6 +1524,7 @@ EXPORT_SYMBOL_GPL(__bpf_call_base);
 	INSN_3(ALU64, DIV,  X),			\
 	INSN_3(ALU64, MOD,  X),			\
 	INSN_2(ALU64, NEG),			\
+	INSN_3(ALU64, END, TO_LE),		\
 	/*   Immediate based. */		\
 	INSN_3(ALU64, ADD,  K),			\
 	INSN_3(ALU64, SUB,  K),			\
@@ -1845,6 +1846,19 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
 			break;
 		}
 		CONT;
+	ALU64_END_TO_LE:
+		switch (IMM) {
+		case 16:
+			DST = (__force u16) __swab16(DST);
+			break;
+		case 32:
+			DST = (__force u32) __swab32(DST);
+			break;
+		case 64:
+			DST = (__force u64) __swab64(DST);
+			break;
+		}
+		CONT;
 
 	/* CALL */
 	JMP_CALL:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5c5b37b6b39a..d515bfee1a8f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12901,7 +12901,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 		} else {
 			if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
 			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
-			    BPF_CLASS(insn->code) == BPF_ALU64) {
+			    (BPF_CLASS(insn->code) == BPF_ALU64 && BPF_SRC(insn->code) != BPF_K)) {
 				verbose(env, "BPF_END uses reserved fields\n");
 				return -EINVAL;
 			}
-- 
2.34.1