bpf: add BPF_J{LT,LE,SLT,SLE} instructions

Currently, eBPF only understands BPF_JGT (>), BPF_JGE (>=),
BPF_JSGT (s>), BPF_JSGE (s>=) instructions, this means that
particularly *JLT/*JLE counterparts involving immediates need
to be rewritten from e.g. X < [IMM] by swapping arguments into
[IMM] > X, meaning the immediate first is required to be loaded
into a register Y := [IMM], such that then we can compare with
Y > X. Note that the destination operand is always required to
be a register.

This has the downside of having unnecessarily increased register
pressure, meaning complex program would need to spill other
registers temporarily to stack in order to obtain an unused
register for the [IMM]. Loading to registers will thus also
affect state pruning since we need to account for that register
use and potentially those registers that had to be spilled/filled
again. As a consequence slightly more stack space might have
been used due to spilling, and BPF programs are a bit longer
due to extra code involving the register load and potentially
required spill/fills.

Thus, add BPF_JLT (<), BPF_JLE (<=), BPF_JSLT (s<), BPF_JSLE (s<=)
counterparts to the eBPF instruction set. Modifying LLVM to
remove the NegateCC() workaround in a PoC patch at [1] and
allowing it to also emit the new instructions resulted in
cilium's BPF programs that are injected into the fast-path to
have a reduced program length in the range of 2-3% (e.g.
accumulated main and tail call sections from one of the object
file reduced from 4864 to 4729 insns), reduced complexity in
the range of 10-30% (e.g. accumulated sections reduced in one
of the cases from 116432 to 88428 insns), and reduced stack
usage in the range of 1-5% (e.g. accumulated sections from one
of the object files reduced from 824 to 784b).

The modification for LLVM will be incorporated in a backwards
compatible way. Plan is for LLVM to have i) a target specific
option to offer a possibility to explicitly enable the extension
by the user (as we have with -m target specific extensions today
for various CPU insns), and ii) have the kernel checked for
presence of the extensions and enable them transparently when
the user is selecting more aggressive options such as -march=native
in a bpf target context. (Other frontends generating BPF byte
code, e.g. ply can probe the kernel directly for its code
generation.)

  [1] https://github.com/borkmann/llvm/tree/bpf-insns

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 364 insertions, 0 deletions

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index d9d5a410955c..aa8812ae6776 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -952,6 +952,32 @@ static struct bpf_test tests[] = {
 		{ { 2, 0 }, { 3, 1 }, { 4, MAX_K } },
 	},
 	{
+		"JGE (jt 0), test 1",
+		.u.insns = {
+			BPF_STMT(BPF_LDX | BPF_LEN, 0),
+			BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 2),
+			BPF_JUMP(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 1),
+			BPF_STMT(BPF_RET | BPF_K, 1),
+			BPF_STMT(BPF_RET | BPF_K, MAX_K)
+		},
+		CLASSIC,
+		{ 4, 4, 4, 3, 3 },
+		{ { 2, 0 }, { 3, 1 }, { 4, 1 } },
+	},
+	{
+		"JGE (jt 0), test 2",
+		.u.insns = {
+			BPF_STMT(BPF_LDX | BPF_LEN, 0),
+			BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 2),
+			BPF_JUMP(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 1),
+			BPF_STMT(BPF_RET | BPF_K, 1),
+			BPF_STMT(BPF_RET | BPF_K, MAX_K)
+		},
+		CLASSIC,
+		{ 4, 4, 5, 3, 3 },
+		{ { 4, 1 }, { 5, 1 }, { 6, MAX_K } },
+	},
+	{
 		"JGE",
 		.u.insns = {
 			BPF_STMT(BPF_LDX | BPF_LEN, 0),
@@ -4492,6 +4518,35 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JSLT | BPF_K */
+	{
+		"JMP_JSLT_K: Signed jump: if (-2 < -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 0xfffffffffffffffeLL),
+			BPF_JMP_IMM(BPF_JSLT, R1, -1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLT_K: Signed jump: if (-1 < -1) return 0",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_LD_IMM64(R1, 0xffffffffffffffffLL),
+			BPF_JMP_IMM(BPF_JSLT, R1, -1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JSGT | BPF_K */
 	{
 		"JMP_JSGT_K: Signed jump: if (-1 > -2) return 1",
@@ -4521,6 +4576,73 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JSLE | BPF_K */
+	{
+		"JMP_JSLE_K: Signed jump: if (-2 <= -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 0xfffffffffffffffeLL),
+			BPF_JMP_IMM(BPF_JSLE, R1, -1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLE_K: Signed jump: if (-1 <= -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 0xffffffffffffffffLL),
+			BPF_JMP_IMM(BPF_JSLE, R1, -1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLE_K: Signed jump: value walk 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 6),
+			BPF_ALU64_IMM(BPF_SUB, R1, 1),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 4),
+			BPF_ALU64_IMM(BPF_SUB, R1, 1),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 2),
+			BPF_ALU64_IMM(BPF_SUB, R1, 1),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 1),
+			BPF_EXIT_INSN(),		/* bad exit */
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),	/* good exit */
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLE_K: Signed jump: value walk 2",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 4),
+			BPF_ALU64_IMM(BPF_SUB, R1, 2),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 2),
+			BPF_ALU64_IMM(BPF_SUB, R1, 2),
+			BPF_JMP_IMM(BPF_JSLE, R1, 0, 1),
+			BPF_EXIT_INSN(),		/* bad exit */
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),	/* good exit */
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JSGE | BPF_K */
 	{
 		"JMP_JSGE_K: Signed jump: if (-1 >= -2) return 1",
@@ -4617,6 +4739,35 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JLT | BPF_K */
+	{
+		"JMP_JLT_K: if (2 < 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 2),
+			BPF_JMP_IMM(BPF_JLT, R1, 3, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JGT_K: Unsigned jump: if (1 < -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 1),
+			BPF_JMP_IMM(BPF_JLT, R1, -1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JGE | BPF_K */
 	{
 		"JMP_JGE_K: if (3 >= 2) return 1",
@@ -4632,6 +4783,21 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JLE | BPF_K */
+	{
+		"JMP_JLE_K: if (2 <= 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 2),
+			BPF_JMP_IMM(BPF_JLE, R1, 3, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JGT | BPF_K jump backwards */
 	{
 		"JMP_JGT_K: if (3 > 2) return 1 (jump backwards)",
@@ -4662,6 +4828,36 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JLT | BPF_K jump backwards */
+	{
+		"JMP_JGT_K: if (2 < 3) return 1 (jump backwards)",
+		.u.insns_int = {
+			BPF_JMP_IMM(BPF_JA, 0, 0, 2), /* goto start */
+			BPF_ALU32_IMM(BPF_MOV, R0, 1), /* out: */
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 0), /* start: */
+			BPF_LD_IMM64(R1, 2), /* note: this takes 2 insns */
+			BPF_JMP_IMM(BPF_JLT, R1, 3, -6), /* goto out */
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JLE_K: if (3 <= 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_JMP_IMM(BPF_JLE, R1, 3, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JNE | BPF_K */
 	{
 		"JMP_JNE_K: if (3 != 2) return 1",
@@ -4752,6 +4948,37 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JSLT | BPF_X */
+	{
+		"JMP_JSLT_X: Signed jump: if (-2 < -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, -1),
+			BPF_LD_IMM64(R2, -2),
+			BPF_JMP_REG(BPF_JSLT, R2, R1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLT_X: Signed jump: if (-1 < -1) return 0",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_LD_IMM64(R1, -1),
+			BPF_LD_IMM64(R2, -1),
+			BPF_JMP_REG(BPF_JSLT, R1, R2, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JSGE | BPF_X */
 	{
 		"JMP_JSGE_X: Signed jump: if (-1 >= -2) return 1",
@@ -4783,6 +5010,37 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JSLE | BPF_X */
+	{
+		"JMP_JSLE_X: Signed jump: if (-2 <= -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, -1),
+			BPF_LD_IMM64(R2, -2),
+			BPF_JMP_REG(BPF_JSLE, R2, R1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JSLE_X: Signed jump: if (-1 <= -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, -1),
+			BPF_LD_IMM64(R2, -1),
+			BPF_JMP_REG(BPF_JSLE, R1, R2, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JGT | BPF_X */
 	{
 		"JMP_JGT_X: if (3 > 2) return 1",
@@ -4814,6 +5072,37 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JLT | BPF_X */
+	{
+		"JMP_JLT_X: if (2 < 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 2),
+			BPF_JMP_REG(BPF_JLT, R2, R1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JLT_X: Unsigned jump: if (1 < -1) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, -1),
+			BPF_LD_IMM64(R2, 1),
+			BPF_JMP_REG(BPF_JLT, R2, R1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JGE | BPF_X */
 	{
 		"JMP_JGE_X: if (3 >= 2) return 1",
@@ -4845,6 +5134,37 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	/* BPF_JMP | BPF_JLE | BPF_X */
+	{
+		"JMP_JLE_X: if (2 <= 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 2),
+			BPF_JMP_REG(BPF_JLE, R2, R1, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
+	{
+		"JMP_JLE_X: if (3 <= 3) return 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 3),
+			BPF_JMP_REG(BPF_JLE, R1, R2, 1),
+			BPF_EXIT_INSN(),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	{
 		/* Mainly testing JIT + imm64 here. */
 		"JMP_JGE_X: ldimm64 test 1",
@@ -4890,6 +5210,50 @@ static struct bpf_test tests[] = {
 		{ },
 		{ { 0, 1 } },
 	},
+	{
+		"JMP_JLE_X: ldimm64 test 1",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 2),
+			BPF_JMP_REG(BPF_JLE, R2, R1, 2),
+			BPF_LD_IMM64(R0, 0xffffffffffffffffULL),
+			BPF_LD_IMM64(R0, 0xeeeeeeeeeeeeeeeeULL),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 0xeeeeeeeeU } },
+	},
+	{
+		"JMP_JLE_X: ldimm64 test 2",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 2),
+			BPF_JMP_REG(BPF_JLE, R2, R1, 0),
+			BPF_LD_IMM64(R0, 0xffffffffffffffffULL),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 0xffffffffU } },
+	},
+	{
+		"JMP_JLE_X: ldimm64 test 3",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_LD_IMM64(R1, 3),
+			BPF_LD_IMM64(R2, 2),
+			BPF_JMP_REG(BPF_JLE, R2, R1, 4),
+			BPF_LD_IMM64(R0, 0xffffffffffffffffULL),
+			BPF_LD_IMM64(R0, 0xeeeeeeeeeeeeeeeeULL),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+	},
 	/* BPF_JMP | BPF_JNE | BPF_X */
 	{
 		"JMP_JNE_X: if (3 != 2) return 1",