[PATCH bpf-next 0/3] Add RISC-V (RV64G) BPF JIT

[PATCH bpf-next 0/3] Add RISC-V (RV64G) BPF JIT

[bjorn.topel]

From: Björn Töpel <bjorn.topel@gmail.com>

Hi!

This series adds an RV64G BPF JIT to the kernel. I've sent out a RFC
for a couple of weeks ago, and think this code is
feature-complete/stable enough (famous last words) for a proper patch.

Unfortunately, kprobes isn't supported by RISC-V yet (Patrick Stählin
sent out an RFC last year), which means that all tests involving
BPF_PROG_TYPE_TRACEPOINT, BPF_PROG_TYPE_PERF_EVENT,
BPF_PROG_TYPE_KPROBE and BPF_PROG_TYPE_RAW_TRACEPOINT will fail.

Further, the implementation does not support "far branching" (>4KiB).
    
The implementation passes all the test_bpf.ko tests: test_bpf:
    Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]
    
All the tail_call tests in the selftest/bpf/test_verifier program
passes.
    
All tests where done on QEMU emulator version 3.1.50
(v3.1.0-688-g8ae951fbc106). I'll test it on real hardware, when I get
access to it.

I'm routing this patch via bpf-next/netdev mailing list (after a
conversation with Palmer at FOSDEM), mainly because the other JITs
went that path.

Thanks for all the comments!

Cheers,
Björn

RFCv1 -> v1:
* Cleaned up the Kconfig and net/Makefile. (Christoph)
* Removed the entry-stub and squashed the build/config changes to be
  part of the JIT implementation. (Christoph)
* Simplified the register tracking code. (Daniel)
* Removed unused macros. (Daniel)
* Added myself as maintainer and updated documentation. (Daniel)
* Removed HAVE_EFFICIENT_UNALIGNED_ACCESS. (Christoph, Palmer)
* Added tail-calls and cleaned up the code.



Björn Töpel (3):
  bpf, riscv: add BPF JIT for RV64G
  MAINTAINERS: add RISC-V BPF JIT maintainer
  bpf, doc: add RISC-V to filter.txt

 Documentation/networking/filter.txt |   16 +-
 MAINTAINERS                         |    6 +
 arch/riscv/Kconfig                  |    1 +
 arch/riscv/Makefile                 |    2 +-
 arch/riscv/net/Makefile             |    1 +
 arch/riscv/net/bpf_jit_comp.c       | 1502 +++++++++++++++++++++++++++
 6 files changed, 1520 insertions(+), 8 deletions(-)
 create mode 100644 arch/riscv/net/Makefile
 create mode 100644 arch/riscv/net/bpf_jit_comp.c

-- 
2.19.1


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[PATCH bpf-next 1/3] bpf, riscv: add BPF JIT for RV64G

[bjorn.topel]

From: Björn Töpel <bjorn.topel@gmail.com>

This commit adds BPF JIT for RV64G.

The JIT is a two-pass JIT, and has a dynamic prolog/epilogue (similar
to the MIPS64 BPF JIT) instead of static ones (e.g. x86_64).

At the moment the RISC-V Linux port does not support HAVE_KPROBES,
which means that CONFIG_BPF_EVENTS is not supported. Thus, no tests
involving BPF_PROG_TYPE_TRACEPOINT passes.

Further, the implementation does not support "far branching" (>4KiB).

The implementation passes all the test_bpf.ko tests:
  test_bpf: Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]

All the tail_call tests in the selftest/bpf/test_verifier program
passes.

All tests where done on QEMU (QEMU emulator version 3.1.50
(v3.1.0-688-g8ae951fbc106)).

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
---
 arch/riscv/Kconfig            |    1 +
 arch/riscv/Makefile           |    2 +-
 arch/riscv/net/Makefile       |    1 +
 arch/riscv/net/bpf_jit_comp.c | 1502 +++++++++++++++++++++++++++++++++
 4 files changed, 1505 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/net/Makefile
 create mode 100644 arch/riscv/net/bpf_jit_comp.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index feeeaa60697c..e64c657060bb 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -49,6 +49,7 @@ config RISCV
 	select RISCV_TIMER
 	select GENERIC_IRQ_MULTI_HANDLER
 	select ARCH_HAS_PTE_SPECIAL
+	select HAVE_EBPF_JIT if 64BIT
 
 config MMU
 	def_bool y
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 4b594f2e4f7e..c6342e638ef7 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -77,7 +77,7 @@ KBUILD_IMAGE	:= $(boot)/Image.gz
 
 head-y := arch/riscv/kernel/head.o
 
-core-y += arch/riscv/kernel/ arch/riscv/mm/
+core-y += arch/riscv/kernel/ arch/riscv/mm/ arch/riscv/net/
 
 libs-y += arch/riscv/lib/
 
diff --git a/arch/riscv/net/Makefile b/arch/riscv/net/Makefile
new file mode 100644
index 000000000000..a132220cc582
--- /dev/null
+++ b/arch/riscv/net/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o
diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
new file mode 100644
index 000000000000..83b1e2f89074
--- /dev/null
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -0,0 +1,1502 @@
+// SPDX-License-Identifier: GPL-2.0
+/* BPF JIT compiler for RV64G
+ *
+ * Copyright(c) 2019 Björn Töpel <bjorn.topel@gmail.com>
+ *
+ */
+
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <asm/cacheflush.h>
+
+enum {
+	RV_REG_ZERO =	0,	/* The constant value 0 */
+	RV_REG_RA =	1,	/* Return address */
+	RV_REG_SP =	2,	/* Stack pointer */
+	RV_REG_GP =	3,	/* Global pointer */
+	RV_REG_TP =	4,	/* Thread pointer */
+	RV_REG_T0 =	5,	/* Temporaries */
+	RV_REG_T1 =	6,
+	RV_REG_T2 =	7,
+	RV_REG_FP =	8,
+	RV_REG_S1 =	9,	/* Saved registers */
+	RV_REG_A0 =	10,	/* Function argument/return values */
+	RV_REG_A1 =	11,	/* Function arguments */
+	RV_REG_A2 =	12,
+	RV_REG_A3 =	13,
+	RV_REG_A4 =	14,
+	RV_REG_A5 =	15,
+	RV_REG_A6 =	16,
+	RV_REG_A7 =	17,
+	RV_REG_S2 =	18,	/* Saved registers */
+	RV_REG_S3 =	19,
+	RV_REG_S4 =	20,
+	RV_REG_S5 =	21,
+	RV_REG_S6 =	22,
+	RV_REG_S7 =	23,
+	RV_REG_S8 =	24,
+	RV_REG_S9 =	25,
+	RV_REG_S10 =	26,
+	RV_REG_S11 =	27,
+	RV_REG_T3 =	28,	/* Temporaries */
+	RV_REG_T4 =	29,
+	RV_REG_T5 =	30,
+	RV_REG_T6 =	31,
+};
+
+#define RV_REG_TCC RV_REG_A6
+#define RV_REG_TCC_SAVED RV_REG_S6 /* Store A6 in S6 if program do calls */
+
+static const int regmap[] = {
+	[BPF_REG_0] =	RV_REG_A5,
+	[BPF_REG_1] =	RV_REG_A0,
+	[BPF_REG_2] =	RV_REG_A1,
+	[BPF_REG_3] =	RV_REG_A2,
+	[BPF_REG_4] =	RV_REG_A3,
+	[BPF_REG_5] =	RV_REG_A4,
+	[BPF_REG_6] =	RV_REG_S1,
+	[BPF_REG_7] =	RV_REG_S2,
+	[BPF_REG_8] =	RV_REG_S3,
+	[BPF_REG_9] =	RV_REG_S4,
+	[BPF_REG_FP] =	RV_REG_S5,
+	[BPF_REG_AX] =	RV_REG_T0,
+};
+
+enum {
+	RV_CTX_F_SEEN_TAIL_CALL =	0,
+	RV_CTX_F_SEEN_CALL =		RV_REG_RA,
+	RV_CTX_F_SEEN_S1 =		RV_REG_S1,
+	RV_CTX_F_SEEN_S2 =		RV_REG_S2,
+	RV_CTX_F_SEEN_S3 =		RV_REG_S3,
+	RV_CTX_F_SEEN_S4 =		RV_REG_S4,
+	RV_CTX_F_SEEN_S5 =		RV_REG_S5,
+	RV_CTX_F_SEEN_S6 =		RV_REG_S6,
+};
+
+struct rv_jit_context {
+	struct bpf_prog *prog;
+	u32 *insns; /* RV insns */
+	int ninsns;
+	int epilogue_offset;
+	int *offset; /* BPF to RV */
+	unsigned long flags;
+	int stack_size;
+};
+
+struct rv_jit_data {
+	struct bpf_binary_header *header;
+	u8 *image;
+	struct rv_jit_context ctx;
+};
+
+static u8 bpf_to_rv_reg(int bpf_reg, struct rv_jit_context *ctx)
+{
+	u8 reg = regmap[bpf_reg];
+
+	switch (reg) {
+	case RV_CTX_F_SEEN_S1:
+	case RV_CTX_F_SEEN_S2:
+	case RV_CTX_F_SEEN_S3:
+	case RV_CTX_F_SEEN_S4:
+	case RV_CTX_F_SEEN_S5:
+	case RV_CTX_F_SEEN_S6:
+		__set_bit(reg, &ctx->flags);
+	}
+	return reg;
+};
+
+static bool seen_reg(int reg, struct rv_jit_context *ctx)
+{
+	switch (reg) {
+	case RV_CTX_F_SEEN_CALL:
+	case RV_CTX_F_SEEN_S1:
+	case RV_CTX_F_SEEN_S2:
+	case RV_CTX_F_SEEN_S3:
+	case RV_CTX_F_SEEN_S4:
+	case RV_CTX_F_SEEN_S5:
+	case RV_CTX_F_SEEN_S6:
+		return test_bit(reg, &ctx->flags);
+	}
+	return false;
+}
+
+static void mark_call(struct rv_jit_context *ctx)
+{
+	__set_bit(RV_CTX_F_SEEN_CALL, &ctx->flags);
+}
+
+static bool seen_call(struct rv_jit_context *ctx)
+{
+	return seen_reg(RV_REG_RA, ctx);
+}
+
+static void mark_tail_call(struct rv_jit_context *ctx)
+{
+	__set_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
+}
+
+static bool seen_tail_call(struct rv_jit_context *ctx)
+{
+	return test_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
+}
+
+static u8 rv_tail_call_reg(struct rv_jit_context *ctx)
+{
+	mark_tail_call(ctx);
+
+	if (seen_call(ctx)) {
+		__set_bit(RV_CTX_F_SEEN_S6, &ctx->flags);
+		return RV_REG_S6;
+	}
+	return RV_REG_A6;
+}
+
+static void emit(const u32 insn, struct rv_jit_context *ctx)
+{
+	if (ctx->insns)
+		ctx->insns[ctx->ninsns] = insn;
+
+	ctx->ninsns++;
+}
+
+static u32 rv_r_insn(u8 funct7, u8 rs2, u8 rs1, u8 funct3, u8 rd, u8 opcode)
+{
+	return (funct7 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
+		(rd << 7) | opcode;
+}
+
+static u32 rv_i_insn(u16 imm11_0, u8 rs1, u8 funct3, u8 rd, u8 opcode)
+{
+	return (imm11_0 << 20) | (rs1 << 15) | (funct3 << 12) | (rd << 7) |
+		opcode;
+}
+
+static u32 rv_s_insn(u16 imm11_0, u8 rs2, u8 rs1, u8 funct3, u8 opcode)
+{
+	u8 imm11_5 = imm11_0 >> 5, imm4_0 = imm11_0 & 0x1f;
+
+	return (imm11_5 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
+		(imm4_0 << 7) | opcode;
+}
+
+static u32 rv_sb_insn(u16 imm12_1, u8 rs2, u8 rs1, u8 funct3, u8 opcode)
+{
+	u8 imm12 = ((imm12_1 & 0x800) >> 5) | ((imm12_1 & 0x3f0) >> 4);
+	u8 imm4_1 = ((imm12_1 & 0xf) << 1) | ((imm12_1 & 0x400) >> 10);
+
+	return (imm12 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
+		(imm4_1 << 7) | opcode;
+}
+
+static u32 rv_u_insn(u32 imm31_12, u8 rd, u8 opcode)
+{
+	return (imm31_12 << 12) | (rd << 7) | opcode;
+}
+
+static u32 rv_uj_insn(u32 imm20_1, u8 rd, u8 opcode)
+{
+	u32 imm;
+
+	imm = (imm20_1 & 0x80000) |  ((imm20_1 & 0x3ff) << 9) |
+	      ((imm20_1 & 0x400) >> 2) | ((imm20_1 & 0x7f800) >> 11);
+
+	return (imm << 12) | (rd << 7) | opcode;
+}
+
+static u32 rv_amo_insn(u8 funct5, u8 aq, u8 rl, u8 rs2, u8 rs1,
+		       u8 funct3, u8 rd, u8 opcode)
+{
+	u8 funct7 = (funct5 << 2) | (aq << 1) | rl;
+
+	return rv_r_insn(funct7, rs2, rs1, funct3, rd, opcode);
+}
+
+static u32 rv_addiw(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 0, rd, 0x1b);
+}
+
+static u32 rv_addi(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 0, rd, 0x13);
+}
+
+static u32 rv_addw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 0, rd, 0x3b);
+}
+
+static u32 rv_add(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 0, rd, 0x33);
+}
+
+static u32 rv_subw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0x20, rs2, rs1, 0, rd, 0x3b);
+}
+
+static u32 rv_sub(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0x20, rs2, rs1, 0, rd, 0x33);
+}
+
+static u32 rv_and(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 7, rd, 0x33);
+}
+
+static u32 rv_or(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 6, rd, 0x33);
+}
+
+static u32 rv_xor(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 4, rd, 0x33);
+}
+
+static u32 rv_mulw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 0, rd, 0x3b);
+}
+
+static u32 rv_mul(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 0, rd, 0x33);
+}
+
+static u32 rv_divuw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 5, rd, 0x3b);
+}
+
+static u32 rv_divu(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 5, rd, 0x33);
+}
+
+static u32 rv_remuw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 7, rd, 0x3b);
+}
+
+static u32 rv_remu(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(1, rs2, rs1, 7, rd, 0x33);
+}
+
+static u32 rv_sllw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 1, rd, 0x3b);
+}
+
+static u32 rv_sll(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 1, rd, 0x33);
+}
+
+static u32 rv_srlw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 5, rd, 0x3b);
+}
+
+static u32 rv_srl(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0, rs2, rs1, 5, rd, 0x33);
+}
+
+static u32 rv_sraw(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0x20, rs2, rs1, 5, rd, 0x3b);
+}
+
+static u32 rv_sra(u8 rd, u8 rs1, u8 rs2)
+{
+	return rv_r_insn(0x20, rs2, rs1, 5, rd, 0x33);
+}
+
+static u32 rv_lui(u8 rd, u32 imm31_12)
+{
+	return rv_u_insn(imm31_12, rd, 0x37);
+}
+
+static u32 rv_slli(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 1, rd, 0x13);
+}
+
+static u32 rv_andi(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 7, rd, 0x13);
+}
+
+static u32 rv_ori(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 6, rd, 0x13);
+}
+
+static u32 rv_xori(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 4, rd, 0x13);
+}
+
+static u32 rv_slliw(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 1, rd, 0x1b);
+}
+
+static u32 rv_srliw(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 5, rd, 0x1b);
+}
+
+static u32 rv_srli(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 5, rd, 0x13);
+}
+
+static u32 rv_sraiw(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(0x400 | imm11_0, rs1, 5, rd, 0x1b);
+}
+
+static u32 rv_srai(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(0x400 | imm11_0, rs1, 5, rd, 0x13);
+}
+
+static u32 rv_jal(u8 rd, u32 imm20_1)
+{
+	return rv_uj_insn(imm20_1, rd, 0x6f);
+}
+
+static u32 rv_jalr(u8 rd, u8 rs1, u16 imm11_0)
+{
+	return rv_i_insn(imm11_0, rs1, 0, rd, 0x67);
+}
+
+static u32 rv_beq(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 0, 0x63);
+}
+
+static u32 rv_bltu(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 6, 0x63);
+}
+
+static u32 rv_bgeu(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 7, 0x63);
+}
+
+static u32 rv_bne(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 1, 0x63);
+}
+
+static u32 rv_blt(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 4, 0x63);
+}
+
+static u32 rv_bge(u8 rs1, u8 rs2, u16 imm12_1)
+{
+	return rv_sb_insn(imm12_1, rs2, rs1, 5, 0x63);
+}
+
+static u32 rv_sb(u8 rs1, u16 imm11_0, u8 rs2)
+{
+	return rv_s_insn(imm11_0, rs2, rs1, 0, 0x23);
+}
+
+static u32 rv_sh(u8 rs1, u16 imm11_0, u8 rs2)
+{
+	return rv_s_insn(imm11_0, rs2, rs1, 1, 0x23);
+}
+
+static u32 rv_sw(u8 rs1, u16 imm11_0, u8 rs2)
+{
+	return rv_s_insn(imm11_0, rs2, rs1, 2, 0x23);
+}
+
+static u32 rv_sd(u8 rs1, u16 imm11_0, u8 rs2)
+{
+	return rv_s_insn(imm11_0, rs2, rs1, 3, 0x23);
+}
+
+static u32 rv_lbu(u8 rd, u16 imm11_0, u8 rs1)
+{
+	return rv_i_insn(imm11_0, rs1, 4, rd, 0x03);
+}
+
+static u32 rv_lhu(u8 rd, u16 imm11_0, u8 rs1)
+{
+	return rv_i_insn(imm11_0, rs1, 5, rd, 0x03);
+}
+
+static u32 rv_lwu(u8 rd, u16 imm11_0, u8 rs1)
+{
+	return rv_i_insn(imm11_0, rs1, 6, rd, 0x03);
+}
+
+static u32 rv_ld(u8 rd, u16 imm11_0, u8 rs1)
+{
+	return rv_i_insn(imm11_0, rs1, 3, rd, 0x03);
+}
+
+static u32 rv_amoadd_w(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
+{
+	return rv_amo_insn(0, aq, rl, rs2, rs1, 2, rd, 0x2f);
+}
+
+static u32 rv_amoadd_d(u8 rd, u8 rs2, u8 rs1, u8 aq, u8 rl)
+{
+	return rv_amo_insn(0, aq, rl, rs2, rs1, 3, rd, 0x2f);
+}
+
+static bool is_12b_int(s64 val)
+{
+	return -(1 << 11) <= val && val < (1 << 11);
+}
+
+static bool is_13b_int(s64 val)
+{
+	return -(1 << 12) <= val && val < (1 << 12);
+}
+
+static bool is_21b_int(s64 val)
+{
+	return -(1L << 20) <= val && val < (1L << 20);
+}
+
+static bool is_32b_int(s64 val)
+{
+	return -(1L << 31) <= val && val < (1L << 31);
+}
+
+static int is_12b_check(int off, int insn)
+{
+	if (!is_12b_int(off)) {
+		pr_err("bpf-jit: insn=%d offset=%d not supported yet!\n",
+		       insn, (int)off);
+		return -1;
+	}
+	return 0;
+}
+
+static int is_13b_check(int off, int insn)
+{
+	if (!is_13b_int(off)) {
+		pr_err("bpf-jit: insn=%d offset=%d not supported yet!\n",
+		       insn, (int)off);
+		return -1;
+	}
+	return 0;
+}
+
+static int is_21b_check(int off, int insn)
+{
+	if (!is_21b_int(off)) {
+		pr_err("bpf-jit: insn=%d offset=%d not supported yet!\n",
+		       insn, (int)off);
+		return -1;
+	}
+	return 0;
+}
+
+static void emit_imm(u8 rd, s64 val, struct rv_jit_context *ctx)
+{
+	/* Note that the immediate from the add is sign-extended,
+	 * which means that we need to compensate this by adding 2^12,
+	 * when the 12th bit is set. A simpler way of doing this, and
+	 * getting rid of the check, is to just add 2**11 before the
+	 * shift. The "Loading a 32-Bit constant" example from the
+	 * "Computer Organization and Design, RISC-V edition" book by
+	 * Patterson/Hennessy highlights this fact.
+	 *
+	 * This also means that we need to process LSB to MSB.
+	 */
+	s64 upper = (val + (1 << 11)) >> 12, lower = val & 0xfff;
+	int shift;
+
+	if (is_32b_int(val)) {
+		if (upper)
+			emit(rv_lui(rd, upper), ctx);
+
+		if (!upper) {
+			emit(rv_addi(rd, RV_REG_ZERO, lower), ctx);
+			return;
+		}
+
+		emit(rv_addiw(rd, rd, lower), ctx);
+		return;
+	}
+
+	shift = __ffs(upper);
+	upper >>= shift;
+	shift += 12;
+
+	emit_imm(rd, upper, ctx);
+
+	emit(rv_slli(rd, rd, shift), ctx);
+	if (lower)
+		emit(rv_addi(rd, rd, lower), ctx);
+}
+
+static int rv_offset(int bpf_to, int bpf_from, struct rv_jit_context *ctx)
+{
+	int from = ctx->offset[bpf_from] - 1, to = ctx->offset[bpf_to];
+
+	return (to - from) << 2;
+}
+
+static int epilogue_offset(struct rv_jit_context *ctx)
+{
+	int to = ctx->epilogue_offset, from = ctx->ninsns;
+
+	return (to - from) << 2;
+}
+
+static void __build_epilogue(u8 reg, struct rv_jit_context *ctx)
+{
+	int stack_adjust = ctx->stack_size, store_offset = stack_adjust - 8;
+
+	if (seen_reg(RV_REG_RA, ctx)) {
+		emit(rv_ld(RV_REG_RA, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	emit(rv_ld(RV_REG_FP, store_offset, RV_REG_SP), ctx);
+	store_offset -= 8;
+	if (seen_reg(RV_REG_S1, ctx)) {
+		emit(rv_ld(RV_REG_S1, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S2, ctx)) {
+		emit(rv_ld(RV_REG_S2, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S3, ctx)) {
+		emit(rv_ld(RV_REG_S3, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S4, ctx)) {
+		emit(rv_ld(RV_REG_S4, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S5, ctx)) {
+		emit(rv_ld(RV_REG_S5, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S6, ctx)) {
+		emit(rv_ld(RV_REG_S6, store_offset, RV_REG_SP), ctx);
+		store_offset -= 8;
+	}
+
+	emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);
+	/* Set return value. */
+	emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
+	emit(rv_jalr(RV_REG_ZERO, reg, 0), ctx);
+}
+
+static void emit_zero_extend_32(u8 reg, struct rv_jit_context *ctx)
+{
+	emit(rv_slli(reg, reg, 32), ctx);
+	emit(rv_srli(reg, reg, 32), ctx);
+}
+
+static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
+{
+	int tc_ninsn, off, start_insn = ctx->ninsns;
+	u8 tcc = rv_tail_call_reg(ctx);
+
+	/* a0: &ctx
+	 * a1: &array
+	 * a2: index
+	 *
+	 * if (index >= array->map.max_entries)
+	 *	goto out;
+	 */
+	tc_ninsn = insn ? ctx->offset[insn] - ctx->offset[insn - 1] :
+		   ctx->offset[0];
+	emit_zero_extend_32(RV_REG_A2, ctx);
+
+	off = offsetof(struct bpf_array, map.max_entries);
+	if (is_12b_check(off, insn))
+		return -1;
+	emit(rv_lwu(RV_REG_T1, off, RV_REG_A1), ctx);
+	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
+	if (is_13b_check(off, insn))
+		return -1;
+	emit(rv_bgeu(RV_REG_A2, RV_REG_T1, off >> 1), ctx);
+
+	/* if (--TCC < 0)
+	 *     goto out;
+	 */
+	emit(rv_addi(RV_REG_T1, tcc, -1), ctx);
+	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
+	if (is_13b_check(off, insn))
+		return -1;
+	emit(rv_blt(RV_REG_T1, RV_REG_ZERO, off >> 1), ctx);
+
+	/* prog = array->ptrs[index];
+	 * if (!prog)
+	 *     goto out;
+	 */
+	emit(rv_slli(RV_REG_T2, RV_REG_A2, 3), ctx);
+	emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_A1), ctx);
+	off = offsetof(struct bpf_array, ptrs);
+	if (is_12b_check(off, insn))
+		return -1;
+	emit(rv_ld(RV_REG_T2, off, RV_REG_T2), ctx);
+	off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2;
+	if (is_13b_check(off, insn))
+		return -1;
+	emit(rv_beq(RV_REG_T2, RV_REG_ZERO, off >> 1), ctx);
+
+	/* goto *(prog->bpf_func + 4); */
+	off = offsetof(struct bpf_prog, bpf_func);
+	if (is_12b_check(off, insn))
+		return -1;
+	emit(rv_ld(RV_REG_T3, off, RV_REG_T2), ctx);
+	emit(rv_addi(RV_REG_T3, RV_REG_T3, 4), ctx);
+	emit(rv_addi(RV_REG_TCC, RV_REG_T1, 0), ctx);
+	__build_epilogue(RV_REG_T3, ctx);
+	return 0;
+}
+
+static void init_regs(u8 *rd, u8 *rs, const struct bpf_insn *insn,
+		      struct rv_jit_context *ctx)
+{
+	u8 code = insn->code;
+
+	switch (code) {
+	case BPF_JMP | BPF_JA:
+	case BPF_JMP | BPF_CALL:
+	case BPF_JMP | BPF_EXIT:
+	case BPF_JMP | BPF_TAIL_CALL:
+		break;
+	default:
+		*rd = bpf_to_rv_reg(insn->dst_reg, ctx);
+	}
+
+	if (code & (BPF_ALU | BPF_X) || code & (BPF_ALU64 | BPF_X) ||
+	    code & (BPF_JMP | BPF_X) || code & BPF_LDX || code & BPF_STX)
+		*rs = bpf_to_rv_reg(insn->src_reg, ctx);
+}
+
+static int rv_offset_check(int *rvoff, s16 off, int insn,
+			   struct rv_jit_context *ctx)
+{
+	*rvoff = rv_offset(insn + off, insn, ctx);
+	return is_13b_check(*rvoff, insn);
+}
+
+static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
+		     bool extra_pass)
+{
+	bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
+	int rvoff, i = insn - ctx->prog->insnsi;
+	u8 rd = -1, rs = -1, code = insn->code;
+	s16 off = insn->off;
+	s32 imm = insn->imm;
+
+	init_regs(&rd, &rs, insn, ctx);
+
+	switch (code) {
+	/* dst = src */
+	case BPF_ALU | BPF_MOV | BPF_X:
+	case BPF_ALU64 | BPF_MOV | BPF_X:
+		emit(is64 ? rv_addi(rd, rs, 0) : rv_addiw(rd, rs, 0), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+
+	/* dst = dst OP src */
+	case BPF_ALU | BPF_ADD | BPF_X:
+	case BPF_ALU64 | BPF_ADD | BPF_X:
+		emit(is64 ? rv_add(rd, rd, rs) : rv_addw(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_SUB | BPF_X:
+	case BPF_ALU64 | BPF_SUB | BPF_X:
+		emit(is64 ? rv_sub(rd, rd, rs) : rv_subw(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_AND | BPF_X:
+	case BPF_ALU64 | BPF_AND | BPF_X:
+		emit(rv_and(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_OR | BPF_X:
+	case BPF_ALU64 | BPF_OR | BPF_X:
+		emit(rv_or(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_XOR | BPF_X:
+	case BPF_ALU64 | BPF_XOR | BPF_X:
+		emit(rv_xor(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_MUL | BPF_X:
+	case BPF_ALU64 | BPF_MUL | BPF_X:
+		emit(is64 ? rv_mul(rd, rd, rs) : rv_mulw(rd, rd, rs), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_DIV | BPF_X:
+	case BPF_ALU64 | BPF_DIV | BPF_X:
+		emit(is64 ? rv_divu(rd, rd, rs) : rv_divuw(rd, rd, rs), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_MOD | BPF_X:
+	case BPF_ALU64 | BPF_MOD | BPF_X:
+		emit(is64 ? rv_remu(rd, rd, rs) : rv_remuw(rd, rd, rs), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_LSH | BPF_X:
+	case BPF_ALU64 | BPF_LSH | BPF_X:
+		emit(is64 ? rv_sll(rd, rd, rs) : rv_sllw(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_RSH | BPF_X:
+	case BPF_ALU64 | BPF_RSH | BPF_X:
+		emit(is64 ? rv_srl(rd, rd, rs) : rv_srlw(rd, rd, rs), ctx);
+		break;
+	case BPF_ALU | BPF_ARSH | BPF_X:
+	case BPF_ALU64 | BPF_ARSH | BPF_X:
+		emit(is64 ? rv_sra(rd, rd, rs) : rv_sraw(rd, rd, rs), ctx);
+		break;
+
+	/* dst = -dst */
+	case BPF_ALU | BPF_NEG:
+	case BPF_ALU64 | BPF_NEG:
+		emit(is64 ? rv_sub(rd, RV_REG_ZERO, rd) :
+		     rv_subw(rd, RV_REG_ZERO, rd), ctx);
+		break;
+
+	/* dst = BSWAP##imm(dst) */
+	case BPF_ALU | BPF_END | BPF_FROM_LE:
+	{
+		int shift = 64 - imm;
+
+		emit(rv_slli(rd, rd, shift), ctx);
+		emit(rv_srli(rd, rd, shift), ctx);
+		break;
+	}
+	case BPF_ALU | BPF_END | BPF_FROM_BE:
+		emit(rv_addi(RV_REG_T2, RV_REG_ZERO, 0), ctx);
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+		if (imm == 16)
+			goto out_be;
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+		if (imm == 32)
+			goto out_be;
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+		emit(rv_slli(RV_REG_T2, RV_REG_T2, 8), ctx);
+		emit(rv_srli(rd, rd, 8), ctx);
+out_be:
+		emit(rv_andi(RV_REG_T1, rd, 0xff), ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, RV_REG_T1), ctx);
+
+		emit(rv_addi(rd, RV_REG_T2, 0), ctx);
+		break;
+
+	/* dst = imm */
+	case BPF_ALU | BPF_MOV | BPF_K:
+	case BPF_ALU64 | BPF_MOV | BPF_K:
+		emit_imm(rd, imm, ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+
+	/* dst = dst OP imm */
+	case BPF_ALU | BPF_ADD | BPF_K:
+	case BPF_ALU64 | BPF_ADD | BPF_K:
+		if (is_12b_int(imm)) {
+			emit(is64 ? rv_addi(rd, rd, imm) :
+			     rv_addiw(rd, rd, imm), ctx);
+		} else {
+			emit_imm(RV_REG_T1, imm, ctx);
+			emit(is64 ? rv_add(rd, rd, RV_REG_T1) :
+			     rv_addw(rd, rd, RV_REG_T1), ctx);
+		}
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_SUB | BPF_K:
+	case BPF_ALU64 | BPF_SUB | BPF_K:
+		if (is_12b_int(-imm)) {
+			emit(is64 ? rv_addi(rd, rd, -imm) :
+			     rv_addiw(rd, rd, -imm), ctx);
+		} else {
+			emit_imm(RV_REG_T1, imm, ctx);
+			emit(is64 ? rv_sub(rd, rd, RV_REG_T1) :
+			     rv_subw(rd, rd, RV_REG_T1), ctx);
+		}
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_AND | BPF_K:
+	case BPF_ALU64 | BPF_AND | BPF_K:
+		if (is_12b_int(imm)) {
+			emit(rv_andi(rd, rd, imm), ctx);
+		} else {
+			emit_imm(RV_REG_T1, imm, ctx);
+			emit(rv_and(rd, rd, RV_REG_T1), ctx);
+		}
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_OR | BPF_K:
+	case BPF_ALU64 | BPF_OR | BPF_K:
+		if (is_12b_int(imm)) {
+			emit(rv_ori(rd, rd, imm), ctx);
+		} else {
+			emit_imm(RV_REG_T1, imm, ctx);
+			emit(rv_or(rd, rd, RV_REG_T1), ctx);
+		}
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_XOR | BPF_K:
+	case BPF_ALU64 | BPF_XOR | BPF_K:
+		if (is_12b_int(imm)) {
+			emit(rv_xori(rd, rd, imm), ctx);
+		} else {
+			emit_imm(RV_REG_T1, imm, ctx);
+			emit(rv_xor(rd, rd, RV_REG_T1), ctx);
+		}
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_MUL | BPF_K:
+	case BPF_ALU64 | BPF_MUL | BPF_K:
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(is64 ? rv_mul(rd, rd, RV_REG_T1) :
+		     rv_mulw(rd, rd, RV_REG_T1), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_DIV | BPF_K:
+	case BPF_ALU64 | BPF_DIV | BPF_K:
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(is64 ? rv_divu(rd, rd, RV_REG_T1) :
+		     rv_divuw(rd, rd, RV_REG_T1), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_MOD | BPF_K:
+	case BPF_ALU64 | BPF_MOD | BPF_K:
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(is64 ? rv_remu(rd, rd, RV_REG_T1) :
+		     rv_remuw(rd, rd, RV_REG_T1), ctx);
+		if (!is64)
+			emit_zero_extend_32(rd, ctx);
+		break;
+	case BPF_ALU | BPF_LSH | BPF_K:
+	case BPF_ALU64 | BPF_LSH | BPF_K:
+		emit(is64 ? rv_slli(rd, rd, imm) : rv_slliw(rd, rd, imm), ctx);
+		break;
+	case BPF_ALU | BPF_RSH | BPF_K:
+	case BPF_ALU64 | BPF_RSH | BPF_K:
+		emit(is64 ? rv_srli(rd, rd, imm) : rv_srliw(rd, rd, imm), ctx);
+		break;
+	case BPF_ALU | BPF_ARSH | BPF_K:
+	case BPF_ALU64 | BPF_ARSH | BPF_K:
+		emit(is64 ? rv_srai(rd, rd, imm) : rv_sraiw(rd, rd, imm), ctx);
+		break;
+
+	/* JUMP off */
+	case BPF_JMP | BPF_JA:
+		rvoff = rv_offset(i + off, i, ctx);
+		if (!is_21b_int(rvoff)) {
+			pr_err("bpf-jit: insn=%d offset=%d not supported yet!\n",
+			       i, rvoff);
+			return -1;
+		}
+
+		emit(rv_jal(RV_REG_ZERO, rvoff >> 1), ctx);
+		break;
+
+	/* IF (dst COND src) JUMP off */
+	case BPF_JMP | BPF_JEQ | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_beq(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JGT | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bltu(rs, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JLT | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bltu(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JGE | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bgeu(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JLE | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bgeu(rs, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JNE | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bne(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSGT | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_blt(rs, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSLT | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_blt(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSGE | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bge(rd, rs, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSLE | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_bge(rs, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSET | BPF_X:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit(rv_and(RV_REG_T1, rd, rs), ctx);
+		emit(rv_bne(RV_REG_T1, RV_REG_ZERO, rvoff >> 1), ctx);
+		break;
+
+	/* IF (dst COND imm) JUMP off */
+	case BPF_JMP | BPF_JEQ | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_beq(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JGT | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bltu(RV_REG_T1, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JLT | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bltu(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JGE | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bgeu(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JLE | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bgeu(RV_REG_T1, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JNE | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bne(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSGT | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_blt(RV_REG_T1, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSLT | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_blt(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSGE | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bge(rd, RV_REG_T1, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSLE | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T1, imm, ctx);
+		emit(rv_bge(RV_REG_T1, rd, rvoff >> 1), ctx);
+		break;
+	case BPF_JMP | BPF_JSET | BPF_K:
+		if (rv_offset_check(&rvoff, off, i, ctx))
+			return -1;
+		emit_imm(RV_REG_T2, imm, ctx);
+		emit(rv_and(RV_REG_T1, rd, RV_REG_T2), ctx);
+		emit(rv_bne(RV_REG_T1, RV_REG_ZERO, rvoff >> 1), ctx);
+		break;
+
+	/* function call */
+	case BPF_JMP | BPF_CALL:
+	{
+		bool fixed;
+		int i, ret;
+		u64 addr;
+
+		mark_call(ctx);
+		ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &addr,
+					    &fixed);
+		if (ret < 0)
+			return ret;
+		if (fixed) {
+			emit_imm(RV_REG_T1, addr, ctx);
+		} else {
+			i = ctx->ninsns;
+			emit_imm(RV_REG_T1, addr, ctx);
+			for (i = ctx->ninsns - i; i < 8; i++) {
+				/* nop */
+				emit(rv_addi(RV_REG_ZERO, RV_REG_ZERO, 0),
+				     ctx);
+			}
+		}
+		emit(rv_jalr(RV_REG_RA, RV_REG_T1, 0), ctx);
+		rd = bpf_to_rv_reg(BPF_REG_0, ctx);
+		emit(rv_addi(rd, RV_REG_A0, 0), ctx);
+		break;
+	}
+	/* tail call */
+	case BPF_JMP | BPF_TAIL_CALL:
+		if (emit_bpf_tail_call(i, ctx))
+			return -1;
+		break;
+
+	/* function return */
+	case BPF_JMP | BPF_EXIT:
+		if (i == ctx->prog->len - 1)
+			break;
+
+		rvoff = epilogue_offset(ctx);
+		if (is_21b_check(rvoff, i))
+			return -1;
+		emit(rv_jal(RV_REG_ZERO, rvoff >> 1), ctx);
+		break;
+
+	/* dst = imm64 */
+	case BPF_LD | BPF_IMM | BPF_DW:
+	{
+		struct bpf_insn insn1 = insn[1];
+		u64 imm64;
+
+		imm64 = (u64)insn1.imm << 32 | (u32)imm;
+		emit_imm(rd, imm64, ctx);
+		return 1;
+	}
+
+	/* LDX: dst = *(size *)(src + off) */
+	case BPF_LDX | BPF_MEM | BPF_B:
+		if (is_12b_int(off)) {
+			emit(rv_lbu(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
+		emit(rv_lbu(rd, 0, RV_REG_T1), ctx);
+		break;
+	case BPF_LDX | BPF_MEM | BPF_H:
+		if (is_12b_int(off)) {
+			emit(rv_lhu(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
+		emit(rv_lhu(rd, 0, RV_REG_T1), ctx);
+		break;
+	case BPF_LDX | BPF_MEM | BPF_W:
+		if (is_12b_int(off)) {
+			emit(rv_lwu(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
+		emit(rv_lwu(rd, 0, RV_REG_T1), ctx);
+		break;
+	case BPF_LDX | BPF_MEM | BPF_DW:
+		if (is_12b_int(off)) {
+			emit(rv_ld(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rs), ctx);
+		emit(rv_ld(rd, 0, RV_REG_T1), ctx);
+		break;
+
+	/* ST: *(size *)(dst + off) = imm */
+	case BPF_ST | BPF_MEM | BPF_B:
+		emit_imm(RV_REG_T1, imm, ctx);
+		if (is_12b_int(off)) {
+			emit(rv_sb(rd, off, RV_REG_T1), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T2, off, ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, rd), ctx);
+		emit(rv_sb(RV_REG_T2, 0, RV_REG_T1), ctx);
+		break;
+
+	case BPF_ST | BPF_MEM | BPF_H:
+		emit_imm(RV_REG_T1, imm, ctx);
+		if (is_12b_int(off)) {
+			emit(rv_sh(rd, off, RV_REG_T1), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T2, off, ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, rd), ctx);
+		emit(rv_sh(RV_REG_T2, 0, RV_REG_T1), ctx);
+		break;
+	case BPF_ST | BPF_MEM | BPF_W:
+		emit_imm(RV_REG_T1, imm, ctx);
+		if (is_12b_int(off)) {
+			emit(rv_sw(rd, off, RV_REG_T1), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T2, off, ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, rd), ctx);
+		emit(rv_sw(RV_REG_T2, 0, RV_REG_T1), ctx);
+		break;
+	case BPF_ST | BPF_MEM | BPF_DW:
+		emit_imm(RV_REG_T1, imm, ctx);
+		if (is_12b_int(off)) {
+			emit(rv_sd(rd, off, RV_REG_T1), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T2, off, ctx);
+		emit(rv_add(RV_REG_T2, RV_REG_T2, rd), ctx);
+		emit(rv_sd(RV_REG_T2, 0, RV_REG_T1), ctx);
+		break;
+
+	/* STX: *(size *)(dst + off) = src */
+	case BPF_STX | BPF_MEM | BPF_B:
+		if (is_12b_int(off)) {
+			emit(rv_sb(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rd), ctx);
+		emit(rv_sb(RV_REG_T1, 0, rs), ctx);
+		break;
+	case BPF_STX | BPF_MEM | BPF_H:
+		if (is_12b_int(off)) {
+			emit(rv_sh(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rd), ctx);
+		emit(rv_sh(RV_REG_T1, 0, rs), ctx);
+		break;
+	case BPF_STX | BPF_MEM | BPF_W:
+		if (is_12b_int(off)) {
+			emit(rv_sw(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rd), ctx);
+		emit(rv_sw(RV_REG_T1, 0, rs), ctx);
+		break;
+	case BPF_STX | BPF_MEM | BPF_DW:
+		if (is_12b_int(off)) {
+			emit(rv_sd(rd, off, rs), ctx);
+			break;
+		}
+
+		emit_imm(RV_REG_T1, off, ctx);
+		emit(rv_add(RV_REG_T1, RV_REG_T1, rd), ctx);
+		emit(rv_sd(RV_REG_T1, 0, rs), ctx);
+		break;
+	/* STX XADD: lock *(u32 *)(dst + off) += src */
+	case BPF_STX | BPF_XADD | BPF_W:
+	/* STX XADD: lock *(u64 *)(dst + off) += src */
+	case BPF_STX | BPF_XADD | BPF_DW:
+		if (off) {
+			if (is_12b_int(off)) {
+				emit(rv_addi(RV_REG_T1, rd, off), ctx);
+			} else {
+				emit_imm(RV_REG_T1, off, ctx);
+				emit(rv_add(RV_REG_T1, RV_REG_T1, rd), ctx);
+			}
+
+			rd = RV_REG_T1;
+		}
+
+		emit(BPF_SIZE(code) == BPF_W ?
+		     rv_amoadd_w(RV_REG_ZERO, rs, rd, 0, 0) :
+		     rv_amoadd_d(RV_REG_ZERO, rs, rd, 0, 0), ctx);
+		break;
+	default:
+		pr_err("bpf-jit: unknown opcode %02x\n", code);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void build_prologue(struct rv_jit_context *ctx)
+{
+	int stack_adjust = 0, store_offset, bpf_stack_adjust;
+
+	if (seen_reg(RV_REG_RA, ctx))
+		stack_adjust += 8;
+	stack_adjust += 8; /* RV_REG_FP */
+	if (seen_reg(RV_REG_S1, ctx))
+		stack_adjust += 8;
+	if (seen_reg(RV_REG_S2, ctx))
+		stack_adjust += 8;
+	if (seen_reg(RV_REG_S3, ctx))
+		stack_adjust += 8;
+	if (seen_reg(RV_REG_S4, ctx))
+		stack_adjust += 8;
+	if (seen_reg(RV_REG_S5, ctx))
+		stack_adjust += 8;
+	if (seen_reg(RV_REG_S6, ctx))
+		stack_adjust += 8;
+
+	stack_adjust = round_up(stack_adjust, 16);
+	bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
+	stack_adjust += bpf_stack_adjust;
+
+	store_offset = stack_adjust - 8;
+
+	/* First instruction is always setting the tail-call-counter
+	 * (TCC) register. This instruction is skipped for tail calls.
+	 */
+	emit(rv_addi(RV_REG_TCC, RV_REG_ZERO, MAX_TAIL_CALL_CNT), ctx);
+
+	emit(rv_addi(RV_REG_SP, RV_REG_SP, -stack_adjust), ctx);
+
+	if (seen_reg(RV_REG_RA, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_RA), ctx);
+		store_offset -= 8;
+	}
+	emit(rv_sd(RV_REG_SP, store_offset, RV_REG_FP), ctx);
+	store_offset -= 8;
+	if (seen_reg(RV_REG_S1, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S1), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S2, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S2), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S3, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S3), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S4, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S4), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S5, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S5), ctx);
+		store_offset -= 8;
+	}
+	if (seen_reg(RV_REG_S6, ctx)) {
+		emit(rv_sd(RV_REG_SP, store_offset, RV_REG_S6), ctx);
+		store_offset -= 8;
+	}
+
+	emit(rv_addi(RV_REG_FP, RV_REG_SP, stack_adjust), ctx);
+
+	if (bpf_stack_adjust)
+		emit(rv_addi(RV_REG_S5, RV_REG_SP, bpf_stack_adjust), ctx);
+
+	/* Program contains calls and tail calls, so RV_REG_TCC need
+	 * to be saved across calls.
+	 */
+	if (seen_tail_call(ctx) && seen_call(ctx))
+		emit(rv_addi(RV_REG_TCC_SAVED, RV_REG_TCC, 0), ctx);
+
+	ctx->stack_size = stack_adjust;
+}
+
+static void build_epilogue(struct rv_jit_context *ctx)
+{
+	__build_epilogue(RV_REG_RA, ctx);
+}
+
+static int build_body(struct rv_jit_context *ctx, bool extra_pass)
+{
+	const struct bpf_prog *prog = ctx->prog;
+	int i;
+
+	for (i = 0; i < prog->len; i++) {
+		const struct bpf_insn *insn = &prog->insnsi[i];
+		int ret;
+
+		ret = emit_insn(insn, ctx, extra_pass);
+		if (ret > 0) {
+			i++;
+			if (ctx->insns == NULL)
+				ctx->offset[i] = ctx->ninsns;
+			continue;
+		}
+		if (ctx->insns == NULL)
+			ctx->offset[i] = ctx->ninsns;
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static void bpf_fill_ill_insns(void *area, unsigned int size)
+{
+	memset(area, 0, size);
+}
+
+static void bpf_flush_icache(void *start, void *end)
+{
+	flush_icache_range((unsigned long)start, (unsigned long)end);
+}
+
+struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
+{
+	bool tmp_blinded = false, extra_pass = false;
+	struct bpf_prog *tmp, *orig_prog = prog;
+	struct rv_jit_data *jit_data;
+	struct rv_jit_context *ctx;
+	unsigned int image_size;
+
+	if (!prog->jit_requested)
+		return orig_prog;
+
+	tmp = bpf_jit_blind_constants(prog);
+	if (IS_ERR(tmp))
+		return orig_prog;
+	if (tmp != prog) {
+		tmp_blinded = true;
+		prog = tmp;
+	}
+
+	jit_data = prog->aux->jit_data;
+	if (!jit_data) {
+		jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
+		if (!jit_data) {
+			prog = orig_prog;
+			goto out;
+		}
+		prog->aux->jit_data = jit_data;
+	}
+
+	ctx = &jit_data->ctx;
+
+	if (ctx->offset) {
+		extra_pass = true;
+		image_size = sizeof(u32) * ctx->ninsns;
+		goto skip_init_ctx;
+	}
+
+	ctx->prog = prog;
+	ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
+	if (!ctx->offset) {
+		prog = orig_prog;
+		goto out_offset;
+	}
+
+	/* First pass generates the ctx->offset, but does not emit an image. */
+	if (build_body(ctx, extra_pass)) {
+		prog = orig_prog;
+		goto out_offset;
+	}
+	build_prologue(ctx);
+	ctx->epilogue_offset = ctx->ninsns;
+	build_epilogue(ctx);
+
+	/* Allocate image, now that we know the size. */
+	image_size = sizeof(u32) * ctx->ninsns;
+	jit_data->header = bpf_jit_binary_alloc(image_size, &jit_data->image,
+						sizeof(u32),
+						bpf_fill_ill_insns);
+	if (!jit_data->header) {
+		prog = orig_prog;
+		goto out_offset;
+	}
+
+	/* Second, real pass, that acutally emits the image. */
+	ctx->insns = (u32 *)jit_data->image;
+skip_init_ctx:
+	ctx->ninsns = 0;
+
+	build_prologue(ctx);
+	if (build_body(ctx, extra_pass)) {
+		bpf_jit_binary_free(jit_data->header);
+		prog = orig_prog;
+		goto out_offset;
+	}
+	build_epilogue(ctx);
+
+	if (bpf_jit_enable > 1)
+		bpf_jit_dump(prog->len, image_size, 2, ctx->insns);
+
+	prog->bpf_func = (void *)ctx->insns;
+	prog->jited = 1;
+	prog->jited_len = image_size;
+
+	bpf_flush_icache(jit_data->header, (u8 *)ctx->insns + ctx->ninsns);
+
+	if (!prog->is_func || extra_pass) {
+out_offset:
+		kfree(ctx->offset);
+		kfree(jit_data);
+		prog->aux->jit_data = NULL;
+	}
+out:
+	if (tmp_blinded)
+		bpf_jit_prog_release_other(prog, prog == orig_prog ?
+					   tmp : orig_prog);
+	return prog;
+}
-- 
2.19.1


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Re: [PATCH bpf-next 1/3] bpf, riscv: add BPF JIT for RV64G

[David Miller]

From: bjorn.topel@gmail.com
Date: Sun,  3 Feb 2019 12:51:29 +0100

> From: Björn Töpel <bjorn.topel@gmail.com>
> 
> This commit adds BPF JIT for RV64G.
> 
> The JIT is a two-pass JIT, and has a dynamic prolog/epilogue (similar
> to the MIPS64 BPF JIT) instead of static ones (e.g. x86_64).
> 
> At the moment the RISC-V Linux port does not support HAVE_KPROBES,
> which means that CONFIG_BPF_EVENTS is not supported. Thus, no tests
> involving BPF_PROG_TYPE_TRACEPOINT passes.
> 
> Further, the implementation does not support "far branching" (>4KiB).
> 
> The implementation passes all the test_bpf.ko tests:
>   test_bpf: Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]
> 
> All the tail_call tests in the selftest/bpf/test_verifier program
> passes.
> 
> All tests where done on QEMU (QEMU emulator version 3.1.50
> (v3.1.0-688-g8ae951fbc106)).
> 
> Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>

Acked-by: David S. Miller <davem@davemloft.net>

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Re: [PATCH bpf-next 1/3] bpf, riscv: add BPF JIT for RV64G

[Daniel Borkmann]

On 02/03/2019 12:51 PM, bjorn.topel@gmail.com wrote:
> From: Björn Töpel <bjorn.topel@gmail.com>
> 
> This commit adds BPF JIT for RV64G.
> 
> The JIT is a two-pass JIT, and has a dynamic prolog/epilogue (similar
> to the MIPS64 BPF JIT) instead of static ones (e.g. x86_64).
> 
> At the moment the RISC-V Linux port does not support HAVE_KPROBES,
> which means that CONFIG_BPF_EVENTS is not supported. Thus, no tests
> involving BPF_PROG_TYPE_TRACEPOINT passes.
> 
> Further, the implementation does not support "far branching" (>4KiB).
> 
> The implementation passes all the test_bpf.ko tests:
>   test_bpf: Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]
> 
> All the tail_call tests in the selftest/bpf/test_verifier program
> passes.
> 
> All tests where done on QEMU (QEMU emulator version 3.1.50
> (v3.1.0-688-g8ae951fbc106)).
> 
> Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>

Some minor comments:

Looks like all the BPF_JMP32 instructions are missing. Would probably
make sense to include these into the initial merge as well unless there
is some good reason not to; presumably the test_verifier parts with
BPF_JMP32 haven't been tried out?

[...]
> +
> +enum {
> +	RV_CTX_F_SEEN_TAIL_CALL =	0,
> +	RV_CTX_F_SEEN_CALL =		RV_REG_RA,
> +	RV_CTX_F_SEEN_S1 =		RV_REG_S1,
> +	RV_CTX_F_SEEN_S2 =		RV_REG_S2,
> +	RV_CTX_F_SEEN_S3 =		RV_REG_S3,
> +	RV_CTX_F_SEEN_S4 =		RV_REG_S4,
> +	RV_CTX_F_SEEN_S5 =		RV_REG_S5,
> +	RV_CTX_F_SEEN_S6 =		RV_REG_S6,
> +};
> +
> +struct rv_jit_context {
> +	struct bpf_prog *prog;
> +	u32 *insns; /* RV insns */
> +	int ninsns;
> +	int epilogue_offset;
> +	int *offset; /* BPF to RV */
> +	unsigned long flags;
> +	int stack_size;
> +};
> +
> +struct rv_jit_data {
> +	struct bpf_binary_header *header;
> +	u8 *image;
> +	struct rv_jit_context ctx;
> +};
> +
> +static u8 bpf_to_rv_reg(int bpf_reg, struct rv_jit_context *ctx)
> +{
> +	u8 reg = regmap[bpf_reg];
> +
> +	switch (reg) {
> +	case RV_CTX_F_SEEN_S1:
> +	case RV_CTX_F_SEEN_S2:
> +	case RV_CTX_F_SEEN_S3:
> +	case RV_CTX_F_SEEN_S4:
> +	case RV_CTX_F_SEEN_S5:
> +	case RV_CTX_F_SEEN_S6:
> +		__set_bit(reg, &ctx->flags);
> +	}
> +	return reg;
> +};
> +
> +static bool seen_reg(int reg, struct rv_jit_context *ctx)
> +{
> +	switch (reg) {
> +	case RV_CTX_F_SEEN_CALL:
> +	case RV_CTX_F_SEEN_S1:
> +	case RV_CTX_F_SEEN_S2:
> +	case RV_CTX_F_SEEN_S3:
> +	case RV_CTX_F_SEEN_S4:
> +	case RV_CTX_F_SEEN_S5:
> +	case RV_CTX_F_SEEN_S6:
> +		return test_bit(reg, &ctx->flags);
> +	}
> +	return false;
> +}
> +
> +static void mark_call(struct rv_jit_context *ctx)
> +{
> +	__set_bit(RV_CTX_F_SEEN_CALL, &ctx->flags);
> +}
> +
> +static bool seen_call(struct rv_jit_context *ctx)
> +{
> +	return seen_reg(RV_REG_RA, ctx);
> +}

Just nit: probably might be more obvious to remove this asymmetry in
seen_reg() and do __set_bit()/test_bit() for RV_CTX_F_SEEN_CALL similar
like below.

> +static void mark_tail_call(struct rv_jit_context *ctx)
> +{
> +	__set_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
> +}
> +
> +static bool seen_tail_call(struct rv_jit_context *ctx)
> +{
> +	return test_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
> +}
> +
> +static u8 rv_tail_call_reg(struct rv_jit_context *ctx)
> +{
> +	mark_tail_call(ctx);
> +
> +	if (seen_call(ctx)) {
> +		__set_bit(RV_CTX_F_SEEN_S6, &ctx->flags);
> +		return RV_REG_S6;
> +	}
> +	return RV_REG_A6;
> +}
> +
> +static void emit(const u32 insn, struct rv_jit_context *ctx)
> +{
> +	if (ctx->insns)
> +		ctx->insns[ctx->ninsns] = insn;
> +
> +	ctx->ninsns++;
> +}
> +
> +static u32 rv_r_insn(u8 funct7, u8 rs2, u8 rs1, u8 funct3, u8 rd, u8 opcode)
> +{
[...]
> +	/* Allocate image, now that we know the size. */
> +	image_size = sizeof(u32) * ctx->ninsns;
> +	jit_data->header = bpf_jit_binary_alloc(image_size, &jit_data->image,
> +						sizeof(u32),
> +						bpf_fill_ill_insns);
> +	if (!jit_data->header) {
> +		prog = orig_prog;
> +		goto out_offset;
> +	}
> +
> +	/* Second, real pass, that acutally emits the image. */
> +	ctx->insns = (u32 *)jit_data->image;
> +skip_init_ctx:
> +	ctx->ninsns = 0;
> +
> +	build_prologue(ctx);
> +	if (build_body(ctx, extra_pass)) {
> +		bpf_jit_binary_free(jit_data->header);
> +		prog = orig_prog;
> +		goto out_offset;
> +	}
> +	build_epilogue(ctx);
> +
> +	if (bpf_jit_enable > 1)
> +		bpf_jit_dump(prog->len, image_size, 2, ctx->insns);
> +
> +	prog->bpf_func = (void *)ctx->insns;
> +	prog->jited = 1;
> +	prog->jited_len = image_size;
> +
> +	bpf_flush_icache(jit_data->header, (u8 *)ctx->insns + ctx->ninsns);

Shouldn't this be '(u32 *)ctx->insns + ctx->ninsns' to cover the range?

> +
> +	if (!prog->is_func || extra_pass) {
> +out_offset:
> +		kfree(ctx->offset);
> +		kfree(jit_data);
> +		prog->aux->jit_data = NULL;
> +	}
> +out:
> +	if (tmp_blinded)
> +		bpf_jit_prog_release_other(prog, prog == orig_prog ?
> +					   tmp : orig_prog);
> +	return prog;
> +}
> 


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Re: [PATCH bpf-next 1/3] bpf, riscv: add BPF JIT for RV64G

[Björn Töpel]

Den mån 4 feb. 2019 kl 21:06 skrev Daniel Borkmann <daniel@iogearbox.net>:
>
> On 02/03/2019 12:51 PM, bjorn.topel@gmail.com wrote:
> > From: Björn Töpel <bjorn.topel@gmail.com>
> >
> > This commit adds BPF JIT for RV64G.
> >
> > The JIT is a two-pass JIT, and has a dynamic prolog/epilogue (similar
> > to the MIPS64 BPF JIT) instead of static ones (e.g. x86_64).
> >
> > At the moment the RISC-V Linux port does not support HAVE_KPROBES,
> > which means that CONFIG_BPF_EVENTS is not supported. Thus, no tests
> > involving BPF_PROG_TYPE_TRACEPOINT passes.
> >
> > Further, the implementation does not support "far branching" (>4KiB).
> >
> > The implementation passes all the test_bpf.ko tests:
> >   test_bpf: Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]
> >
> > All the tail_call tests in the selftest/bpf/test_verifier program
> > passes.
> >
> > All tests where done on QEMU (QEMU emulator version 3.1.50
> > (v3.1.0-688-g8ae951fbc106)).
> >
> > Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
>
> Some minor comments:
>
> Looks like all the BPF_JMP32 instructions are missing. Would probably
> make sense to include these into the initial merge as well unless there
> is some good reason not to; presumably the test_verifier parts with
> BPF_JMP32 haven't been tried out?
>

Yes indeed. My bad, I didn't realize that Jiong's patches were in the
tree! BPF_JMP32 should definitely be in the initial merge.

> [...]
> > +
> > +enum {
> > +     RV_CTX_F_SEEN_TAIL_CALL =       0,
> > +     RV_CTX_F_SEEN_CALL =            RV_REG_RA,
> > +     RV_CTX_F_SEEN_S1 =              RV_REG_S1,
> > +     RV_CTX_F_SEEN_S2 =              RV_REG_S2,
> > +     RV_CTX_F_SEEN_S3 =              RV_REG_S3,
> > +     RV_CTX_F_SEEN_S4 =              RV_REG_S4,
> > +     RV_CTX_F_SEEN_S5 =              RV_REG_S5,
> > +     RV_CTX_F_SEEN_S6 =              RV_REG_S6,
> > +};
> > +
> > +struct rv_jit_context {
> > +     struct bpf_prog *prog;
> > +     u32 *insns; /* RV insns */
> > +     int ninsns;
> > +     int epilogue_offset;
> > +     int *offset; /* BPF to RV */
> > +     unsigned long flags;
> > +     int stack_size;
> > +};
> > +
> > +struct rv_jit_data {
> > +     struct bpf_binary_header *header;
> > +     u8 *image;
> > +     struct rv_jit_context ctx;
> > +};
> > +
> > +static u8 bpf_to_rv_reg(int bpf_reg, struct rv_jit_context *ctx)
> > +{
> > +     u8 reg = regmap[bpf_reg];
> > +
> > +     switch (reg) {
> > +     case RV_CTX_F_SEEN_S1:
> > +     case RV_CTX_F_SEEN_S2:
> > +     case RV_CTX_F_SEEN_S3:
> > +     case RV_CTX_F_SEEN_S4:
> > +     case RV_CTX_F_SEEN_S5:
> > +     case RV_CTX_F_SEEN_S6:
> > +             __set_bit(reg, &ctx->flags);
> > +     }
> > +     return reg;
> > +};
> > +
> > +static bool seen_reg(int reg, struct rv_jit_context *ctx)
> > +{
> > +     switch (reg) {
> > +     case RV_CTX_F_SEEN_CALL:
> > +     case RV_CTX_F_SEEN_S1:
> > +     case RV_CTX_F_SEEN_S2:
> > +     case RV_CTX_F_SEEN_S3:
> > +     case RV_CTX_F_SEEN_S4:
> > +     case RV_CTX_F_SEEN_S5:
> > +     case RV_CTX_F_SEEN_S6:
> > +             return test_bit(reg, &ctx->flags);
> > +     }
> > +     return false;
> > +}
> > +
> > +static void mark_call(struct rv_jit_context *ctx)
> > +{
> > +     __set_bit(RV_CTX_F_SEEN_CALL, &ctx->flags);
> > +}
> > +
> > +static bool seen_call(struct rv_jit_context *ctx)
> > +{
> > +     return seen_reg(RV_REG_RA, ctx);
> > +}
>
> Just nit: probably might be more obvious to remove this asymmetry in
> seen_reg() and do __set_bit()/test_bit() for RV_CTX_F_SEEN_CALL similar
> like below.
>

Yeah, let's do that.

> > +static void mark_tail_call(struct rv_jit_context *ctx)
> > +{
> > +     __set_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
> > +}
> > +
> > +static bool seen_tail_call(struct rv_jit_context *ctx)
> > +{
> > +     return test_bit(RV_CTX_F_SEEN_TAIL_CALL, &ctx->flags);
> > +}
> > +
> > +static u8 rv_tail_call_reg(struct rv_jit_context *ctx)
> > +{
> > +     mark_tail_call(ctx);
> > +
> > +     if (seen_call(ctx)) {
> > +             __set_bit(RV_CTX_F_SEEN_S6, &ctx->flags);
> > +             return RV_REG_S6;
> > +     }
> > +     return RV_REG_A6;
> > +}
> > +
> > +static void emit(const u32 insn, struct rv_jit_context *ctx)
> > +{
> > +     if (ctx->insns)
> > +             ctx->insns[ctx->ninsns] = insn;
> > +
> > +     ctx->ninsns++;
> > +}
> > +
> > +static u32 rv_r_insn(u8 funct7, u8 rs2, u8 rs1, u8 funct3, u8 rd, u8 opcode)
> > +{
> [...]
> > +     /* Allocate image, now that we know the size. */
> > +     image_size = sizeof(u32) * ctx->ninsns;
> > +     jit_data->header = bpf_jit_binary_alloc(image_size, &jit_data->image,
> > +                                             sizeof(u32),
> > +                                             bpf_fill_ill_insns);
> > +     if (!jit_data->header) {
> > +             prog = orig_prog;
> > +             goto out_offset;
> > +     }
> > +
> > +     /* Second, real pass, that acutally emits the image. */
> > +     ctx->insns = (u32 *)jit_data->image;
> > +skip_init_ctx:
> > +     ctx->ninsns = 0;
> > +
> > +     build_prologue(ctx);
> > +     if (build_body(ctx, extra_pass)) {
> > +             bpf_jit_binary_free(jit_data->header);
> > +             prog = orig_prog;
> > +             goto out_offset;
> > +     }
> > +     build_epilogue(ctx);
> > +
> > +     if (bpf_jit_enable > 1)
> > +             bpf_jit_dump(prog->len, image_size, 2, ctx->insns);
> > +
> > +     prog->bpf_func = (void *)ctx->insns;
> > +     prog->jited = 1;
> > +     prog->jited_len = image_size;
> > +
> > +     bpf_flush_icache(jit_data->header, (u8 *)ctx->insns + ctx->ninsns);
>
> Shouldn't this be '(u32 *)ctx->insns + ctx->ninsns' to cover the range?
>

Yikes! Indeed so, I'll make sure this is corrected!

Thanks for the comments!


Björn

> > +
> > +     if (!prog->is_func || extra_pass) {
> > +out_offset:
> > +             kfree(ctx->offset);
> > +             kfree(jit_data);
> > +             prog->aux->jit_data = NULL;
> > +     }
> > +out:
> > +     if (tmp_blinded)
> > +             bpf_jit_prog_release_other(prog, prog == orig_prog ?
> > +                                        tmp : orig_prog);
> > +     return prog;
> > +}
> >
>

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[PATCH bpf-next 2/3] MAINTAINERS: add RISC-V BPF JIT maintainer

[bjorn.topel]

From: Björn Töpel <bjorn.topel@gmail.com>

Add Björn Töpel as RISC-V BPF JIT maintainer.

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
---
 MAINTAINERS | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 019a2bcfbd09..b4491132b9ce 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2907,6 +2907,12 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	arch/powerpc/net/
 
+BPF JIT for RISC-V (RV64G)
+M:	Björn Töpel <bjorn.topel@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	arch/riscv/net/
+
 BPF JIT for S390
 M:	Martin Schwidefsky <schwidefsky@de.ibm.com>
 M:	Heiko Carstens <heiko.carstens@de.ibm.com>
-- 
2.19.1


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Re: [PATCH bpf-next 2/3] MAINTAINERS: add RISC-V BPF JIT maintainer

[David Miller]

From: bjorn.topel@gmail.com
Date: Sun,  3 Feb 2019 12:51:30 +0100

> From: Björn Töpel <bjorn.topel@gmail.com>
> 
> Add Björn Töpel as RISC-V BPF JIT maintainer.
> 
> Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>

Acked-by: David S. Miller <davem@davemloft.net>

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[PATCH bpf-next 3/3] bpf, doc: add RISC-V to filter.txt

[bjorn.topel]

From: Björn Töpel <bjorn.topel@gmail.com>

Update Documentation/networking/filter.txt to mention RISC-V.

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
---
 Documentation/networking/filter.txt | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
index 01603bc2eff1..b5e060edfc38 100644
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -464,10 +464,11 @@ breakpoints: 0 1
 JIT compiler
 ------------
 
-The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
-ARM, ARM64, MIPS and s390 and can be enabled through CONFIG_BPF_JIT. The JIT
-compiler is transparently invoked for each attached filter from user space
-or for internal kernel users if it has been previously enabled by root:
+The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC,
+PowerPC, ARM, ARM64, MIPS, RISC-V and s390 and can be enabled through
+CONFIG_BPF_JIT. The JIT compiler is transparently invoked for each
+attached filter from user space or for internal kernel users if it has
+been previously enabled by root:
 
   echo 1 > /proc/sys/net/core/bpf_jit_enable
 
@@ -603,9 +604,10 @@ got from bpf_prog_create(), and 'ctx' the given context (e.g.
 skb pointer). All constraints and restrictions from bpf_check_classic() apply
 before a conversion to the new layout is being done behind the scenes!
 
-Currently, the classic BPF format is being used for JITing on most 32-bit
-architectures, whereas x86-64, aarch64, s390x, powerpc64, sparc64, arm32 perform
-JIT compilation from eBPF instruction set.
+Currently, the classic BPF format is being used for JITing on most
+32-bit architectures, whereas x86-64, aarch64, s390x, powerpc64,
+sparc64, arm32, riscv (RV64G) perform JIT compilation from eBPF
+instruction set.
 
 Some core changes of the new internal format:
 
-- 
2.19.1


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Re: [PATCH bpf-next 3/3] bpf, doc: add RISC-V to filter.txt

[David Miller]

From: bjorn.topel@gmail.com
Date: Sun,  3 Feb 2019 12:51:31 +0100

> From: Björn Töpel <bjorn.topel@gmail.com>
> 
> Update Documentation/networking/filter.txt to mention RISC-V.
> 
> Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>

Acked-by: David S. Miller <davem@davemloft.net>

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Re: [PATCH bpf-next 3/3] bpf, doc: add RISC-V to filter.txt

[Daniel Borkmann]

On 02/03/2019 12:51 PM, bjorn.topel@gmail.com wrote:
> From: Björn Töpel <bjorn.topel@gmail.com>
> 
> Update Documentation/networking/filter.txt to mention RISC-V.
> 
> Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>

Nit: in Documentation/sysctl/net.txt under bpf_jit_enable there is also
a concrete list of eBPF/cBPF JITs, would be good to add riscv64 there as
well.

>  Documentation/networking/filter.txt | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
> index 01603bc2eff1..b5e060edfc38 100644
> --- a/Documentation/networking/filter.txt
> +++ b/Documentation/networking/filter.txt
> @@ -464,10 +464,11 @@ breakpoints: 0 1
>  JIT compiler
>  ------------
>  
> -The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
> -ARM, ARM64, MIPS and s390 and can be enabled through CONFIG_BPF_JIT. The JIT
> -compiler is transparently invoked for each attached filter from user space
> -or for internal kernel users if it has been previously enabled by root:
> +The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC,
> +PowerPC, ARM, ARM64, MIPS, RISC-V and s390 and can be enabled through
> +CONFIG_BPF_JIT. The JIT compiler is transparently invoked for each
> +attached filter from user space or for internal kernel users if it has
> +been previously enabled by root:
>  
>    echo 1 > /proc/sys/net/core/bpf_jit_enable
>  
> @@ -603,9 +604,10 @@ got from bpf_prog_create(), and 'ctx' the given context (e.g.
>  skb pointer). All constraints and restrictions from bpf_check_classic() apply
>  before a conversion to the new layout is being done behind the scenes!
>  
> -Currently, the classic BPF format is being used for JITing on most 32-bit
> -architectures, whereas x86-64, aarch64, s390x, powerpc64, sparc64, arm32 perform
> -JIT compilation from eBPF instruction set.
> +Currently, the classic BPF format is being used for JITing on most
> +32-bit architectures, whereas x86-64, aarch64, s390x, powerpc64,
> +sparc64, arm32, riscv (RV64G) perform JIT compilation from eBPF
> +instruction set.
>  
>  Some core changes of the new internal format:
>  
> 


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Re: [PATCH bpf-next 3/3] bpf, doc: add RISC-V to filter.txt

[Björn Töpel]

Den mån 4 feb. 2019 kl 21:09 skrev Daniel Borkmann <daniel@iogearbox.net>:
>
> On 02/03/2019 12:51 PM, bjorn.topel@gmail.com wrote:
> > From: Björn Töpel <bjorn.topel@gmail.com>
> >
> > Update Documentation/networking/filter.txt to mention RISC-V.
> >
> > Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
>
> Nit: in Documentation/sysctl/net.txt under bpf_jit_enable there is also
> a concrete list of eBPF/cBPF JITs, would be good to add riscv64 there as
> well.
>

Thanks for pointing this out! I'll do a v2.


Björn

> >  Documentation/networking/filter.txt | 16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
> > index 01603bc2eff1..b5e060edfc38 100644
> > --- a/Documentation/networking/filter.txt
> > +++ b/Documentation/networking/filter.txt
> > @@ -464,10 +464,11 @@ breakpoints: 0 1
> >  JIT compiler
> >  ------------
> >
> > -The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
> > -ARM, ARM64, MIPS and s390 and can be enabled through CONFIG_BPF_JIT. The JIT
> > -compiler is transparently invoked for each attached filter from user space
> > -or for internal kernel users if it has been previously enabled by root:
> > +The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC,
> > +PowerPC, ARM, ARM64, MIPS, RISC-V and s390 and can be enabled through
> > +CONFIG_BPF_JIT. The JIT compiler is transparently invoked for each
> > +attached filter from user space or for internal kernel users if it has
> > +been previously enabled by root:
> >
> >    echo 1 > /proc/sys/net/core/bpf_jit_enable
> >
> > @@ -603,9 +604,10 @@ got from bpf_prog_create(), and 'ctx' the given context (e.g.
> >  skb pointer). All constraints and restrictions from bpf_check_classic() apply
> >  before a conversion to the new layout is being done behind the scenes!
> >
> > -Currently, the classic BPF format is being used for JITing on most 32-bit
> > -architectures, whereas x86-64, aarch64, s390x, powerpc64, sparc64, arm32 perform
> > -JIT compilation from eBPF instruction set.
> > +Currently, the classic BPF format is being used for JITing on most
> > +32-bit architectures, whereas x86-64, aarch64, s390x, powerpc64,
> > +sparc64, arm32, riscv (RV64G) perform JIT compilation from eBPF
> > +instruction set.
> >
> >  Some core changes of the new internal format:
> >
> >
>

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