[PATCH bpf-next v2 0/9] riscv: BPF JIT fix, optimizations and far jumps support · Björn Töpel <hidden> · 2019-12-16
[PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls · Björn Töpel <hidden> · 2019-12-16
[PATCH bpf-next v2 3/9] riscv, bpf: add support for far branching when emitting tail call · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 3/9] riscv, bpf: add support for far branching when emitting tail call · Palmer Dabbelt <hidden> · 2019-12-23
[PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching · Palmer Dabbelt <hidden> · 2019-12-23
Re: [PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching · Björn Töpel <hidden> · 2020-01-07
Re: [PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching · Palmer Dabbelt <hidden> · 2020-01-23
[PATCH bpf-next v2 4/9] riscv, bpf: add support for far jumps and exits · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 4/9] riscv, bpf: add support for far jumps and exits · Palmer Dabbelt <hidden> · 2019-12-23
[PATCH bpf-next v2 5/9] riscv, bpf: optimize BPF tail calls · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 5/9] riscv, bpf: optimize BPF tail calls · Palmer Dabbelt <hidden> · 2019-12-23
[PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Daniel Borkmann <daniel@iogearbox.net> · 2019-12-16
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Björn Töpel <hidden> · 2019-12-18
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Paul Walmsley <hidden> · 2020-01-04
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Björn Töpel <hidden> · 2020-01-07
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Paul Walmsley <hidden> · 2020-01-07
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Palmer Dabbelt <hidden> · 2019-12-23
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Alex Ghiti <alex@ghiti.fr> · 2020-02-02
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Björn Töpel <hidden> · 2020-02-03
Re: [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free · Alex Ghiti <alex@ghiti.fr> · 2020-02-03
[PATCH bpf-next v2 7/9] riscv, bpf: optimize calls · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls · Palmer Dabbelt <hidden> · 2019-12-23
Re: [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls · Björn Töpel <hidden> · 2020-01-07
Re: [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls · Palmer Dabbelt <hidden> · 2020-01-28
Re: [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls · Björn Töpel <hidden> · 2020-02-03
[PATCH bpf-next v2 8/9] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 8/9] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs · Palmer Dabbelt <hidden> · 2019-12-23
[PATCH bpf-next v2 9/9] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs · Björn Töpel <hidden> · 2019-12-16
Re: [PATCH bpf-next v2 9/9] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs · Palmer Dabbelt <hidden> · 2019-12-23
Re: [PATCH bpf-next v2 0/9] riscv: BPF JIT fix, optimizations and far jumps support · Daniel Borkmann <daniel@iogearbox.net> · 2019-12-19

STALE2362d LANDED: 1 (0M)

Revisions (2)

2019-12-09 v1 [diff vs current]
2019-12-16 v2 current

[PATCH bpf-next v2 4/9] riscv, bpf: add support for far jumps and exits

From: Björn Töpel <hidden>
Date: 2019-12-16 09:14:07
Also in: bpf, linux-riscv
Subsystem: bpf jit for risc-v (32-bit), bpf jit for risc-v (64-bit), bpf [general] (safe dynamic programs and tools), risc-v architecture, the rest · Maintainers: Luke Nelson, Xi Wang, Björn Töpel, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Paul Walmsley, Palmer Dabbelt, Albert Ou, Linus Torvalds

This commit add support for far (offset > 21b) jumps and exits.

Reviewed-by: Luke Nelson <redacted>
Cc: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Björn Töpel <redacted>
---
 arch/riscv/net/bpf_jit_comp.c | 37 ++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 20 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index c38c95df3440..2fc0f24ad30f 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c

@@ -496,16 +496,6 @@ static int is_12b_check(int off, int insn)
 	return 0;
 }
 
-static int is_21b_check(int off, int insn)
-{
-	if (!is_21b_int(off)) {
-		pr_err("bpf-jit: insn=%d 21b < 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,

@@ -820,6 +810,21 @@ static void emit_sext_32_rd(u8 *rd, struct rv_jit_context *ctx)
 	*rd = RV_REG_T2;
 }
 
+static void emit_jump_and_link(u8 rd, int rvoff, struct rv_jit_context *ctx)
+{
+	s64 upper, lower;
+
+	if (is_21b_int(rvoff)) {
+		emit(rv_jal(rd, rvoff >> 1), ctx);
+		return;
+	}
+
+	upper = (rvoff + (1 << 11)) >> 12;
+	lower = rvoff & 0xfff;
+	emit(rv_auipc(RV_REG_T1, upper), ctx);
+	emit(rv_jalr(rd, RV_REG_T1, lower), ctx);
+}
+
 static bool is_signed_bpf_cond(u8 cond)
 {
 	return cond == BPF_JSGT || cond == BPF_JSLT ||

@@ -1101,13 +1106,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 	/* JUMP off */
 	case BPF_JMP | BPF_JA:
 		rvoff = rv_offset(i, off, 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);
+		emit_jump_and_link(RV_REG_ZERO, rvoff, ctx);
 		break;
 
 	/* IF (dst COND src) JUMP off */

@@ -1245,9 +1244,7 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 			break;
 
 		rvoff = epilogue_offset(ctx);
-		if (is_21b_check(rvoff, i))
-			return -1;
-		emit(rv_jal(RV_REG_ZERO, rvoff >> 1), ctx);
+		emit_jump_and_link(RV_REG_ZERO, rvoff, ctx);
 		break;
 
 	/* dst = imm64 */

-- 
2.20.1