[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

Revisions (2)

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

[PATCH bpf-next v2 3/9] riscv, bpf: add support for far branching when emitting tail call

From: Björn Töpel <hidden>
Date: 2019-12-16 09:14:04
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

Start use the emit_branch() function in the tail call emitter in order
to support far branching.

Signed-off-by: Björn Töpel <redacted>
---
 arch/riscv/net/bpf_jit_comp.c | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index e599458a9bcd..c38c95df3440 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_13b_check(int off, int insn)
-{
-	if (!is_13b_int(off)) {
-		pr_err("bpf-jit: insn=%d 13b < 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)) {

@@ -744,18 +734,14 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
 		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);
+	emit_branch(BPF_JGE, RV_REG_A2, RV_REG_T1, off, 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);
+	emit_branch(BPF_JSLT, RV_REG_T1, RV_REG_ZERO, off, ctx);
 
 	/* prog = array->ptrs[index];
 	 * if (!prog)

@@ -768,9 +754,7 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
 		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);
+	emit_branch(BPF_JEQ, RV_REG_T2, RV_REG_ZERO, off, ctx);
 
 	/* goto *(prog->bpf_func + 4); */
 	off = offsetof(struct bpf_prog, bpf_func);

-- 
2.20.1