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From: "Björn Töpel" <bjorn.topel@gmail.com>
To: daniel@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org
Cc: "Björn Töpel" <bjorn.topel@gmail.com>,
	linux-riscv@lists.infradead.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next 3/8] riscv, bpf: add support for far jumps and exits
Date: Mon,  9 Dec 2019 18:31:31 +0100	[thread overview]
Message-ID: <20191209173136.29615-4-bjorn.topel@gmail.com> (raw)
In-Reply-To: <20191209173136.29615-1-bjorn.topel@gmail.com>

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

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
---
 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 e2f6724b64f7..e9cc9832ac2c 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -506,16 +506,6 @@ static int is_13b_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,
@@ -733,6 +723,21 @@ 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);
+}
+
 /* return -1 or inverted cond */
 static int invert_bpf_cond(u8 cond)
 {
@@ -1117,13 +1122,7 @@ 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 */
@@ -1261,9 +1260,7 @@ 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


  parent reply	other threads:[~2019-12-09 17:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 17:31 [PATCH bpf-next 0/8] riscv: BPF JIT fix, optimizations and far jumps support Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 1/8] riscv, bpf: fix broken BPF tail calls Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 2/8] riscv, bpf: add support for far branching Björn Töpel
2019-12-09 21:08   ` Luke Nelson
2019-12-09 21:27     ` Daniel Borkmann
2019-12-10  7:02       ` Luke Nelson
2019-12-10  5:32     ` Björn Töpel
2019-12-10  5:31   ` Björn Töpel
2019-12-09 17:31 ` Björn Töpel [this message]
2019-12-09 21:15   ` [PATCH bpf-next 3/8] riscv, bpf: add support for far jumps and exits Luke Nelson
2019-12-09 17:31 ` [PATCH bpf-next 4/8] riscv, bpf: optimize BPF tail calls Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 5/8] riscv, bpf: provide RISC-V specific JIT image alloc/free Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 6/8] riscv, bpf: optimize calls Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 7/8] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs Björn Töpel
2019-12-09 17:31 ` [PATCH bpf-next 8/8] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs Björn Töpel

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