From 33203c02f2f8ae8e19d7dbbabf55cfd0025efede Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Mon, 16 Dec 2019 10:13:38 +0100 Subject: [PATCH] riscv, bpf: Add support for far jumps and exits MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This commit add support for far (offset > 21b) jumps and exits. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Reviewed-by: Luke Nelson Link: https://lore.kernel.org/bpf/20191216091343.23260-5-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 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 @@ out_be: /* 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 @@ out_be: 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 */