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| author | Björn Töpel <bjorn.topel@gmail.com> | 2019-12-16 10:13:38 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-12-19 16:03:30 +0100 |
| commit | 33203c02f2f8ae8e19d7dbbabf55cfd0025efede (patch) | |
| tree | c78d70bc3448490b030379dbc9b87826be37e30a /arch/riscv | |
| parent | riscv, bpf: Add support for far branching when emitting tail call (diff) | |
| download | linux-33203c02f2f8ae8e19d7dbbabf55cfd0025efede.tar.xz linux-33203c02f2f8ae8e19d7dbbabf55cfd0025efede.zip | |
riscv, bpf: Add support for far jumps and exits
This commit add support for far (offset > 21b) jumps and exits.
Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Luke Nelson <lukenels@cs.washington.edu>
Link: https://lore.kernel.org/bpf/20191216091343.23260-5-bjorn.topel@gmail.com
Diffstat (limited to 'arch/riscv')
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp.c | 37 |
1 files 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 */ |