diff options
Diffstat (limited to 'drivers/net/ethernet/netronome/nfp/bpf/jit.c')
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/bpf/jit.c | 85 |
1 files changed, 66 insertions, 19 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c index 74423d3e714d..b393f9dea584 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c @@ -3132,7 +3132,9 @@ bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) NFP_CSR_ACT_LM_ADDR0); } - /* The following steps are performed: + /* Two cases for jumping to the callee: + * + * - If callee uses and needs to save R6~R9 then: * 1. Put the start offset of the callee into imm_b(). This will * require a fixup step, as we do not necessarily know this * address yet. @@ -3140,8 +3142,12 @@ bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) * register ret_reg(). * 3. (After defer slots are consumed) Jump to the subroutine that * pushes the registers to the stack. - * The subroutine acts as a trampoline, and returns to the address in - * imm_b(), i.e. jumps to the callee. + * The subroutine acts as a trampoline, and returns to the address in + * imm_b(), i.e. jumps to the callee. + * + * - If callee does not need to save R6~R9 then just load return + * address to the caller in ret_reg(), and jump to the callee + * directly. * * Using ret_reg() to pass the return address to the callee is set here * as a convention. The callee can then push this address onto its @@ -3157,11 +3163,21 @@ bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) * execution of the callee, we will not have to push the return * address to the stack for leaf functions. */ - ret_tgt = nfp_prog_current_offset(nfp_prog) + 3; - emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, - RELO_BR_GO_CALL_PUSH_REGS); - offset_br = nfp_prog_current_offset(nfp_prog); - wrp_immed_relo(nfp_prog, imm_b(nfp_prog), 0, RELO_IMMED_REL); + if (!meta->jmp_dst) { + pr_err("BUG: BPF-to-BPF call has no destination recorded\n"); + return -ELOOP; + } + if (nfp_prog->subprog[meta->jmp_dst->subprog_idx].needs_reg_push) { + ret_tgt = nfp_prog_current_offset(nfp_prog) + 3; + emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2, + RELO_BR_GO_CALL_PUSH_REGS); + offset_br = nfp_prog_current_offset(nfp_prog); + wrp_immed_relo(nfp_prog, imm_b(nfp_prog), 0, RELO_IMMED_REL); + } else { + ret_tgt = nfp_prog_current_offset(nfp_prog) + 2; + emit_br(nfp_prog, BR_UNC, meta->n + 1 + meta->insn.imm, 1); + offset_br = nfp_prog_current_offset(nfp_prog); + } wrp_immed_relo(nfp_prog, ret_reg(nfp_prog), ret_tgt, RELO_IMMED_REL); if (!nfp_prog_confirm_current_offset(nfp_prog, ret_tgt)) @@ -3227,15 +3243,24 @@ static int goto_out(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) static int nfp_subprog_epilogue(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) { - /* Pop R6~R9 to the stack via related subroutine. - * Pop return address for BPF-to-BPF call from the stack and load it - * into ret_reg() before we jump. This means that the subroutine does - * not come back here, we make it jump back to the subprogram caller - * directly! - */ - emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 1, - RELO_BR_GO_CALL_POP_REGS); - wrp_mov(nfp_prog, ret_reg(nfp_prog), reg_lm(0, 0)); + if (nfp_prog->subprog[meta->subprog_idx].needs_reg_push) { + /* Pop R6~R9 to the stack via related subroutine. + * We loaded the return address to the caller into ret_reg(). + * This means that the subroutine does not come back here, we + * make it jump back to the subprogram caller directly! + */ + emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 1, + RELO_BR_GO_CALL_POP_REGS); + /* Pop return address from the stack. */ + wrp_mov(nfp_prog, ret_reg(nfp_prog), reg_lm(0, 0)); + } else { + /* Pop return address from the stack. */ + wrp_mov(nfp_prog, ret_reg(nfp_prog), reg_lm(0, 0)); + /* Jump back to caller if no callee-saved registers were used + * by the subprogram. + */ + emit_rtn(nfp_prog, ret_reg(nfp_prog), 0); + } return 0; } @@ -3410,7 +3435,8 @@ static int nfp_fixup_branches(struct nfp_prog *nfp_prog) return -ELOOP; } - if (is_mbpf_pseudo_call(meta)) { + if (is_mbpf_pseudo_call(meta) && + nfp_prog->subprog[jmp_dst->subprog_idx].needs_reg_push) { err = nfp_fixup_immed_relo(nfp_prog, meta, jmp_dst, br_idx); if (err) @@ -3549,6 +3575,17 @@ static void nfp_outro_xdp(struct nfp_prog *nfp_prog) emit_ld_field(nfp_prog, reg_a(0), 0xc, reg_b(2), SHF_SC_L_SHF, 16); } +static bool nfp_prog_needs_callee_reg_save(struct nfp_prog *nfp_prog) +{ + unsigned int idx; + + for (idx = 1; idx < nfp_prog->subprog_cnt; idx++) + if (nfp_prog->subprog[idx].needs_reg_push) + return true; + + return false; +} + static void nfp_push_callee_registers(struct nfp_prog *nfp_prog) { u8 reg; @@ -3612,7 +3649,7 @@ static void nfp_outro(struct nfp_prog *nfp_prog) WARN_ON(1); } - if (nfp_prog->subprog_cnt == 1) + if (!nfp_prog_needs_callee_reg_save(nfp_prog)) return; nfp_push_callee_registers(nfp_prog); @@ -4354,10 +4391,20 @@ void *nfp_bpf_relo_for_vnic(struct nfp_prog *nfp_prog, struct nfp_bpf_vnic *bv) nfp_prog->tgt_abort + bv->start_off); break; case RELO_BR_GO_CALL_PUSH_REGS: + if (!nfp_prog->tgt_call_push_regs) { + pr_err("BUG: failed to detect subprogram registers needs\n"); + err = -EINVAL; + goto err_free_prog; + } off = nfp_prog->tgt_call_push_regs + bv->start_off; br_set_offset(&prog[i], off); break; case RELO_BR_GO_CALL_POP_REGS: + if (!nfp_prog->tgt_call_pop_regs) { + pr_err("BUG: failed to detect subprogram registers needs\n"); + err = -EINVAL; + goto err_free_prog; + } off = nfp_prog->tgt_call_pop_regs + bv->start_off; br_set_offset(&prog[i], off); break; |