diff options
Diffstat (limited to 'riscv/csrs.cc')
| -rw-r--r-- | riscv/csrs.cc | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/riscv/csrs.cc b/riscv/csrs.cc index c887c4e..1e9b544 100644 --- a/riscv/csrs.cc +++ b/riscv/csrs.cc @@ -120,7 +120,9 @@ bool pmpaddr_csr_t::unlogged_write(const reg_t val) noexcept { if (proc->n_pmp == 0) return false; - bool locked = cfg & PMP_L; + const bool lock_bypass = state->mseccfg->get_rlb(); + const bool locked = !lock_bypass && (cfg & PMP_L); + if (pmpidx < proc->n_pmp && !locked && !next_locked_and_tor()) { this->val = val & ((reg_t(1) << (MAX_PADDR_BITS - PMP_SHIFT)) - 1); } @@ -132,8 +134,9 @@ bool pmpaddr_csr_t::unlogged_write(const reg_t val) noexcept { bool pmpaddr_csr_t::next_locked_and_tor() const noexcept { if (pmpidx+1 >= state->max_pmp) return false; // this is the last entry - bool next_locked = state->pmpaddr[pmpidx+1]->cfg & PMP_L; - bool next_tor = (state->pmpaddr[pmpidx+1]->cfg & PMP_A) == PMP_TOR; + const bool lock_bypass = state->mseccfg->get_rlb(); + const bool next_locked = !lock_bypass && (state->pmpaddr[pmpidx+1]->cfg & PMP_L); + const bool next_tor = (state->pmpaddr[pmpidx+1]->cfg & PMP_A) == PMP_TOR; return next_locked && next_tor; } @@ -214,14 +217,35 @@ bool pmpcfg_csr_t::unlogged_write(const reg_t val) noexcept { return false; bool write_success = false; + const bool rlb = state->mseccfg->get_rlb(); + const bool mml = state->mseccfg->get_mml(); for (size_t i0 = (address - CSR_PMPCFG0) * 4, i = i0; i < i0 + proc->get_xlen() / 8; i++) { if (i < proc->n_pmp) { - if (!(state->pmpaddr[i]->cfg & PMP_L)) { + const bool locked = (state->pmpaddr[i]->cfg & PMP_L); + if (rlb || (!locked && !state->pmpaddr[i]->next_locked_and_tor())) { uint8_t cfg = (val >> (8 * (i - i0))) & (PMP_R | PMP_W | PMP_X | PMP_A | PMP_L); - cfg &= ~PMP_W | ((cfg & PMP_R) ? PMP_W : 0); // Disallow R=0 W=1 + // Drop R=0 W=1 when MML = 0 + // Remove the restriction when MML = 1 + if (!mml) { + cfg &= ~PMP_W | ((cfg & PMP_R) ? PMP_W : 0); + } + // Disallow A=NA4 when granularity > 4 if (proc->lg_pmp_granularity != PMP_SHIFT && (cfg & PMP_A) == PMP_NA4) - cfg |= PMP_NAPOT; // Disallow A=NA4 when granularity > 4 - state->pmpaddr[i]->cfg = cfg; + cfg |= PMP_NAPOT; + /* + * Adding a rule with executable privileges that either is M-mode-only or a locked Shared-Region + * is not possible and such pmpcfg writes are ignored, leaving pmpcfg unchanged. + * This restriction can be temporarily lifted e.g. during the boot process, by setting mseccfg.RLB. + */ + const bool cfgx = cfg & PMP_X; + const bool cfgw = cfg & PMP_W; + const bool cfgr = cfg & PMP_R; + if (rlb || !(mml && ((cfg & PMP_L) // M-mode-only or a locked Shared-Region + && !(cfgx && cfgw && cfgr) // RWX = 111 is allowed + && (cfgx || (cfgw && !cfgr)) // X=1 or RW=01 is not allowed + ))) { + state->pmpaddr[i]->cfg = cfg; + } } write_success = true; } |