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[rtl] Cannot add M mode executable PMP regions when MML = 1

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A rule that allows M mode execution (either M mode only or shared M/U
mode) cannot be added when MML is set, unless RLB is also set.

Fixes #1740
This commit is contained in:
Greg Chadwick 2022-08-18 09:47:40 +01:00 • committed by Greg Chadwick
parent 2ff233726d
commit a646737d4d
1 changed files with 26 additions and 1 deletions
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27
rtl/ibex_cs_registers.sv
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@ -124,6 +124,22 @@ module ibex_cs_registers #(
import ibex_pkg::*;
// Is a PMP config a locked one that allows M-mode execution when MSECCFG.MML is set (either
// M mode alone or shared M/U mode execution)?
function automatic logic is_mml_m_exec_cfg(ibex_pkg::pmp_cfg_t pmp_cfg);
logic unused_cfg;
unused_cfg = ^{pmp_cfg.mode};
if (pmp_cfg.lock) begin
case ({pmp_cfg.read, pmp_cfg.write, pmp_cfg.exec})
3'b001, 3'b010, 3'b011, 3'b101: return 1'b1;
default: return 1'b0;
endcase
end
return 1'b0;
endfunction
localparam int unsigned RV32BExtra = (RV32B == RV32BOTEarlGrey) || (RV32B == RV32BFull) ? 1 : 0;
localparam int unsigned RV32MEnabled = (RV32M == RV32MNone) ? 0 : 1;
localparam int unsigned PMPAddrWidth = (PMPGranularity > 0) ? 33 - PMPGranularity : 32;
@ -1045,6 +1061,7 @@ module ibex_cs_registers #(
logic pmp_mseccfg_err;
pmp_cfg_t pmp_cfg [PMPNumRegions];
logic [PMPNumRegions-1:0] pmp_cfg_locked;
logic [PMPNumRegions-1:0] pmp_cfg_wr_suppress;
pmp_cfg_t pmp_cfg_wdata [PMPNumRegions];
logic [PMPAddrWidth-1:0] pmp_addr [PMPNumRegions];
logic [PMPNumRegions-1:0] pmp_cfg_we;
@ -1100,7 +1117,9 @@ module ibex_cs_registers #(
// -------------------------
// Instantiate cfg registers
// -------------------------
assign pmp_cfg_we[i] = csr_we_int & ~pmp_cfg_locked[i] &
assign pmp_cfg_we[i] = csr_we_int &
~pmp_cfg_locked[i] &
~pmp_cfg_wr_suppress[i] &
(csr_addr == (CSR_OFF_PMP_CFG + (i[11:0] >> 2)));
// Select the correct WDATA (each CSR contains 4 CFG fields, each with 2 RES bits)
@ -1140,6 +1159,12 @@ module ibex_cs_registers #(
// set).
assign pmp_cfg_locked[i] = pmp_cfg[i].lock & ~pmp_mseccfg_q.rlb;
// When MSECCFG.MML is set cannot add new regions allowing M mode execution unless MSECCFG.RLB
// is set
assign pmp_cfg_wr_suppress[i] = pmp_mseccfg_q.mml &
~pmp_mseccfg.rlb &
is_mml_m_exec_cfg(pmp_cfg_wdata[i]);
// --------------------------
// Instantiate addr registers
// --------------------------