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Fix bad AMO asserts. Fix hwdata instability during stalled AMO write dphase, which meant AMOs were fundamentally broken following yesterday's datapath origami

This commit is contained in:
Luke Wren 2021-12-18 14:51:46 +00:00
parent d1b5f83b7a
commit 1b0e205f87
3 changed files with 19 additions and 36 deletions
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15
hdl/hazard3_core.v
View File

@ -458,10 +458,14 @@ always @ (posedge clk) if (rst_n) begin
// Should be in resting state between AMOs // Should be in resting state between AMOs
if (!d_memop_is_amo) if (!d_memop_is_amo)
assert(x_amo_phase == 3'h0); assert(x_amo_phase == 3'h0);
// Error phase should never block, so it can always pass to stage 3 to raise // Error phase should have no stage 2 blockers, so it can pass to stage 3 to
// excepting trap entry. // raise exception entry. It's ok to block behind a younger instruction, but..
if (x_amo_phase == 3'h4) if (x_amo_phase == 3'h4)
assert(!x_stall); assert(!x_stall || m_stall);
// ..the only way to reach AMO error phase without stage 3 clearing out should
// be an unaligned AMO address, which goes straight to error phase.
if (x_amo_phase == 3'h4 && m_stall)
assert(x_unaligned_addr);
// Error phase is either due to a bus response, or a misaligned address. // Error phase is either due to a bus response, or a misaligned address.
// Neither of these are write-address-phase. // Neither of these are write-address-phase.
if (x_amo_phase == 3'h4) if (x_amo_phase == 3'h4)
@ -770,7 +774,10 @@ always @ (posedge clk or negedge rst_n) begin
if (!rst_n) begin if (!rst_n) begin
xm_result <= {W_DATA{1'b0}}; xm_result <= {W_DATA{1'b0}};
xm_addr_align <= 2'b00; xm_addr_align <= 2'b00;
end else if (!m_stall || (d_memop_is_amo && x_amo_phase == 3'h2 && bus_dph_ready_d)) begin end else if (!m_stall && !(|EXTENSION_A && x_amo_phase == 3'h3 && !bus_dph_ready_d)) begin
// AMOs need special attention (of course):
// - Steer captured read phase data in mw_result back through xm_result at end of AMO
// - Make sure xm_result (store data) doesn't transition during stalled write dphase
xm_result <= xm_result <=
d_csr_ren ? x_csr_rdata : d_csr_ren ? x_csr_rdata :
|EXTENSION_A && x_amo_phase == 3'h3 ? mw_result : |EXTENSION_A && x_amo_phase == 3'h3 ? mw_result :

20
test/formal/common/ahbl_master_assertions.v
View File

@ -1,19 +1,7 @@
/****************************************************************************** /*****************************************************************************\
* DO WHAT THE FUCK YOU WANT TO AND DON'T BLAME US PUBLIC LICENSE * | Copyright (C) 2021 Luke Wren |
* Version 3, April 2008 * | SPDX-License-Identifier: Apache-2.0 |
* * \*****************************************************************************/
* Copyright (C) 2021 Luke Wren *
* *
* Everyone is permitted to copy and distribute verbatim or modified *
* copies of this license document and accompanying software, and *
* changing either is allowed. *
* *
* TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION *
* *
* 0. You just DO WHAT THE FUCK YOU WANT TO. *
* 1. We're NOT RESPONSIBLE WHEN IT DOESN'T FUCKING WORK. *
* *
*****************************************************************************/
// Assert that an AHB-Lite master is relatively well-behaved // Assert that an AHB-Lite master is relatively well-behaved

20
test/formal/common/ahbl_slave_assumptions.v
View File

@ -1,19 +1,7 @@
/****************************************************************************** /*****************************************************************************\
* DO WHAT THE FUCK YOU WANT TO AND DON'T BLAME US PUBLIC LICENSE * | Copyright (C) 2021 Luke Wren |
* Version 3, April 2008 * | SPDX-License-Identifier: Apache-2.0 |
* * \*****************************************************************************/
* Copyright (C) 2021 Luke Wren *
* *
* Everyone is permitted to copy and distribute verbatim or modified *
* copies of this license document and accompanying software, and *
* changing either is allowed. *
* *
* TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION *
* *
* 0. You just DO WHAT THE FUCK YOU WANT TO. *
* 1. We're NOT RESPONSIBLE WHEN IT DOESN'T FUCKING WORK. *
* *
*****************************************************************************/
// Assumptions to constrain an AHB-Lite slave to be relatively well-behaved // Assumptions to constrain an AHB-Lite slave to be relatively well-behaved