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qualifying and using skencode error as assertion
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msg interface fsm doesn't unconditionally move on held last msg
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@Nitsirks
Nitsirks committed Jan 3, 2025
1 parent a734774 commit 802d230
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Showing 3 changed files with 26 additions and 38 deletions.
44 changes: 20 additions & 24 deletions src/mldsa_top/rtl/mldsa_ctrl.sv
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Original file line number Diff line number Diff line change
Expand Up @@ -873,26 +873,22 @@ always_comb mldsa_privkey_lock = '0;
if (!rst_b) begin
msg_data <= '0;
end else begin
if (msg_hold) begin
msg_data <= msg_data;
end else begin
unique case (sampler_src) inside
MLDSA_SEED_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : {seed_reg[{sampler_src_offset[1:0],1'b1}],seed_reg[{sampler_src_offset[1:0],1'b0}]};
MLDSA_RHO_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : rho_reg[sampler_src_offset[1:0]];
MLDSA_RHO_P_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : rho_p_reg[sampler_src_offset[2:0]];
MLDSA_TR_ID: msg_data <= privatekey_reg.enc.tr[sampler_src_offset[2:0]];
MLDSA_MSG_ID: msg_data <= {msg_p_reg[{sampler_src_offset[3:0],1'b1}],msg_p_reg[{sampler_src_offset[3:0],1'b0}]};
MLDSA_K_ID: msg_data <= privatekey_reg.enc.K[sampler_src_offset[1:0]];
MLDSA_MU_ID: msg_data <= mu_reg[sampler_src_offset[2:0]];
MLDSA_SIGN_RND_ID: msg_data <= {sign_rnd_reg[{sampler_src_offset[1:0],1'b1}],sign_rnd_reg[{sampler_src_offset[1:0],1'b0}]};
MLDSA_RHO_P_KAPPA_ID: msg_data <= msg_done ? {48'b0,(kappa_reg + sampler_imm[2:0])} : rho_p_reg[sampler_src_offset[2:0]];
MLDSA_SIG_C_REG_ID: msg_data <= {signature_reg.enc.c[{sampler_src_offset[2:0],1'b1}], signature_reg.enc.c[{sampler_src_offset[2:0],1'b0}]};
MLDSA_PK_REG_ID: msg_data <= {publickey_reg.enc.rho[{sampler_src_offset[1:0],1'b1}],publickey_reg.enc.rho[{sampler_src_offset[1:0],1'b0}]};
MLDSA_ENTROPY_ID: msg_data <= lfsr_entropy_reg[sampler_src_offset[2:0]];
MLDSA_CNT_ID: msg_data <= counter_reg;
default: msg_data <= '0;
endcase
end
unique case (sampler_src) inside
MLDSA_SEED_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : {seed_reg[{sampler_src_offset[1:0],1'b1}],seed_reg[{sampler_src_offset[1:0],1'b0}]};
MLDSA_RHO_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : rho_reg[sampler_src_offset[1:0]];
MLDSA_RHO_P_ID: msg_data <= msg_done ? {48'b0,sampler_imm} : rho_p_reg[sampler_src_offset[2:0]];
MLDSA_TR_ID: msg_data <= privatekey_reg.enc.tr[sampler_src_offset[2:0]];
MLDSA_MSG_ID: msg_data <= {msg_p_reg[{sampler_src_offset[3:0],1'b1}],msg_p_reg[{sampler_src_offset[3:0],1'b0}]};
MLDSA_K_ID: msg_data <= privatekey_reg.enc.K[sampler_src_offset[1:0]];
MLDSA_MU_ID: msg_data <= mu_reg[sampler_src_offset[2:0]];
MLDSA_SIGN_RND_ID: msg_data <= {sign_rnd_reg[{sampler_src_offset[1:0],1'b1}],sign_rnd_reg[{sampler_src_offset[1:0],1'b0}]};
MLDSA_RHO_P_KAPPA_ID: msg_data <= msg_done ? {48'b0,(kappa_reg + sampler_imm[2:0])} : rho_p_reg[sampler_src_offset[2:0]];
MLDSA_SIG_C_REG_ID: msg_data <= {signature_reg.enc.c[{sampler_src_offset[2:0],1'b1}], signature_reg.enc.c[{sampler_src_offset[2:0],1'b0}]};
MLDSA_PK_REG_ID: msg_data <= {publickey_reg.enc.rho[{sampler_src_offset[1:0],1'b1}],publickey_reg.enc.rho[{sampler_src_offset[1:0],1'b0}]};
MLDSA_ENTROPY_ID: msg_data <= lfsr_entropy_reg[sampler_src_offset[2:0]];
MLDSA_CNT_ID: msg_data <= counter_reg;
default: msg_data <= '0;
endcase
end
end

Expand Down Expand Up @@ -1233,7 +1229,7 @@ always_comb msg_hold = msg_valid_o & ~msg_rdy_i;

//Done when msg count is equal to length
//length is in bytes - compare against MSB from strobe width gets us the length in msg interface chunks
always_comb msg_done = ~msg_hold & (msg_cnt >= prim_instr.length[MLDSA_OPR_WIDTH-1:$clog2(MsgStrbW)]);
always_comb msg_done = (msg_cnt >= prim_instr.length[MLDSA_OPR_WIDTH-1:$clog2(MsgStrbW)]);

always_ff @(posedge clk or negedge rst_b) begin
if (!rst_b) begin
Expand All @@ -1247,8 +1243,8 @@ always_ff @(posedge clk or negedge rst_b) begin
msg_strobe_o <= 0;
end
else begin
msg_cnt <= msg_done ? 'd0 :
msg_hold ? msg_cnt :
msg_cnt <= msg_hold ? msg_cnt :
msg_done ? 'd0 :
msg_valid ? msg_cnt + 'd1 : msg_cnt;
msg_valid_o <= msg_hold ? msg_valid_o : msg_valid;
msg_strobe_o <= msg_hold ? msg_strobe_o :
Expand Down Expand Up @@ -1299,7 +1295,7 @@ always_comb begin : primary_ctrl_fsm_out_combo
msg_valid = 1;
sampler_src = prim_instr.operand1;
sampler_imm = prim_instr.imm;
if (msg_done) begin
if (msg_done & ~msg_hold) begin
if (prim_instr.opcode.sampler_en) ctrl_fsm_ns = MLDSA_CTRL_FUNC_START;
else ctrl_fsm_ns = MLDSA_CTRL_MSG_WAIT;
end
Expand Down
1 change: 0 additions & 1 deletion src/mldsa_top/rtl/mldsa_top.sv
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Original file line number Diff line number Diff line change
Expand Up @@ -630,7 +630,6 @@ skencode_inst

.skencode_enable(skencode_enable),
.skencode_done(skencode_done),
.skencode_error(),

.keymem_a_wr_req(skencode_keymem_if),
.keymem_a_wr_data(skencode_wr_data),
Expand Down
19 changes: 6 additions & 13 deletions src/sk_encode/rtl/skencode.sv
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,6 @@ module skencode
output mem_if_t mem_b_rd_req,
output logic [AHB_DATA_WIDTH-1:0] keymem_a_wr_data,

output logic skencode_error,
output logic skencode_done
);

Expand All @@ -80,7 +79,7 @@ module skencode


logic [2:0] main_state, next_main_state, write_state, next_write_state;
logic error_flag, asserted_error_flag;
logic error_flag;
logic [7:0][2:0] encoded_coeffs;
logic [7:0] encoding_error;
logic [23:0] one_encoding_string;
Expand All @@ -92,10 +91,6 @@ module skencode

assign one_encoding_string = {encoded_coeffs[7],encoded_coeffs[6],encoded_coeffs[5],encoded_coeffs[4],
encoded_coeffs[3],encoded_coeffs[2],encoded_coeffs[1],encoded_coeffs[0]};

//FIXME enable this later?
assign error_flag = 0;//encoding_error[0] | encoding_error[1] | encoding_error[2] | encoding_error[3] |
//encoding_error[4] | encoding_error[5] | encoding_error[6] | encoding_error[7];


// State Machine: Updates main_state and write_state based on current conditions and next states.
Expand All @@ -109,7 +104,7 @@ module skencode
write_state <= IDLE;
end
else begin
if (skencode_error) begin
if (error_flag) begin
main_state <= IDLE;
write_state <= IDLE;
end
Expand Down Expand Up @@ -241,7 +236,7 @@ module skencode
// Locks destination and source addresses when skencode_enable is active.
// Manages write_buffer and producer_selector based on the main state machine.
// Issues read requests to memory and increments num_mem_operands during appropriate states.
// Signals completion (skencode_done) and checks for errors (skencode_error) based on operation progress.
// Signals completion (skencode_done) based on operation progress.
always_ff @(posedge clk or negedge reset_n) begin
if (!reset_n) begin
write_buffer <= 'h0;
Expand All @@ -250,7 +245,6 @@ module skencode
locked_dest_addr <= 'h0;
locked_src_addr <= 'h0;
skencode_done <= 'h0;
skencode_error <= 'h0;
mem_a_rd_req <= '{rd_wr_en: RW_IDLE, addr: '0};
mem_b_rd_req <= '{rd_wr_en: RW_IDLE, addr: '0};
end
Expand All @@ -261,7 +255,6 @@ module skencode
locked_dest_addr <= 'h0;
locked_src_addr <= 'h0;
skencode_done <= 'h0;
skencode_error <= 'h0;
mem_a_rd_req <= '{rd_wr_en: RW_IDLE, addr: '0};
mem_b_rd_req <= '{rd_wr_en: RW_IDLE, addr: '0};
end
Expand Down Expand Up @@ -300,9 +293,6 @@ module skencode
else begin
skencode_done <= 'h0;
end

if (skencode_error == 1'b0 && main_state != IDLE)
skencode_error <= error_flag;
end
end

Expand Down Expand Up @@ -396,5 +386,8 @@ module skencode
end
end : encoding

assign error_flag = (|encoding_error) & main_state inside {READ_ENC_and_CONSUME, ENC_and_CONSUME, CONSUME, CONSUME_LAST};

`ABR_ASSERT_NEVER(SKENCODE_ERROR_FLAG, error_flag, clk, !reset_n)

endmodule

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