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Fixed SSTC being unusable in M-MODE without Status.TM. Disable STIMECMP registers when SSTC_SUPPORTED = 0

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This commit is contained in:
David Harris 2023-02-26 06:30:43 -08:00
parent db5aa5a0fd
commit 27acb90217
2 changed files with 16 additions and 10 deletions
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4
src/mmu/pmpadrdec.sv
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@ -85,5 +85,9 @@ module pmpadrdec (
assign W = PMPCfg[1]; assign W = PMPCfg[1];
assign R = PMPCfg[0]; assign R = PMPCfg[0];
assign Active = |PMPCfg[4:3]; assign Active = |PMPCfg[4:3];
// known bug: The size of the access is not yet checked. For example, if an NA4 entry matches 0xC-0xF and the system
// attempts an 8-byte access to 0x8, the access should fail (see page 60 of privileged specification 20211203). This
// implementation will not detect the failure.
endmodule endmodule

22
src/privileged/csrs.sv
View File

@ -86,8 +86,8 @@ module csrs #(parameter
assign WriteSTVALM = STrapM | (CSRSWriteM & (CSRAdrM == STVAL)) & InstrValidNotFlushedM; assign WriteSTVALM = STrapM | (CSRSWriteM & (CSRAdrM == STVAL)) & InstrValidNotFlushedM;
assign WriteSATPM = CSRSWriteM & (CSRAdrM == SATP) & (PrivilegeModeW == `M_MODE | ~STATUS_TVM) & InstrValidNotFlushedM; assign WriteSATPM = CSRSWriteM & (CSRAdrM == SATP) & (PrivilegeModeW == `M_MODE | ~STATUS_TVM) & InstrValidNotFlushedM;
assign WriteSCOUNTERENM = CSRSWriteM & (CSRAdrM == SCOUNTEREN) & InstrValidNotFlushedM; assign WriteSCOUNTERENM = CSRSWriteM & (CSRAdrM == SCOUNTEREN) & InstrValidNotFlushedM;
assign WriteSTIMECMPM = CSRSWriteM & (CSRAdrM == STIMECMP) & MCOUNTEREN_TM & InstrValidNotFlushedM; assign WriteSTIMECMPM = CSRSWriteM & (CSRAdrM == STIMECMP) & (PrivilegeModeW == `M_MODE | MCOUNTEREN_TM) & InstrValidNotFlushedM;
assign WriteSTIMECMPHM = CSRSWriteM & (CSRAdrM == STIMECMPH) & MCOUNTEREN_TM & (`XLEN == 32) & InstrValidNotFlushedM; assign WriteSTIMECMPHM = CSRSWriteM & (CSRAdrM == STIMECMPH) & (PrivilegeModeW == `M_MODE | MCOUNTEREN_TM) & (`XLEN == 32) & InstrValidNotFlushedM;
// CSRs // CSRs
flopenr #(`XLEN) STVECreg(clk, reset, WriteSTVECM, {CSRWriteValM[`XLEN-1:2], 1'b0, CSRWriteValM[0]}, STVEC_REGW); flopenr #(`XLEN) STVECreg(clk, reset, WriteSTVECM, {CSRWriteValM[`XLEN-1:2], 1'b0, CSRWriteValM[0]}, STVEC_REGW);
@ -100,12 +100,14 @@ module csrs #(parameter
else else
assign SATP_REGW = 0; // hardwire to zero if virtual memory not supported assign SATP_REGW = 0; // hardwire to zero if virtual memory not supported
flopens #(32) SCOUNTERENreg(clk, reset, WriteSCOUNTERENM, CSRWriteValM[31:0], SCOUNTEREN_REGW); flopens #(32) SCOUNTERENreg(clk, reset, WriteSCOUNTERENM, CSRWriteValM[31:0], SCOUNTEREN_REGW);
if (`XLEN == 64) if (`SSTC_SUPPORTED) begin
flopenr #(`XLEN) STIMECMPreg(clk, reset, WriteSTIMECMPM, CSRWriteValM, STIMECMP_REGW); if (`XLEN == 64)
else begin flopenr #(`XLEN) STIMECMPreg(clk, reset, WriteSTIMECMPM, CSRWriteValM, STIMECMP_REGW);
flopenr #(`XLEN) STIMECMPreg(clk, reset, WriteSTIMECMPM, CSRWriteValM, STIMECMP_REGW[31:0]); else begin
flopenr #(`XLEN) STIMECMPHreg(clk, reset, WriteSTIMECMPHM, CSRWriteValM, STIMECMP_REGW[63:32]); flopenr #(`XLEN) STIMECMPreg(clk, reset, WriteSTIMECMPM, CSRWriteValM, STIMECMP_REGW[31:0]);
end flopenr #(`XLEN) STIMECMPHreg(clk, reset, WriteSTIMECMPHM, CSRWriteValM, STIMECMP_REGW[63:32]);
end
end else STIMECMP_REGW = 0;
// Supervisor timer interrupt logic // Supervisor timer interrupt logic
// Spec is a bit peculiar - Machine timer interrupts are produced in CLINT, while Supervisor timer interrupts are in CSRs // Spec is a bit peculiar - Machine timer interrupts are produced in CLINT, while Supervisor timer interrupts are in CSRs
@ -132,12 +134,12 @@ module csrs #(parameter
if (PrivilegeModeW == `S_MODE & STATUS_TVM) IllegalCSRSAccessM = 1; if (PrivilegeModeW == `S_MODE & STATUS_TVM) IllegalCSRSAccessM = 1;
end end
SCOUNTEREN:CSRSReadValM = {{(`XLEN-32){1'b0}}, SCOUNTEREN_REGW}; SCOUNTEREN:CSRSReadValM = {{(`XLEN-32){1'b0}}, SCOUNTEREN_REGW};
STIMECMP: if (MCOUNTEREN_TM) CSRSReadValM = STIMECMP_REGW[`XLEN-1:0]; STIMECMP: if (`SSTC_SUPPORTED & (PrivilegeModeW == `M_MODE | MCOUNTEREN_TM)) CSRSReadValM = STIMECMP_REGW[`XLEN-1:0];
else begin else begin
CSRSReadValM = 0; CSRSReadValM = 0;
IllegalCSRSAccessM = 1; IllegalCSRSAccessM = 1;
end end
STIMECMPH: if (MCOUNTEREN_TM & (`XLEN == 32)) CSRSReadValM[31:0] = STIMECMP_REGW[63:32]; STIMECMPH: if (`SSTC_SUPPORTED & (`XLEN == 32) & (PrivilegeModeW == `M_MODE | MCOUNTEREN_TM)) CSRSReadValM[31:0] = STIMECMP_REGW[63:32];
else begin // not supported for RV64 else begin // not supported for RV64
CSRSReadValM = 0; CSRSReadValM = 0;
IllegalCSRSAccessM = 1; IllegalCSRSAccessM = 1;