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https://github.com/antonblanchard/microwatt.git
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3d4712ad43
This adds a direct-mapped TLB to the icache, with 64 entries by default. Execute1 now sends a "virt_mode" signal from MSR[IR] to fetch1 along with redirects to indicate whether instruction addresses should be translated through the TLB, and fetch1 sends that on to icache. Similarly a "priv_mode" signal is sent to indicate the privilege mode for instruction fetches. This means that changes to MSR[IR] or MSR[PR] don't take effect until the next redirect, meaning an isync, rfid, branch, etc. The icache uses a hash of the effective address (i.e. next instruction address) to index the TLB. The hash is an XOR of three fields of the address; with a 64-entry TLB, the fields are bits 12--17, 18--23 and 24--29 of the address. TLB invalidations simply invalidate the indexed TLB entry without checking the contents. If the icache detects a TLB miss with virt_mode=1, it will send a fetch_failed indication through fetch2 to decode1, which will turn it into a special OP_FETCH_FAILED opcode with unit=LDST. That will get sent down to loadstore1 which will currently just raise a Instruction Storage Interrupt (0x400) exception. One bit in the PTE obtained from the TLB is used to check whether an instruction access is allowed -- the privilege bit (bit 3). If bit 3 is 1 and priv_mode=0, then a fetch_failed indication is sent down to fetch2 and to decode1, which generates an OP_FETCH_FAILED. Any PTEs with PTE bit 0 (EAA[3]) clear or bit 8 (R) clear should not be put into the iTLB since such PTEs would not allow execution by any context. Tlbie operations get sent from mmu to icache over a new connection. Unfortunately the privileged instruction tests are broken for now. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
96 lines
3.0 KiB
VHDL
96 lines
3.0 KiB
VHDL
library ieee;
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use ieee.std_logic_1164.all;
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package decode_types is
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type insn_type_t is (OP_ILLEGAL, OP_NOP, OP_ADD,
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OP_ADDPCIS, OP_AND, OP_ATTN, OP_B, OP_BC, OP_BCREG,
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OP_BPERM, OP_CMP, OP_CMPB, OP_CMPEQB, OP_CMPRB,
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OP_CNTZ, OP_CROP,
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OP_DARN, OP_DCBF, OP_DCBST, OP_DCBT, OP_DCBTST,
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OP_DCBZ, OP_DIV, OP_DIVE, OP_EXTS,
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OP_EXTSWSLI, OP_ICBI, OP_ICBT, OP_ISEL, OP_ISYNC,
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OP_LOAD, OP_STORE, OP_MADDHD, OP_MADDHDU, OP_MADDLD,
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OP_MCRXR, OP_MCRXRX, OP_MFCR, OP_MFMSR, OP_MFSPR, OP_MOD,
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OP_MTCRF, OP_MTMSRD, OP_MTSPR, OP_MUL_L64,
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OP_MUL_H64, OP_MUL_H32, OP_OR,
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OP_POPCNT, OP_PRTY, OP_RFID,
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OP_RLC, OP_RLCL, OP_RLCR, OP_SC, OP_SETB,
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OP_SHL, OP_SHR,
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OP_SYNC, OP_TLBIE, OP_TRAP,
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OP_XOR,
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OP_FETCH_FAILED
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);
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type input_reg_a_t is (NONE, RA, RA_OR_ZERO, SPR);
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type input_reg_b_t is (NONE, RB, CONST_UI, CONST_SI, CONST_SI_HI, CONST_UI_HI, CONST_LI, CONST_BD, CONST_DS, CONST_M1, CONST_SH, CONST_SH32, SPR);
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type input_reg_c_t is (NONE, RS);
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type output_reg_a_t is (NONE, RT, RA, SPR);
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type rc_t is (NONE, ONE, RC);
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type carry_in_t is (ZERO, CA, ONE);
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constant SH_OFFSET : integer := 0;
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constant MB_OFFSET : integer := 1;
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constant ME_OFFSET : integer := 1;
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constant SH32_OFFSET : integer := 0;
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constant MB32_OFFSET : integer := 1;
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constant ME32_OFFSET : integer := 2;
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constant FXM_OFFSET : integer := 0;
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constant BO_OFFSET : integer := 0;
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constant BI_OFFSET : integer := 1;
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constant BH_OFFSET : integer := 2;
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constant BF_OFFSET : integer := 0;
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constant L_OFFSET : integer := 1;
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constant TOO_OFFSET : integer := 0;
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type unit_t is (NONE, ALU, LDST);
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type length_t is (NONE, is1B, is2B, is4B, is8B);
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type decode_rom_t is record
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unit : unit_t;
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insn_type : insn_type_t;
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input_reg_a : input_reg_a_t;
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input_reg_b : input_reg_b_t;
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input_reg_c : input_reg_c_t;
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output_reg_a : output_reg_a_t;
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input_cr : std_ulogic;
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output_cr : std_ulogic;
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invert_a : std_ulogic;
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invert_out : std_ulogic;
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input_carry : carry_in_t;
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output_carry : std_ulogic;
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-- load/store signals
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length : length_t;
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byte_reverse : std_ulogic;
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sign_extend : std_ulogic;
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update : std_ulogic;
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reserve : std_ulogic;
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-- multiplier and ALU signals
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is_32bit : std_ulogic;
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is_signed : std_ulogic;
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rc : rc_t;
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lr : std_ulogic;
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sgl_pipe : std_ulogic;
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end record;
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constant decode_rom_init : decode_rom_t := (unit => NONE,
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insn_type => OP_ILLEGAL, input_reg_a => NONE,
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input_reg_b => NONE, input_reg_c => NONE,
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output_reg_a => NONE, input_cr => '0', output_cr => '0',
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invert_a => '0', invert_out => '0', input_carry => ZERO, output_carry => '0',
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length => NONE, byte_reverse => '0', sign_extend => '0',
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update => '0', reserve => '0', is_32bit => '0',
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is_signed => '0', rc => NONE, lr => '0', sgl_pipe => '0');
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end decode_types;
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package body decode_types is
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end decode_types;
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