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Add sc, illegal and decrementer exceptions and some supervisor state

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This adds the following exceptions:
 - 0x700 program check (for illegal instructions)
 - 0x900 decrementer
 - 0xc00 system call

This also adds some supervisor state:
 - decremeter
 - msr
(SPRG0/1 and SRR0/1 already exist as fast SPRs)

It also adds some supporting instructions:
 - rfid
 - mtmsrd
 - mfmsr
 - sc

MSR state is added but only EE is used in this patch set. Other bits
are read/written but are not used at all.

This adds a 2 stage state machine to execute1.vhdl. This state machine
allows fast SPRS SRR0/1 to be written in different cycles. This state
machine can be extended later to add DAR and DSISR SPR writing for
more complex exceptions like page faults.

Signed-off-by: Michael Neuling <mikey@neuling.org>
pull/155/head
Michael Neuling 5 years ago
parent 594a19de37
commit 5ef5604b65
4 changed files with 128 additions and 14 deletions
Show Stats Download Patch File Download Diff File

8
common.vhdl
Unescape Escape View File

@ -16,6 +16,7 @@ package common is
constant SPR_LR : spr_num_t := 8;
constant SPR_CTR : spr_num_t := 9;
constant SPR_TB : spr_num_t := 268;
constant SPR_DEC : spr_num_t := 22;
constant SPR_SRR0 : spr_num_t := 26;
constant SPR_SRR1 : spr_num_t := 27;
constant SPR_HSRR0 : spr_num_t := 314;
@ -62,9 +63,16 @@ package common is
end record;
constant xerc_init : xer_common_t := (others => '0');

type irq_state_t is (WRITE_SRR0, WRITE_SRR1);

-- This needs to die...
type ctrl_t is record
tb: std_ulogic_vector(63 downto 0);
dec: std_ulogic_vector(63 downto 0);
msr: std_ulogic_vector(63 downto 0);
irq_state : irq_state_t;
irq_nia: std_ulogic_vector(63 downto 0);
srr1: std_ulogic_vector(63 downto 0);
end record;

type Fetch1ToIcacheType is record

13
decode1.vhdl
Unescape Escape View File

@ -94,6 +94,7 @@ architecture behaviour of decode1 is
2#0011000001# => '1', -- crxor
2#0010010110# => '1', -- isync
2#0000000000# => '1', -- mcrf
2#0000010010# => '1', -- rfid
others => '0'
);

@ -109,6 +110,8 @@ architecture behaviour of decode1 is
2#100# => (ALU, OP_BCREG, SPR, SPR, NONE, SPR, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '1', '0'),
-- isync
2#111# => (ALU, OP_ISYNC, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'),
-- rfid
2#101# => (ALU, OP_RFID, SPR, SPR, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'),
others => illegal_inst
);

@ -241,12 +244,14 @@ architecture behaviour of decode1 is
-- 2#1000000000# mcrxr
-- 2#1001000000# mcrxrx
2#0000010011# => (ALU, OP_MFCR, NONE, NONE, NONE, RT, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- mfcr/mfocrf
2#0001010011# => (ALU, OP_MFMSR, NONE, NONE, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- mfmsr
2#0101010011# => (ALU, OP_MFSPR, SPR, NONE, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- mfspr
2#0100001001# => (ALU, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- modud
2#0100001011# => (ALU, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', NONE, '0', '0'), -- moduw
2#1100001001# => (ALU, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '1', NONE, '0', '0'), -- modsd
2#1100001011# => (ALU, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '1', NONE, '0', '0'), -- modsw
2#0010010000# => (ALU, OP_MTCRF, NONE, NONE, RS, NONE, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- mtcrf/mtocrf
2#0010110010# => (ALU, OP_MTMSRD, NONE, NONE, RS, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- mtmsrd # ignore top bits and d
2#0111010011# => (ALU, OP_MTSPR, NONE, NONE, RS, SPR, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- mtspr
2#0001001001# => (ALU, OP_MUL_H64, RA, RB, NONE, RT, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '1', RC, '0', '0'), -- mulhd
2#0000001001# => (ALU, OP_MUL_H64, RA, RB, NONE, RT, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- mulhdu
@ -339,6 +344,7 @@ architecture behaviour of decode1 is
-- op in out A out in out len ext pipe
constant attn_instr : decode_rom_t := (ALU, OP_ATTN, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1');
constant nop_instr : decode_rom_t := (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0');
constant sc_instr : decode_rom_t := (ALU, OP_SC, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0');
constant sim_cfg_instr : decode_rom_t := (ALU, OP_SIM_CONFIG,NONE, NONE, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1');

begin
@ -397,6 +403,9 @@ begin
elsif std_match(f_in.insn, "01100000000000000000000000000000") then
report "PPC_nop";
v.decode := nop_instr;
elsif std_match(f_in.insn, "010001--------------0000000---1-") then
report "PPC_sc";
v.decode := sc_instr;
elsif std_match(f_in.insn, "000001---------------0000000011-") then
report "PPC_SIM_CONFIG";
v.decode := sim_cfg_instr;
@ -433,6 +442,10 @@ begin
if is_fast_spr(v.ispr1) = '0' then
v.decode.sgl_pipe := '1';
end if;
elsif v.decode.insn_type = OP_RFID then
report "PPC RFID";
v.ispr1 := fast_spr_num(SPR_SRR0);
v.ispr2 := fast_spr_num(SPR_SRR1);
end if;

if flush_in = '1' then

9
decode_types.vhdl
Unescape Escape View File

@ -11,16 +11,15 @@ package decode_types is
OP_DCBZ, OP_DIV, OP_DIVE, OP_EXTS,
OP_EXTSWSLI, OP_ICBI, OP_ICBT, OP_ISEL, OP_ISYNC,
OP_LOAD, OP_STORE, OP_MADDHD, OP_MADDHDU, OP_MADDLD, OP_MCRF,
OP_MCRXR, OP_MCRXRX, OP_MFCR, OP_MFSPR, OP_MOD,
OP_MTCRF, OP_MTSPR, OP_MUL_L64,
OP_MCRXR, OP_MCRXRX, OP_MFCR, OP_MFMSR, OP_MFSPR, OP_MOD,
OP_MTCRF, OP_MTMSRD, OP_MTSPR, OP_MUL_L64,
OP_MUL_H64, OP_MUL_H32, OP_OR,
OP_POPCNT, OP_PRTY,
OP_RLC, OP_RLCL, OP_RLCR, OP_SETB,
OP_POPCNT, OP_PRTY, OP_RFID,
OP_RLC, OP_RLCL, OP_RLCR, OP_SC, OP_SETB,
OP_SHL, OP_SHR,
OP_SYNC, OP_TD, OP_TDI, OP_TW,
OP_TWI, OP_XOR, OP_SIM_CONFIG
);

type input_reg_a_t is (NONE, RA, RA_OR_ZERO, SPR);
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);
type input_reg_c_t is (NONE, RS);

112
execute1.vhdl
Unescape Escape View File

@ -53,9 +53,8 @@ architecture behaviour of execute1 is

signal a_in, b_in, c_in : std_ulogic_vector(63 downto 0);

signal ctrl: ctrl_t := (others => (others => '0'));
signal ctrl_tmp: ctrl_t := (others => (others => '0'));

signal ctrl: ctrl_t := (irq_state => WRITE_SRR0, others => (others => '0'));
signal ctrl_tmp: ctrl_t := (irq_state => WRITE_SRR0, others => (others => '0'));
signal right_shift, rot_clear_left, rot_clear_right: std_ulogic;
signal rotator_result: std_ulogic_vector(63 downto 0);
signal rotator_carry: std_ulogic;
@ -112,6 +111,27 @@ architecture behaviour of execute1 is
end case;
end;

function msr_copy(msr: std_ulogic_vector(63 downto 0))
return std_ulogic_vector is
variable msr_out: std_ulogic_vector(63 downto 0);
begin
-- ISA says this:
-- Defined MSR bits are classified as either full func-
-- tion or partial function. Full function MSR bits are
-- saved in SRR1 or HSRR1 when an interrupt other
-- than a System Call Vectored interrupt occurs and
-- restored by rfscv, rfid, or hrfid, while partial func-
-- tion MSR bits are not saved or restored.
-- Full function MSR bits lie in the range 0:32, 37:41, and
-- 48:63, and partial function MSR bits lie in the range
-- 33:36 and 42:47.
msr_out := (others => '0');
msr_out(32 downto 0) := msr(32 downto 0);
msr_out(41 downto 37) := msr(41 downto 37);
msr_out(63 downto 48) := msr(63 downto 48);
return msr_out;
end;

begin

rotator_0: entity work.rotator
@ -215,6 +235,8 @@ begin
variable msb_a, msb_b : std_ulogic;
variable a_lt : std_ulogic;
variable lv : Execute1ToLoadstore1Type;
variable irq_valid : std_ulogic;
variable exception : std_ulogic;
begin
result := (others => '0');
result_with_carry := (others => '0');
@ -341,6 +363,13 @@ begin
ctrl_tmp <= ctrl;
-- FIXME: run at 512MHz not core freq
ctrl_tmp.tb <= std_ulogic_vector(unsigned(ctrl.tb) + 1);
ctrl_tmp.dec <= std_ulogic_vector(unsigned(ctrl.dec) - 1);

irq_valid := '0';
if ctrl.msr(63 - 48) = '1' and ctrl.dec(63) = '1' then
report "IRQ valid";
irq_valid := '1';
end if;

terminate_out <= '0';
icache_inval <= '0';
@ -355,7 +384,28 @@ begin
rot_clear_left <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCL else '0';
rot_clear_right <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCR else '0';

if e_in.valid = '1' then
ctrl_tmp.irq_state <= WRITE_SRR0;
exception := '0';

if ctrl.irq_state = WRITE_SRR1 then
v.e.write_reg := fast_spr_num(SPR_SRR1);
result := ctrl.srr1;
result_en := '1';
ctrl_tmp.msr(63 - 48) <= '0'; -- clear EE
f_out.redirect <= '1';
f_out.redirect_nia <= ctrl.irq_nia;
v.e.valid := '1';
report "Writing SRR1: " & to_hstring(ctrl.srr1);

elsif irq_valid = '1' then
-- we need two cycles to write srr0 and 1
-- will need more when we have to write DSISR, DAR and HIER
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#900#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
result := e_in.nia;

elsif e_in.valid = '1' then

v.e.valid := '1';
v.e.write_reg := e_in.write_reg;
@ -367,8 +417,25 @@ begin
case_0: case e_in.insn_type is

when OP_ILLEGAL =>
terminate_out <= '1';
-- we need two cycles to write srr0 and 1
-- will need more when we have to write DSISR, DAR and HIER
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#700#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
-- Since we aren't doing Hypervisor emulation assist (0xe40) we
-- set bit 44 to indicate we have an illegal
ctrl_tmp.srr1(63 - 44) <= '1';
result := e_in.nia;
report "illegal";
when OP_SC =>
-- FIXME Assume everything is SC (not SCV) for now
-- we need two cycles to write srr0 and 1
-- will need more when we have to write DSISR, DAR and HIER
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#C00#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
result := std_logic_vector(unsigned(e_in.nia) + 4);
report "sc";
when OP_ATTN =>
terminate_out <= '1';
report "ATTN";
@ -477,6 +544,11 @@ begin
f_out.redirect <= '1';
f_out.redirect_nia <= b_in(63 downto 2) & "00";
end if;

when OP_RFID =>
f_out.redirect <= '1';
f_out.redirect_nia <= a_in(63 downto 2) & "00"; -- srr0
ctrl_tmp.msr <= msr_copy(std_ulogic_vector(signed(b_in))); -- srr1
when OP_CMPB =>
result := ppc_cmpb(c_in, b_in);
result_en := '1';
@ -549,7 +621,12 @@ begin
end if;
end loop;
end if;
when OP_MFMSR =>
result := msr_copy(ctrl.msr);
result_en := '1';
when OP_MFSPR =>
report "MFSPR to SPR " & integer'image(decode_spr_num(e_in.insn)) &
"=" & to_hstring(a_in);
if is_fast_spr(e_in.read_reg1) then
result := a_in;
if decode_spr_num(e_in.insn) = SPR_XER then
@ -566,6 +643,8 @@ begin
case decode_spr_num(e_in.insn) is
when SPR_TB =>
result := ctrl.tb;
when SPR_DEC =>
result := ctrl.dec;
when others =>
result := (others => '0');
end case;
@ -599,6 +678,9 @@ begin
v.e.write_cr_mask := num_to_fxm(crnum);
end if;
v.e.write_cr_data := c_in(31 downto 0);
when OP_MTMSRD =>
-- FIXME handle just the bits we need to.
ctrl_tmp.msr <= msr_copy(c_in);
when OP_MTSPR =>
report "MTSPR to SPR " & integer'image(decode_spr_num(e_in.insn)) &
"=" & to_hstring(c_in);
@ -614,10 +696,12 @@ begin
v.e.write_xerc_enable := '1';
end if;
else
-- TODO: Implement slow SPRs
-- case decode_spr_num(e_in.insn) is
-- when others =>
-- end case;
-- slow spr
case decode_spr_num(e_in.insn) is
when SPR_DEC =>
ctrl_tmp.dec <= c_in;
when others =>
end case;
end if;
when OP_POPCNT =>
result := popcnt_result;
@ -733,6 +817,16 @@ begin
end if;
end if;

if exception = '1' then
v.e.write_reg := fast_spr_num(SPR_SRR0);
if e_in.valid = '1' then
result_en := '1';
ctrl_tmp.irq_state <= WRITE_SRR1;
stall_out <= '1';
v.e.valid := '0';
end if;
end if;

v.e.write_data := result;
v.e.write_enable := result_en;


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