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microwatt/common.vhdl

387 lines
13 KiB
VHDL

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work;
use work.decode_types.all;
package common is
-- MSR bit numbers
constant MSR_SF : integer := (63 - 0); -- Sixty-Four bit mode
constant MSR_EE : integer := (63 - 48); -- External interrupt Enable
constant MSR_PR : integer := (63 - 49); -- PRoblem state
constant MSR_IR : integer := (63 - 58); -- Instruction Relocation
constant MSR_DR : integer := (63 - 59); -- Data Relocation
constant MSR_RI : integer := (63 - 62); -- Recoverable Interrupt
constant MSR_LE : integer := (63 - 63); -- Little Endian
-- SPR numbers
subtype spr_num_t is integer range 0 to 1023;
function decode_spr_num(insn: std_ulogic_vector(31 downto 0)) return spr_num_t;
constant SPR_XER : spr_num_t := 1;
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;
constant SPR_HSRR1 : spr_num_t := 315;
constant SPR_SPRG0 : spr_num_t := 272;
constant SPR_SPRG1 : spr_num_t := 273;
constant SPR_SPRG2 : spr_num_t := 274;
constant SPR_SPRG3 : spr_num_t := 275;
constant SPR_SPRG3U : spr_num_t := 259;
constant SPR_HSPRG0 : spr_num_t := 304;
constant SPR_HSPRG1 : spr_num_t := 305;
-- GPR indices in the register file (GPR only)
subtype gpr_index_t is std_ulogic_vector(4 downto 0);
-- Extended GPR indice (can hold an SPR)
subtype gspr_index_t is std_ulogic_vector(5 downto 0);
-- Some SPRs are stored in the register file, they use the magic
-- GPR numbers above 31.
--
-- The function fast_spr_num() returns the corresponding fast
-- pseudo-GPR number for a given SPR number. The result MSB
-- indicates if this is indeed a fast SPR. If clear, then
-- the SPR is not stored in the GPR file.
--
function fast_spr_num(spr: spr_num_t) return gspr_index_t;
-- Indices conversion functions
function gspr_to_gpr(i: gspr_index_t) return gpr_index_t;
function gpr_to_gspr(i: gpr_index_t) return gspr_index_t;
function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t;
function is_fast_spr(s: gspr_index_t) return std_ulogic;
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
-- The XER is split: the common bits (CA, OV, SO, OV32 and CA32) are
-- in the CR file as a kind of CR extension (with a separate write
-- control). The rest is stored as a fast SPR.
type xer_common_t is record
ca : std_ulogic;
ca32 : std_ulogic;
ov : std_ulogic;
ov32 : std_ulogic;
so : std_ulogic;
end record;
constant xerc_init : xer_common_t := (others => '0');
type irq_state_t is (WRITE_SRR0, WRITE_SRR1);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
-- 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
req: std_ulogic;
stop_mark: std_ulogic;
nia: std_ulogic_vector(63 downto 0);
end record;
type IcacheToFetch2Type is record
valid: std_ulogic;
stop_mark: std_ulogic;
nia: std_ulogic_vector(63 downto 0);
insn: std_ulogic_vector(31 downto 0);
end record;
type Fetch2ToDecode1Type is record
valid: std_ulogic;
stop_mark : std_ulogic;
nia: std_ulogic_vector(63 downto 0);
insn: std_ulogic_vector(31 downto 0);
end record;
constant Fetch2ToDecode1Init : Fetch2ToDecode1Type := (valid => '0', stop_mark => '0', others => (others => '0'));
type Decode1ToDecode2Type is record
valid: std_ulogic;
stop_mark : std_ulogic;
nia: std_ulogic_vector(63 downto 0);
insn: std_ulogic_vector(31 downto 0);
ispr1: gspr_index_t; -- (G)SPR used for branch condition (CTR) or mfspr
ispr2: gspr_index_t; -- (G)SPR used for branch target (CTR, LR, TAR)
decode: decode_rom_t;
end record;
constant Decode1ToDecode2Init : Decode1ToDecode2Type := (valid => '0', stop_mark => '0', decode => decode_rom_init, others => (others => '0'));
type Decode2ToExecute1Type is record
valid: std_ulogic;
unit : unit_t;
insn_type: insn_type_t;
nia: std_ulogic_vector(63 downto 0);
write_reg: gspr_index_t;
read_reg1: gspr_index_t;
read_reg2: gspr_index_t;
read_data1: std_ulogic_vector(63 downto 0);
read_data2: std_ulogic_vector(63 downto 0);
read_data3: std_ulogic_vector(63 downto 0);
bypass_data1: std_ulogic;
bypass_data2: std_ulogic;
bypass_data3: std_ulogic;
cr: std_ulogic_vector(31 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
xerc: xer_common_t;
lr: std_ulogic;
rc: std_ulogic;
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
oe: std_ulogic;
invert_a: std_ulogic;
invert_out: std_ulogic;
input_carry: carry_in_t;
output_carry: std_ulogic;
input_cr: std_ulogic;
output_cr: std_ulogic;
is_32bit: std_ulogic;
is_signed: std_ulogic;
insn: std_ulogic_vector(31 downto 0);
data_len: std_ulogic_vector(3 downto 0);
byte_reverse : std_ulogic;
sign_extend : std_ulogic; -- do we need to sign extend?
update : std_ulogic; -- is this an update instruction?
reserve : std_ulogic; -- set for larx/stcx
end record;
constant Decode2ToExecute1Init : Decode2ToExecute1Type :=
(valid => '0', unit => NONE, insn_type => OP_ILLEGAL, bypass_data1 => '0', bypass_data2 => '0', bypass_data3 => '0',
lr => '0', rc => '0', oe => '0', invert_a => '0',
invert_out => '0', input_carry => ZERO, output_carry => '0', input_cr => '0', output_cr => '0',
is_32bit => '0', is_signed => '0', xerc => xerc_init, reserve => '0',
byte_reverse => '0', sign_extend => '0', update => '0', others => (others => '0'));
type Execute1ToMultiplyType is record
valid: std_ulogic;
insn_type: insn_type_t;
data1: std_ulogic_vector(64 downto 0);
data2: std_ulogic_vector(64 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
is_32bit: std_ulogic;
end record;
constant Execute1ToMultiplyInit : Execute1ToMultiplyType := (valid => '0', insn_type => OP_ILLEGAL,
is_32bit => '0',
others => (others => '0'));
type Execute1ToDividerType is record
valid: std_ulogic;
dividend: std_ulogic_vector(63 downto 0);
divisor: std_ulogic_vector(63 downto 0);
is_signed: std_ulogic;
is_32bit: std_ulogic;
is_extended: std_ulogic;
is_modulus: std_ulogic;
neg_result: std_ulogic;
end record;
constant Execute1ToDividerInit: Execute1ToDividerType := (valid => '0', is_signed => '0', is_32bit => '0',
is_extended => '0', is_modulus => '0',
neg_result => '0', others => (others => '0'));
type Decode2ToRegisterFileType is record
read1_enable : std_ulogic;
read1_reg : gspr_index_t;
read2_enable : std_ulogic;
read2_reg : gspr_index_t;
read3_enable : std_ulogic;
read3_reg : gpr_index_t;
end record;
type RegisterFileToDecode2Type is record
read1_data : std_ulogic_vector(63 downto 0);
read2_data : std_ulogic_vector(63 downto 0);
read3_data : std_ulogic_vector(63 downto 0);
end record;
type Decode2ToCrFileType is record
read : std_ulogic;
end record;
type CrFileToDecode2Type is record
read_cr_data : std_ulogic_vector(31 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
read_xerc_data : xer_common_t;
end record;
type Execute1ToFetch1Type is record
redirect: std_ulogic;
redirect_nia: std_ulogic_vector(63 downto 0);
end record;
constant Execute1ToFetch1TypeInit : Execute1ToFetch1Type := (redirect => '0', others => (others => '0'));
type Execute1ToLoadstore1Type is record
valid : std_ulogic;
op : insn_type_t; -- what ld/st op to do
addr1 : std_ulogic_vector(63 downto 0);
addr2 : std_ulogic_vector(63 downto 0);
data : std_ulogic_vector(63 downto 0); -- data to write, unused for read
write_reg : gpr_index_t;
length : std_ulogic_vector(3 downto 0);
ci : std_ulogic; -- cache-inhibited load/store
byte_reverse : std_ulogic;
sign_extend : std_ulogic; -- do we need to sign extend?
update : std_ulogic; -- is this an update instruction?
update_reg : gpr_index_t; -- if so, the register to update
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
xerc : xer_common_t;
reserve : std_ulogic; -- set for larx/stcx.
rc : std_ulogic; -- set for stcx.
end record;
constant Execute1ToLoadstore1Init : Execute1ToLoadstore1Type := (valid => '0', op => OP_ILLEGAL, ci => '0', byte_reverse => '0',
sign_extend => '0', update => '0', xerc => xerc_init,
reserve => '0', rc => '0', others => (others => '0'));
type Loadstore1ToDcacheType is record
valid : std_ulogic;
load : std_ulogic;
dcbz : std_ulogic;
nc : std_ulogic;
reserve : std_ulogic;
addr : std_ulogic_vector(63 downto 0);
data : std_ulogic_vector(63 downto 0);
byte_sel : std_ulogic_vector(7 downto 0);
end record;
type DcacheToLoadstore1Type is record
valid : std_ulogic;
data : std_ulogic_vector(63 downto 0);
store_done : std_ulogic;
error : std_ulogic;
end record;
type Loadstore1ToWritebackType is record
valid : std_ulogic;
write_enable: std_ulogic;
write_reg : gpr_index_t;
write_data : std_ulogic_vector(63 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
xerc : xer_common_t;
rc : std_ulogic;
store_done : std_ulogic;
end record;
constant Loadstore1ToWritebackInit : Loadstore1ToWritebackType := (valid => '0', write_enable => '0', xerc => xerc_init,
rc => '0', store_done => '0', others => (others => '0'));
type Execute1ToWritebackType is record
valid: std_ulogic;
rc : std_ulogic;
write_enable : std_ulogic;
write_reg: gspr_index_t;
write_data: std_ulogic_vector(63 downto 0);
write_cr_enable : std_ulogic;
write_cr_mask : std_ulogic_vector(7 downto 0);
write_cr_data : std_ulogic_vector(31 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
write_xerc_enable : std_ulogic;
xerc : xer_common_t;
exc_write_enable : std_ulogic;
exc_write_reg : gspr_index_t;
exc_write_data : std_ulogic_vector(63 downto 0);
end record;
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
constant Execute1ToWritebackInit : Execute1ToWritebackType := (valid => '0', rc => '0', write_enable => '0',
write_cr_enable => '0', exc_write_enable => '0',
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
write_xerc_enable => '0', xerc => xerc_init,
others => (others => '0'));
type MultiplyToExecute1Type is record
valid: std_ulogic;
write_reg_data: std_ulogic_vector(63 downto 0);
overflow : std_ulogic;
end record;
constant MultiplyToExecute1Init : MultiplyToExecute1Type := (valid => '0', overflow => '0',
others => (others => '0'));
type DividerToExecute1Type is record
valid: std_ulogic;
write_reg_data: std_ulogic_vector(63 downto 0);
overflow : std_ulogic;
end record;
constant DividerToExecute1Init : DividerToExecute1Type := (valid => '0', overflow => '0',
others => (others => '0'));
type WritebackToRegisterFileType is record
write_reg : gspr_index_t;
write_data : std_ulogic_vector(63 downto 0);
write_enable : std_ulogic;
end record;
constant WritebackToRegisterFileInit : WritebackToRegisterFileType := (write_enable => '0', others => (others => '0'));
type WritebackToCrFileType is record
write_cr_enable : std_ulogic;
write_cr_mask : std_ulogic_vector(7 downto 0);
write_cr_data : std_ulogic_vector(31 downto 0);
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
write_xerc_enable : std_ulogic;
write_xerc_data : xer_common_t;
end record;
Add basic XER support The carry is currently internal to execute1. We don't handle any of the other XER fields. This creates type called "xer_common_t" that contains the commonly used XER bits (CA, CA32, SO, OV, OV32). The value is stored in the CR file (though it could be a separate module). The rest of the bits will be implemented as a separate SPR and the two parts reconciled in mfspr/mtspr in latter commits. We always read XER in decode2 (there is little point not to) and send it down all pipeline branches as it will be needed in writeback for all type of instructions when CR0:SO needs to be updated (such forms exist for all pipeline branches even if we don't yet implement them). To avoid having to track XER hazards, we forward it back in EX1. This assumes that other pipeline branches that can modify it (mult and div) are running single issue for now. One additional hazard to beware of is an XER:SO modifying instruction in EX1 followed immediately by a store conditional. Due to our writeback latency, the store will go down the LSU with the previous XER value, thus the stcx. will set CR0:SO using an obsolete SO value. I doubt there exist any code relying on this behaviour being correct but we should account for it regardless, possibly by ensuring that stcx. remain single issue initially, or later by adding some minimal tracking or moving the LSU into the same pipeline as execute. Missing some obscure XER affecting instructions like addex or mcrxrx. [paulus@ozlabs.org - fix CA32 and OV32 for OP_ADD, fix order of arguments to set_ov] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
constant WritebackToCrFileInit : WritebackToCrFileType := (write_cr_enable => '0', write_xerc_enable => '0',
write_xerc_data => xerc_init,
others => (others => '0'));
end common;
package body common is
function decode_spr_num(insn: std_ulogic_vector(31 downto 0)) return spr_num_t is
begin
return to_integer(unsigned(insn(15 downto 11) & insn(20 downto 16)));
end;
function fast_spr_num(spr: spr_num_t) return gspr_index_t is
variable n : integer range 0 to 31;
begin
case spr is
when SPR_LR =>
n := 0;
when SPR_CTR =>
n:= 1;
when SPR_SRR0 =>
n := 2;
when SPR_SRR1 =>
n := 3;
when SPR_HSRR0 =>
n := 4;
when SPR_HSRR1 =>
n := 5;
when SPR_SPRG0 =>
n := 6;
when SPR_SPRG1 =>
n := 7;
when SPR_SPRG2 =>
n := 8;
when SPR_SPRG3 | SPR_SPRG3U =>
n := 9;
when SPR_HSPRG0 =>
n := 10;
when SPR_HSPRG1 =>
n := 11;
when SPR_XER =>
n := 12;
when others =>
n := 0;
return "000000";
end case;
return "1" & std_ulogic_vector(to_unsigned(n, 5));
end;
function gspr_to_gpr(i: gspr_index_t) return gpr_index_t is
begin
return i(4 downto 0);
end;
function gpr_to_gspr(i: gpr_index_t) return gspr_index_t is
begin
return "0" & i;
end;
function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t is
begin
if s(5) = '1' then
return s;
else
return gpr_to_gspr(g);
end if;
end;
function is_fast_spr(s: gspr_index_t) return std_ulogic is
begin
return s(5);
end;
end common;