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execute1: Add latch to redirect path

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This latches the redirect signal inside execute1, so that it is sent
a cycle later to fetch1 (and to decode/icache as flush).  This breaks
a long combinatorial chain from the branch and interrupt detection
in execute1 through the redirect/flush signals all the way back to
fetch1, icache and decode.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
pull/216/head
Paul Mackerras 5 years ago
parent 9b40b5a77b
commit 0f0573903b
2 changed files with 44 additions and 40 deletions
Show Stats Download Patch File Download Diff File

5
common.vhdl
Unescape Escape View File

@ -97,7 +97,6 @@ package common is
msr: std_ulogic_vector(63 downto 0);
cfar: 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;

@ -234,8 +233,8 @@ package common is
priv_mode: std_ulogic;
redirect_nia: std_ulogic_vector(63 downto 0);
end record;
constant Execute1ToFetch1TypeInit : Execute1ToFetch1Type := (redirect => '0', virt_mode => '0',
priv_mode => '0', others => (others => '0'));
constant Execute1ToFetch1Init : Execute1ToFetch1Type := (redirect => '0', virt_mode => '0',
priv_mode => '0', others => (others => '0'));

type Execute1ToLoadstore1Type is record
valid : std_ulogic;

79
execute1.vhdl
Unescape Escape View File

@ -48,6 +48,7 @@ end entity execute1;
architecture behaviour of execute1 is
type reg_type is record
e : Execute1ToWritebackType;
f : Execute1ToFetch1Type;
busy: std_ulogic;
terminate: std_ulogic;
lr_update : std_ulogic;
@ -64,7 +65,8 @@ architecture behaviour of execute1 is
log_addr_spr : std_ulogic_vector(31 downto 0);
end record;
constant reg_type_init : reg_type :=
(e => Execute1ToWritebackInit, busy => '0', lr_update => '0', terminate => '0',
(e => Execute1ToWritebackInit, f => Execute1ToFetch1Init,
busy => '0', lr_update => '0', terminate => '0',
mul_in_progress => '0', div_in_progress => '0', cntz_in_progress => '0',
slow_op_insn => OP_ILLEGAL, slow_op_rc => '0', slow_op_oe => '0', slow_op_xerc => xerc_init,
next_lr => (others => '0'), last_nia => (others => '0'), others => (others => '0'));
@ -316,6 +318,7 @@ begin
v := r;
v.e := Execute1ToWritebackInit;
lv := Execute1ToLoadstore1Init;
v.f.redirect := '0';

-- XER forwarding. To avoid having to track XER hazards, we
-- use the previously latched value.
@ -423,11 +426,11 @@ begin
irq_valid := '0';
if ctrl.msr(MSR_EE) = '1' then
if ctrl.dec(63) = '1' then
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#900#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#900#, 64));
report "IRQ valid: DEC";
irq_valid := '1';
elsif ext_irq_in = '1' then
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#500#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#500#, 64));
report "IRQ valid: External";
irq_valid := '1';
end if;
@ -436,10 +439,9 @@ begin
v.terminate := '0';
icache_inval <= '0';
v.busy := '0';
f_out <= Execute1ToFetch1TypeInit;
-- send MSR[IR] and ~MSR[PR] up to fetch1
f_out.virt_mode <= ctrl.msr(MSR_IR);
f_out.priv_mode <= not ctrl.msr(MSR_PR);
v.f.virt_mode := ctrl.msr(MSR_IR);
v.f.priv_mode := not ctrl.msr(MSR_PR);

-- Next insn adder used in a couple of places
next_nia := std_ulogic_vector(unsigned(e_in.nia) + 4);
@ -450,6 +452,7 @@ begin
rot_clear_right <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCR else '0';
rot_sign_ext <= '1' when e_in.insn_type = OP_EXTSWSLI else '0';

ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
ctrl_tmp.irq_state <= WRITE_SRR0;
exception := '0';
illegal := '0';
@ -472,10 +475,6 @@ begin
ctrl_tmp.msr(MSR_DR) <= '0';
ctrl_tmp.msr(MSR_RI) <= '0';
ctrl_tmp.msr(MSR_LE) <= '1';
f_out.redirect <= '1';
f_out.virt_mode <= '0';
f_out.priv_mode <= '1';
f_out.redirect_nia <= ctrl.irq_nia;
v.e.valid := '1';
report "Writing SRR1: " & to_hstring(ctrl.srr1);

@ -485,14 +484,12 @@ begin
-- Don't deliver the interrupt until we have a valid instruction
-- coming in, so we have a valid NIA to put in SRR0.
exception := '1';
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);

elsif valid_in = '1' and ctrl.msr(MSR_PR) = '1' and
instr_is_privileged(e_in.insn_type, e_in.insn) then
-- generate a program interrupt
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#700#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
v.f.redirect_nia := std_logic_vector(to_unsigned(16#700#, 64));
-- set bit 45 to indicate privileged instruction type interrupt
ctrl_tmp.srr1(63 - 45) <= '1';
report "privileged instruction";
@ -522,8 +519,7 @@ begin
if e_in.insn(1) = '1' then
exception := '1';
exception_nextpc := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#C00#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
v.f.redirect_nia := std_logic_vector(to_unsigned(16#C00#, 64));
report "sc";
else
illegal := '1';
@ -615,8 +611,7 @@ begin
if or (trapval and insn_to(e_in.insn)) = '1' then
-- generate trap-type program interrupt
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#700#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
v.f.redirect_nia := std_logic_vector(to_unsigned(16#700#, 64));
-- set bit 46 to say trap occurred
ctrl_tmp.srr1(63 - 46) <= '1';
report "trap";
@ -657,8 +652,8 @@ begin
abs_branch := '1';

when OP_RFID =>
f_out.virt_mode <= a_in(MSR_IR) or a_in(MSR_PR);
f_out.priv_mode <= not a_in(MSR_PR);
v.f.virt_mode := a_in(MSR_IR) or a_in(MSR_PR);
v.f.priv_mode := not a_in(MSR_PR);
-- Can't use msr_copy here because the partial function MSR
-- bits should be left unchanged, not zeroed.
ctrl_tmp.msr(63 downto 31) <= a_in(63 downto 31);
@ -856,8 +851,8 @@ begin
result_en := '1';

when OP_ISYNC =>
f_out.redirect <= '1';
f_out.redirect_nia <= next_nia;
v.f.redirect := '1';
v.f.redirect_nia := next_nia;

when OP_ICBI =>
icache_inval <= '1';
@ -885,16 +880,18 @@ begin
if is_branch = '1' then
if taken_branch = '1' then
ctrl_tmp.cfar <= e_in.nia;
end if;
if e_in.br_pred = '0' then
if abs_branch = '1' then
f_out.redirect_nia <= b_in;
v.f.redirect_nia := b_in;
else
f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(b_in));
v.f.redirect_nia := std_ulogic_vector(signed(e_in.nia) + signed(b_in));
end if;
else
f_out.redirect_nia <= next_nia;
v.f.redirect_nia := next_nia;
end if;
if taken_branch /= e_in.br_pred then
f_out.redirect <= '1';
v.f.redirect := '1';
end if;
end if;

@ -923,6 +920,8 @@ begin
lv.valid := '1';
end if;

elsif r.f.redirect = '1' then
v.e.valid := '1';
elsif r.lr_update = '1' then
v.e.exc_write_enable := '1';
v.e.exc_write_data := r.next_lr;
@ -979,8 +978,7 @@ begin

if illegal = '1' then
exception := '1';
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#700#, 64));
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
v.f.redirect_nia := std_logic_vector(to_unsigned(16#700#, 64));
-- 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';
@ -991,23 +989,19 @@ begin
if exception_nextpc = '1' then
v.e.exc_write_data := next_nia;
end if;
ctrl_tmp.irq_state <= WRITE_SRR1;
v.busy := '1';
v.e.valid := '0';
end if;

v.e.write_data := result;
v.e.write_enable := result_en;
v.e.write_enable := result_en and not exception;

-- generate DSI or DSegI for load/store exceptions
-- or ISI or ISegI for instruction fetch exceptions
if l_in.exception = '1' then
ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
if l_in.instr_fault = '0' then
if l_in.segment_fault = '0' then
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#300#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#300#, 64));
else
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#380#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#380#, 64));
end if;
else
if l_in.segment_fault = '0' then
@ -1015,16 +1009,27 @@ begin
ctrl_tmp.srr1(63 - 35) <= l_in.perm_error; -- noexec fault
ctrl_tmp.srr1(63 - 44) <= l_in.badtree;
ctrl_tmp.srr1(63 - 45) <= l_in.rc_error;
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#400#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#400#, 64));
else
ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#480#, 64));
v.f.redirect_nia := std_logic_vector(to_unsigned(16#480#, 64));
end if;
end if;
v.e.exc_write_enable := '1';
v.e.exc_write_reg := fast_spr_num(SPR_SRR0);
v.e.exc_write_data := r.last_nia;
report "ldst exception writing srr0=" & to_hstring(r.last_nia);
end if;

if exception = '1' or l_in.exception = '1' then
ctrl_tmp.irq_state <= WRITE_SRR1;
v.f.redirect := '1';
v.f.virt_mode := '0';
v.f.priv_mode := '1';
end if;

if v.f.redirect = '1' then
v.busy := '1';
v.e.valid := '0';
end if;

-- Outputs to loadstore1 (async)
@ -1055,7 +1060,7 @@ begin
rin <= v;

-- update outputs
--f_out <= r.f;
f_out <= r.f;
l_out <= lv;
e_out <= r.e;
flush_out <= f_out.redirect;

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