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(fpga) First attempt at PoC of HW trampoline for syscall.

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This commit adds a first attempt at adding a HW based syscall
       trampoline. Basicallt the FW can set a fixed address in a
       register in the API. The app can write an API adress. When
       written the HW will (should) force the CPU to read the
       instruction pointed to by the address set by the FW.

       This probably doesn't work. One problem is probably timing
       (cycles between writing the API and loading of the next
       instruction). We need to try.

Signed-off-by: Joachim Strömbergson <joachim@assured.se>
This commit is contained in:
Joachim Strömbergson 2024-08-29 13:53:46 +02:00
parent 7f93b7817b
commit e8762d80fc
No known key found for this signature in database
GPG Key ID: 865B8A548EA61679
2 changed files with 46 additions and 4 deletions
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31
hw/application_fpga/core/tk1/rtl/tk1.v
View File

@ -26,6 +26,9 @@ module tk1(
output wire force_trap,
output system_reset,
output wire [31 : 0] syscall_addr,
output wire syscall,
output wire [14 : 0] ram_addr_rand,
output wire [31 : 0] ram_data_rand,
@ -81,6 +84,9 @@ module tk1(
localparam ADDR_BLAKE2S = 8'h10;
localparam ADDR_SYSCALL_ADDR = 8'h12;
localparam ADDR_SYSCALL_START = 8'h13;
localparam ADDR_CDI_FIRST = 8'h20;
localparam ADDR_CDI_LAST = 8'h27;
@ -138,6 +144,9 @@ module tk1(
reg [31 : 0] blake2s_addr_reg;
reg blake2s_addr_we;
reg [31 : 0] syscall_addr_reg;
reg syscall_addr_we;
reg [23 : 0] cpu_trap_ctr_reg;
reg [23 : 0] cpu_trap_ctr_new;
reg [2 : 0] cpu_trap_led_reg;
@ -175,6 +184,8 @@ module tk1(
wire [31:0] udi_rdata;
reg start_syscall;
`ifdef INCLUDE_SPI_MASTER
reg spi_enable;
reg spi_enable_vld;
@ -204,6 +215,9 @@ module tk1(
assign system_reset = system_reset_reg;
assign syscall_addr = syscall_addr_reg;
assign syscall = start_syscall;
//----------------------------------------------------------------
// Module instance.
@ -268,6 +282,7 @@ module tk1(
app_start_reg <= 32'h0;
app_size_reg <= 32'h0;
blake2s_addr_reg <= 32'h0;
syscall_addr_reg <= 32'h0;
cdi_mem[0] <= 32'h0;
cdi_mem[1] <= 32'h0;
cdi_mem[2] <= 32'h0;
@ -326,6 +341,10 @@ module tk1(
blake2s_addr_reg <= write_data;
end
if (syscall_addr_we) begin
syscall_addr_reg <= write_data;
end
if (cdi_mem_we) begin
cdi_mem[address[2 : 0]] <= write_data;
end
@ -436,6 +455,8 @@ module tk1(
app_start_we = 1'h0;
app_size_we = 1'h0;
blake2s_addr_we = 1'h0;
syscall_addr_we = 1'h0;
start_syscall = 1'h0;
cdi_mem_we = 1'h0;
cdi_mem_we = 1'h0;
ram_addr_rand_we = 1'h0;
@ -495,6 +516,16 @@ module tk1(
end
end
if (address == ADDR_SYSCALL_ADDR) begin
if (!switch_app_reg) begin
syscall_addr_we = 1'h1;
end
end
if (address == ADDR_SYSCALL_START) begin
start_syscall = 1'h1;
end
if ((address >= ADDR_CDI_FIRST) && (address <= ADDR_CDI_LAST)) begin
if (!switch_app_reg) begin
cdi_mem_we = 1'h1;

11
hw/application_fpga/rtl/application_fpga.v
View File

@ -149,6 +149,8 @@ module application_fpga(
wire [14 : 0] ram_addr_rand;
wire [31 : 0] ram_data_rand;
wire tk1_system_reset;
wire [31 : 0] tk1_syscall_addr;
wire tk1_syscall;
/* verilator lint_on UNOPTFLAT */
@ -328,6 +330,9 @@ module application_fpga(
.system_reset(tk1_system_reset),
.syscall_addr(tk1_syscall_addr),
.syscall(tk1_syscall),
.ram_addr_rand(ram_addr_rand),
.ram_data_rand(ram_data_rand),
@ -443,11 +448,17 @@ module application_fpga(
end
RAM_PREFIX: begin
if (tk1_syscall) begin
muxed_rdata_new = tk1_syscall_addr;
muxed_ready_new = 1'h1;
end
else begin
ram_cs = 1'h1;
ram_we = cpu_wstrb;
muxed_rdata_new = ram_read_data ^ ram_data_rand ^ {2{cpu_addr[15 : 0]}};
muxed_ready_new = ram_ready;
end
end
RESERVED_PREFIX: begin
muxed_rdata_new = 32'h0;