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PoC: Trap when executing from ROM in app mode

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Only allow executing from ROM when in one of the following execution
contexts:
- Firmware mode
- IRQ_SYSCALL_LO
- IRQ_SYSCALL_HI

Co-authored-by: Daniel Jobson <jobson@tillitis.se>
This commit is contained in:
Mikael Ågren 2024-12-11 11:49:41 +01:00
parent b53666e497
commit e4d19e83ce
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GPG key ID: E02DA3D397792C46
4 changed files with 48 additions and 11 deletions
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14
hw/application_fpga/core/tk1/rtl/tk1.v
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@ -45,6 +45,9 @@ module tk1 #(
output wire gpio3,
output wire gpio4,
input wire access_level_hi,
input wire access_level_med,
input wire cs,
input wire we,
input wire [ 7 : 0] address,
@ -178,6 +181,7 @@ module tk1 #(
wire spi_ready;
wire [ 7 : 0] spi_rx_data;
wire rom_exec_en;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
@ -197,6 +201,7 @@ module tk1 #(
assign system_reset = system_reset_reg;
assign rom_exec_en = !system_mode | access_level_med | access_level_hi;
//----------------------------------------------------------------
// Module instance.
@ -378,6 +383,9 @@ module tk1 #(
//
// Trying to execute instructions in FW-RAM.
//
// Executing instructions in ROM, while ROM is marked as not
// executable.
//
// Trying to execute code in mem area set to be data access only.
// This requires execution monitor to have been setup and
// enabled.
@ -395,6 +403,12 @@ module tk1 #(
force_trap_set = 1'h1;
end
if (!rom_exec_en) begin
if (cpu_addr <= FW_ROM_LAST) begin // Only valid as long as ROM starts at address 0x00.
force_trap_set = 1'h1;
end
end
if (cpu_mon_en_reg) begin
if ((cpu_addr >= cpu_mon_first_reg) && (cpu_addr <= cpu_mon_last_reg)) begin
force_trap_set = 1'h1;