[test_rom] Unlock ePMP before accessing outside the initial ePMP RX region
Signed-off-by: Alphan Ulusoy <alphan@google.com>
diff --git a/sw/device/lib/testing/test_rom/test_rom_start.S b/sw/device/lib/testing/test_rom/test_rom_start.S
index 11e56c1..26e1da1 100644
--- a/sw/device/lib/testing/test_rom/test_rom_start.S
+++ b/sw/device/lib/testing/test_rom/test_rom_start.S
@@ -196,6 +196,19 @@
(MULTIBIT_ASM_BOOL4_FALSE << EDN_CTRL_CMD_FIFO_RST_OFFSET)
sw t0, EDN_CTRL_REG_OFFSET(a0)
#endif
+ // Remove address space protections by configuring entry 15 as
+ // read-write-execute for the entire address space and then clearing
+ // all other entries.
+ // NOTE: This should happen before attemting to access any address outside
+ // the initial ePMP RX region at reset, e.g. `kDeviceType` which is in
+ // .rodata.
+ li t0, (0x9f << 24) // Locked NAPOT read-write-execute.
+ csrw pmpcfg3, t0
+ li t0, 0x7fffffff // NAPOT encoded region covering entire 34-bit address space.
+ csrw pmpaddr15, t0
+ csrw pmpcfg0, zero
+ csrw pmpcfg1, zero
+ csrw pmpcfg2, zero
// Scramble and initialize main memory (main SRAM).
// Memory accesses will stall until initialization is complete.
@@ -208,17 +221,6 @@
sw t0, SRAM_CTRL_CTRL_REG_OFFSET(a0)
.L_sram_init_skip:
- // Remove address space protections by configuring entry 15 as
- // read-write-execute for the entire address space and then clearing
- // all other entries.
- li t0, (0x9f << 24) // Locked NAPOT read-write-execute.
- csrw pmpcfg3, t0
- li t0, -1 // NAPOT encoded region covering entire 32-bit address space.
- csrw pmpaddr15, t0
- csrw pmpcfg0, zero
- csrw pmpcfg1, zero
- csrw pmpcfg2, zero
-
// Zero out the `.bss` segment.
la a0, _bss_start
la a1, _bss_end
