From 5dc9acdf3db383c9385bee695d75134d2a252c68 Mon Sep 17 00:00:00 2001
From: Toby Jaffey <toby@ringtailsoftware.co.uk>
Date: Sun, 14 Dec 2025 11:00:45 +0000
Subject: [PATCH] When a trap occurs in mini-rv32ima, always pass to the host
 rather than allowing running code to handle it. This would be important for a
 real OS, but the aim of uvm32 is embeddable logic - not full emulation.

As all traps are caught by host, begin testing mini-rv32ima internals by checking PC oob and PC alignment.
---
 precompiled/self.bin                | Bin 5260 -> 5180 bytes
 test/Makefile                       |   5 ++-
 test/minirv32_internal/Makefile     |   2 +
 test/minirv32_internal/rom/Makefile |   2 +
 test/minirv32_internal/rom/rom.c    |   6 +++
 test/minirv32_internal/test/tests.c |  55 ++++++++++++++++++++++++++++
 uvm32/mini-rv32ima.h                |   7 +++-
 uvm32/uvm32.h                       |   1 +
 8 files changed, 75 insertions(+), 3 deletions(-)
 create mode 100644 test/minirv32_internal/Makefile
 create mode 100644 test/minirv32_internal/rom/Makefile
 create mode 100644 test/minirv32_internal/rom/rom.c
 create mode 100644 test/minirv32_internal/test/tests.c

diff --git a/precompiled/self.bin b/precompiled/self.bin
index 344ae738c8769cb83ec9ec5c0de6493cda77a406..d80139bc226e8fb4e5987bf43c4872319ef26a9c 100755
GIT binary patch
delta 636
zcmYLHUr19?82`@h&OP_;Pu_LP847C4{tU~}Dlv+t(+nEfLp}t(#0e6Tq$i`7R%_mw
zD>gsDFu|9=Fdu>&EvScHLQu&CiBLkpDt(AtkW)xn$Mw*8_`cuw{W!n#{mwbbeXsVW
z!gb-yc8Fq}ZsqhAS%GL}#tTv2Z+c4EP7LgC_oTa?5X0I=nrv)>wV>G^#&gPf=BF*3
zwuP-{3b)Y!-gPwKEWPOLZ3ppyY1m6O45<|%S*Xh7fR@o9n%NCtu__||EZDKo2x3IF
z^TdG5V(SnaXAqlo>RbsZINuAru*NW11(;GTvJ+d`F!AFeyXLh&SCO6t@on`&Y5L(k
zARW}>CGABZHty81?<9!z4Jmk9N7D<wiQk&<@k8DB=%Xfi5GnmCH`j`yigjZ|Pb)VT
zy705!K=xaP;~oj#R?moX3TT#tNU%t-ZQj<CADb0@Y9!dXi9gNclInDcA7YSG=`?1Y
z<K!S-cLnQ$mbp;!ayiOC-lEiDuLTrZ{$cM=v852gtjkLd<Fd;~j-bo!BaIkvSCS@-
zxU0!g?3SHln3DK7K9%tVX5BlKFH?T&yStMp6>AP`Et|ws#(|sFgPa*4hL&t%Q2!uC
znJrT%&y2@iTn!N`{t`H~!%Ds*-IMQl$5{ZZJBONcqe~meYQR_X3wrW%b6jFEvh-GZ
zyN|R+_R79;3Y%P!(|l3xm3gxso9Aj_2Bl7Jd1^7k<aa@HDuf$GZP}02_x~T{O*7Ve
VcG*ELE8@u#nlK=muxj}g@)sQ@+r9t*

delta 716
zcmYLHUr19?7(ZvXd(XYwUEaF7SxQ<rvmkOcWBsGBbQ>fjkx&ptoWP)H<b(FOu)OL_
zXP;=0WQb_gi0Fpvp@&|=a03@;doXY`XhA|Na<eAb*?j2be82PkJ-^>~-tO+*6FgPr
z4VNH4+~e&ke+U0S{<5$g`PFXSR<Ike0^J_lz_sVN#3;sxO=OICLHBs!9Cv~2;Jqr}
z;5A-zs);`cJ?2`7@>gh^2hoRu2<^Pcg#uzn$Rg1`f;uKG7RVBjcI9zIgshH|56HH#
zi2MdA$KhQFL2o%q{)(4E#)XnWp<L|>$Oc(q`2?w)gM;~Yq-L@Nf`Wmop`Hxm8u(0Z
z+0m2?d=sKymoF9w4Ob&ZYCl{R-#DPtogXgIl~ra>OQ744_ADoAPajFz_=3n{h>l3D
zs-9h=rKA-ar2(!jeiIT>4L)Ef=KI*$Bb)`@hUg$cNs*5_8|F>E^k|g!2~E!CJYI|>
zdxaTl<53~6lQcohGKpPqTXt3*GW2+XLyMmvCM?S#@2H${uVed9YR<SJCfo55_$F)k
zD9Ba~9|MQA3?GL^YXv?5H<+gmf()O8m+Y*Em~{)6n06RT)@IBVXBDU~3Y`a1$+~CP
zK#-C4Bq!&U)?O@_q0NP0*n?nb3gx$8q~b_zaiNZhh*=8-EZPJUWbC`_OIP#*Q4nL4
z3lsJ=^mc|vbC53Dw{f&rWg$A4GSMMv4)!WrFU<yg>Dh=%9LTs^TbCS3t>#~#RsLpG
zXJ%A}>EqM~U;1)4@RiKhzo_!*H5U7;@`&AM|E$}Jm?~r<!1^SYrav)V*yQO37+1Cz
deOZqE-|2fd%qcrxZHi((p&)<4__+Bx{s)mW2a*5)

diff --git a/test/Makefile b/test/Makefile
index 3d2dae1..5f31482 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -6,7 +6,8 @@ TESTS = \
     meter \
     extram \
     badcode \
-    invalid_opcodes
+    invalid_opcodes \
+    minirv32_internal
 
 RUNCMD = $(foreach TEST,${TESTS},make -C ${TEST} &&)
 CLEANCMD = $(foreach TEST,${TESTS},make -C ${TEST} clean &&)
@@ -14,7 +15,7 @@ CLEANCMD = $(foreach TEST,${TESTS},make -C ${TEST} clean &&)
 ifeq (,$(shell which gcovr))
 	GCOVRCMD=echo Install gcovr for code coverage reports
 else
-    GCOVRCMD=gcovr -r ../ --filter ".*uvm32.c"
+    GCOVRCMD=gcovr -r ../ --filter ".*uvm32.c" --filter ".*mini.*"
 	PERC=$(shell gcovr -r ../ --filter ".*uvm32.c" | grep uvm | awk '{print $$4}')
 endif
 
diff --git a/test/minirv32_internal/Makefile b/test/minirv32_internal/Makefile
new file mode 100644
index 0000000..dc44dd1
--- /dev/null
+++ b/test/minirv32_internal/Makefile
@@ -0,0 +1,2 @@
+TOPDIR=../..
+include ${TOPDIR}/test/common/makefile.common
diff --git a/test/minirv32_internal/rom/Makefile b/test/minirv32_internal/rom/Makefile
new file mode 100644
index 0000000..4cd3f50
--- /dev/null
+++ b/test/minirv32_internal/rom/Makefile
@@ -0,0 +1,2 @@
+TOPDIR=../../..
+include ${TOPDIR}/test/common/makefile-rom.common
diff --git a/test/minirv32_internal/rom/rom.c b/test/minirv32_internal/rom/rom.c
new file mode 100644
index 0000000..072ab1d
--- /dev/null
+++ b/test/minirv32_internal/rom/rom.c
@@ -0,0 +1,6 @@
+#include "uvm32_target.h"
+
+void main(void) {
+    println("Hello world");
+}
+
diff --git a/test/minirv32_internal/test/tests.c b/test/minirv32_internal/test/tests.c
new file mode 100644
index 0000000..0b1ee7d
--- /dev/null
+++ b/test/minirv32_internal/test/tests.c
@@ -0,0 +1,55 @@
+#include <string.h>
+#include "unity.h"
+#include "uvm32.h"
+#include "../common/uvm32_common_custom.h"
+
+#include "rom-header.h"
+
+static uvm32_state_t vmst;
+static uvm32_evt_t evt;
+
+void setUp(void) {
+    // runs before each test
+    uvm32_init(&vmst);
+    uvm32_load(&vmst, rom_bin, rom_bin_len);
+}
+
+void tearDown(void) {
+}
+
+void test_pc_too_big(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 1024 * 16 * 4; // off end
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_1(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 1;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_2(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 2;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
+void test_pc_unaligned_3(void) {
+    // No code should be doing this, but...
+    TEST_ASSERT_EQUAL(0x80000000, uvm32_getProgramCounter(&vmst));
+    vmst._core.pc = 0x80000000 + 3;
+    uvm32_run(&vmst, &evt, 1);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_ERR);
+    TEST_ASSERT_EQUAL(evt.data.err.errcode, UVM32_ERR_INTERNAL_CORE);
+}
+
diff --git a/uvm32/mini-rv32ima.h b/uvm32/mini-rv32ima.h
index 531648e..e33c52c 100644
--- a/uvm32/mini-rv32ima.h
+++ b/uvm32/mini-rv32ima.h
@@ -501,6 +501,7 @@ MINIRV32_STEPPROTO
 	// Handle traps and interrupts.
 	if( trap )
 	{
+#ifndef MINIRV32_RETURN_TRAP
 		if( trap & 0x80000000 ) // If prefixed with 1 in MSB, it's an interrupt, not a trap.
 		{
 			SETCSR( mcause, trap );
@@ -520,9 +521,13 @@ MINIRV32_STEPPROTO
 
 		// If trapping, always enter machine mode.
 		CSR( extraflags ) |= 3;
-
 		trap = 0;
 		pc += 4;
+#else
+        if (trap > 0) {
+            return trap;
+        }
+#endif
 	}
 
 	if( CSR( cyclel ) > cycle ) CSR( cycleh )++;
diff --git a/uvm32/uvm32.h b/uvm32/uvm32.h
index ceb92d2..d397ba5 100644
--- a/uvm32/uvm32.h
+++ b/uvm32/uvm32.h
@@ -40,6 +40,7 @@ SOFTWARE.
 
 // Setup and hooks for mini-rv32ima emulator core
 #define MINIRV32_DECORATE static
+#define MINIRV32_RETURN_TRAP
 #define MINI_RV32_RAM_SIZE UVM32_MEMORY_SIZE
 #define MINIRV32_POSTEXEC(pc, ir, retval) {if (retval > 0) return retval;}
 uint32_t _uvm32_extramLoad(void *userdata, uint32_t addr, uint32_t accessTyp);