dnomem: allow register dump

doc/reference/devices.rst

@@ -359,6 +359,9 @@ In ``break`` mode, the simulation is switched to interactive mode after each
 access.
 And in ``halt`` mode, the simulation is immediately terminated.
 
+It is possible to dump registers of the CPU that caused the violation
+automatically by setting ``rd yes``.
+
 
 Initialization parameters: ``address`` ``size``
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -377,6 +380,8 @@ Commands
    Print the device information (block address, size and mode)
 ``mode``
    Set device mode (either ``warn``, ``halt`` or ``break``).
+``rd``
+   Whether to dump registers on violation (``yes`` or ``no``).
 
 
 Examples
@@ -400,10 +405,12 @@ All attempts to read/write into this memory are reported.
     /* <msim> Alert: Ignoring READ (at 0x008000004, 0x4 inside nomem). */
 
 If we configure the device to ``mode`` ``halt``, the simulation is halted upon
-reaching the ``lw`` instruction.
+reaching the ``lw`` instruction. By using ``nomem rd yes``, registers are
+dumped before the machine is halted.
 
 .. code:: msim
 
+   [msim] nomem rd yes
    [msim] nomem mode halt
    [msim]
    # la $a0, 0x88000004

src/device/dnomem.c

@@ -14,8 +14,10 @@
 #include <string.h>
 #include <inttypes.h>
 #include "dnomem.h"
+#include "../assert.h"
 #include "../fault.h"
 #include "../utils.h"
+#include "cpu/general_cpu.h"
 
 /** Access handling. */
 typedef struct {
@@ -29,6 +31,8 @@ typedef struct {
 	ptr36_t addr;
 	/** No-memory size. */
 	uint64_t size;
+	/** Dump registers of CPU that caused the access. */
+	bool register_dump;
 	/** No-memory behavior on access. */
 	dnomem_access_mode_t *mode;
 } dnomem_data_s;
@@ -103,6 +107,7 @@ static bool dnomem_init(token_t *parm, device_t *dev)
 	data->addr = start_addr;
 	data->size = size;
 	data->mode = &access_mode_warn;
+	data->register_dump = false;
 
 	return true;
 }
@@ -133,6 +138,30 @@ static bool dnomem_setmode(token_t *parm, device_t *dev)
 	return true;
 }
 
+/** rd command implementation.
+ *
+ * @param parm Command-line parameters
+ * @param dev  Device instance structure
+ *
+ * @return True if successful
+ */
+static bool dnomem_setrd(token_t *parm, device_t *dev)
+{
+	dnomem_data_s *data = (dnomem_data_s *) dev->data;
+	const char *const yes_no = parm_str(parm);
+
+	if (strcmp(yes_no, "yes") == 0) {
+		data->register_dump = true;
+	} else if (strcmp(yes_no, "no") == 0) {
+		data->register_dump = false;
+	} else {
+		error("Unknown register dump mode %s, expecting yes or no.", yes_no);
+		return false;
+	}
+
+	return true;
+}
+
 /** Info command implementation
  *
  * @param parm Command-line parameters
@@ -145,9 +174,9 @@ static bool dnomem_info(token_t *parm, device_t *dev)
 {
 	dnomem_data_s *data = (dnomem_data_s *) dev->data;
 
-	printf("[address  ] [size     ] [mode]\n"
-	    "%#011" PRIx64 " %#011" PRIx64 " %s\n",
-	    data->addr, data->size, data->mode->name);
+	printf("[address  ] [size     ] [mode  ] [regdump]\n"
+	    "%#011" PRIx64 " %#011" PRIx64 " %-8s %s\n",
+	    data->addr, data->size, data->mode->name, data->register_dump ? "yes" : "no");
 
 	return true;
 }
@@ -162,14 +191,19 @@ static void dnomem_done(device_t *dev) {
 	safe_free(dev->data);
 }
 
-static void dnomem_access32(const char *operation_name, device_t *dev, ptr36_t addr)
+static void dnomem_access32(const char *operation_name, unsigned int procno, device_t *dev, ptr36_t addr)
 {
 	dnomem_data_s *data = (dnomem_data_s *) dev->data;
 	ptr36_t offset = addr - data->addr;
 	if (offset >= data->size) {
 		return;
 	}
 
+	if (data->register_dump) {
+		general_cpu_t* causing_cpu = get_cpu(procno);
+		ASSERT((causing_cpu != NULL) && "CPU that causes illegal access to dnomem not found");
+		cpu_reg_dump(causing_cpu);
+	}
 	data->mode->access32(operation_name, dev, addr, offset);
 }
 
@@ -183,7 +217,7 @@ static void dnomem_access32(const char *operation_name, device_t *dev, ptr36_t a
 static void dnomem_read32(unsigned int procno, device_t *dev, ptr36_t addr,
     uint32_t *val)
 {
-	dnomem_access32("READ", dev, addr);
+	dnomem_access32("READ", procno, dev, addr);
 }
 
 /** Write command implementation
@@ -196,7 +230,7 @@ static void dnomem_read32(unsigned int procno, device_t *dev, ptr36_t addr,
 static void dnomem_write32(unsigned int procno, device_t *dev, ptr36_t addr,
     uint32_t val)
 {
-	dnomem_access32("WRITE", dev, addr);
+	dnomem_access32("WRITE", procno, dev, addr);
 }
 
 
@@ -221,6 +255,15 @@ cmd_t dnomem_cmds[] = {
 		"Set mode",
 		REQ STR "mode/Mode name (warn, break, halt)" END
 	},
+	{
+		"rd",
+		(fcmd_t) dnomem_setrd,
+		DEFAULT,
+		DEFAULT,
+		"Whether to dump registers on access",
+		"Whether to dump registers on access",
+		REQ STR "rd/Dump registers on access (yes, no)" END
+	},
 	{
 		"help",
 		(fcmd_t) dev_generic_help,

tests/system/Makefile

@@ -4,6 +4,7 @@ MIPS32_TOOLCHAIN_DIR =
 MIPS32_TESTS = \
 	dnomem-break \
 	dnomem-halt \
+	dnomem-rd \
 	dnomem-warn \
 	dval \
 	hello \

tests/system/mips32-dnomem-rd/guest.expected

@@ -0,0 +1 @@
+read

tests/system/mips32-dnomem-rd/host.expected

@@ -0,0 +1,11 @@
+processor 0
+   0                0   at                0   v0                0   v1                0   a0 ffffffff90000000
+  a1                a   a2 ffffffff88000004   a3                0   t0                0   t1                0
+  t2                0   t3                0   t4                0   t5                0   t6                0
+  t7                0   s0                0   s1                0   s2                0   s3                0
+  s4                0   s5                0   s6                0   s7                0   t8                0
+  t9                0   k0                0   k1                0   gp                0   sp                0
+  fp                0   ra                0   pc ffffffffbfc00038   lo                0   hi                0
+<msim> Alert: Halting after forbidden READ (at 0x008000004, 0x4 inside nomem).
+
+Cycles: 15

tests/system/mips32-dnomem-rd/main.S

@@ -0,0 +1 @@
+../mips32-dnomem-warn/main.S

tests/system/mips32-dnomem-rd/msim.conf

@@ -0,0 +1,8 @@
+add dr4kcpu cpu0
+add rom boot 0x1FC00000
+boot generic 4K
+boot load "boot.bin"
+add dprinter printer 0x10000000
+add dnomem nomem 0x08000000 0x1000
+nomem rd yes
+nomem mode halt

tests/system/mips32-dnomem-warn/host.expected

@@ -2,4 +2,4 @@
 <msim> Alert: Ignoring WRITE (at 0x008000004, 0x4 inside nomem).
 <msim> Alert: XHLT: Machine halt
 
-Cycles: 29
+Cycles: 31

tests/system/mips32.bats

@@ -18,6 +18,10 @@ load "common"
     msim_run_code "mips32-dnomem-halt"
 }
 
+@test "MIPS32: dnomem device in halt mode with register dump" {
+    msim_run_code "mips32-dnomem-rd"
+}
+
 @test "MIPS32: XINT instruction" {
     msim_run_code "mips32-xint"
 }