target/riscv: added translation drivers

Existing flags: 'enable_virtual' and 'enable_virt2phys' were
replaced with explicit translation drivers. Motivation:

(1) Having 'enable_virtual' and 'enable_virt2phys' flags set simultaneously
may cause double address translation which is unacceptable

(2) Flags were global for all targets which is wrong too

Signed-off-by: Farid Khaydari <f.khaydari@syntacore.com>

doc/openocd.texi

@@ -11356,16 +11356,18 @@ This command can be used to change the memory access methods if the default
 behavior is not suitable for a particular target.
 @end deffn
 
-@deffn {Command} {riscv set_enable_virtual} on|off
+@deffn {Command} {riscv virt2phys_mode} [@option{hw}|@option{sw}|@option{off}]
-When on, memory accesses are performed on physical or virtual memory depending
+Configure how OpenOCD translates virtual addresses to physical:
-on the current system configuration. When off (default), all memory accessses are performed
+@itemize @bullet
-on physical memory.
+@item @option{sw} - OpenOCD translates virtual addresses explicitly by
-@end deffn
+traversing the page table entries (by performing physical memory accesses to
-
+read the respective entries). This is the default mode.
-@deffn {Command} {riscv set_enable_virt2phys} on|off
+@item @option{hw} - Virtual addresses are translated implicitly by hardware.
-When on (default), memory accesses are performed on physical or virtual memory
+(Virtual memory access will fail with an error if the hardware doesn't
-depending on the current satp configuration. When off, all memory accessses are
+support the necessary functionality.)
-performed on physical memory.
+@item @option{off} - Virtual addresses are not translated (identity mapping is assumed).
+@end itemize
+Returns current translation mode if called without arguments.
 @end deffn
 
 @deffn {Command} {riscv resume_order} normal|reversed

src/target/riscv/Makefile.am

@@ -26,3 +26,5 @@ noinst_LTLIBRARIES += %D%/libriscv.la
        %D%/riscv_semihosting.c \
        %D%/debug_defines.c \
        %D%/debug_reg_printer.c
+
+STARTUP_TCL_SRCS += %D%/startup.tcl

src/target/riscv/riscv-013.c

@@ -1974,11 +1974,11 @@ static int examine(struct target *target)
 				info->impebreak);
 	}
 
-	if (info->progbufsize < 4 && riscv_enable_virtual) {
+	if (info->progbufsize < 4 && riscv_virt2phys_mode_is_hw(target)) {
-		LOG_TARGET_ERROR(target, "set_enable_virtual is not available on this target. It "
+		LOG_TARGET_ERROR(target, "software address translation "
-				"requires a program buffer size of at least 4. (progbufsize=%d) "
+				"is not available on this target. It requires a "
-				"Use `riscv set_enable_virtual off` to continue."
+				"program buffer size of at least 4. (progbufsize=%d) "
-					, info->progbufsize);
+				"Use `riscv set_enable_virtual off` to continue.", info->progbufsize);
 	}
 
 	/* Don't call any riscv_* functions until after we've counted the number of
@@ -3054,7 +3054,8 @@ static int read_sbcs_nonbusy(struct target *target, uint32_t *sbcs)
 
 static int modify_privilege(struct target *target, uint64_t *mstatus, uint64_t *mstatus_old)
 {
-	if (riscv_enable_virtual && has_sufficient_progbuf(target, 5)) {
+	if (riscv_virt2phys_mode_is_hw(target)
+			&& has_sufficient_progbuf(target, 5)) {
 		/* Read DCSR */
 		uint64_t dcsr;
 		if (register_read_direct(target, &dcsr, GDB_REGNO_DCSR) != ERROR_OK)
@@ -4259,7 +4260,8 @@ read_memory_progbuf(struct target *target, target_addr_t address,
 	if (modify_privilege(target, &mstatus, &mstatus_old) != ERROR_OK)
 		return MEM_ACCESS_FAILED_PRIV_MOD_FAILED;
 
-	const bool mprven = riscv_enable_virtual && get_field(mstatus, MSTATUS_MPRV);
+	const bool mprven = riscv_virt2phys_mode_is_hw(target)
+			&& get_field(mstatus, MSTATUS_MPRV);
 	const struct memory_access_info access = {
 		.target_address = address,
 		.increment = increment,
@@ -4831,7 +4833,8 @@ write_memory_progbuf(struct target *target, target_addr_t address,
 	if (modify_privilege(target, &mstatus, &mstatus_old) != ERROR_OK)
 		return MEM_ACCESS_FAILED_PRIV_MOD_FAILED;
 
-	const bool mprven = riscv_enable_virtual && get_field(mstatus, MSTATUS_MPRV);
+	const bool mprven = riscv_virt2phys_mode_is_hw(target)
+			&& get_field(mstatus, MSTATUS_MPRV);
 
 	int result = write_memory_progbuf_inner(target, address, size, count, buffer, mprven);
 

src/target/riscv/riscv.c

@@ -139,6 +139,35 @@ struct tdata1_cache {
 	struct list_head elem_tdata1;
 };
 
+bool riscv_virt2phys_mode_is_hw(const struct target *target)
+{
+	assert(target);
+	RISCV_INFO(r);
+	return r->virt2phys_mode == RISCV_VIRT2PHYS_MODE_HW;
+}
+
+bool riscv_virt2phys_mode_is_sw(const struct target *target)
+{
+	assert(target);
+	RISCV_INFO(r);
+	return r->virt2phys_mode == RISCV_VIRT2PHYS_MODE_SW;
+}
+
+const char *riscv_virt2phys_mode_to_str(riscv_virt2phys_mode_t mode)
+{
+	assert(mode == RISCV_VIRT2PHYS_MODE_OFF
+			|| mode == RISCV_VIRT2PHYS_MODE_SW
+			|| mode == RISCV_VIRT2PHYS_MODE_HW);
+
+	static const char *const names[] = {
+		[RISCV_VIRT2PHYS_MODE_HW] = "hw",
+		[RISCV_VIRT2PHYS_MODE_SW] = "sw",
+		[RISCV_VIRT2PHYS_MODE_OFF] = "off",
+	};
+
+	return names[mode];
+}
+
 /* Wall-clock timeout for a command/access. Settable via RISC-V Target commands.*/
 static int riscv_command_timeout_sec_value = DEFAULT_COMMAND_TIMEOUT_SEC;
 
@@ -150,10 +179,6 @@ int riscv_get_command_timeout_sec(void)
 	return MAX(riscv_command_timeout_sec_value, riscv_reset_timeout_sec);
 }
 
-static bool riscv_enable_virt2phys = true;
-
-bool riscv_enable_virtual;
-
 static enum {
 	RO_NORMAL,
 	RO_REVERSED
@@ -2714,7 +2739,7 @@ static int riscv_mmu(struct target *target, int *enabled)
 {
 	*enabled = 0;
 
-	if (!riscv_enable_virt2phys)
+	if (!riscv_virt2phys_mode_is_sw(target))
 		return ERROR_OK;
 
 	/* Don't use MMU in explicit or effective M (machine) mode */
@@ -3938,16 +3963,6 @@ COMMAND_HANDLER(riscv_set_mem_access)
 	return ERROR_OK;
 }
 
-COMMAND_HANDLER(riscv_set_enable_virtual)
-{
-	if (CMD_ARGC != 1) {
-		LOG_ERROR("Command takes exactly 1 parameter");
-		return ERROR_COMMAND_SYNTAX_ERROR;
-	}
-	COMMAND_PARSE_ON_OFF(CMD_ARGV[0], riscv_enable_virtual);
-	return ERROR_OK;
-}
-
 static int parse_ranges(struct list_head *ranges, const char *tcl_arg, const char *reg_type, unsigned int max_val)
 {
 	char *args = strdup(tcl_arg);
@@ -4459,16 +4474,6 @@ COMMAND_HANDLER(riscv_set_maskisr)
 	return ERROR_OK;
 }
 
-COMMAND_HANDLER(riscv_set_enable_virt2phys)
-{
-	if (CMD_ARGC != 1) {
-		LOG_ERROR("Command takes exactly 1 parameter");
-		return ERROR_COMMAND_SYNTAX_ERROR;
-	}
-	COMMAND_PARSE_ON_OFF(CMD_ARGV[0], riscv_enable_virt2phys);
-	return ERROR_OK;
-}
-
 COMMAND_HANDLER(riscv_set_ebreakm)
 {
 	struct target *target = get_current_target(CMD_CTX);
@@ -5093,6 +5098,36 @@ COMMAND_HANDLER(handle_reserve_trigger)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_riscv_virt2phys_mode)
+{
+	struct riscv_info *info = riscv_info(get_current_target(CMD_CTX));
+	if (CMD_ARGC == 0) {
+		riscv_virt2phys_mode_t mode = info->virt2phys_mode;
+		command_print(CMD, "%s", riscv_virt2phys_mode_to_str(mode));
+		return ERROR_OK;
+	}
+
+	if (CMD_ARGC != 1)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	// TODO: add auto mode to allow OpenOCD choose translation mode
+	if (!strcmp(CMD_ARGV[0],
+			riscv_virt2phys_mode_to_str(RISCV_VIRT2PHYS_MODE_SW))) {
+		info->virt2phys_mode = RISCV_VIRT2PHYS_MODE_SW;
+	} else if (!strcmp(CMD_ARGV[0],
+			riscv_virt2phys_mode_to_str(RISCV_VIRT2PHYS_MODE_HW))) {
+		info->virt2phys_mode = RISCV_VIRT2PHYS_MODE_HW;
+	} else if (!strcmp(CMD_ARGV[0],
+			riscv_virt2phys_mode_to_str(RISCV_VIRT2PHYS_MODE_OFF))) {
+		info->virt2phys_mode = RISCV_VIRT2PHYS_MODE_OFF;
+	} else {
+		command_print(CMD, "Unsupported address translation mode: %s", CMD_ARGV[0]);
+		return ERROR_COMMAND_ARGUMENT_INVALID;
+	}
+
+	return ERROR_OK;
+}
+
 static const struct command_registration riscv_exec_command_handlers[] = {
 	{
 		.name = "dump_sample_buf",
@@ -5144,15 +5179,6 @@ static const struct command_registration riscv_exec_command_handlers[] = {
 		.help = "Set which memory access methods shall be used and in which order "
 			"of priority. Method can be one of: 'progbuf', 'sysbus' or 'abstract'."
 	},
-	{
-		.name = "set_enable_virtual",
-		.handler = riscv_set_enable_virtual,
-		.mode = COMMAND_ANY,
-		.usage = "on|off",
-		.help = "When on, memory accesses are performed on physical or virtual "
-				"memory depending on the current system configuration. "
-				"When off (default), all memory accessses are performed on physical memory."
-	},
 	{
 		.name = "expose_csrs",
 		.handler = riscv_set_expose_csrs,
@@ -5277,14 +5303,6 @@ static const struct command_registration riscv_exec_command_handlers[] = {
 		.help = "mask riscv interrupts",
 		.usage = "['off'|'steponly']",
 	},
-	{
-		.name = "set_enable_virt2phys",
-		.handler = riscv_set_enable_virt2phys,
-		.mode = COMMAND_ANY,
-		.usage = "on|off",
-		.help = "When on (default), enable translation from virtual address to "
-			"physical address."
-	},
 	{
 		.name = "set_ebreakm",
 		.handler = riscv_set_ebreakm,
@@ -5353,6 +5371,16 @@ static const struct command_registration riscv_exec_command_handlers[] = {
 		.usage = "[index ('on'|'off')]",
 		.help = "Controls which RISC-V triggers shall not be touched by OpenOCD.",
 	},
+	{
+		.name = "virt2phys_mode",
+		.handler = handle_riscv_virt2phys_mode,
+		.mode = COMMAND_ANY,
+		.usage = "['sw'|'hw'|'off']",
+		.help = "Configure the virtual address translation mode: "
+				"sw - translate vaddr to paddr by manually traversing page tables, "
+				"hw - translate vaddr to paddr by hardware, "
+				"off - no address translation."
+	},
 	COMMAND_REGISTRATION_DONE
 };
 
@@ -5469,6 +5497,8 @@ static void riscv_info_init(struct target *target, struct riscv_info *r)
 
 	r->xlen = -1;
 
+	r->virt2phys_mode = RISCV_VIRT2PHYS_MODE_SW;
+
 	r->isrmask_mode = RISCV_ISRMASK_OFF;
 
 	r->mem_access_methods[0] = RISCV_MEM_ACCESS_PROGBUF;

src/target/riscv/riscv.h

@@ -57,6 +57,14 @@ typedef enum riscv_mem_access_method {
 	RISCV_MEM_ACCESS_MAX_METHODS_NUM
 } riscv_mem_access_method_t;
 
+typedef enum riscv_virt2phys_mode {
+	RISCV_VIRT2PHYS_MODE_HW,
+	RISCV_VIRT2PHYS_MODE_SW,
+	RISCV_VIRT2PHYS_MODE_OFF
+} riscv_virt2phys_mode_t;
+
+const char *riscv_virt2phys_mode_to_str(riscv_virt2phys_mode_t mode);
+
 enum riscv_halt_reason {
 	RISCV_HALT_INTERRUPT,
 	RISCV_HALT_EBREAK,
@@ -165,6 +173,9 @@ struct riscv_info {
 	 * most recent halt was not caused by a trigger, then this is -1. */
 	int64_t trigger_hit;
 
+	/* The configured approach to translate virtual addresses to physical */
+	riscv_virt2phys_mode_t virt2phys_mode;
+
 	bool triggers_enumerated;
 
 	/* Decremented every scan, and when it reaches 0 we clear the learned
@@ -331,11 +342,12 @@ typedef struct {
 	unsigned pa_ppn_mask[PG_MAX_LEVEL];
 } virt2phys_info_t;
 
+bool riscv_virt2phys_mode_is_hw(const struct target *target);
+bool riscv_virt2phys_mode_is_sw(const struct target *target);
+
 /* Wall-clock timeout for a command/access. Settable via RISC-V Target commands.*/
 int riscv_get_command_timeout_sec(void);
 
-extern bool riscv_enable_virtual;
-
 /* Everything needs the RISC-V specific info structure, so here's a nice macro
  * that provides that. */
 static inline struct riscv_info *riscv_info(const struct target *target) __attribute__((unused));

src/target/riscv/startup.tcl

@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+lappend _telnet_autocomplete_skip "riscv set_enable_virtual"
+proc {riscv set_enable_virtual} on_off {
+	echo {DEPRECATED! use 'riscv virt2phys_mode' not 'riscv set_enable_virtual'}
+	foreach t [target names] {
+		if {[$t cget -type] ne "riscv"} { continue }
+		switch -- [$t riscv virt2phys_mode] {
+			off -
+			hw {
+				switch -- $on_off {
+					on  {$t riscv virt2phys_mode hw}
+					off {$t riscv virt2phys_mode off}
+				}
+			}
+			sw {
+				if {$on_off eq "on"} {
+					error {Can't enable virtual while translation mode is SW}
+				}
+			}
+		}
+	}
+	return {}
+}
+
+lappend _telnet_autocomplete_skip "riscv set_enable_virt2phys"
+proc {riscv set_enable_virt2phys} on_off {
+	echo {DEPRECATED! use 'riscv virt2phys_mode' not 'riscv set_enable_virt2phys'}
+	foreach t [target names] {
+		if {[$t cget -type] ne "riscv"} { continue }
+		switch -- [riscv virt2phys_mode] {
+			off -
+			sw {
+				switch -- $on_off {
+					on  {riscv virt2phys_mode sw}
+					off {riscv virt2phys_mode off}
+				}
+			}
+			hw {
+				if {$on_off eq "on"} {
+					error {Can't enable virt2phys while translation mode is HW}
+				}
+			}
+		}
+	}
+	return {}
+}
+
+proc riscv {cmd args} {
+	tailcall "riscv $cmd" {*}$args
+}