Simulator exit

sw/cheri/checks/CMakeLists.txt

@@ -6,6 +6,7 @@ set(CHECKS
   gpio_check.cc
   lcd_check.cc
   uart_check.cc
+  uart_simexit_check.cc
   sdraw_check.cc
   spi_test.cc
   system_info_check.cc

sw/cheri/checks/uart_simexit_check.cc

@@ -0,0 +1,40 @@
+/**
+ * Copyright lowRISC contributors.
+ * Licensed under the Apache License, Version 2.0, see LICENSE for details.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define CHERIOT_NO_AMBIENT_MALLOC
+#define CHERIOT_NO_NEW_DELETE
+#define CHERIOT_PLATFORM_CUSTOM_UART
+
+#include <stdint.h>
+
+// clang-format off
+#include "../../common/defs.h"
+#include <cheri.hh>
+// clang-format on
+#include <platform-uart.hh>
+#include "../common/uart-utils.hh"
+
+using namespace CHERI;
+
+/**
+ * C++ entry point for the loader.  This is called from assembly, with the
+ * read-write root in the first argument.
+ */
+[[noreturn]] extern "C" void entry_point(void* rwRoot) {
+  Capability<void> root{rwRoot};
+
+  // Create a bounded capability to the UART
+  Capability<volatile OpenTitanUart> uart = root.cast<volatile OpenTitanUart>();
+  uart.address()                          = UART_ADDRESS;
+  uart.bounds()                           = UART_BOUNDS;
+
+  uart->init(BAUD_RATE);
+  write_str(uart, "Trying out simulation exit!\r\n");
+  write_str(uart, "Safe to exit simulator.\xd8\xaf\xfb\xa0\xc7\xe1\xa9\xd7");
+  write_str(uart, "This should not be printed.\r\n");
+  write_str(uart, "FAIL\r\n");
+  while (true);
+}

vendor/lowrisc_ip.lock.hjson

@@ -9,6 +9,6 @@
   upstream:
   {
     url: https://github.com/lowRISC/opentitan
-    rev: 4fe1b8dd1a09af9dbc242434481ae031955dfd85
+    rev: a78922f14a8cc20c7ee569f322a04626f2ac6127
   }
 }

vendor/lowrisc_ip/dv/dpi/uartdpi/uartdpi.c

@@ -19,9 +19,13 @@
 #include <string.h>
 #include <unistd.h>
 
+#define EXIT_MESSAGE_LENGTH (32)
+
 // This keeps the necessary uart state.
 struct uartdpi_ctx {
   char ptyname[64];
+  char exitstring[EXIT_MESSAGE_LENGTH];
+  int exittracker;
   int host;
   int device;
   char tmp_read;
@@ -84,6 +88,9 @@ void *uartdpi_create(const char *name, const char *log_file_path) {
     }
   }
 
+  ctx->exittracker = 0;
+  strncpy(ctx->exitstring, "Safe to exit simulator.\xd8\xaf\xfb\xa0\xc7\xe1\xa9\xd7", EXIT_MESSAGE_LENGTH);
+
   return (void *)ctx;
 }
 
@@ -123,11 +130,12 @@ char uartdpi_read(void *ctx_void) {
   return ctx->tmp_read;
 }
 
-void uartdpi_write(void *ctx_void, char c) {
+// Returns true when simulator should exit.
+int uartdpi_write(void *ctx_void, char c) {
   int rv;
   struct uartdpi_ctx *ctx = (struct uartdpi_ctx *)ctx_void;
   if (ctx == NULL) {
-    return;
+    return 0;
   }
 
   rv = write(ctx->host, &c, 1);
@@ -143,4 +151,13 @@ void uartdpi_write(void *ctx_void, char c) {
       fprintf(stderr, "UART: Write to log file failed: %s\n", strerror(errno));
     }
   }
+
+  if (c == ctx->exitstring[ctx->exittracker]) {
+    ctx->exittracker++;
+  } else {
+    ctx->exittracker = 0;
+  }
+
+  // Don't require 0 to be sent at the end.
+  return ctx->exittracker == (EXIT_MESSAGE_LENGTH - 1);
 }

vendor/lowrisc_ip/dv/dpi/uartdpi/uartdpi.h

@@ -13,7 +13,7 @@ void *uartdpi_create(const char *name, const char *log_file_path);
 void uartdpi_close(void *ctx_void);
 int uartdpi_can_read(void *ctx_void);
 char uartdpi_read(void *ctx_void);
-void uartdpi_write(void *ctx_void, char c);
+int uartdpi_write(void *ctx_void, char c);
 
 #ifdef __cplusplus
 }  // extern "C"

vendor/lowrisc_ip/dv/dpi/uartdpi/uartdpi.sv

@@ -33,7 +33,7 @@ module uartdpi #(
     int uartdpi_can_read(input chandle ctx);
 
   import "DPI-C" function
-    void uartdpi_write(input chandle ctx, int data);
+    int uartdpi_write(input chandle ctx, int data);
 
   chandle ctx;
   string log_file_path = DEFAULT_LOG_FILE;
@@ -133,7 +133,10 @@ module uartdpi #(
           if (rxcyccount == CYCLES_PER_SYMBOL - 1) begin
             rxactive <= 0;
             if (rx_i) begin
-              uartdpi_write(ctx, rxsymbol);
+              if(uartdpi_write(ctx, rxsymbol)) begin
+                $display("Exiting the Sonata simulator because the magic UART string was seen.");
+                $exit;
+              end
             end
           end
         end

vendor/patches/lowrisc_ip/uartdpi/0002-Simulator-Exit-Condition.patch

@@ -0,0 +1,95 @@
+diff --git a/uartdpi.c b/uartdpi.c
+index f99b9da3..97366a91 100644
+--- a/uartdpi.c
++++ b/uartdpi.c
+@@ -19,9 +19,13 @@
+ #include <string.h>
+ #include <unistd.h>
+
++#define EXIT_MESSAGE_LENGTH (32)
++
+ // This keeps the necessary uart state.
+ struct uartdpi_ctx {
+   char ptyname[64];
++  char exitstring[EXIT_MESSAGE_LENGTH];
++  int exittracker;
+   int host;
+   int device;
+   char tmp_read;
+@@ -84,6 +88,9 @@ void *uartdpi_create(const char *name, const char *log_file_path) {
+     }
+   }
+
++  ctx->exittracker = 0;
++  strncpy(ctx->exitstring, "Safe to exit simulator.\xd8\xaf\xfb\xa0\xc7\xe1\xa9\xd7", EXIT_MESSAGE_LENGTH);
++
+   return (void *)ctx;
+ }
+
+@@ -123,11 +130,12 @@ char uartdpi_read(void *ctx_void) {
+   return ctx->tmp_read;
+ }
+
+-void uartdpi_write(void *ctx_void, char c) {
++// Returns true when simulator should exit.
++int uartdpi_write(void *ctx_void, char c) {
+   int rv;
+   struct uartdpi_ctx *ctx = (struct uartdpi_ctx *)ctx_void;
+   if (ctx == NULL) {
+-    return;
++    return 0;
+   }
+
+   rv = write(ctx->host, &c, 1);
+@@ -143,4 +151,13 @@ void uartdpi_write(void *ctx_void, char c) {
+       fprintf(stderr, "UART: Write to log file failed: %s\n", strerror(errno));
+     }
+   }
++
++  if (c == ctx->exitstring[ctx->exittracker]) {
++    ctx->exittracker++;
++  } else {
++    ctx->exittracker = 0;
++  }
++
++  // Don't require 0 to be sent at the end.
++  return ctx->exittracker == (EXIT_MESSAGE_LENGTH - 1);
+ }
+diff --git a/uartdpi.h b/uartdpi.h
+index 63834078..5e1152c9 100644
+--- a/uartdpi.h
++++ b/uartdpi.h
+@@ -13,7 +13,7 @@ void *uartdpi_create(const char *name, const char *log_file_path);
+ void uartdpi_close(void *ctx_void);
+ int uartdpi_can_read(void *ctx_void);
+ char uartdpi_read(void *ctx_void);
+-void uartdpi_write(void *ctx_void, char c);
++int uartdpi_write(void *ctx_void, char c);
+
+ #ifdef __cplusplus
+ }  // extern "C"
+diff --git a/uartdpi.sv b/uartdpi.sv
+index d476c519..0d46e79e 100644
+--- a/uartdpi.sv
++++ b/uartdpi.sv
+@@ -33,7 +33,7 @@ module uartdpi #(
+     int uartdpi_can_read(input chandle ctx);
+
+   import "DPI-C" function
+-    void uartdpi_write(input chandle ctx, int data);
++    int uartdpi_write(input chandle ctx, int data);
+
+   chandle ctx;
+   string log_file_path = DEFAULT_LOG_FILE;
+@@ -133,7 +133,10 @@ module uartdpi #(
+           if (rxcyccount == CYCLES_PER_SYMBOL - 1) begin
+             rxactive <= 0;
+             if (rx_i) begin
+-              uartdpi_write(ctx, rxsymbol);
++              if(uartdpi_write(ctx, rxsymbol)) begin
++                $display("Exiting the Sonata simulator because the magic UART string was seen.");
++                $exit;
++              end
+             end
+           end
+         end