Support loading multiple ELF files via a new payload HTIF option

Firmware implementations, such as OpenSBI's fw_jump, make use of this
feature on other targets to avoid having to be rebuilt every time the
payload is updated.

fesvr/htif.cc

@@ -83,21 +83,21 @@ void htif_t::start()
   reset();
 }
 
-void htif_t::load_program()
+std::map<std::string, uint64_t> htif_t::load_payload(const std::string& payload, reg_t* entry)
 {
   std::string path;
-  if (access(targs[0].c_str(), F_OK) == 0)
-    path = targs[0];
-  else if (targs[0].find('/') == std::string::npos)
+  if (access(payload.c_str(), F_OK) == 0)
+    path = payload;
+  else if (payload.find('/') == std::string::npos)
   {
-    std::string test_path = PREFIX TARGET_DIR + targs[0];
+    std::string test_path = PREFIX TARGET_DIR + payload;
     if (access(test_path.c_str(), F_OK) == 0)
       path = test_path;
   }
 
   if (path.empty())
     throw std::runtime_error(
-        "could not open " + targs[0] +
+        "could not open " + payload +
         " (did you misspell it? If VCS, did you forget +permissive/+permissive-off?)");
 
   // temporarily construct a memory interface that skips writing bytes
@@ -116,7 +116,12 @@ void htif_t::load_program()
     htif_t* htif;
   } preload_aware_memif(this);
 
-  std::map<std::string, uint64_t> symbols = load_elf(path.c_str(), &preload_aware_memif, &entry);
+  return load_elf(path.c_str(), &preload_aware_memif, entry);
+}
+
+void htif_t::load_program()
+{
+  std::map<std::string, uint64_t> symbols = load_payload(targs[0], &entry);
 
   if (symbols.count("tohost") && symbols.count("fromhost")) {
     tohost_addr = symbols["tohost"];
@@ -131,6 +136,12 @@ void htif_t::load_program()
     sig_addr = symbols["begin_signature"];
     sig_len = symbols["end_signature"] - sig_addr;
   }
+
+  for (auto payload : payloads)
+  {
+    reg_t dummy_entry;
+    load_payload(payload, &dummy_entry);
+  }
 }
 
 void htif_t::stop()
@@ -243,6 +254,9 @@ void htif_t::parse_arguments(int argc, char ** argv)
       case HTIF_LONG_OPTIONS_OPTIND + 3:
         syscall_proxy.set_chroot(optarg);
         break;
+      case HTIF_LONG_OPTIONS_OPTIND + 4:
+        payloads.push_back(optarg);
+        break;
       case '?':
         if (!opterr)
           break;
@@ -273,6 +287,10 @@ void htif_t::parse_arguments(int argc, char ** argv)
           c = HTIF_LONG_OPTIONS_OPTIND + 3;
           optarg = optarg + 8;
         }
+        else if (arg.find("+payload=") == 0) {
+          c = HTIF_LONG_OPTIONS_OPTIND + 4;
+          optarg = optarg + 9;
+        }
         else if (arg.find("+permissive-off") == 0) {
           if (opterr)
             throw std::invalid_argument("Found +permissive-off when not parsing permissively");

fesvr/htif.h

@@ -7,6 +7,7 @@
 #include "syscall.h"
 #include "device.h"
 #include <string.h>
+#include <map>
 #include <vector>
 
 class htif_t : public chunked_memif_t
@@ -36,6 +37,7 @@ class htif_t : public chunked_memif_t
   virtual size_t chunk_align() = 0;
   virtual size_t chunk_max_size() = 0;
 
+  virtual std::map<std::string, uint64_t> load_payload(const std::string& payload, reg_t* entry);
   virtual void load_program();
   virtual void idle() {}
 
@@ -69,6 +71,7 @@ class htif_t : public chunked_memif_t
   syscall_t syscall_proxy;
   bcd_t bcd;
   std::vector<device_t*> dynamic_devices;
+  std::vector<std::string> payloads;
 
   const std::vector<std::string>& target_args() { return targs; }
 
@@ -94,6 +97,8 @@ class htif_t : public chunked_memif_t
        +signature=FILE\n\
       --chroot=PATH        Use PATH as location of syscall-servicing binaries\n\
        +chroot=PATH\n\
+      --payload=PATH       Load PATH memory as an additional ELF payload\n\
+       +payload=PATH\n\
 \n\
 HOST OPTIONS (currently unsupported)\n\
       --disk=DISK          Add DISK device. Use a ramdisk since this isn't\n\
@@ -110,6 +115,7 @@ TARGET (RISC-V BINARY) OPTIONS\n\
 {"disk",      required_argument, 0, HTIF_LONG_OPTIONS_OPTIND + 1 },     \
 {"signature", required_argument, 0, HTIF_LONG_OPTIONS_OPTIND + 2 },     \
 {"chroot",    required_argument, 0, HTIF_LONG_OPTIONS_OPTIND + 3 },     \
+{"payload",   required_argument, 0, HTIF_LONG_OPTIONS_OPTIND + 4 },     \
 {0, 0, 0, 0}
 
 #endif // __HTIF_H