get rid of struct mainvars

pk/bbl.c

@@ -13,7 +13,7 @@ static void enter_entry_point()
   __builtin_unreachable();
 }
 
-void run_loaded_program(struct mainvars* args)
+void run_loaded_program(size_t argc, char** argv)
 {
   if (!current.is_supervisor)
     die("bbl can't run user binaries; try using pk instead");

pk/boot.h

@@ -8,11 +8,6 @@
 #include <stdint.h>
 #include <stddef.h>
 
-struct mainvars {
-  uint64_t argc;
-  uint64_t argv[127]; // this space is shared with the arg strings themselves
-};
-
 typedef struct {
   int phent;
   int phnum;
@@ -36,7 +31,7 @@ typedef struct {
 extern elf_info current;
 
 void prepare_supervisor_mode();
-void run_loaded_program(struct mainvars*);
+void run_loaded_program(size_t argc, char** argv);
 void boot_loader();
 void boot_other_hart();
 void load_elf(const char* fn, elf_info* info);

pk/init.c

@@ -44,31 +44,39 @@ static void handle_option(const char* s)
   }
 }
 
-static struct mainvars* parse_args(struct mainvars* args)
+#define MAX_ARGS 64
+typedef union {
+  uint64_t buf[MAX_ARGS];
+  char* argv[MAX_ARGS];
+} arg_buf;
+
+static size_t parse_args(arg_buf* args)
 {
   long r = frontend_syscall(SYS_getmainvars, (uintptr_t)args, sizeof(*args), 0, 0, 0, 0, 0);
   kassert(r == 0);
+  uint64_t* pk_argv = &args->buf[1];
+  // pk_argv[0] is the proxy kernel itself.  skip it and any flags.
+  size_t pk_argc = args->buf[0], arg = 1;
+  for ( ; arg < pk_argc && *(char*)(uintptr_t)pk_argv[arg] == '-'; arg++)
+    handle_option((const char*)(uintptr_t)pk_argv[arg]);
 
-  // argv[0] is the proxy kernel itself.  skip it and any flags.
-  unsigned a0 = 1;
-  for ( ; a0 < args->argc && *(char*)(uintptr_t)args->argv[a0] == '-'; a0++)
-    handle_option((const char*)(uintptr_t)args->argv[a0]);
-  args->argv[a0-1] = args->argc - a0;
-  return (struct mainvars*)&args->argv[a0-1];
+  for (size_t i = 0; arg + i < pk_argc; i++)
+    args->argv[i] = (char*)(uintptr_t)pk_argv[arg + i];
+  return pk_argc - arg;
 }
 
 void boot_loader()
 {
-  struct mainvars arg_buffer;
-  struct mainvars *args = parse_args(&arg_buffer);
+  arg_buf args;
+  size_t argc = parse_args(&args);
+  if (!argc)
+    panic("tell me what ELF to load!");
 
   // load program named by argv[0]
   long phdrs[128];
   current.phdr = (uintptr_t)phdrs;
   current.phdr_size = sizeof(phdrs);
-  if (!args->argc)
-    panic("tell me what ELF to load!");
-  load_elf((char*)(uintptr_t)args->argv[0], &current);
+  load_elf(args.argv[0], &current);
 
-  run_loaded_program(args);
+  run_loaded_program(argc, args.argv);
 }

pk/pk.c

@@ -3,7 +3,7 @@
 #include "vm.h"
 #include "elf.h"
 
-void run_loaded_program(struct mainvars* args)
+void run_loaded_program(size_t argc, char** argv)
 {
   if (current.is_supervisor)
     panic("pk can't run kernel binaries; try using bbl instead");
@@ -25,11 +25,11 @@ void run_loaded_program(struct mainvars* args)
   current.phdr = stack_top;
 
   // copy argv to user stack
-  for (size_t i = 0; i < args->argc; i++) {
-    size_t len = strlen((char*)(uintptr_t)args->argv[i])+1;
+  for (size_t i = 0; i < argc; i++) {
+    size_t len = strlen((char*)(uintptr_t)argv[i])+1;
     stack_top -= len;
-    memcpy((void*)stack_top, (void*)(uintptr_t)args->argv[i], len);
-    args->argv[i] = stack_top;
+    memcpy((void*)stack_top, (void*)(uintptr_t)argv[i], len);
+    argv[i] = (void*)stack_top;
   }
   stack_top &= -sizeof(void*);
 
@@ -49,18 +49,18 @@ void run_loaded_program(struct mainvars* args)
 
   // place argc, argv, envp, auxp on stack
   #define PUSH_ARG(type, value) do { \
-    *((type*)sp) = value; \
+    *((type*)sp) = (type)value; \
     sp += sizeof(type); \
   } while (0)
 
   #define STACK_INIT(type) do { \
     unsigned naux = sizeof(aux)/sizeof(aux[0]); \
-    stack_top -= (1 + args->argc + 1 + 1 + 2*naux) * sizeof(type); \
+    stack_top -= (1 + argc + 1 + 1 + 2*naux) * sizeof(type); \
     stack_top &= -16; \
     long sp = stack_top; \
-    PUSH_ARG(type, args->argc); \
-    for (unsigned i = 0; i < args->argc; i++) \
-      PUSH_ARG(type, args->argv[i]); \
+    PUSH_ARG(type, argc); \
+    for (unsigned i = 0; i < argc; i++) \
+      PUSH_ARG(type, argv[i]); \
     PUSH_ARG(type, 0); /* argv[argc] = NULL */ \
     PUSH_ARG(type, 0); /* envp[0] = NULL */ \
     for (unsigned i = 0; i < naux; i++) { \