More exec hacking, userspace crt.S to help with testing

38f3a4da · Silas Boyd-Wickizer · 4ce84865 · 38f3a4da · 38f3a4da · 38f3a4da
--- a/bin/Makefrag
+++ b/bin/Makefrag
@@ -33,7 +33,7 @@ UPROGS := $(addprefix $(O)/bin/, $(UPROGS))
 $(O)/bin/%.unstripped: $(O)/bin/%.o $(ULIB)
 	@echo "  LD     $@"
 	$(Q)mkdir -p $(@D)
-	$(Q)$(LD) $(LDFLAGS) -N -e main -Ttext 0x100000 -o $@ $^
+	$(Q)$(LD) $(LDFLAGS) -N -Ttext 0x100000 -o $@ $^

 $(O)/bin/%: $(O)/bin/%.unstripped
 	@echo "  STRIP  $@"

--- a/kernel/exec.cc
+++ b/kernel/exec.cc
@@ -68,7 +68,7 @@ static void
 dostack(struct eargs *args)
 {
  struct vmnode *vmn = nullptr;
-  uptr ustack[1+MAXARG+1];
+  uptr argstck[1+MAXARG];
  const char *s, *last;
  s64 argc;
  uptr sp;
@@ -91,9 +91,6 @@ dostack(struct eargs *args)
    if(argc >= MAXARG)
      goto bad;

-  // Fake return %rip between stack 
-  ustack[0] = 0ull;
-
  // Push argument strings
  sp = USERTOP;
  for(int i = argc-1; i >= 0; i--) {
@@ -101,15 +98,19 @@ dostack(struct eargs *args)
    sp &= ~7;
    if(args->vmap->copyout(sp, args->argv[i], strlen(args->argv[i]) + 1) < 0)
      goto bad;
-    ustack[1+i] = sp;
+    argstck[i] = sp;
  }
-  ustack[1+argc] = 0;
+  argstck[argc] = 0;

  args->proc->tf->rdi = argc;
  args->proc->tf->rsi = sp - (argc+1)*8;

-  sp -= (1+argc+1) * 8;
-  if(args->vmap->copyout(sp, ustack, (1+argc+1)*8) < 0)
+  sp -= (argc+1) * 8;
+  if(args->vmap->copyout(sp, argstck, (argc+1)*8) < 0)
+    goto bad;
+
+  sp -= 8;
+  if(args->vmap->copyout(sp, &argc, 8) < 0)
    goto bad;

  // Save program name for debugging.

--- a/lib/Makefrag
+++ b/lib/Makefrag
 ULIB = ulib.o usys.o printf.o umalloc.o uthread.o fmt.o stream.o ipc.o \
-       threads.o
+       threads.o crt.o
 ULIB := $(addprefix $(O)/lib/, $(ULIB))

 .PRECIOUS: $(O)/lib/%.o

--- a/lib/crt.S
+++ b/lib/crt.S
+.code64
+.align 8
+.globl _start
+_start:
+        call main