Removing CSU patches

* Removed startup code patches in lib/csu regarding kernel to userland
   ABI.

 * Aligned stack layout on NetBSD stack layout.

 * Generate valid stack pointers instead of offsets by taking into account
   _minix_kerninfo->kinfo->user_sp.

 * Refactored stack generation, by moving part of execve in two
   functions {minix_stack_params(), minix_stack_fill()} and using them
   in execve(), rs and vm.

 * Changed load offset of rtld (ld.so) to:
      execi.args.stack_high - execi.args.stack_size - 0xa00000
   which is 10MB below the main executable stack.

Change-Id: I839daf3de43321cded44105634102d419cb36cec

lib/libexec/exec_general.c

@@ -75,33 +75,6 @@ int libexec_clear_memset(struct exec_info *execi, vir_bytes vaddr, size_t len)
 	return OK;
 }
 
-void libexec_patch_ptr(char stack[ARG_MAX], vir_bytes base)
-{
-/* When doing an exec(name, argv, envp) call, the user builds up a stack
- * image with arg and env pointers relative to the start of the stack.  Now
- * these pointers must be relocated, since the stack is not positioned at
- * address 0 in the user's address space.
- */
-
-  char **ap, flag;
-  vir_bytes v;
-
-  flag = 0;                     /* counts number of 0-pointers seen */
-  ap = (char **) stack;         /* points initially to 'nargs' */
-  ap++;                         /* now points to argv[0] */
-  while (flag < 2) {
-        if (ap >= (char **) &stack[ARG_MAX]) return;    /* too bad */
-        if (*ap != NULL) {
-                v = (vir_bytes) *ap;    /* v is relative pointer */
-                v += base;              /* relocate it */
-                *ap = (char *) v;       /* put it back */
-        } else {
-                flag++;
-        }
-        ap++;
-  }
-}
-
 int libexec_pm_newexec(endpoint_t proc_e, struct exec_info *e)
 {
   int r;

lib/libexec/libexec.h

@@ -55,7 +55,6 @@ struct exec_info {
 int elf_has_interpreter(char *exec_hdr, int hdr_len, char *interp, int maxsz);
 int elf_phdr(char *exec_hdr, int hdr_len, vir_bytes *phdr);
 
-void libexec_patch_ptr(char stack[ARG_MAX], vir_bytes base);
 int libexec_pm_newexec(endpoint_t proc_e, struct exec_info *execi);
 
 typedef int (*libexec_exec_loadfunc_t)(struct exec_info *execi);