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/* ld.so _start code.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <ldsodefs.h>
asm(""
".global _start\n"
".type _start, %function\n"
"_start:\n"
" .cfi_startproc\n"
" .cfi_undefined c30\n"
" mov c29, czr\n"
" mov c30, czr\n"
" b __real_start\n"
" .cfi_endproc\n"
" .size _start, .-_start\n");
typedef void (entry_t) (int, char **, char **, void *, void (*)(void));
__attribute__ ((noinline, noreturn))
void
_dl_start_user (uintptr_t *args, entry_t *entry)
{
/* Setup argv, envp, auxv for the application. */
uintptr_t *p;
long n;
int argc = args[0];
p = args + 1;
n = argc + 1;
char **argv = (char **) __builtin_cheri_bounds_set (p, n * sizeof *p);
p += n;
for (n = 0; p[n]; n++);
n++;
char **envp = (char **) __builtin_cheri_bounds_set (p, n * sizeof *p);
p += n;
for (n = 0; p[n] != AT_NULL; n += 2);
n += 2;
uintptr_t *auxv = __builtin_cheri_bounds_set (p, n * sizeof *p);
_dl_init (GL(dl_ns)[LM_ID_BASE]._ns_loaded, argc, argv, envp);
entry (argc, argv, envp, auxv, _dl_fini);
__builtin_trap ();
}
/* Count the array length needed for traditional ELF entry. */
static inline long
count_args (int argc, char **argv, char **envp, uintptr_t *auxv)
{
char **p;
uintptr_t *q;
long nargs = argc + 2;
for (p = envp; *p != NULL; p++);
nargs += p - envp + 1;
for (q = auxv; *q != AT_NULL; q += 2);
nargs += q - auxv + 2;
return nargs;
}
/* Generic ld.so start code in rtld.c. */
uintptr_t
_dl_start (void *) attribute_hidden;
/* ld.so entry point. */
void
__real_start (int argc, char **argv, char **envp, void *auxv)
{
long nargs = count_args (argc, argv, envp, auxv);
{
/* _dl_start requires continuous argv, envp, auxv. */
uintptr_t args[nargs];
long i = 0, j;
args[i++] = argc;
for (j = 0; argv[j] != NULL; j++)
args[i++] = (uintptr_t) argv[j];
args[i++] = 0;
for (j = 0; envp[j] != NULL; j++)
args[i++] = (uintptr_t) envp[j];
args[i++] = 0;
uintptr_t *a = auxv;
for (j = 0; a[j] != AT_NULL; j += 2)
{
args[i++] = a[j];
args[i++] = a[j+1];
}
args[i++] = AT_NULL;
args[i++] = 0;
assert (i == nargs);
/* Run ls.so setup. */
entry_t *entry = (entry_t *) _dl_start (args);
_dl_start_user (args, entry);
}
}
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