bsd-user: Move stack initializtion into a per-os file.

Move all of the stack initialization into target_os_stack.h. Each BSD
sets up processes a little differently.

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 181 insertions, 0 deletions

diff --git a/bsd-user/freebsd/target_os_stack.h b/bsd-user/freebsd/target_os_stack.h
new file mode 100644
index 0000000000..1bb1a2bf56
--- /dev/null
+++ b/bsd-user/freebsd/target_os_stack.h
@@ -0,0 +1,181 @@
+/*
+ *  FreeBSD setup_initial_stack() implementation.
+ *
+ *  Copyright (c) 2013-14 Stacey D. Son
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _TARGET_OS_STACK_H_
+#define _TARGET_OS_STACK_H_
+
+#include <sys/param.h>
+#include "target_arch_sigtramp.h"
+#include "qemu/guest-random.h"
+
+/*
+ * The inital FreeBSD stack is as follows:
+ * (see kern/kern_exec.c exec_copyout_strings() )
+ *
+ *  Hi Address -> char **ps_argvstr  (struct ps_strings for ps, w, etc.)
+ *                unsigned ps_nargvstr
+ *                char **ps_envstr
+ *  PS_STRINGS -> unsigned ps_nenvstr
+ *
+ *                machine dependent sigcode (sv_sigcode of size
+ *                                           sv_szsigcode)
+ *
+ *                execpath          (absolute image path for rtld)
+ *
+ *                SSP Canary        (sizeof(long) * 8)
+ *
+ *                page sizes array  (usually sizeof(u_long) )
+ *
+ *  "destp" ->    argv, env strings (up to 262144 bytes)
+ */
+static inline int setup_initial_stack(struct bsd_binprm *bprm,
+        abi_ulong *ret_addr, abi_ulong *stringp)
+{
+    int i;
+    abi_ulong stack_hi_addr;
+    size_t execpath_len, stringspace;
+    abi_ulong destp, argvp, envp, p;
+    struct target_ps_strings ps_strs;
+    char canary[sizeof(abi_long) * 8];
+
+    stack_hi_addr = p = target_stkbas + target_stksiz;
+
+    /* Save some space for ps_strings. */
+    p -= sizeof(struct target_ps_strings);
+
+    /* Add machine depedent sigcode. */
+    p -= TARGET_SZSIGCODE;
+    if (setup_sigtramp(p, (unsigned)offsetof(struct target_sigframe, sf_uc),
+            TARGET_FREEBSD_NR_sigreturn)) {
+        errno = EFAULT;
+        return -1;
+    }
+    if (bprm->fullpath) {
+        execpath_len = strlen(bprm->fullpath) + 1;
+        p -= roundup(execpath_len, sizeof(abi_ulong));
+        if (memcpy_to_target(p, bprm->fullpath, execpath_len)) {
+            errno = EFAULT;
+            return -1;
+        }
+    }
+    /* Add canary for SSP. */
+    qemu_guest_getrandom_nofail(canary, sizeof(canary));
+    p -= roundup(sizeof(canary), sizeof(abi_ulong));
+    if (memcpy_to_target(p, canary, sizeof(canary))) {
+        errno = EFAULT;
+        return -1;
+    }
+    /* Add page sizes array. */
+    p -= sizeof(abi_ulong);
+    if (put_user_ual(TARGET_PAGE_SIZE, p)) {
+        errno = EFAULT;
+        return -1;
+    }
+    /*
+     * Deviate from FreeBSD stack layout: force stack to new page here
+     * so that signal trampoline is not sharing the page with user stack
+     * frames. This is actively harmful in qemu as it marks pages with
+     * code it translated as read-only, which is somewhat problematic
+     * for user trying to use the stack as intended.
+     */
+    p = rounddown(p, TARGET_PAGE_SIZE);
+
+    /* Calculate the string space needed */
+    stringspace = 0;
+    for (i = 0; i < bprm->argc; ++i) {
+        stringspace += strlen(bprm->argv[i]) + 1;
+    }
+    for (i = 0; i < bprm->envc; ++i) {
+        stringspace += strlen(bprm->envp[i]) + 1;
+    }
+    if (stringspace > TARGET_ARG_MAX) {
+        errno = ENOMEM;
+        return -1;
+    }
+    /* Make room for the argv and envp strings */
+    destp = rounddown(p - stringspace, sizeof(abi_ulong));
+    p = argvp = destp - (bprm->argc + bprm->envc + 2) * sizeof(abi_ulong);
+    /* Remember the strings pointer */
+    if (stringp) {
+        *stringp = destp;
+    }
+    /*
+     * Add argv strings.  Note that the argv[] vectors are added by
+     * loader_build_argptr()
+     */
+    /* XXX need to make room for auxargs */
+    ps_strs.ps_argvstr = tswapl(argvp);
+    ps_strs.ps_nargvstr = tswap32(bprm->argc);
+    for (i = 0; i < bprm->argc; ++i) {
+        size_t len = strlen(bprm->argv[i]) + 1;
+
+        if (memcpy_to_target(destp, bprm->argv[i], len)) {
+            errno = EFAULT;
+            return -1;
+        }
+        if (put_user_ual(destp, argvp)) {
+            errno = EFAULT;
+            return -1;
+        }
+        argvp += sizeof(abi_ulong);
+        destp += len;
+    }
+    if (put_user_ual(0, argvp)) {
+        errno = EFAULT;
+        return -1;
+    }
+    /*
+     * Add env strings. Note that the envp[] vectors are added by
+     * loader_build_argptr().
+     */
+    envp = argvp + sizeof(abi_ulong);
+    ps_strs.ps_envstr = tswapl(envp);
+    ps_strs.ps_nenvstr = tswap32(bprm->envc);
+    for (i = 0; i < bprm->envc; ++i) {
+        size_t len = strlen(bprm->envp[i]) + 1;
+
+        if (memcpy_to_target(destp, bprm->envp[i], len)) {
+            errno = EFAULT;
+            return -1;
+        }
+        if (put_user_ual(destp, envp)) {
+            errno = EFAULT;
+            return -1;
+        }
+        envp += sizeof(abi_ulong);
+        destp += len;
+    }
+    if (put_user_ual(0, envp)) {
+        errno = EFAULT;
+        return -1;
+    }
+    if (memcpy_to_target(stack_hi_addr - sizeof(ps_strs), &ps_strs,
+                sizeof(ps_strs))) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    if (ret_addr) {
+        *ret_addr = p;
+    }
+
+    return 0;
+ }
+
+#endif /* !_TARGET_OS_STACK_H_ */