Use uintptr_t instead of register_t * for the stack base.

- Use ustringp for the location of the argv and environment strings
  and allow destp to travel further down the stack for the stackgap
  and auxv regions.
- Update the Linux copyout_strings variants to move destp down the
  stack as was done for the native ABIs in r263349.
- Stop allocating a space for a stack gap in the Linux ABIs.  This
  used to hold translated system call arguments, but hasn't been used
  since r159992.

Reviewed by:	kib
Tested on:	md64 (amd64, i386, linux64), i386 (i386, linux)
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D22501

3 files changed, 64 insertions, 54 deletions

diff --git a/sys/i386/cloudabi32/cloudabi32_sysvec.c b/sys/i386/cloudabi32/cloudabi32_sysvec.c
index 31035a121f01..76cab063501d 100644
--- a/sys/i386/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/i386/cloudabi32/cloudabi32_sysvec.c
@@ -48,7 +48,7 @@ extern const char *cloudabi32_syscallnames[];
 extern struct sysent cloudabi32_sysent[];
 
 static int
-cloudabi32_fixup_tcb(register_t **stack_base, struct image_params *imgp)
+cloudabi32_fixup_tcb(uintptr_t *stack_base, struct image_params *imgp)
 {
 	int error;
 	uint32_t args[2];
@@ -68,16 +68,16 @@ cloudabi32_fixup_tcb(register_t **stack_base, struct image_params *imgp)
 	 * refer to the auxiliary vector, which is stored right after
 	 * the TCB.
 	 */
-	args[0] = (uintptr_t)*stack_base;
-	args[1] = (uintptr_t)*stack_base +
+	args[0] = *stack_base;
+	args[1] = *stack_base +
 	    roundup(sizeof(cloudabi32_tcb_t), sizeof(register_t));
-	*stack_base -= howmany(sizeof(args), sizeof(register_t));
-	return (copyout(args, *stack_base, sizeof(args)));
+	*stack_base -= roundup(sizeof(args), sizeof(register_t));
+	return (copyout(args, (void *)*stack_base, sizeof(args)));
 }
 
 static void
 cloudabi32_proc_setregs(struct thread *td, struct image_params *imgp,
-    unsigned long stack)
+    uintptr_t stack)
 {
 
 	exec_setregs(td, imgp, stack);
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index 77ab78b526a1..60ebb3a3510e 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -1124,7 +1124,7 @@ setup_priv_lcall_gate(struct proc *p)
  * Reset registers to default values on exec.
  */
 void
-exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
+exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
 {
 	struct trapframe *regs;
 	struct pcb *pcb;
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 787fb83c534b..e067e1f82123 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -88,15 +88,15 @@ extern struct sysent linux_sysent[LINUX_SYS_MAXSYSCALL];
 
 SET_DECLARE(linux_ioctl_handler_set, struct linux_ioctl_handler);
 
-static int	linux_fixup(register_t **stack_base,
+static int	linux_fixup(uintptr_t *stack_base,
 		    struct image_params *iparams);
-static int	linux_fixup_elf(register_t **stack_base,
+static int	linux_fixup_elf(uintptr_t *stack_base,
 		    struct image_params *iparams);
 static void     linux_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask);
 static void	linux_exec_setregs(struct thread *td,
-		    struct image_params *imgp, u_long stack);
+		    struct image_params *imgp, uintptr_t stack);
 static int	linux_copyout_strings(struct image_params *imgp,
-		    register_t **stack_base);
+		    uintptr_t *stack_base);
 static bool	linux_trans_osrel(const Elf_Note *note, int32_t *osrel);
 static void	linux_vdso_install(void *param);
 static void	linux_vdso_deinstall(void *param);
@@ -174,23 +174,25 @@ linux_translate_traps(int signal, int trap_code)
 }
 
 static int
-linux_fixup(register_t **stack_base, struct image_params *imgp)
+linux_fixup(uintptr_t *stack_base, struct image_params *imgp)
 {
-	register_t *argv, *envp;
-
-	argv = *stack_base;
-	envp = *stack_base + (imgp->args->argc + 1);
-	(*stack_base)--;
-	suword(*stack_base, (intptr_t)(void *)envp);
-	(*stack_base)--;
-	suword(*stack_base, (intptr_t)(void *)argv);
-	(*stack_base)--;
-	suword(*stack_base, imgp->args->argc);
+	register_t *base, *argv, *envp;
+
+	base = (register_t *)*stack_base;
+	argv = base;
+	envp = base + (imgp->args->argc + 1);
+	base--;
+	suword(base, (intptr_t)envp);
+	base--;
+	suword(base, (intptr_t)argv);
+	base--;
+	suword(base, imgp->args->argc);
+	*stack_base = (uintptr_t)base;
 	return (0);
 }
 
 static int
-linux_copyout_auxargs(struct image_params *imgp, u_long *base)
+linux_copyout_auxargs(struct image_params *imgp, uintptr_t *base)
 {
 	struct proc *p;
 	Elf32_Auxargs *args;
@@ -255,12 +257,15 @@ linux_copyout_auxargs(struct image_params *imgp, u_long *base)
 }
 
 static int
-linux_fixup_elf(register_t **stack_base, struct image_params *imgp)
+linux_fixup_elf(uintptr_t *stack_base, struct image_params *imgp)
 {
+	register_t *base;
 
-	(*stack_base)--;
-	if (suword(*stack_base, (register_t)imgp->args->argc) == -1)
+	base = (register_t *)*stack_base;
+	base--;
+	if (suword(base, (register_t)imgp->args->argc) == -1)
 		return (EFAULT);
+	*stack_base = (uintptr_t)base;
 	return (0);
 }
 
@@ -268,11 +273,12 @@ linux_fixup_elf(register_t **stack_base, struct image_params *imgp)
  * Copied from kern/kern_exec.c
  */
 static int
-linux_copyout_strings(struct image_params *imgp, register_t **stack_base)
+linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 {
 	int argc, envc, error;
 	char **vectp;
-	char *stringp, *destp;
+	char *stringp;
+	uintptr_t destp, ustringp;
 	struct ps_strings *arginfo;
 	char canary[LINUX_AT_RANDOM_LEN];
 	size_t execpath_len;
@@ -285,43 +291,45 @@ linux_copyout_strings(struct image_params *imgp, register_t **stack_base)
 	else
 		execpath_len = 0;
 	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
-	destp = (caddr_t)arginfo - SPARE_USRSPACE - linux_szplatform -
-	    roundup(sizeof(canary), sizeof(char *)) -
-	    roundup(execpath_len, sizeof(char *)) -
-	    roundup(ARG_MAX - imgp->args->stringspace, sizeof(char *));
+	destp = (uintptr_t)arginfo;
 
 	/* Install LINUX_PLATFORM. */
-	error = copyout(linux_kplatform, ((caddr_t)arginfo - linux_szplatform),
-	    linux_szplatform);
+	destp -= linux_szplatform;
+	destp = rounddown2(destp, sizeof(void *));
+	error = copyout(linux_kplatform, (void *)destp, linux_szplatform);
 	if (error != 0)
 		return (error);
 
 	if (execpath_len != 0) {
-		imgp->execpathp = (uintptr_t)arginfo -
-		linux_szplatform - execpath_len;
-		error = copyout(imgp->execpath, (void *)imgp->execpathp,
-		    execpath_len);
+		destp -= execpath_len;
+		destp = rounddown2(destp, sizeof(void *));
+		imgp->execpathp = destp;
+		error = copyout(imgp->execpath, (void *)destp, execpath_len);
 		if (error != 0)
 			return (error);
 	}
 
 	/* Prepare the canary for SSP. */
 	arc4rand(canary, sizeof(canary), 0);
-	imgp->canary = (uintptr_t)arginfo - linux_szplatform -
-	    roundup(execpath_len, sizeof(char *)) -
-	    roundup(sizeof(canary), sizeof(char *));
-	error = copyout(canary, (void *)imgp->canary, sizeof(canary));
+	destp -= roundup(sizeof(canary), sizeof(void *));
+	imgp->canary = destp;
+	error = copyout(canary, (void *)destp, sizeof(canary));
 	if (error != 0)
 		return (error);
 
-	vectp = (char **)destp;
+	/* Allocate room for the argument and environment strings. */
+	destp -= ARG_MAX - imgp->args->stringspace;
+	destp = rounddown2(destp, sizeof(void *));
+	ustringp = destp;
+
 	if (imgp->auxargs) {
-		error = imgp->sysent->sv_copyout_auxargs(imgp,
-		    (u_long *)&vectp);
+		error = imgp->sysent->sv_copyout_auxargs(imgp, &destp);
 		if (error != 0)
 			return (error);
 	}
 
+	vectp = (char **)destp;
+
 	/*
 	 * Allocate room for the argv[] and env vectors including the
 	 * terminating NULL pointers.
@@ -329,14 +337,15 @@ linux_copyout_strings(struct image_params *imgp, register_t **stack_base)
 	vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
 
 	/* vectp also becomes our initial stack base. */
-	*stack_base = (register_t *)vectp;
+	*stack_base = (uintptr_t)vectp;
 
 	stringp = imgp->args->begin_argv;
 	argc = imgp->args->argc;
 	envc = imgp->args->envc;
 
 	/* Copy out strings - arguments and environment. */
-	error = copyout(stringp, destp, ARG_MAX - imgp->args->stringspace);
+	error = copyout(stringp, (void *)ustringp,
+	    ARG_MAX - imgp->args->stringspace);
 	if (error != 0)
 		return (error);
 
@@ -347,11 +356,11 @@ linux_copyout_strings(struct image_params *imgp, register_t **stack_base)
 
 	/* Fill in argument portion of vector table. */
 	for (; argc > 0; --argc) {
-		if (suword(vectp++, (long)(intptr_t)destp) != 0)
+		if (suword(vectp++, ustringp) != 0)
 			return (EFAULT);
 		while (*stringp++ != 0)
-			destp++;
-		destp++;
+			ustringp++;
+		ustringp++;
 	}
 
 	/* A null vector table pointer separates the argp's from the envp's. */
@@ -364,11 +373,11 @@ linux_copyout_strings(struct image_params *imgp, register_t **stack_base)
 
 	/* Fill in environment portion of vector table. */
 	for (; envc > 0; --envc) {
-		if (suword(vectp++, (long)(intptr_t)destp) != 0)
+		if (suword(vectp++, ustringp) != 0)
 			return (EFAULT);
 		while (*stringp++ != 0)
-			destp++;
-		destp++;
+			ustringp++;
+		ustringp++;
 	}
 
 	/* The end of the vector table is a null pointer. */
@@ -781,7 +790,8 @@ linux_fetch_syscall_args(struct thread *td)
  * override the exec_setregs default(s) here.
  */
 static void
-linux_exec_setregs(struct thread *td, struct image_params *imgp, u_long stack)
+linux_exec_setregs(struct thread *td, struct image_params *imgp,
+    uintptr_t stack)
 {
 	struct pcb *pcb = td->td_pcb;