git: 1562fe492a79 - stable/13 - exec: Simplify sv_copyout_strings implementations a bit

From: Mark Johnston <markj_at_FreeBSD.org>
Date: Fri, 14 Jan 2022 13:50:17 UTC
The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=1562fe492a7994bacefe4d0a6f6f91fa37972e79

commit 1562fe492a7994bacefe4d0a6f6f91fa37972e79
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2021-12-31 17:50:15 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-01-14 13:50:06 +0000

    exec: Simplify sv_copyout_strings implementations a bit
    
    Simplify control flow around handling of the execpath length and signal
    trampoline.  Cache the sysentvec pointer in a local variable.
    
    No functional change intended.
    
    Reviewed by:    kib
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit f04a096049382637178b54ffb45089f5f9fb3db9)
---
 sys/amd64/linux/linux_sysvec.c        |  9 ++------
 sys/amd64/linux32/linux32_sysvec.c    |  9 ++------
 sys/arm64/linux/linux_sysvec.c        |  9 ++------
 sys/compat/freebsd32/freebsd32_misc.c | 28 +++++++++---------------
 sys/i386/linux/linux_sysvec.c         |  8 ++-----
 sys/kern/kern_exec.c                  | 40 +++++++++++++----------------------
 6 files changed, 33 insertions(+), 70 deletions(-)

diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index e02221c324ec..03e17d851a8d 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -327,17 +327,12 @@ linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	size_t execpath_len;
 	struct proc *p;
 
-	/* Calculate string base and vector table pointers. */
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
-
 	p = imgp->proc;
 	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
 	destp = (uintptr_t)arginfo;
 
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		destp = rounddown2(destp, sizeof(void *));
 		imgp->execpathp = (void *)destp;
diff --git a/sys/amd64/linux32/linux32_sysvec.c b/sys/amd64/linux32/linux32_sysvec.c
index 9a8f86ecce10..2e65763062e3 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -740,16 +740,11 @@ linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	char canary[LINUX_AT_RANDOM_LEN];
 	size_t execpath_len;
 
-	/* Calculate string base and vector table pointers. */
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
-
 	arginfo = (struct linux32_ps_strings *)LINUX32_PS_STRINGS;
 	destp = (uintptr_t)arginfo;
 
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		destp = rounddown2(destp, sizeof(uint32_t));
 		imgp->execpathp = (void *)destp;
diff --git a/sys/arm64/linux/linux_sysvec.c b/sys/arm64/linux/linux_sysvec.c
index 30938251acd9..50bd53d4b08c 100644
--- a/sys/arm64/linux/linux_sysvec.c
+++ b/sys/arm64/linux/linux_sysvec.c
@@ -231,17 +231,12 @@ linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	struct proc *p;
 	int argc, envc, error;
 
-	/* Calculate string base and vector table pointers. */
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
-
 	p = imgp->proc;
 	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
 	destp = (uintptr_t)arginfo;
 
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		destp = rounddown2(destp, sizeof(void *));
 		imgp->execpathp = (void *)destp;
diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
index db707fdbf44d..5e70a3194c1a 100644
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -3340,6 +3340,7 @@ syscall32_helper_unregister(struct syscall_helper_data *sd)
 int
 freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 {
+	struct sysentvec *sysent;
 	int argc, envc, i;
 	u_int32_t *vectp;
 	char *stringp;
@@ -3350,30 +3351,20 @@ freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	size_t execpath_len;
 	int error, szsigcode;
 
-	/*
-	 * Calculate string base and vector table pointers.
-	 * Also deal with signal trampoline code for this exec type.
-	 */
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
-	arginfo = (struct freebsd32_ps_strings *)curproc->p_sysent->
-	    sv_psstrings;
+	sysent = imgp->sysent;
+
+	arginfo = (struct freebsd32_ps_strings *)sysent->sv_psstrings;
 	imgp->ps_strings = arginfo;
-	if (imgp->proc->p_sysent->sv_sigcode_base == 0)
-		szsigcode = *(imgp->proc->p_sysent->sv_szsigcode);
-	else
-		szsigcode = 0;
 	destp =	(uintptr_t)arginfo;
 
 	/*
-	 * install sigcode
+	 * Install sigcode.
 	 */
-	if (szsigcode != 0) {
+	if (sysent->sv_sigcode_base == 0) {
+		szsigcode = *sysent->sv_szsigcode;
 		destp -= szsigcode;
 		destp = rounddown2(destp, sizeof(uint32_t));
-		error = copyout(imgp->proc->p_sysent->sv_sigcode, (void *)destp,
+		error = copyout(sysent->sv_sigcode, (void *)destp,
 		    szsigcode);
 		if (error != 0)
 			return (error);
@@ -3382,7 +3373,8 @@ freebsd32_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	/*
 	 * Copy the image path for the rtld.
 	 */
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		imgp->execpathp = (void *)destp;
 		error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 045c82aaf681..20108f37584f 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -277,12 +277,7 @@ linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	size_t execpath_len;
 	struct proc *p;
 
-	/* Calculate string base and vector table pointers. */
 	p = imgp->proc;
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
 	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
 	destp = (uintptr_t)arginfo;
 
@@ -293,7 +288,8 @@ linux_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	if (error != 0)
 		return (error);
 
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		destp = rounddown2(destp, sizeof(void *));
 		imgp->execpathp = (void *)destp;
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index 612797c2e075..2031f8b46ef9 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1690,37 +1690,26 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	uintptr_t destp, ustringp;
 	struct ps_strings *arginfo;
 	struct proc *p;
+	struct sysentvec *sysent;
 	size_t execpath_len;
-	int error, szsigcode, szps;
+	int error, szsigcode;
 	char canary[sizeof(long) * 8];
 
-	szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
-	/*
-	 * Calculate string base and vector table pointers.
-	 * Also deal with signal trampoline code for this exec type.
-	 */
-	if (imgp->execpath != NULL && imgp->auxargs != NULL)
-		execpath_len = strlen(imgp->execpath) + 1;
-	else
-		execpath_len = 0;
 	p = imgp->proc;
-	szsigcode = 0;
-	arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
-	imgp->ps_strings = arginfo;
-	if (p->p_sysent->sv_sigcode_base == 0) {
-		if (p->p_sysent->sv_szsigcode != NULL)
-			szsigcode = *(p->p_sysent->sv_szsigcode);
-	}
+	sysent = p->p_sysent;
+
+	arginfo = (struct ps_strings *)sysent->sv_psstrings;
 	destp =	(uintptr_t)arginfo;
+	imgp->ps_strings = arginfo;
 
 	/*
-	 * install sigcode
+	 * Install sigcode.
 	 */
-	if (szsigcode != 0) {
+	if (sysent->sv_sigcode_base == 0 && sysent->sv_szsigcode != NULL) {
+		szsigcode = *(sysent->sv_szsigcode);
 		destp -= szsigcode;
 		destp = rounddown2(destp, sizeof(void *));
-		error = copyout(p->p_sysent->sv_sigcode, (void *)destp,
-		    szsigcode);
+		error = copyout(sysent->sv_sigcode, (void *)destp, szsigcode);
 		if (error != 0)
 			return (error);
 	}
@@ -1728,7 +1717,8 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	/*
 	 * Copy the image path for the rtld.
 	 */
-	if (execpath_len != 0) {
+	if (imgp->execpath != NULL && imgp->auxargs != NULL) {
+		execpath_len = strlen(imgp->execpath) + 1;
 		destp -= execpath_len;
 		destp = rounddown2(destp, sizeof(void *));
 		imgp->execpathp = (void *)destp;
@@ -1751,13 +1741,13 @@ exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
 	/*
 	 * Prepare the pagesizes array.
 	 */
-	destp -= szps;
+	imgp->pagesizeslen = sizeof(pagesizes[0]) * MAXPAGESIZES;
+	destp -= imgp->pagesizeslen;
 	destp = rounddown2(destp, sizeof(void *));
 	imgp->pagesizes = (void *)destp;
-	error = copyout(pagesizes, imgp->pagesizes, szps);
+	error = copyout(pagesizes, imgp->pagesizes, imgp->pagesizeslen);
 	if (error != 0)
 		return (error);
-	imgp->pagesizeslen = szps;
 
 	/*
 	 * Allocate room for the argument and environment strings.