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memfd_create: move implementation to libc/gen

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Due to memfd_create(3)'s construction of a path to pass to shm_open2(2),
it has a much larger than typical dependency footprint for a system
call wrapper (the list currently includes calloc, memset, sprintf, and
strlen).  As such, split it off into its own file under libc/gen to
lighten libc/sys's dependency list.

Reviewed by:	kevans, imp, emaste
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D42709

(cherry picked from commit c3207e2d2554c8e36f9cf5950f8cd52a19fedfd5)
This commit is contained in:
Brooks Davis 2023-11-27 17:06:33 +00:00
parent f6d8ea893b
commit 89ebe0ce1f
5 changed files with 133 additions and 94 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
lib/libc/gen/Makefile.inc
View file

@ -102,6 +102,7 @@ SRCS+= __getosreldate.c \
lockf.c \
lrand48.c \
memalign.c \
memfd_create.c \
mrand48.c \
nftw.c \
nftw-compat11.c \

1
lib/libc/gen/Symbol.map
View file

@ -433,6 +433,7 @@ FBSD_1.6 {
eventfd_write;
getlogin_r;
memalign;
memfd_create;
pthread_getname_np;
scandir_b;
sigandset;

131
lib/libc/gen/memfd_create.c Normal file
View file

@ -0,0 +1,131 @@
/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/param.h>
#include <sys/filio.h>
#include <sys/mman.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libc_private.h"
#define MEMFD_NAME_PREFIX "memfd:"
/*
* The path argument is passed to the kernel, but the kernel doesn't currently
* do anything with it. Linux exposes it in linprocfs for debugging purposes
* only, but our kernel currently will not do the same.
*/
int
memfd_create(const char *name, unsigned int flags)
{
char memfd_name[NAME_MAX + 1];
size_t namelen, *pgs, pgsize;
struct shm_largepage_conf slc;
int error, fd, npgs, oflags, pgidx, saved_errno, shmflags;
if (name == NULL) {
errno = EBADF;
return (-1);
}
namelen = strlen(name);
if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX) {
errno = EINVAL;
return (-1);
}
if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
MFD_HUGE_MASK)) != 0) {
errno = EINVAL;
return (-1);
}
/* Size specified but no HUGETLB. */
if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) {
errno = EINVAL;
return (-1);
}
/* We've already validated that we're sufficiently sized. */
snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
oflags = O_RDWR;
shmflags = 0;
if ((flags & MFD_CLOEXEC) != 0)
oflags |= O_CLOEXEC;
if ((flags & MFD_ALLOW_SEALING) != 0)
shmflags |= SHM_ALLOW_SEALING;
if ((flags & MFD_HUGETLB) != 0)
shmflags |= SHM_LARGEPAGE;
else
shmflags |= SHM_GROW_ON_WRITE;
fd = __sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name);
if (fd == -1 || (flags & MFD_HUGETLB) == 0)
return (fd);
pgs = NULL;
npgs = getpagesizes(NULL, 0);
if (npgs == -1)
goto clean;
pgs = calloc(npgs, sizeof(size_t));
if (pgs == NULL)
goto clean;
error = getpagesizes(pgs, npgs);
if (error == -1)
goto clean;
pgsize = (size_t)1 << ((flags & MFD_HUGE_MASK) >> MFD_HUGE_SHIFT);
for (pgidx = 0; pgidx < npgs; pgidx++) {
if (pgsize == pgs[pgidx])
break;
}
if (pgidx == npgs) {
errno = EOPNOTSUPP;
goto clean;
}
free(pgs);
pgs = NULL;
memset(&slc, 0, sizeof(slc));
slc.psind = pgidx;
slc.alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
error = ioctl(fd, FIOSSHMLPGCNF, &slc);
if (error == -1)
goto clean;
return (fd);
clean:
saved_errno = errno;
close(fd);
free(pgs);
errno = saved_errno;
return (-1);
}

1
lib/libc/sys/Symbol.map
View file

@ -409,7 +409,6 @@ FBSD_1.6 {
fhreadlink;
getfhat;
funlinkat;
memfd_create;
shm_create_largepage;
shm_rename;
};

93
lib/libc/sys/shm_open.c
View file

@ -34,9 +34,6 @@
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
@ -45,12 +42,9 @@
__weak_reference(shm_open, _shm_open);
__weak_reference(shm_open, __sys_shm_open);
#define MEMFD_NAME_PREFIX "memfd:"
int
shm_open(const char *path, int flags, mode_t mode)
{
return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0, NULL));
}
@ -77,90 +71,3 @@ shm_create_largepage(const char *path, int flags, int psind, int alloc_policy,
}
return (fd);
}
/*
* The path argument is passed to the kernel, but the kernel doesn't currently
* do anything with it. Linux exposes it in linprocfs for debugging purposes
* only, but our kernel currently will not do the same.
*/
int
memfd_create(const char *name, unsigned int flags)
{
char memfd_name[NAME_MAX + 1];
size_t namelen, *pgs, pgsize;
struct shm_largepage_conf slc;
int error, fd, npgs, oflags, pgidx, saved_errno, shmflags;
if (name == NULL) {
errno = EBADF;
return (-1);
}
namelen = strlen(name);
if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX) {
errno = EINVAL;
return (-1);
}
if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
MFD_HUGE_MASK)) != 0) {
errno = EINVAL;
return (-1);
}
/* Size specified but no HUGETLB. */
if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) {
errno = EINVAL;
return (-1);
}
/* We've already validated that we're sufficiently sized. */
snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
oflags = O_RDWR;
shmflags = 0;
if ((flags & MFD_CLOEXEC) != 0)
oflags |= O_CLOEXEC;
if ((flags & MFD_ALLOW_SEALING) != 0)
shmflags |= SHM_ALLOW_SEALING;
if ((flags & MFD_HUGETLB) != 0)
shmflags |= SHM_LARGEPAGE;
else
shmflags |= SHM_GROW_ON_WRITE;
fd = __sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name);
if (fd == -1 || (flags & MFD_HUGETLB) == 0)
return (fd);
pgs = NULL;
npgs = getpagesizes(NULL, 0);
if (npgs == -1)
goto clean;
pgs = calloc(npgs, sizeof(size_t));
if (pgs == NULL)
goto clean;
error = getpagesizes(pgs, npgs);
if (error == -1)
goto clean;
pgsize = (size_t)1 << ((flags & MFD_HUGE_MASK) >> MFD_HUGE_SHIFT);
for (pgidx = 0; pgidx < npgs; pgidx++) {
if (pgsize == pgs[pgidx])
break;
}
if (pgidx == npgs) {
errno = EOPNOTSUPP;
goto clean;
}
free(pgs);
pgs = NULL;
memset(&slc, 0, sizeof(slc));
slc.psind = pgidx;
slc.alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
error = ioctl(fd, FIOSSHMLPGCNF, &slc);
if (error == -1)
goto clean;
return (fd);
clean:
saved_errno = errno;
close(fd);
free(pgs);
errno = saved_errno;
return (-1);
}