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Add shm_create_largepage(3) helper for creation and configuration of

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largepage shm objects.

And since we can, add memfd_create(MFD_HUGETLB) support, hopefully
close enough to the Linux feature.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D24652
This commit is contained in:
Konstantin Belousov 2020-09-09 22:20:36 +00:00
parent 1352798db3
commit 3ef55e8f25
2 changed files with 109 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lib/libc/sys/Symbol.map
View File

@ -411,6 +411,7 @@ FBSD_1.6 {
getfhat;
funlinkat;
memfd_create;
shm_create_largepage;
shm_rename;
};
@ -919,6 +920,7 @@ FBSDprivate_1.0 {
__sys_setuid;
_shm_open;
__sys_shm_open;
__sys_shm_open2;
_shm_unlink;
__sys_shm_unlink;
_shmat;

115
lib/libc/sys/shm_open.c
View File

@ -31,14 +31,17 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/param.h>
#include <sys/filio.h>
#include <sys/mman.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "libc_private.h"
@ -54,6 +57,51 @@ shm_open(const char *path, int flags, mode_t mode)
return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0, NULL));
}
int
shm_create_largepage(const char *path, int flags, int psind, int alloc_policy,
mode_t mode)
{
struct shm_largepage_conf slc;
int error, fd, saved_errno;
fd = __sys_shm_open2(path, flags | O_CREAT, mode, SHM_LARGEPAGE, NULL);
if (error == -1)
return (-1);
memset(&slc, 0, sizeof(slc));
slc.psind = psind;
slc.alloc_policy = alloc_policy;
error = ioctl(fd, FIOSSHMLPGCNF, &slc);
if (error == -1) {
saved_errno = errno;
close(fd);
errno = saved_errno;
return (-1);
}
return (fd);
}
#define K(x) ((size_t)(x) * 1024)
#define M(x) (K(x) * 1024)
#define G(x) (M(x) * 1024)
static const struct {
int mask;
size_t pgsize;
} mfd_huge_sizes[] = {
{ .mask = MFD_HUGE_64KB, .pgsize = K(64) },
{ .mask = MFD_HUGE_512KB, .pgsize = K(512) },
{ .mask = MFD_HUGE_1MB, .pgsize = M(1) },
{ .mask = MFD_HUGE_2MB, .pgsize = M(2) },
{ .mask = MFD_HUGE_8MB, .pgsize = M(8) },
{ .mask = MFD_HUGE_16MB, .pgsize = M(16) },
{ .mask = MFD_HUGE_32MB, .pgsize = M(32) },
{ .mask = MFD_HUGE_256MB, .pgsize = M(256) },
{ .mask = MFD_HUGE_512MB, .pgsize = M(512) },
{ .mask = MFD_HUGE_1GB, .pgsize = G(1) },
{ .mask = MFD_HUGE_2GB, .pgsize = G(2) },
{ .mask = MFD_HUGE_16GB, .pgsize = G(16) },
};
/*
* 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
@ -63,8 +111,9 @@ int
memfd_create(const char *name, unsigned int flags)
{
char memfd_name[NAME_MAX + 1];
size_t namelen;
int oflags, shmflags;
size_t namelen, *pgs;
struct shm_largepage_conf slc;
int error, fd, i, npgs, oflags, pgidx, saved_errno, shmflags;
if (name == NULL)
return (EBADF);
@ -75,11 +124,9 @@ memfd_create(const char *name, unsigned int flags)
MFD_HUGE_MASK)) != 0)
return (EINVAL);
/* Size specified but no HUGETLB. */
if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0)
if (((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0) ||
__bitcount(flags & MFD_HUGE_MASK) > 1)
return (EINVAL);
/* We don't actually support HUGETLB. */
if ((flags & MFD_HUGETLB) != 0)
return (ENOSYS);
/* We've already validated that we're sufficiently sized. */
snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
@ -89,5 +136,57 @@ memfd_create(const char *name, unsigned int flags)
oflags |= O_CLOEXEC;
if ((flags & MFD_ALLOW_SEALING) != 0)
shmflags |= SHM_ALLOW_SEALING;
return (__sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name));
if ((flags & MFD_HUGETLB) == 0)
shmflags |= SHM_LARGEPAGE;
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;
if ((flags & MFD_HUGE_MASK) == 0) {
if (npgs == 1) {
errno = EOPNOTSUPP;
goto clean;
}
pgidx = 1;
} else {
for (i = 0; i < nitems(mfd_huge_sizes); i++) {
if (mfd_huge_sizes[i].mask == (flags & MFD_HUGE_MASK))
break;
}
for (pgidx = 0; pgidx < npgs; pgidx++) {
if (mfd_huge_sizes[i].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);
}