freebsd-dev/sys/compat/linux/linux_mmap.c
Matt Macy cbd92ce62e Eliminate the overhead of gratuitous repeated reinitialization of cap_rights
- Add macros to allow preinitialization of cap_rights_t.

- Convert most commonly used code paths to use preinitialized cap_rights_t.
  A 3.6% speedup in fstat was measured with this change.

Reported by:	mjg
Reviewed by:	oshogbo
Approved by:	sbruno
MFC after:	1 month
2018-05-09 18:47:24 +00:00

251 lines
7.5 KiB
C

/*-
* Copyright (c) 2004 Tim J. Robbins
* Copyright (c) 2002 Doug Rabson
* Copyright (c) 2000 Marcel Moolenaar
* Copyright (c) 1994-1995 Søren Schmidt
* All rights reserved.
*
* 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, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/capsicum.h>
#include <sys/file.h>
#include <sys/imgact.h>
#include <sys/ktr.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_mmap.h>
#include <compat/linux/linux_persona.h>
#include <compat/linux/linux_util.h>
#define STACK_SIZE (2 * 1024 * 1024)
#define GUARD_SIZE (4 * PAGE_SIZE)
#if defined(__amd64__)
static void linux_fixup_prot(struct thread *td, int *prot);
#endif
int
linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
int flags, int fd, off_t pos)
{
struct proc *p = td->td_proc;
struct vmspace *vms = td->td_proc->p_vmspace;
int bsd_flags, error;
struct file *fp;
LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
addr, len, prot, flags, fd, pos);
error = 0;
bsd_flags = 0;
fp = NULL;
/*
* Linux mmap(2):
* You must specify exactly one of MAP_SHARED and MAP_PRIVATE
*/
if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
return (EINVAL);
if (flags & LINUX_MAP_SHARED)
bsd_flags |= MAP_SHARED;
if (flags & LINUX_MAP_PRIVATE)
bsd_flags |= MAP_PRIVATE;
if (flags & LINUX_MAP_FIXED)
bsd_flags |= MAP_FIXED;
if (flags & LINUX_MAP_ANON) {
/* Enforce pos to be on page boundary, then ignore. */
if ((pos & PAGE_MASK) != 0)
return (EINVAL);
pos = 0;
bsd_flags |= MAP_ANON;
} else
bsd_flags |= MAP_NOSYNC;
if (flags & LINUX_MAP_GROWSDOWN)
bsd_flags |= MAP_STACK;
/*
* PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
* on Linux/i386 if the binary requires executable stack.
* We do this only for IA32 emulation as on native i386 this is does not
* make sense without PAE.
*
* XXX. Linux checks that the file system is not mounted with noexec.
*/
#if defined(__amd64__)
linux_fixup_prot(td, &prot);
#endif
/* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
fd = (bsd_flags & MAP_ANON) ? -1 : fd;
if (fd != -1) {
/*
* Linux follows Solaris mmap(2) description:
* The file descriptor fildes is opened with
* read permission, regardless of the
* protection options specified.
*/
error = fget(td, fd, &cap_mmap_rights, &fp);
if (error != 0)
return (error);
if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_DEV) {
fdrop(fp, td);
return (EINVAL);
}
/* Linux mmap() just fails for O_WRONLY files */
if (!(fp->f_flag & FREAD)) {
fdrop(fp, td);
return (EACCES);
}
fdrop(fp, td);
}
if (flags & LINUX_MAP_GROWSDOWN) {
/*
* The Linux MAP_GROWSDOWN option does not limit auto
* growth of the region. Linux mmap with this option
* takes as addr the initial BOS, and as len, the initial
* region size. It can then grow down from addr without
* limit. However, Linux threads has an implicit internal
* limit to stack size of STACK_SIZE. Its just not
* enforced explicitly in Linux. But, here we impose
* a limit of (STACK_SIZE - GUARD_SIZE) on the stack
* region, since we can do this with our mmap.
*
* Our mmap with MAP_STACK takes addr as the maximum
* downsize limit on BOS, and as len the max size of
* the region. It then maps the top SGROWSIZ bytes,
* and auto grows the region down, up to the limit
* in addr.
*
* If we don't use the MAP_STACK option, the effect
* of this code is to allocate a stack region of a
* fixed size of (STACK_SIZE - GUARD_SIZE).
*/
if ((caddr_t)addr + len > vms->vm_maxsaddr) {
/*
* Some Linux apps will attempt to mmap
* thread stacks near the top of their
* address space. If their TOS is greater
* than vm_maxsaddr, vm_map_growstack()
* will confuse the thread stack with the
* process stack and deliver a SEGV if they
* attempt to grow the thread stack past their
* current stacksize rlimit. To avoid this,
* adjust vm_maxsaddr upwards to reflect
* the current stacksize rlimit rather
* than the maximum possible stacksize.
* It would be better to adjust the
* mmap'ed region, but some apps do not check
* mmap's return value.
*/
PROC_LOCK(p);
vms->vm_maxsaddr = (char *)p->p_sysent->sv_usrstack -
lim_cur_proc(p, RLIMIT_STACK);
PROC_UNLOCK(p);
}
/*
* This gives us our maximum stack size and a new BOS.
* If we're using VM_STACK, then mmap will just map
* the top SGROWSIZ bytes, and let the stack grow down
* to the limit at BOS. If we're not using VM_STACK
* we map the full stack, since we don't have a way
* to autogrow it.
*/
if (len <= STACK_SIZE - GUARD_SIZE) {
addr = addr - (STACK_SIZE - GUARD_SIZE - len);
len = STACK_SIZE - GUARD_SIZE;
}
}
/*
* FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
* passed. However, some Linux applications, like the ART runtime,
* depend on the hint. If the MAP_FIXED wasn't passed, but the
* address is not zero, try with MAP_FIXED and MAP_EXCL first,
* and fall back to the normal behaviour if that fails.
*/
if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
(bsd_flags & MAP_EXCL) == 0) {
error = kern_mmap(td, addr, len, prot,
bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos);
if (error == 0)
goto out;
}
error = kern_mmap(td, addr, len, prot, bsd_flags, fd, pos);
out:
LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
return (error);
}
int
linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
{
#if defined(__amd64__)
linux_fixup_prot(td, &prot);
#endif
return (kern_mprotect(td, addr, len, prot));
}
#if defined(__amd64__)
static void
linux_fixup_prot(struct thread *td, int *prot)
{
struct linux_pemuldata *pem;
if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
pem = pem_find(td->td_proc);
if (pem->persona & LINUX_READ_IMPLIES_EXEC)
*prot |= PROT_EXEC;
}
}
#endif