int
linux_mmap2(struct thread *td, struct linux_mmap2_args *args)
{
struct proc *p = td->td_proc;
struct mmap_args /* {
caddr_t addr;
size_t len;
int prot;
int flags;
int fd;
long pad;
off_t pos;
} */ bsd_args;
int error;
struct file *fp;
cap_rights_t rights;
LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
args->addr, args->len, args->prot,
args->flags, args->fd, args->pgoff);
error = 0;
bsd_args.flags = 0;
fp = NULL;
/*
* Linux mmap(2):
* You must specify exactly one of MAP_SHARED and MAP_PRIVATE
*/
if (! ((args->flags & LINUX_MAP_SHARED) ^
(args->flags & LINUX_MAP_PRIVATE)))
return (EINVAL);
if (args->flags & LINUX_MAP_SHARED)
bsd_args.flags |= MAP_SHARED;
if (args->flags & LINUX_MAP_PRIVATE)
bsd_args.flags |= MAP_PRIVATE;
if (args->flags & LINUX_MAP_FIXED)
bsd_args.flags |= MAP_FIXED;
if (args->flags & LINUX_MAP_ANON)
bsd_args.flags |= MAP_ANON;
else
bsd_args.flags |= MAP_NOSYNC;
if (args->flags & LINUX_MAP_GROWSDOWN)
bsd_args.flags |= MAP_STACK;
/*
* PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
* on Linux/i386. We do this to ensure maximum compatibility.
* Linux/ia64 does the same in i386 emulation mode.
*/
bsd_args.prot = args->prot;
if (bsd_args.prot & (PROT_READ | PROT_WRITE | PROT_EXEC))
bsd_args.prot |= PROT_READ | PROT_EXEC;
/* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
bsd_args.fd = (bsd_args.flags & MAP_ANON) ? -1 : args->fd;
if (bsd_args.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, bsd_args.fd,
cap_rights_init(&rights, CAP_MMAP), &fp);
if (error != 0 )
return (error);
if (fp->f_type != DTYPE_VNODE) {
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 (args->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 inital 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)PTRIN(args->addr) + args->len >
p->p_vmspace->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);
p->p_vmspace->vm_maxsaddr = (char *)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 (args->len > STACK_SIZE - GUARD_SIZE) {
bsd_args.addr = (caddr_t)PTRIN(args->addr);
bsd_args.len = args->len;
} else {
bsd_args.addr = (caddr_t)PTRIN(args->addr) -
(STACK_SIZE - GUARD_SIZE - args->len);
bsd_args.len = STACK_SIZE - GUARD_SIZE;
}
} else {
bsd_args.addr = (caddr_t)PTRIN(args->addr);
bsd_args.len = args->len;
}
bsd_args.pos = (off_t)args->pgoff;
error = sys_mmap(td, &bsd_args);
LINUX_CTR2(mmap2, "return: %d (%p)",
error, td->td_retval[0]);
return (error);
}
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;
struct mmap_args /* {
caddr_t addr;
size_t len;
int prot;
int flags;
int fd;
off_t pos;
} */ bsd_args;
int error;
struct file *fp;
cap_rights_t rights;
LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
addr, len, prot, flags, fd, pos);
error = 0;
bsd_args.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_args.flags |= MAP_SHARED;
if (flags & LINUX_MAP_PRIVATE)
bsd_args.flags |= MAP_PRIVATE;
if (flags & LINUX_MAP_FIXED)
bsd_args.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_args.flags |= MAP_ANON;
} else
bsd_args.flags |= MAP_NOSYNC;
if (flags & LINUX_MAP_GROWSDOWN)
bsd_args.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.
*/
bsd_args.prot = prot;
#if defined(__amd64__)
linux_fixup_prot(td, &bsd_args.prot);
#endif
/* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
bsd_args.fd = (bsd_args.flags & MAP_ANON) ? -1 : fd;
if (bsd_args.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, bsd_args.fd,
cap_rights_init(&rights, CAP_MMAP), &fp);
if (error != 0)
return (error);
if (fp->f_type != DTYPE_VNODE) {
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) {
bsd_args.addr = (caddr_t)addr;
bsd_args.len = len;
} else {
bsd_args.addr = (caddr_t)addr -
(STACK_SIZE - GUARD_SIZE - len);
bsd_args.len = STACK_SIZE - GUARD_SIZE;
}
} else {
bsd_args.addr = (caddr_t)addr;
bsd_args.len = len;
}
bsd_args.pos = pos;
error = sys_mmap(td, &bsd_args);
LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
return (error);
}
