Author: kib
Date: Sat Jul 9 15:21:10 2011
New Revision: 223889
URL: http://svn.freebsd.org/changeset/base/223889
Log:
Add a facility to disable processing page faults. When activated,
uiomove generates EFAULT if any accessed address is not mapped, as
opposed to handling the fault.
Sponsored by: The FreeBSD Foundation
Reviewed by: alc (previous version)
Modified:
head/sys/kern/subr_uio.c
head/sys/sys/proc.h
head/sys/sys/systm.h
head/sys/sys/uio.h
head/sys/vm/vm_extern.h
head/sys/vm/vm_fault.c
Modified: head/sys/kern/subr_uio.c
==============================================================================
--- head/sys/kern/subr_uio.c Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/kern/subr_uio.c Sat Jul 9 15:21:10 2011 (r223889)
@@ -64,6 +64,8 @@ __FBSDID("$FreeBSD$");
SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
"Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
+static int uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault);
+
#ifdef ZERO_COPY_SOCKETS
/* Declared in uipc_socket.c */
extern int so_zero_copy_receive;
@@ -129,23 +131,65 @@ retry:
#endif /* ZERO_COPY_SOCKETS */
int
+copyin_nofault(const void *udaddr, void *kaddr, size_t len)
+{
+ int error, save;
+
+ save = vm_fault_disable_pagefaults();
+ error = copyin(udaddr, kaddr, len);
+ vm_fault_enable_pagefaults(save);
+ return (error);
+}
+
+int
+copyout_nofault(const void *kaddr, void *udaddr, size_t len)
+{
+ int error, save;
+
+ save = vm_fault_disable_pagefaults();
+ error = copyout(kaddr, udaddr, len);
+ vm_fault_enable_pagefaults(save);
+ return (error);
+}
+
+int
uiomove(void *cp, int n, struct uio *uio)
{
- struct thread *td = curthread;
+
+ return (uiomove_faultflag(cp, n, uio, 0));
+}
+
+int
+uiomove_nofault(void *cp, int n, struct uio *uio)
+{
+
+ return (uiomove_faultflag(cp, n, uio, 1));
+}
+
+static int
+uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
+{
+ struct thread *td;
struct iovec *iov;
u_int cnt;
- int error = 0;
- int save = 0;
+ int error, newflags, save;
+
+ td = curthread;
+ error = 0;
KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
("uiomove: mode"));
- KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
+ KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == td,
("uiomove proc"));
- WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
- "Calling uiomove()");
-
- save = td->td_pflags & TDP_DEADLKTREAT;
- td->td_pflags |= TDP_DEADLKTREAT;
+ if (!nofault)
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
+ "Calling uiomove()");
+
+ /* XXX does it make a sense to set TDP_DEADLKTREAT for UIO_SYSSPACE ? */
+ newflags = TDP_DEADLKTREAT;
+ if (uio->uio_segflg == UIO_USERSPACE && nofault)
+ newflags |= TDP_NOFAULTING;
+ save = curthread_pflags_set(newflags);
while (n > 0 && uio->uio_resid) {
iov = uio->uio_iov;
@@ -187,8 +231,7 @@ uiomove(void *cp, int n, struct uio *uio
n -= cnt;
}
out:
- if (save == 0)
- td->td_pflags &= ~TDP_DEADLKTREAT;
+ curthread_pflags_restore(save);
return (error);
}
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/sys/proc.h Sat Jul 9 15:21:10 2011 (r223889)
@@ -393,7 +393,7 @@ do {
\
#define TDP_COWINPROGRESS 0x00000010 /* Snapshot copy-on-write in
progress. */
#define TDP_ALTSTACK 0x00000020 /* Have alternate signal stack. */
#define TDP_DEADLKTREAT 0x00000040 /* Lock aquisition - deadlock
treatment. */
-#define TDP_UNUSED80 0x00000080 /* available. */
+#define TDP_NOFAULTING 0x00000080 /* Do not handle page faults. */
#define TDP_NOSLEEPING 0x00000100 /* Thread is not allowed to sleep on
a sq. */
#define TDP_OWEUPC 0x00000200 /* Call addupc() at next AST. */
#define TDP_ITHREAD 0x00000400 /* Thread is an interrupt thread. */
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/sys/systm.h Sat Jul 9 15:21:10 2011 (r223889)
@@ -217,8 +217,12 @@ int copyinstr(const void * __restrict ud
__nonnull(1) __nonnull(2);
int copyin(const void * __restrict udaddr, void * __restrict kaddr,
size_t len) __nonnull(1) __nonnull(2);
+int copyin_nofault(const void * __restrict udaddr, void * __restrict kaddr,
+ size_t len) __nonnull(1) __nonnull(2);
int copyout(const void * __restrict kaddr, void * __restrict udaddr,
size_t len) __nonnull(1) __nonnull(2);
+int copyout_nofault(const void * __restrict kaddr, void * __restrict udaddr,
+ size_t len) __nonnull(1) __nonnull(2);
int fubyte(const void *base);
long fuword(const void *base);
Modified: head/sys/sys/uio.h
==============================================================================
--- head/sys/sys/uio.h Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/sys/uio.h Sat Jul 9 15:21:10 2011 (r223889)
@@ -100,6 +100,7 @@ int uiomove(void *cp, int n, struct uio
int uiomove_frombuf(void *buf, int buflen, struct uio *uio);
int uiomove_fromphys(struct vm_page *ma[], vm_offset_t offset, int n,
struct uio *uio);
+int uiomove_nofault(void *cp, int n, struct uio *uio);
int uiomoveco(void *cp, int n, struct uio *uio, int disposable);
#else /* !_KERNEL */
Modified: head/sys/vm/vm_extern.h
==============================================================================
--- head/sys/vm/vm_extern.h Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/vm/vm_extern.h Sat Jul 9 15:21:10 2011 (r223889)
@@ -61,6 +61,8 @@ int useracc(void *, int, int);
int vm_fault(vm_map_t, vm_offset_t, vm_prot_t, int);
void vm_fault_copy_entry(vm_map_t, vm_map_t, vm_map_entry_t, vm_map_entry_t,
vm_ooffset_t *);
+int vm_fault_disable_pagefaults(void);
+void vm_fault_enable_pagefaults(int save);
int vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
int fault_flags, vm_page_t *m_hold);
int vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c Sat Jul 9 15:16:07 2011 (r223888)
+++ head/sys/vm/vm_fault.c Sat Jul 9 15:21:10 2011 (r223889)
@@ -209,6 +209,8 @@ vm_fault(vm_map_t map, vm_offset_t vaddr
int fault_flags)
{
+ if ((curthread->td_pflags & TDP_NOFAULTING) != 0)
+ return (KERN_PROTECTION_FAILURE);
return (vm_fault_hold(map, vaddr, fault_type, fault_flags, NULL));
}
@@ -1475,3 +1477,17 @@ vm_fault_additional_pages(m, rbehind, ra
/* return number of pages */
return i;
}
+
+int
+vm_fault_disable_pagefaults(void)
+{
+
+ return (curthread_pflags_set(TDP_NOFAULTING));
+}
+
+void
+vm_fault_enable_pagefaults(int save)
+{
+
+ curthread_pflags_restore(save);
+}
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