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)
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parent
58f9394c50
commit
2801687d56
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=223889
@ -64,6 +64,8 @@ __FBSDID("$FreeBSD$");
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SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
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"Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
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static int uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault);
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#ifdef ZERO_COPY_SOCKETS
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/* Declared in uipc_socket.c */
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extern int so_zero_copy_receive;
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@ -128,24 +130,66 @@ vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
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}
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#endif /* ZERO_COPY_SOCKETS */
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int
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copyin_nofault(const void *udaddr, void *kaddr, size_t len)
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{
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int error, save;
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save = vm_fault_disable_pagefaults();
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error = copyin(udaddr, kaddr, len);
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vm_fault_enable_pagefaults(save);
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return (error);
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}
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int
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copyout_nofault(const void *kaddr, void *udaddr, size_t len)
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{
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int error, save;
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save = vm_fault_disable_pagefaults();
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error = copyout(kaddr, udaddr, len);
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vm_fault_enable_pagefaults(save);
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return (error);
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}
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int
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uiomove(void *cp, int n, struct uio *uio)
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{
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struct thread *td = curthread;
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return (uiomove_faultflag(cp, n, uio, 0));
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}
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int
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uiomove_nofault(void *cp, int n, struct uio *uio)
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{
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return (uiomove_faultflag(cp, n, uio, 1));
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}
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static int
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uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
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{
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struct thread *td;
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struct iovec *iov;
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u_int cnt;
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int error = 0;
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int save = 0;
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int error, newflags, save;
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td = curthread;
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error = 0;
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KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
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("uiomove: mode"));
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == td,
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("uiomove proc"));
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
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"Calling uiomove()");
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if (!nofault)
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
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"Calling uiomove()");
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save = td->td_pflags & TDP_DEADLKTREAT;
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td->td_pflags |= TDP_DEADLKTREAT;
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/* XXX does it make a sense to set TDP_DEADLKTREAT for UIO_SYSSPACE ? */
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newflags = TDP_DEADLKTREAT;
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if (uio->uio_segflg == UIO_USERSPACE && nofault)
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newflags |= TDP_NOFAULTING;
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save = curthread_pflags_set(newflags);
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while (n > 0 && uio->uio_resid) {
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iov = uio->uio_iov;
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@ -187,8 +231,7 @@ uiomove(void *cp, int n, struct uio *uio)
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n -= cnt;
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}
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out:
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if (save == 0)
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td->td_pflags &= ~TDP_DEADLKTREAT;
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curthread_pflags_restore(save);
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return (error);
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}
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@ -393,7 +393,7 @@ do { \
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#define TDP_COWINPROGRESS 0x00000010 /* Snapshot copy-on-write in progress. */
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#define TDP_ALTSTACK 0x00000020 /* Have alternate signal stack. */
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#define TDP_DEADLKTREAT 0x00000040 /* Lock aquisition - deadlock treatment. */
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#define TDP_UNUSED80 0x00000080 /* available. */
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#define TDP_NOFAULTING 0x00000080 /* Do not handle page faults. */
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#define TDP_NOSLEEPING 0x00000100 /* Thread is not allowed to sleep on a sq. */
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#define TDP_OWEUPC 0x00000200 /* Call addupc() at next AST. */
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#define TDP_ITHREAD 0x00000400 /* Thread is an interrupt thread. */
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@ -217,8 +217,12 @@ int copyinstr(const void * __restrict udaddr, void * __restrict kaddr,
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__nonnull(1) __nonnull(2);
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int copyin(const void * __restrict udaddr, void * __restrict kaddr,
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size_t len) __nonnull(1) __nonnull(2);
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int copyin_nofault(const void * __restrict udaddr, void * __restrict kaddr,
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size_t len) __nonnull(1) __nonnull(2);
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int copyout(const void * __restrict kaddr, void * __restrict udaddr,
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size_t len) __nonnull(1) __nonnull(2);
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int copyout_nofault(const void * __restrict kaddr, void * __restrict udaddr,
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size_t len) __nonnull(1) __nonnull(2);
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int fubyte(const void *base);
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long fuword(const void *base);
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@ -100,6 +100,7 @@ int uiomove(void *cp, int n, struct uio *uio);
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int uiomove_frombuf(void *buf, int buflen, struct uio *uio);
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int uiomove_fromphys(struct vm_page *ma[], vm_offset_t offset, int n,
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struct uio *uio);
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int uiomove_nofault(void *cp, int n, struct uio *uio);
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int uiomoveco(void *cp, int n, struct uio *uio, int disposable);
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#else /* !_KERNEL */
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@ -61,6 +61,8 @@ int useracc(void *, int, int);
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int vm_fault(vm_map_t, vm_offset_t, vm_prot_t, int);
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void vm_fault_copy_entry(vm_map_t, vm_map_t, vm_map_entry_t, vm_map_entry_t,
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vm_ooffset_t *);
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int vm_fault_disable_pagefaults(void);
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void vm_fault_enable_pagefaults(int save);
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int vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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int fault_flags, vm_page_t *m_hold);
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int vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
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@ -209,6 +209,8 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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int fault_flags)
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{
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if ((curthread->td_pflags & TDP_NOFAULTING) != 0)
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return (KERN_PROTECTION_FAILURE);
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return (vm_fault_hold(map, vaddr, fault_type, fault_flags, NULL));
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}
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@ -1475,3 +1477,17 @@ vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
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/* return number of pages */
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return i;
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}
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int
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vm_fault_disable_pagefaults(void)
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{
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return (curthread_pflags_set(TDP_NOFAULTING));
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}
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void
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vm_fault_enable_pagefaults(int save)
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{
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curthread_pflags_restore(save);
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}
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