From: David Howells Make the futex code compilable and usable on NOMMU by making the attempt to handle page faults conditional on CONFIG_MMU. If this is not enabled, then we can assume that EFAULT returned from futex_atomic_op_inuser() is not recoverable, and that the address lies outside of valid memory. handle_mm_fault() is made to BUG if called on NOMMU without attempting to invoke the actual handler (__handle_mm_fault). Signed-off-by: David Howells Signed-off-by: Andrew Morton --- include/linux/mm.h | 22 +++++++++++++++++++--- kernel/futex.c | 7 +++++++ 2 files changed, 26 insertions(+), 3 deletions(-) diff -puN include/linux/mm.h~frv-make-futex-code-compilable-on-nommu include/linux/mm.h --- devel/include/linux/mm.h~frv-make-futex-code-compilable-on-nommu 2005-12-22 05:08:57.000000000 -0800 +++ devel-akpm/include/linux/mm.h 2005-12-22 05:08:57.000000000 -0800 @@ -717,12 +717,28 @@ extern int vmtruncate(struct inode * ino extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end); extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot); extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot); -extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access); -static inline int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, int write_access) +#ifdef CONFIG_MMU +extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, + unsigned long address, int write_access); + +static inline int handle_mm_fault(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long address, + int write_access) { - return __handle_mm_fault(mm, vma, address, write_access) & (~VM_FAULT_WRITE); + return __handle_mm_fault(mm, vma, address, write_access) & + (~VM_FAULT_WRITE); } +#else +static inline int handle_mm_fault(struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long address, + int write_access) +{ + /* should never happen if there's no MMU */ + BUG(); + return VM_FAULT_SIGBUS; +} +#endif extern int make_pages_present(unsigned long addr, unsigned long end); extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); diff -puN kernel/futex.c~frv-make-futex-code-compilable-on-nommu kernel/futex.c --- devel/kernel/futex.c~frv-make-futex-code-compilable-on-nommu 2005-12-22 05:08:57.000000000 -0800 +++ devel-akpm/kernel/futex.c 2005-12-22 05:08:57.000000000 -0800 @@ -350,6 +350,13 @@ retry: if (bh1 != bh2) spin_unlock(&bh2->lock); +#ifndef CONFIG_MMU + /* we don't get EFAULT from MMU faults if we don't have an MMU, + * but we might get them from range checking */ + ret = op_ret; + goto out; +#endif + if (unlikely(op_ret != -EFAULT)) { ret = op_ret; goto out; _