Messages in this thread Patch in this message | | | Subject | [patch 05/18] remap_file_pages protection support: enhance syscall interface | From | blaisorblade@yahoo ... | Date | Fri, 26 Aug 2005 18:53:14 +0200 |
| |
From: Ingo Molnar <mingo@elte.hu>, Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
This contains simply the changes to the syscall code, based on Ingo's patch. Differently from his one, I've *not* added a new syscall, choosing to add a new flag (MAP_NOINHERIT) which the application must specify to get the new behavior (prot != 0 is accepted and prot == 0 means PROT_NONE).
Enable the 'prot' parameter for shared-writable mappings (the ones which are the primary target for remap_file_pages), without breaking up the vma.
*** remap_file_pages protection support: use EOVERFLOW ret code
Use -EOVERFLOW ("Value too large for defined data type") rather than -EINVAL when we cannot store the file offset in the PTE.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> ---
linux-2.6.git-paolo/mm/fremap.c | 40 +++++++++++++++++++++++++++++++--------- 1 files changed, 31 insertions(+), 9 deletions(-)
diff -puN mm/fremap.c~rfp-enhance-syscall mm/fremap.c --- linux-2.6.git/mm/fremap.c~rfp-enhance-syscall 2005-08-24 20:55:35.000000000 +0200 +++ linux-2.6.git-paolo/mm/fremap.c 2005-08-24 20:56:49.000000000 +0200 @@ -4,6 +4,10 @@ * Explicit pagetable population and nonlinear (random) mappings support. * * started by Ingo Molnar, Copyright (C) 2002, 2003 + * + * support of nonuniform remappings: + * Copyright (C) 2004 Ingo Molnar + * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso */ #include <linux/mm.h> @@ -164,18 +168,14 @@ err_unlock: * file within an existing vma. * @start: start of the remapped virtual memory range * @size: size of the remapped virtual memory range - * @prot: new protection bits of the range + * @prot: new protection bits of the range, must be 0 if not using MAP_NOINHERIT * @pgoff: to be mapped page of the backing store file - * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO. + * @flags: bits MAP_NOINHERIT or MAP_NONBLOCKED - the later will cause no IO. * * this syscall works purely via pagetables, so it's the most efficient * way to map the same (large) file into a given virtual window. Unlike * mmap()/mremap() it does not create any new vmas. The new mappings are * also safe across swapout. - * - * NOTE: the 'prot' parameter right now is ignored, and the vma's default - * protection is used. Arbitrary protections might be implemented in the - * future. */ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, unsigned long prot, unsigned long pgoff, unsigned long flags) @@ -188,7 +188,7 @@ asmlinkage long sys_remap_file_pages(uns int has_write_lock = 0; pgprot_t pgprot; - if (prot) + if (prot && !(flags & MAP_NOINHERIT)) goto out; /* * Sanitize the syscall parameters: @@ -203,7 +203,7 @@ asmlinkage long sys_remap_file_pages(uns /* Can we represent this offset inside this architecture's pte's? */ #if PTE_FILE_MAX_BITS < BITS_PER_LONG if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS)) - return err; + return -EOVERFLOW; #endif /* We need down_write() to change vma->vm_flags. */ @@ -228,7 +228,18 @@ retry: vma->vm_start || end > vma->vm_end) goto out_unlock; - pgprot = vma->vm_page_prot; + if (flags & MAP_NOINHERIT) { + err = -EPERM; + if (((prot & PROT_READ) && !(vma->vm_flags & VM_MAYREAD))) + goto out_unlock; + if (((prot & PROT_WRITE) && !(vma->vm_flags & VM_MAYWRITE))) + goto out_unlock; + if (((prot & PROT_EXEC) && !(vma->vm_flags & VM_MAYEXEC))) + goto out_unlock; + err = -EINVAL; + pgprot = protection_map[calc_vm_prot_bits(prot) | VM_SHARED]; + } else + pgprot = vma->vm_page_prot; if (!vma->vm_private_data || (vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) { @@ -251,6 +262,17 @@ retry: spin_unlock(&mapping->i_mmap_lock); } + if (pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot) && + !(vma->vm_flags & VM_NONUNIFORM)) { + if (!has_write_lock) { + up_read(&mm->mmap_sem); + down_write(&mm->mmap_sem); + has_write_lock = 1; + goto retry; + } + vma->vm_flags |= VM_NONUNIFORM; + } + /* Do NOT hold the write lock while doing any I/O, nor when * iterating over too many PTEs. Values might need tuning. */ if (has_write_lock && (!(flags & MAP_NONBLOCK) || size > INSTALL_SIZE)) { _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |