On Thu, Jan 31, 2019 at 08:38:12AM +0530, Souptick Joarder wrote: > Previouly drivers have their own way of mapping range of > kernel pages/memory into user vma and this was done by > invoking vm_insert_page() within a loop. > > As this pattern is common across different drivers, it can > be generalized by creating new functions and use it across > the drivers. > > vm_insert_range() is the API which could be used to mapped > kernel memory/pages in drivers which has considered vm_pgoff > > vm_insert_range_buggy() is the API which could be used to map > range of kernel memory/pages in drivers which has not considered > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > > We _could_ then at a later "fix" these drivers which are using > vm_insert_range_buggy() to behave according to the normal vm_pgoff > offsetting simply by removing the _buggy suffix on the function > name and if that causes regressions, it gives us an easy way to revert. > > Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx> > Suggested-by: Russell King <linux@xxxxxxxxxxxxxxx> > Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> > --- > include/linux/mm.h | 4 +++ > mm/memory.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > mm/nommu.c | 14 ++++++++++ > 3 files changed, 99 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 80bb640..25752b0 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2565,6 +2565,10 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, > int remap_pfn_range(struct vm_area_struct *, unsigned long addr, > unsigned long pfn, unsigned long size, pgprot_t); > int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > + unsigned long num); > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > + unsigned long num); > vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, > unsigned long pfn); > vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, > diff --git a/mm/memory.c b/mm/memory.c > index e11ca9d..0a4bf57 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1520,6 +1520,87 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > } > EXPORT_SYMBOL(vm_insert_page); > > +/** > + * __vm_insert_range - insert range of kernel pages into user vma > + * @vma: user vma to map to > + * @pages: pointer to array of source kernel pages > + * @num: number of pages in page array > + * @offset: user's requested vm_pgoff > + * > + * This allows drivers to insert range of kernel pages they've allocated > + * into a user vma. > + * > + * If we fail to insert any page into the vma, the function will return > + * immediately leaving any previously inserted pages present. Callers > + * from the mmap handler may immediately return the error as their caller > + * will destroy the vma, removing any successfully inserted pages. Other > + * callers should make their own arrangements for calling unmap_region(). > + * > + * Context: Process context. > + * Return: 0 on success and error code otherwise. > + */ > +static int __vm_insert_range(struct vm_area_struct *vma, struct page **pages, > + unsigned long num, unsigned long offset) > +{ > + unsigned long count = vma_pages(vma); > + unsigned long uaddr = vma->vm_start; > + int ret, i; > + > + /* Fail if the user requested offset is beyond the end of the object */ > + if (offset > num) > + return -ENXIO; > + > + /* Fail if the user requested size exceeds available object size */ > + if (count > num - offset) > + return -ENXIO; > + > + for (i = 0; i < count; i++) { > + ret = vm_insert_page(vma, uaddr, pages[offset + i]); > + if (ret < 0) > + return ret; > + uaddr += PAGE_SIZE; > + } > + > + return 0; > +} > + > +/** > + * vm_insert_range - insert range of kernel pages starts with non zero offset > + * @vma: user vma to map to > + * @pages: pointer to array of source kernel pages > + * @num: number of pages in page array > + * > + * Maps an object consisting of `num' `pages', catering for the user's > + * requested vm_pgoff > + * The elaborate description you've added to __vm_insert_range() is better put here, as this is the "public" function. > + * Context: Process context. Called by mmap handlers. > + * Return: 0 on success and error code otherwise. > + */ > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > + unsigned long num) > +{ > + return __vm_insert_range(vma, pages, num, vma->vm_pgoff); > +} > +EXPORT_SYMBOL(vm_insert_range); > + > +/** > + * vm_insert_range_buggy - insert range of kernel pages starts with zero offset > + * @vma: user vma to map to > + * @pages: pointer to array of source kernel pages > + * @num: number of pages in page array > + * > + * Maps a set of pages, always starting at page[0] Here I'd add something like: Similar to vm_insert_range(), except that it explicitly sets @vm_pgoff to 0. This function is intended for the drivers that did not consider @vm_pgoff. > vm_insert_range_buggy() is the API which could be used to map > range of kernel memory/pages in drivers which has not considered > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > + * > + * Context: Process context. Called by mmap handlers. > + * Return: 0 on success and error code otherwise. > + */ > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > + unsigned long num) > +{ > + return __vm_insert_range(vma, pages, num, 0); > +} > +EXPORT_SYMBOL(vm_insert_range_buggy); > + > static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, > pfn_t pfn, pgprot_t prot, bool mkwrite) > { > diff --git a/mm/nommu.c b/mm/nommu.c > index 749276b..21d101e 100644 > --- a/mm/nommu.c > +++ b/mm/nommu.c > @@ -473,6 +473,20 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > } > EXPORT_SYMBOL(vm_insert_page); > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > + unsigned long num) > +{ > + return -EINVAL; > +} > +EXPORT_SYMBOL(vm_insert_range); > + > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > + unsigned long num) > +{ > + return -EINVAL; > +} > +EXPORT_SYMBOL(vm_insert_range_buggy); > + > /* > * sys_brk() for the most part doesn't need the global kernel > * lock, except when an application is doing something nasty > -- > 1.9.1 > -- Sincerely yours, Mike. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel