| Message ID | 20190111150712.GA2696@jordon-HP-15-Notebook-PC (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Use vm_insert_range and vm_insert_range_buggy | expand |
On Fri, Jan 11, 2019 at 8:33 PM Souptick Joarder <jrdr.linux@gmail.com> 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@gmail.com> > Suggested-by: Russell King <linux@armlinux.org.uk> > Suggested-by: Matthew Wilcox <willy@infradead.org> Any comment on these APIs ? > --- > 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 5411de9..9d1dff6 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2514,6 +2514,10 @@ 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 4ad2d29..00e66df 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 > + * > + * 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] > + * > + * 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 >
diff --git a/include/linux/mm.h b/include/linux/mm.h index 5411de9..9d1dff6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2514,6 +2514,10 @@ 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 4ad2d29..00e66df 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 + * + * 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] + * + * 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
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@gmail.com> Suggested-by: Russell King <linux@armlinux.org.uk> Suggested-by: Matthew Wilcox <willy@infradead.org> --- include/linux/mm.h | 4 +++ mm/memory.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ mm/nommu.c | 14 ++++++++++ 3 files changed, 99 insertions(+)