| Message ID | 20150730165345.33962.80299.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 2e872f92dbac..84b05ebedb2d 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) > } > > extern int page_is_ram(unsigned long pfn); > -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); > + > +enum { > + REGION_INTERSECTS, > + REGION_DISJOINT, > + REGION_MIXED, > +}; > + Can you Kdoc'ify this? Part of the reason for the enum request was this could be then documented really well. The helper is documented but here you can go into more detail about each region intersection. Luis
On Thu, Jul 30, 2015 at 1:42 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: > On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 2e872f92dbac..84b05ebedb2d 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) >> } >> >> extern int page_is_ram(unsigned long pfn); >> -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); >> + >> +enum { >> + REGION_INTERSECTS, >> + REGION_DISJOINT, >> + REGION_MIXED, >> +}; >> + > > Can you Kdoc'ify this? Part of the reason for the enum request was this > could be then documented really well. The helper is documented but here > you can go into more detail about each region intersection. Given region_intersects() has its own kdoc I'd probably just say "See region_intersects() for details".
On Thu, Jul 30, 2015 at 01:44:44PM -0700, Dan Williams wrote: > On Thu, Jul 30, 2015 at 1:42 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: > > On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: > >> diff --git a/include/linux/mm.h b/include/linux/mm.h > >> index 2e872f92dbac..84b05ebedb2d 100644 > >> --- a/include/linux/mm.h > >> +++ b/include/linux/mm.h > >> @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) > >> } > >> > >> extern int page_is_ram(unsigned long pfn); > >> -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); > >> + > >> +enum { > >> + REGION_INTERSECTS, > >> + REGION_DISJOINT, > >> + REGION_MIXED, > >> +}; > >> + > > > > Can you Kdoc'ify this? Part of the reason for the enum request was this > > could be then documented really well. The helper is documented but here > > you can go into more detail about each region intersection. > > Given region_intersects() has its own kdoc I'd probably just say "See > region_intersects() for details". With the kdoc in place in the enum you'd kick people to elaborate when extending the enums, whereas without this you'd hope they do it. With the enum in place you can also be more verbose. Luis
On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: > region_is_ram() is used to prevent the establishment of aliased mappings > to physical "System RAM" with incompatible cache settings. However, it > uses "-1" to indicate both "unknown" memory ranges (ranges not described > by platform firmware) and "mixed" ranges (where the parameters describe > a range that partially overlaps "System RAM"). > > Fix this up by explicitly tracking the "unknown" vs "mixed" resource > cases and returning REGION_INTERSECTS, REGION_MIXED, or REGION_DISJOINT. > This re-write also adds support for detecting when the requested region > completely eclipses all of a resource. Note, the implementation treats > overlaps between "unknown" and the requested memory type as > REGION_INTERSECTS. > > Finally, other memory types can be passed in by name, for now the only > usage "System RAM". > > Suggested-by: Luis R. Rodriguez <mcgrof@suse.com> > Reviewed-by: Toshi Kani <toshi.kani@hp.com> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > --- > include/linux/mm.h | 9 +++++++- > kernel/resource.c | 61 +++++++++++++++++++++++++++++++--------------------- > 2 files changed, 44 insertions(+), 26 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 2e872f92dbac..84b05ebedb2d 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) > } > > extern int page_is_ram(unsigned long pfn); > -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); > + > +enum { If you gave the enum a name, say enum region_intersect_type, you could then use that for the return type of region_intersects. > + REGION_INTERSECTS, > + REGION_DISJOINT, > + REGION_MIXED, > +}; > + > +int region_intersects(resource_size_t offset, size_t size, const char *type); If you used say a return type enum region_intersect_type, at compile time you'd get a complaint if any branch was not handled for the different enum types. Luis
On Thu, Jul 30, 2015 at 1:54 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: > On Thu, Jul 30, 2015 at 01:44:44PM -0700, Dan Williams wrote: >> On Thu, Jul 30, 2015 at 1:42 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: >> > On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> >> index 2e872f92dbac..84b05ebedb2d 100644 >> >> --- a/include/linux/mm.h >> >> +++ b/include/linux/mm.h >> >> @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) >> >> } >> >> >> >> extern int page_is_ram(unsigned long pfn); >> >> -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); >> >> + >> >> +enum { >> >> + REGION_INTERSECTS, >> >> + REGION_DISJOINT, >> >> + REGION_MIXED, >> >> +}; >> >> + >> > >> > Can you Kdoc'ify this? Part of the reason for the enum request was this >> > could be then documented really well. The helper is documented but here >> > you can go into more detail about each region intersection. >> >> Given region_intersects() has its own kdoc I'd probably just say "See >> region_intersects() for details". > > With the kdoc in place in the enum you'd kick people to elaborate when > extending the enums, whereas without this you'd hope they do it. With > the enum in place you can also be more verbose. > Care to send a patch on what you are thinking? I wasn't planning on this enum growing any other entries.
On Thu, Jul 30, 2015 at 01:59:20PM -0700, Dan Williams wrote: > On Thu, Jul 30, 2015 at 1:54 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: > > On Thu, Jul 30, 2015 at 01:44:44PM -0700, Dan Williams wrote: > >> On Thu, Jul 30, 2015 at 1:42 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote: > >> > On Thu, Jul 30, 2015 at 12:53:45PM -0400, Dan Williams wrote: > >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h > >> >> index 2e872f92dbac..84b05ebedb2d 100644 > >> >> --- a/include/linux/mm.h > >> >> +++ b/include/linux/mm.h > >> >> @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) > >> >> } > >> >> > >> >> extern int page_is_ram(unsigned long pfn); > >> >> -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); > >> >> + > >> >> +enum { > >> >> + REGION_INTERSECTS, > >> >> + REGION_DISJOINT, > >> >> + REGION_MIXED, > >> >> +}; > >> >> + > >> > > >> > Can you Kdoc'ify this? Part of the reason for the enum request was this > >> > could be then documented really well. The helper is documented but here > >> > you can go into more detail about each region intersection. > >> > >> Given region_intersects() has its own kdoc I'd probably just say "See > >> region_intersects() for details". > > > > With the kdoc in place in the enum you'd kick people to elaborate when > > extending the enums, whereas without this you'd hope they do it. With > > the enum in place you can also be more verbose. > > > > Care to send a patch on what you are thinking? I wasn't planning on > this enum growing any other entries. I mean something like this: /** * enum region_intersect_type * * @REGION_INTERSECTS: explain and you you can go into any elaborate * detail as you wish. * @REGION_DISJOINT: explain * @REGION_MIXED: explain */ enum region_intersect_type { REGION_INTERSECTS, REGION_DISJOINT, REGION_MIXED, }; Luis
diff --git a/include/linux/mm.h b/include/linux/mm.h index 2e872f92dbac..84b05ebedb2d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -369,7 +369,14 @@ static inline int put_page_unless_one(struct page *page) } extern int page_is_ram(unsigned long pfn); -extern int region_is_ram(resource_size_t phys_addr, unsigned long size); + +enum { + REGION_INTERSECTS, + REGION_DISJOINT, + REGION_MIXED, +}; + +int region_intersects(resource_size_t offset, size_t size, const char *type); /* Support for virtually mapped pages */ struct page *vmalloc_to_page(const void *addr); diff --git a/kernel/resource.c b/kernel/resource.c index fed052a1bc9f..f150dbbe6f62 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -492,40 +492,51 @@ int __weak page_is_ram(unsigned long pfn) } EXPORT_SYMBOL_GPL(page_is_ram); -/* - * Search for a resouce entry that fully contains the specified region. - * If found, return 1 if it is RAM, 0 if not. - * If not found, or region is not fully contained, return -1 +/** + * region_intersects() - determine intersection of region with known resources + * @start: region start address + * @size: size of region + * @name: name of resource (in iomem_resource) * - * Used by the ioremap functions to ensure the user is not remapping RAM and is - * a vast speed up over walking through the resource table page by page. + * Check if the specified region partially overlaps or fully eclipses a + * resource identified by @name. Return REGION_DISJOINT if the region + * does not overlap @name, return REGION_MIXED if the region overlaps + * @type and another resource, and return REGION_INTERSECTS if the + * region overlaps @type and no other defined resource. Note, that + * REGION_INTERSECTS is also returned in the case when the specified + * region overlaps RAM and undefined memory holes. + * + * region_intersect() is used by memory remapping functions to ensure + * the user is not remapping RAM and is a vast speed up over walking + * through the resource table page by page. */ -int region_is_ram(resource_size_t start, unsigned long size) +int region_intersects(resource_size_t start, size_t size, const char *name) { - struct resource *p; - resource_size_t end = start + size - 1; unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY; - const char *name = "System RAM"; - int ret = -1; + resource_size_t end = start + size - 1; + int type = 0; int other = 0; + struct resource *p; read_lock(&resource_lock); for (p = iomem_resource.child; p ; p = p->sibling) { - if (p->end < start) - continue; - - if (p->start <= start && end <= p->end) { - /* resource fully contains region */ - if ((p->flags != flags) || strcmp(p->name, name)) - ret = 0; - else - ret = 1; - break; - } - if (end < p->start) - break; /* not found */ + bool is_type = strcmp(p->name, name) == 0 && p->flags == flags; + + if (start >= p->start && start <= p->end) + is_type ? type++ : other++; + if (end >= p->start && end <= p->end) + is_type ? type++ : other++; + if (p->start >= start && p->end <= end) + is_type ? type++ : other++; } read_unlock(&resource_lock); - return ret; + + if (other == 0) + return type ? REGION_INTERSECTS : REGION_DISJOINT; + + if (type) + return REGION_MIXED; + + return REGION_DISJOINT; } void __weak arch_remove_reservations(struct resource *avail)