On Mon, 5 Oct 2020 14:40:39 +0200
Andrew Jones <drjones@xxxxxxxxxx> wrote:
> On Fri, Oct 02, 2020 at 05:44:17PM +0200, Claudio Imbrenda wrote:
> > This is a complete rewrite of the page allocator.
> >
> > This will bring a few improvements:
> > * no need to specify the size when freeing
> > * allocate small areas with a large alignment without wasting memory
> > * ability to initialize and use multiple memory areas (e.g. DMA)
> > * more sanity checks
> >
> > A few things have changed:
> > * initialization cannot be done with free_pages like before,
> > page_alloc_init_area has to be used instead
> >
> > Arch-specific changes:
> > * s390x now uses the area below 2GiB for SMP lowcore initialization.
> >
> > Details:
> > Each memory area has metadata at the very beginning. The metadata
> > is a byte array with one entry per usable page (so, excluding the
> > metadata itself). Each entry indicates if the page is special
> > (unused for now), if it is allocated, and the order of the block.
> > Both free and allocated pages are part of larger blocks.
> >
> > Some more fixed size metadata is present in a fixed-size static
> > array. This metadata contains start and end page frame numbers, the
> > pointer to the metadata array, and the array of freelists. The
> > array of freelists has an entry for each possible order (indicated
> > by the macro NLISTS, defined as BITS_PER_LONG - PAGE_SHIFT).
> >
> > On allocation, if the free list for the needed size is empty, larger
> > blocks are split. When a small allocation with a large alignment is
> > requested, an appropriately large block is split, to guarantee the
> > alignment.
> >
> > When a block is freed, an attempt will be made to merge it into the
> > neighbour, iterating the process as long as possible.
> >
> > Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> > ---
> > lib/alloc_page.h | 63 +++++-
> > lib/alloc_page.c | 484
> > +++++++++++++++++++++++++++++++++++++---------- lib/arm/setup.c |
> > 2 +- lib/s390x/sclp.c | 6 +-
> > lib/s390x/smp.c | 2 +-
> > lib/vmalloc.c | 13 +-
> > 6 files changed, 453 insertions(+), 117 deletions(-)
> >
> > diff --git a/lib/alloc_page.h b/lib/alloc_page.h
> > index 88540d1..81847ae 100644
> > --- a/lib/alloc_page.h
> > +++ b/lib/alloc_page.h
> > @@ -8,12 +8,71 @@
> > #ifndef ALLOC_PAGE_H
> > #define ALLOC_PAGE_H 1
> >
> > +#include <asm/memory_areas.h>
> > +
> > +/* Returns true if the page allocator has been initialized */
> > bool page_alloc_initialized(void);
> > +
> > +/*
> > + * Initializes a memory area.
> > + * n is the number of the area to initialize
> > + * base_pfn is the physical frame number of the start of the area
> > to initialize
> > + * top_pfn is the physical frame number of the first page
> > immediately after
> > + * the end of the area to initialize
> > + */
> > +void page_alloc_init_area(u8 n, uintptr_t base_pfn, uintptr_t
> > top_pfn); +
> > +/* Enables the page allocator. At least one area must have been
> > initialized */ void page_alloc_ops_enable(void);
> > +
> > +/*
> > + * Allocate aligned memory from the specified areas.
> > + * areas is a bitmap of allowed areas
> > + * alignment must be a power of 2
> > + */
> > +void *memalign_pages_area(unsigned int areas, size_t alignment,
> > size_t size);
>
> I guess 'size' is the number of pages? Or is it bytes that
> automatically get rounded up to a multiple of PAGE_SIZE?
it's the latter, since this is the backend for memalign. it has the
same parameters as memalign. I will improve the comments.
> > +
> > +/*
> > + * Allocate aligned memory from any area.
> > + * Equivalent to memalign_pages_area(~0, alignment, size).
> > + */
> > +void *memalign_pages(size_t alignment, size_t size);
> > +
> > +/*
> > + * Allocate naturally aligned memory from the specified areas.
> > + * Equivalent to memalign_pages_area(areas, 1ull << order, 1ull <<
> > order).
> > + */
> > +void *alloc_pages_area(unsigned int areas, unsigned int order);
> > +
> > +/*
> > + * Allocate one page from any area.
> > + * Equivalent to alloc_pages(0);
> > + */
> > void *alloc_page(void);
> > +
> > +/*
> > + * Allocate naturally aligned memory from any area.
> > + * Equivalent to alloc_pages_area(~0, order);
> > + */
> > void *alloc_pages(unsigned int order);
> > -void free_page(void *page);
> > +
> > +/*
> > + * Frees a memory block allocated with any of the memalign_pages*
> > or
> > + * alloc_pages* functions.
> > + * The pointer must point to the start of the block.
> > + */
> > void free_pages(void *mem, size_t size);
> > -void free_pages_by_order(void *mem, unsigned int order);
> > +
> > +/* For backwards compatibility */
> > +static inline void free_page(void *mem)
> > +{
> > + return free_pages(mem, 1);
> > +}
> > +
> > +/* For backwards compatibility */
>
> We don't preserve interfaces for backwards compatibility in
> kvm-unit-tests. If the interface is no longer a good idea,
> then we can change all the call sites. However, in this case,
> it is a good idea, as it balances alloc_page(), so I'd just
> write "Equivalent to free_pages(mem, 1)".
I will fix the comment
> > +static inline void free_pages_by_order(void *mem, unsigned int
> > order) +{
> > + free_pages(mem, 1ull << order);
> > +}
> >
> > #endif
> > diff --git a/lib/alloc_page.c b/lib/alloc_page.c
> > index 74fe726..29d221f 100644
> > --- a/lib/alloc_page.c
> > +++ b/lib/alloc_page.c
> > @@ -9,169 +9,445 @@
> > #include "alloc_phys.h"
> > #include "alloc_page.h"
> > #include "bitops.h"
> > +#include "list.h"
> > #include <asm/page.h>
> > #include <asm/io.h>
> > #include <asm/spinlock.h>
> > +#include <asm/memory_areas.h>
> >
> > +#define IS_ALIGNED_ORDER(x,order) IS_ALIGNED((x),BIT_ULL(order))
> > +#define NLISTS ((BITS_PER_LONG) - (PAGE_SHIFT))
>
> nit: too many ()
will fix
> > +#define PFN(x) ((uintptr_t)(x) >> PAGE_SHIFT)
> > +
> > +#define MAX_AREAS 6
>
> This looks like something that should be defined memory_areas.h.
makes sense. fill fix
> > +
> > +#define ORDER_MASK 0x3f
> > +#define ALLOC_MASK 0x40
> > +
> > +struct mem_area {
> > + /* Physical frame number of the first usable frame in the
> > area */
> > + uintptr_t base;
> > + /* Physical frame number of the first frame outside the
> > area */
> > + uintptr_t top;
> > + /* Combination ALLOC_MASK and order */
> > + u8 *page_states;
>
> I can't tell what page_states is supposed to be by its name nor the
> comment.
it's the per-page metadata array, as described in the patch
description. it has one entry for each usable page in the area.
> > + /* One freelist for each possible block size, up to NLISTS
> > */
> > + struct linked_list freelists[NLISTS];
> > +};
> > +
> > +static struct mem_area areas[MAX_AREAS];
> > +static unsigned int areas_mask;
> > static struct spinlock lock;
> > -static void *freelist = 0;
> >
> > bool page_alloc_initialized(void)
> > {
> > - return freelist != 0;
> > + return areas_mask != 0;
> > }
> >
> > -void free_pages(void *mem, size_t size)
> > +static inline bool area_or_metadata_contains(struct mem_area *a,
> > uintptr_t pfn)
>
> I can't tell what this function is suppose to return by its name and
> it has no comment.
>
> > {
> > - void *old_freelist;
> > - void *end;
> > + return (pfn >= PFN(a->page_states)) && (pfn < a->top);
>
> Why are we comparing an input pfn with the page_states virtual
> pfn? I guess you want 'pfn >= base' ?
no, I want to see if the address overlaps the start of the metadata,
which is placed immediately before the usable range. it is used in one
place below, unfortunately below the point at which you gave up reading
> > +}
> >
> > - assert_msg((unsigned long) mem % PAGE_SIZE == 0,
> > - "mem not page aligned: %p", mem);
> > +static inline bool area_contains(struct mem_area *a, uintptr_t
> > pfn)
>
> Please complete the sentence in these function names, e.g.
> area_contains_pfn(), which appears to be what this function
> is checking. I still don't understand what the
> area_or_metadata_contains() function is supposed to be checking
> though.
as written in the patch description, at the very beginning of an area
there is a metadata array, with one entry per page.
area_or_metadata_contains checks if a pfn falls in the usable area or
in its metadata area, whereas area_contains only checks if a pfn falls
in the usable area.
I will add some more comments to clarify
> > +{
> > + return (pfn >= a->base) && (pfn < a->top);
> > +}
> >
> > - assert_msg(size % PAGE_SIZE == 0, "size not page aligned:
> > %#zx", size); +/*
> > + * Splits the free block starting at addr into 2 blocks of half
> > the size.
> > + *
> > + * The function depends on the following assumptions:
> > + * - The allocator must have been initialized
> > + * - the block must be within the memory area
> > + * - all pages in the block must be free and not special
> > + * - the pointer must point to the start of the block
> > + * - all pages in the block must have the same block size.
>
> pages should all have the same page size, no? How does a
> page have a block size?
no, a page belongs to a power-of-two aligned block of pages, in the
worst case it's an order 0 block (so one page), but in most cases it
will belong to a larger block.
this is basically where we store the size of an allocation so we don't
have to provide it back again when freeing
> > + * - the block size must be greater than 0
> > + * - the block size must be smaller than the maximum allowed
> > + * - the block must be in a free list
> > + * - the function is called with the lock held
> > + */
> > +static void split(struct mem_area *a, void *addr)
> > +{
> > + uintptr_t pfn = PFN(addr);
>
> addr appears to be virtual, since it's a 'void *', not a phys_addr_t.
it's a pointer, doesn't mean it's virtual. In fact it will be physical,
since the page allocator only works with physical addresses.
if the MMU has been activated and all of memory is virtual but identity
mapped, it does not make any difference.
the addresses do not belong to the vmalloc range
> PFN() only does a shift, so that's the virtual PFN. However we're
again, it's just a PFN
> comparing that with memory area pfn's, which are supposed to be
> physical frame numbers, at least according to the comments in the
correct. we are comparing physical PFNs with other physical PFNs
> struct.
>
> > + struct linked_list *p;
> > + uintptr_t i, idx;
> > + u8 order;
> >
> > - assert_msg(size == 0 || (uintptr_t)mem == -size ||
> > - (uintptr_t)mem + size > (uintptr_t)mem,
> > - "mem + size overflow: %p + %#zx", mem, size);
> > + assert(a && area_contains(a, pfn));
> > + idx = pfn - a->base;
> > + order = a->page_states[idx];
>
> pfn - a->base could potentially be huge, so we can't be using that
> as an array index.
this is exactly what we are doing. we need the index of the page in the
per-page metadata array.
from the array we get the order of the block the page belongs to.
> I think what you want is something like
>
> pfn = PFN(virt_to_phys(addr));
> order = ffs(pfn) - 1;
> if (pfn != order)
> order <<= 1;
>
> Then you have order and can use it as a index into an array if
> necessary.
now this does not make any sense
> > + assert(!(order & ~ORDER_MASK) && order && (order <
> > NLISTS));
>
> What's wrong with order==0? What is ORDER_MASK good for?
as written in the comment in the struct, the metadata contains the
order and a bit to mark when a page is allocated. ORDER_MASK is used to
extract the order part.
a block with order 0 is a single page. you cannot split a page. that's
why order 0 is bad.
split takes a pointer to a free block and splits the block in two blocks
of half the size each. this is needed when there are no free blocks of
the suitable size, but there are bigger free blocks
> > + assert(IS_ALIGNED_ORDER(pfn, order));
>
> I'm getting the feeling that split() shouldn't operate on an addr, but
> rather some internal index of a block list or something. There are
> just too many requirements as to what addr is supposed to be.
split is an internal function, it's static for a reason. basically
there is exactly one spot where it should be used, and that is the one
where it is used.
> > + assert(area_contains(a, pfn + BIT(order) - 1));
> >
> > - if (size == 0) {
> > - freelist = NULL;
> > - return;
> > - }
> > + /* Remove the block from its free list */
> > + p = list_remove(addr);
>
> So addr is a pointer to a linked_list object? I'm getting really
> confused.
it's literally a free list; the beginning of each free block of memory
contains the pointers so that it can be handled using list operations
> My editor says I'm only 30% of my way through this patch, so I don't
> think I'm going to have time to look at the rest. I think this patch
> is trying to do too much at once. IMO, we need to implement a single
this patch is implementing the page allocator; it is a single new
feature.
> new feature at a time. Possibly starting with some cleanup patches
> for the current code first.
there is no way to split this any further, I need to break some
interfaces, so I need to do it all at once.
> Thanks,
> drew
>
> > + assert(p);
> >
> > - spin_lock(&lock);
> > - old_freelist = freelist;
> > - freelist = mem;
> > - end = mem + size;
> > - while (mem + PAGE_SIZE != end) {
> > - *(void **)mem = (mem + PAGE_SIZE);
> > - mem += PAGE_SIZE;
> > + /* update the block size for each page in the block */
> > + for (i = 0; i < BIT(order); i++) {
> > + assert(a->page_states[idx + i] == order);
> > + a->page_states[idx + i] = order - 1;
> > }
> > -
> > - *(void **)mem = old_freelist;
> > - spin_unlock(&lock);
> > + order--;
> > + /* add the first half block to the appropriate free list */
> > + list_add(a->freelists + order, p);
> > + /* add the second half block to the appropriate free list
> > */
> > + list_add(a->freelists + order, (void *)((pfn + BIT(order))
> > * PAGE_SIZE)); }
> >
> > -void free_pages_by_order(void *mem, unsigned int order)
> > +/*
> > + * Returns a block whose alignment and size are at least the
> > parameter values.
> > + * If there is not enough free memory, NULL is returned.
> > + *
> > + * Both parameters must be not larger than the largest allowed
> > order
> > + */
> > +static void *page_memalign_order(struct mem_area *a, u8 al, u8 sz)
> > {
> > - free_pages(mem, 1ul << (order + PAGE_SHIFT));
> > + struct linked_list *p, *res = NULL;
> > + u8 order;
> > +
> > + assert((al < NLISTS) && (sz < NLISTS));
> > + /* we need the bigger of the two as starting point */
> > + order = sz > al ? sz : al;
> > +
> > + /* search all free lists for some memory */
> > + for ( ; order < NLISTS; order++) {
> > + p = a->freelists[order].next;
> > + if (!is_list_empty(p))
> > + break;
> > + }
> > + /* out of memory */
> > + if (order >= NLISTS)
> > + return NULL;
> > +
> > + /*
> > + * the block is bigger than what we need because either
> > there were
> > + * no smaller blocks, or the smaller blocks were not
> > aligned to our
> > + * needs; therefore we split the block until we reach the
> > needed size
> > + */
> > + for (; order > sz; order--)
> > + split(a, p);
> > +
> > + res = list_remove(p);
> > + memset(a->page_states + (PFN(res) - a->base), ALLOC_MASK |
> > order, BIT(order));
> > + return res;
> > }
> >
> > -void *alloc_page()
> > +/*
> > + * Try to merge two blocks into a bigger one.
> > + * Returns true in case of a successful merge.
> > + * Merging will succeed only if both blocks have the same block
> > size and are
> > + * both free.
> > + *
> > + * The function depends on the following assumptions:
> > + * - the first parameter is strictly smaller than the second
> > + * - the parameters must point each to the start of their block
> > + * - the two parameters point to adjacent blocks
> > + * - the two blocks are both in a free list
> > + * - all of the pages of the two blocks must be free
> > + * - all of the pages of the two blocks must have the same block
> > size
> > + * - the function is called with the lock held
> > + */
> > +static bool coalesce(struct mem_area *a, u8 order, uintptr_t pfn,
> > uintptr_t pfn2) {
> > - void *p;
> > + uintptr_t first, second, i;
> > + struct linked_list *li;
> >
> > - if (!freelist)
> > - return 0;
> > + assert(IS_ALIGNED_ORDER(pfn, order) &&
> > IS_ALIGNED_ORDER(pfn2, order));
> > + assert(pfn2 == pfn + BIT(order));
> > + assert(a);
> >
> > - spin_lock(&lock);
> > - p = freelist;
> > - freelist = *(void **)freelist;
> > - spin_unlock(&lock);
> > + /* attempting to coalesce two blocks that belong to
> > different areas */
> > + if (!area_contains(a, pfn) || !area_contains(a, pfn2 +
> > BIT(order) - 1))
> > + return false;
> > + first = pfn - a->base;
> > + second = pfn2 - a->base;
> > + /* the two blocks have different sizes, cannot coalesce */
> > + if ((a->page_states[first] != order) ||
> > (a->page_states[second] != order))
> > + return false;
> >
> > - if (p)
> > - memset(p, 0, PAGE_SIZE);
> > - return p;
> > + /* we can coalesce, remove both blocks from their
> > freelists */
> > + li = list_remove((void *)(pfn2 << PAGE_SHIFT));
> > + assert(li);
> > + li = list_remove((void *)(pfn << PAGE_SHIFT));
> > + assert(li);
> > + /* check the metadata entries and update with the new size
> > */
> > + for (i = 0; i < (2ull << order); i++) {
> > + assert(a->page_states[first + i] == order);
> > + a->page_states[first + i] = order + 1;
> > + }
> > + /* finally add the newly coalesced block to the
> > appropriate freelist */
> > + list_add(a->freelists + order + 1, li);
> > + return true;
> > }
> >
> > /*
> > - * Allocates (1 << order) physically contiguous and naturally
> > aligned pages.
> > - * Returns NULL if there's no memory left.
> > + * Free a block of memory.
> > + * The parameter can be NULL, in which case nothing happens.
> > + *
> > + * The function depends on the following assumptions:
> > + * - the parameter is page aligned
> > + * - the parameter belongs to an existing memory area
> > + * - the parameter points to the beginning of the block
> > + * - the size of the block is less than the maximum allowed
> > + * - the block is completely contained in its memory area
> > + * - all pages in the block have the same block size
> > + * - no pages in the memory block were already free
> > + * - no pages in the memory block are special
> > */
> > -void *alloc_pages(unsigned int order)
> > +static void _free_pages(void *mem)
> > {
> > - /* Generic list traversal. */
> > - void *prev;
> > - void *curr = NULL;
> > - void *next = freelist;
> > -
> > - /* Looking for a run of length (1 << order). */
> > - unsigned long run = 0;
> > - const unsigned long n = 1ul << order;
> > - const unsigned long align_mask = (n << PAGE_SHIFT) - 1;
> > - void *run_start = NULL;
> > - void *run_prev = NULL;
> > - unsigned long run_next_pa = 0;
> > - unsigned long pa;
> > + uintptr_t pfn2, pfn = PFN(mem);
> > + struct mem_area *a = NULL;
> > + uintptr_t i, p;
> > + u8 order;
> >
> > - assert(order < sizeof(unsigned long) * 8);
> > + if (!mem)
> > + return;
> > + assert(IS_ALIGNED((uintptr_t)mem, PAGE_SIZE));
> >
> > - spin_lock(&lock);
> > - for (;;) {
> > - prev = curr;
> > - curr = next;
> > + /* find which area this pointer belongs to*/
> > + for (i = 0; !a && (i < MAX_AREAS); i++) {
> > + if ((areas_mask & BIT(i)) && area_contains(areas +
> > i, pfn))
> > + a = areas + i;
> > + }
> > + assert_msg(a, "memory does not belong to any area: %p",
> > mem);
> > - if (!curr) {
> > - run_start = NULL;
> > - break;
> > - }
> > + p = pfn - a->base;
> > + order = a->page_states[p] & ORDER_MASK;
> >
> > - next = *((void **) curr);
> > - pa = virt_to_phys(curr);
> > -
> > - if (run == 0) {
> > - if (!(pa & align_mask)) {
> > - run_start = curr;
> > - run_prev = prev;
> > - run_next_pa = pa + PAGE_SIZE;
> > - run = 1;
> > - }
> > - } else if (pa == run_next_pa) {
> > - run_next_pa += PAGE_SIZE;
> > - run += 1;
> > - } else {
> > - run = 0;
> > - }
> > + /* ensure that the first page is allocated and not special
> > */
> > + assert(a->page_states[p] == (order | ALLOC_MASK));
> > + /* ensure that the order has a sane value */
> > + assert(order < NLISTS);
> > + /* ensure that the block is aligned properly for its size
> > */
> > + assert(IS_ALIGNED_ORDER(pfn, order));
> > + /* ensure that the area can contain the whole block */
> > + assert(area_contains(a, pfn + BIT(order) - 1));
> >
> > - if (run == n) {
> > - if (run_prev)
> > - *((void **) run_prev) = next;
> > - else
> > - freelist = next;
> > - break;
> > - }
> > + for (i = 0; i < BIT(order); i++) {
> > + /* check that all pages of the block have
> > consistent metadata */
> > + assert(a->page_states[p + i] == (ALLOC_MASK |
> > order));
> > + /* set the page as free */
> > + a->page_states[p + i] &= ~ALLOC_MASK;
> > }
> > - spin_unlock(&lock);
> > - if (run_start)
> > - memset(run_start, 0, n * PAGE_SIZE);
> > - return run_start;
> > + /* provisionally add the block to the appropriate free
> > list */
> > + list_add(a->freelists + order, mem);
> > + /* try to coalesce the block with neighbouring blocks if
> > possible */
> > + do {
> > + /*
> > + * get the order again since it might have changed
> > after
> > + * coalescing in a previous iteration
> > + */
> > + order = a->page_states[p] & ORDER_MASK;
> > + /*
> > + * let's consider this block and the next one if
> > this block
> > + * is aligned to the next size, otherwise let's
> > consider the
> > + * previous block and this one
> > + */
> > + if (!IS_ALIGNED_ORDER(pfn, order + 1))
> > + pfn = pfn - BIT(order);
> > + pfn2 = pfn + BIT(order);
> > + /* repeat as long as we manage to coalesce
> > something */
> > + } while (coalesce(a, order, pfn, pfn2));
> > }
> >
> > +void free_pages(void *mem, size_t size)
> > +{
> > + spin_lock(&lock);
> > + _free_pages(mem);
> > + spin_unlock(&lock);
> > +}
> >
> > -void free_page(void *page)
> > +static void *page_memalign_order_area(unsigned area, u8 ord, u8 al)
> > {
> > + void *res = NULL;
> > + int i;
> > +
> > spin_lock(&lock);
> > - *(void **)page = freelist;
> > - freelist = page;
> > + area &= areas_mask;
> > + for (i = 0; !res && (i < MAX_AREAS); i++)
> > + if (area & BIT(i))
> > + res = page_memalign_order(areas + i, ord,
> > al); spin_unlock(&lock);
> > + return res;
> > }
> >
> > -static void *page_memalign(size_t alignment, size_t size)
> > +/*
> > + * Allocates (1 << order) physically contiguous and naturally
> > aligned pages.
> > + * Returns NULL if the allocation was not possible.
> > + */
> > +void *alloc_pages_area(unsigned int area, unsigned int order)
> > {
> > - unsigned long n = ALIGN(size, PAGE_SIZE) >> PAGE_SHIFT;
> > - unsigned int order;
> > + return page_memalign_order_area(area, order, order);
> > +}
> >
> > - if (!size)
> > - return NULL;
> > +void *alloc_pages(unsigned int order)
> > +{
> > + return alloc_pages_area(AREA_ANY, order);
> > +}
> >
> > - order = get_order(n);
> > +/*
> > + * Allocates (1 << order) physically contiguous aligned pages.
> > + * Returns NULL if the allocation was not possible.
> > + */
> > +void *memalign_pages_area(unsigned int area, size_t alignment,
> > size_t size) +{
> > + assert(is_power_of_2(alignment));
> > + alignment = get_order(PAGE_ALIGN(alignment) >> PAGE_SHIFT);
> > + size = get_order(PAGE_ALIGN(size) >> PAGE_SHIFT);
> > + assert(alignment < NLISTS);
> > + assert(size < NLISTS);
> > + return page_memalign_order_area(area, size, alignment);
> > +}
> >
> > - return alloc_pages(order);
> > +void *memalign_pages(size_t alignment, size_t size)
> > +{
> > + return memalign_pages_area(AREA_ANY, alignment, size);
> > }
> >
> > -static void page_free(void *mem, size_t size)
> > +/*
> > + * Allocates one page
> > + */
> > +void *alloc_page()
> > {
> > - free_pages(mem, size);
> > + return alloc_pages(0);
> > }
> >
> > static struct alloc_ops page_alloc_ops = {
> > - .memalign = page_memalign,
> > - .free = page_free,
> > + .memalign = memalign_pages,
> > + .free = free_pages,
> > .align_min = PAGE_SIZE,
> > };
> >
> > +/*
> > + * Enables the page allocator.
> > + *
> > + * Prerequisites:
> > + * - at least one memory area has been initialized
> > + */
> > void page_alloc_ops_enable(void)
> > {
> > + spin_lock(&lock);
> > + assert(page_alloc_initialized());
> > alloc_ops = &page_alloc_ops;
> > + spin_unlock(&lock);
> > +}
> > +
> > +/*
> > + * Adds a new memory area to the pool of available memory.
> > + *
> > + * Prerequisites:
> > + * - the lock is held
> > + * - start and top are page frame numbers
> > + * - start is smaller than top
> > + * - top does not fall outside of addressable memory
> > + * - there is at least one more slot free for memory areas
> > + * - if a specific memory area number has been indicated, it needs
> > to be free
> > + * - the memory area to add does not overlap with existing areas
> > + * - the memory area to add has at least 5 pages available
> > + */
> > +static void _page_alloc_init_area(u8 n, uintptr_t start_pfn,
> > uintptr_t top_pfn) +{
> > + size_t table_size, npages, i;
> > + struct mem_area *a;
> > + u8 order = 0;
> > +
> > + /* the number must be within the allowed range */
> > + assert(n < MAX_AREAS);
> > + /* the new area number must be unused */
> > + assert(!(areas_mask & BIT(n)));
> > +
> > + /* other basic sanity checks */
> > + assert(top_pfn > start_pfn);
> > + assert(top_pfn - start_pfn > 4);
> > + assert(top_pfn < BIT_ULL(sizeof(void *) * 8 - PAGE_SHIFT));
> > +
> > + /* calculate the size of the metadata table in pages */
> > + table_size = (top_pfn - start_pfn + PAGE_SIZE) /
> > (PAGE_SIZE + 1); +
> > + /* fill in the values of the new area */
> > + a = areas + n;
> > + a->page_states = (void *)(start_pfn << PAGE_SHIFT);
> > + a->base = start_pfn + table_size;
> > + a->top = top_pfn;
> > + npages = top_pfn - a->base;
> > + assert((a->base - start_pfn) * PAGE_SIZE >= npages);
> > +
> > + /* check that the new area does not overlap with any
> > existing areas */
> > + for (i = 0; i < MAX_AREAS; i++) {
> > + if (!(areas_mask & BIT(i)))
> > + continue;
> > + assert(!area_or_metadata_contains(areas + i,
> > start_pfn));
> > + assert(!area_or_metadata_contains(areas + i,
> > top_pfn - 1));
> > + assert(!area_or_metadata_contains(a,
> > PFN(areas[i].page_states)));
> > + assert(!area_or_metadata_contains(a, areas[i].top
> > - 1));
> > + }
> > + /* initialize all freelists for the new area */
> > + for (i = 0; i < NLISTS; i++)
> > + a->freelists[i].next = a->freelists[i].prev =
> > a->freelists + i; +
> > + /* initialize the metadata for the available memory */
> > + for (i = a->base; i < a->top; i += 1ull << order) {
> > + /* search which order to start from */
> > + while (i + BIT(order) > a->top) {
> > + assert(order);
> > + order--;
> > + }
> > + /*
> > + * we need both loops, one for the start and the
> > other for
> > + * the end of the block, in case it spans a power
> > of two
> > + * boundary
> > + */
> > + while (IS_ALIGNED_ORDER(i, order + 1) && (i +
> > BIT(order + 1) <= a->top))
> > + order++;
> > + assert(order < NLISTS);
> > + /* initialize the metadata and add to the freelist
> > */
> > + memset(a->page_states + (i - a->base), order,
> > BIT(order));
> > + list_add(a->freelists + order, (void *)(i <<
> > PAGE_SHIFT));
> > + }
> > + /* finally mark the area as present */
> > + areas_mask |= BIT(n);
> > +}
> > +
> > +static void __page_alloc_init_area(u8 n, uintptr_t cutoff,
> > uintptr_t base_pfn, uintptr_t *top_pfn) +{
> > + if (*top_pfn > cutoff) {
> > + spin_lock(&lock);
> > + if (base_pfn >= cutoff) {
> > + _page_alloc_init_area(n, base_pfn,
> > *top_pfn);
> > + *top_pfn = 0;
> > + } else {
> > + _page_alloc_init_area(n, cutoff, *top_pfn);
> > + *top_pfn = cutoff;
> > + }
> > + spin_unlock(&lock);
> > + }
> > +}
> > +
> > +/*
> > + * Adds a new memory area to the pool of available memory.
> > + *
> > + * Prerequisites:
> > + * see _page_alloc_init_area
> > + */
> > +void page_alloc_init_area(u8 n, uintptr_t base_pfn, uintptr_t
> > top_pfn) +{
> > + if (n != AREA_ANY_NUMBER) {
> > + __page_alloc_init_area(n, 0, base_pfn, &top_pfn);
> > + return;
> > + }
> > +#ifdef AREA_HIGH_PFN
> > + __page_alloc_init_area(AREA_HIGH_NUMBER, AREA_HIGH_PFN),
> > base_pfn, &top_pfn); +#endif
> > + __page_alloc_init_area(AREA_NORMAL_NUMBER,
> > AREA_NORMAL_PFN, base_pfn, &top_pfn); +#ifdef AREA_LOW_PFN
> > + __page_alloc_init_area(AREA_LOW_NUMBER, AREA_LOW_PFN,
> > base_pfn, &top_pfn); +#endif
> > +#ifdef AREA_LOWEST_PFN
> > + __page_alloc_init_area(AREA_LOWEST_NUMBER,
> > AREA_LOWEST_PFN, base_pfn, &top_pfn); +#endif
> > }
> > diff --git a/lib/arm/setup.c b/lib/arm/setup.c
> > index 78562e4..3f03ca6 100644
> > --- a/lib/arm/setup.c
> > +++ b/lib/arm/setup.c
> > @@ -155,7 +155,7 @@ static void mem_init(phys_addr_t freemem_start)
> > assert(sizeof(long) == 8 || !(base >> 32));
> > if (sizeof(long) != 8 && (top >> 32) != 0)
> > top = ((uint64_t)1 << 32);
> > - free_pages((void *)(unsigned long)base, top - base);
> > + page_alloc_init_area(0, base >> PAGE_SHIFT, top >>
> > PAGE_SHIFT); page_alloc_ops_enable();
> > }
> >
> > diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> > index 4054d0e..4e2ac18 100644
> > --- a/lib/s390x/sclp.c
> > +++ b/lib/s390x/sclp.c
> > @@ -37,11 +37,11 @@ static void mem_init(phys_addr_t mem_end)
> >
> > phys_alloc_init(freemem_start, mem_end - freemem_start);
> > phys_alloc_get_unused(&base, &top);
> > - base = (base + PAGE_SIZE - 1) & -PAGE_SIZE;
> > - top = top & -PAGE_SIZE;
> > + base = PAGE_ALIGN(base) >> PAGE_SHIFT;
> > + top = top >> PAGE_SHIFT;
> >
> > /* Make the pages available to the physical allocator */
> > - free_pages((void *)(unsigned long)base, top - base);
> > + page_alloc_init_area(AREA_ANY_NUMBER, base, top);
> > page_alloc_ops_enable();
> > }
> >
> > diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
> > index 2860e9c..ea93329 100644
> > --- a/lib/s390x/smp.c
> > +++ b/lib/s390x/smp.c
> > @@ -190,7 +190,7 @@ int smp_cpu_setup(uint16_t addr, struct psw psw)
> >
> > sigp_retry(cpu->addr, SIGP_INITIAL_CPU_RESET, 0, NULL);
> >
> > - lc = alloc_pages(1);
> > + lc = alloc_pages_area(AREA_DMA31, 1);
> > cpu->lowcore = lc;
> > memset(lc, 0, PAGE_SIZE * 2);
> > sigp_retry(cpu->addr, SIGP_SET_PREFIX, (unsigned long )lc,
> > NULL); diff --git a/lib/vmalloc.c b/lib/vmalloc.c
> > index 2f25734..3aec5ac 100644
> > --- a/lib/vmalloc.c
> > +++ b/lib/vmalloc.c
> > @@ -217,18 +217,19 @@ void setup_vm()
> > * so that it can be used to allocate page tables.
> > */
> > if (!page_alloc_initialized()) {
> > - base = PAGE_ALIGN(base);
> > - top = top & -PAGE_SIZE;
> > - free_pages(phys_to_virt(base), top - base);
> > + base = PAGE_ALIGN(base) >> PAGE_SHIFT;
> > + top = top >> PAGE_SHIFT;
> > + page_alloc_init_area(AREA_ANY_NUMBER, base, top);
> > + page_alloc_ops_enable();
> > }
> >
> > find_highmem();
> > phys_alloc_get_unused(&base, &top);
> > page_root = setup_mmu(top);
> > if (base != top) {
> > - base = PAGE_ALIGN(base);
> > - top = top & -PAGE_SIZE;
> > - free_pages(phys_to_virt(base), top - base);
> > + base = PAGE_ALIGN(base) >> PAGE_SHIFT;
> > + top = top >> PAGE_SHIFT;
> > + page_alloc_init_area(AREA_ANY_NUMBER, base, top);
> > }
> >
> > spin_lock(&lock);
> > --
> > 2.26.2
> >
>
