| Message ID | 20220809091558.14379-7-alexandru.elisei@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm/arm64: Rework cache maintenance at boot | expand |
On Tue, Aug 09, 2022 at 10:15:45AM +0100, Alexandru Elisei wrote: > The page allocator has better allocation tracking and is used by all > architectures, while the physical allocator is now never used for > allocating memory. > > Simplify the physical allocator by removing allocation accounting. This > accomplishes two things: > > 1. It makes the allocator more useful, as the warning that was displayed > each allocation after the 256th is removed. > > 2. Together with the lock removal, the physical allocator becomes more > appealing as a very early allocator, when using the page allocator might > not be desirable or feasible. How does the locking cause problems when used in an early allocator? > > Also, phys_alloc_show() has received a slight change in the way it displays > the use and free regions: the end of the region is now non-inclusive, to > allow phys_alloc_show() to express that no memory has been used, or no > memory is free, in which case the start and the end adresses are equal. > > Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> > --- > lib/alloc_phys.c | 65 ++++++++++++++---------------------------------- > lib/alloc_phys.h | 5 ++-- > 2 files changed, 21 insertions(+), 49 deletions(-) > Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Hi, On Tue, Sep 20, 2022 at 10:40:47AM +0200, Andrew Jones wrote: > On Tue, Aug 09, 2022 at 10:15:45AM +0100, Alexandru Elisei wrote: > > The page allocator has better allocation tracking and is used by all > > architectures, while the physical allocator is now never used for > > allocating memory. > > > > Simplify the physical allocator by removing allocation accounting. This > > accomplishes two things: > > > > 1. It makes the allocator more useful, as the warning that was displayed > > each allocation after the 256th is removed. > > > > 2. Together with the lock removal, the physical allocator becomes more > > appealing as a very early allocator, when using the page allocator might > > not be desirable or feasible. > > How does the locking cause problems when used in an early allocator? By "early allocator" I mean here an allocator that can be used with the MMU off. The "desirable or feasible" part refers to the fact that the page allocator cannot be used an early allocator (when the MMU is off) because 1. It doesn't do the necessary cache maintenance operations and 2. It would be hard to do add them, as the internal structures that the page allocator maintains are significantly more complex than what the physical allocator uses. With this part: "together with the lock removal, the physical allocator becomes more appealing as a very early allocator [..]" I was trying to say that the physical allocator has now become as simple as it can possibly be (well, align_min could also be removed and leave it up to the calling code to request correctly aligned allocations but it's debatable if users of the allocator should know about how it's implemented). I can reword or remove this part if you feel it's confusing. Thanks, Alex > > > > > Also, phys_alloc_show() has received a slight change in the way it displays > > the use and free regions: the end of the region is now non-inclusive, to > > allow phys_alloc_show() to express that no memory has been used, or no > > memory is free, in which case the start and the end adresses are equal. > > > > Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> > > --- > > lib/alloc_phys.c | 65 ++++++++++++++---------------------------------- > > lib/alloc_phys.h | 5 ++-- > > 2 files changed, 21 insertions(+), 49 deletions(-) > > > > Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
diff --git a/lib/alloc_phys.c b/lib/alloc_phys.c index 2e0b9c079d1d..1e1fc179f108 100644 --- a/lib/alloc_phys.c +++ b/lib/alloc_phys.c @@ -11,17 +11,11 @@ #include "asm/io.h" #include "alloc_phys.h" -#define PHYS_ALLOC_NR_REGIONS 256 - -struct phys_alloc_region { - phys_addr_t base; - phys_addr_t size; -}; - -static struct phys_alloc_region regions[PHYS_ALLOC_NR_REGIONS]; -static int nr_regions; - -static phys_addr_t base, top; +/* + * used is the end address of the currently allocated memory, non-inclusive. + * used equals top means that all memory has been allocated. + */ +static phys_addr_t base, used, top; #define DEFAULT_MINIMUM_ALIGNMENT 32 static size_t align_min = DEFAULT_MINIMUM_ALIGNMENT; @@ -34,23 +28,15 @@ struct alloc_ops *alloc_ops = &early_alloc_ops; void phys_alloc_show(void) { - int i; - printf("phys_alloc minimum alignment: %#" PRIx64 "\n", (u64)align_min); - for (i = 0; i < nr_regions; ++i) - printf("%016" PRIx64 "-%016" PRIx64 " [%s]\n", - (u64)regions[i].base, - (u64)(regions[i].base + regions[i].size - 1), - "USED"); - printf("%016" PRIx64 "-%016" PRIx64 " [%s]\n", - (u64)base, (u64)(top - 1), "FREE"); + printf("%016" PRIx64 "-%016" PRIx64 " [USED]\n", (u64)base, (u64)used); + printf("%016" PRIx64 "-%016" PRIx64 " [FREE]\n", (u64)used, (u64)top); } void phys_alloc_init(phys_addr_t base_addr, phys_addr_t size) { - base = base_addr; + used = base = base_addr; top = base + size; - nr_regions = 0; } void phys_alloc_set_minimum_alignment(phys_addr_t align) @@ -61,7 +47,6 @@ void phys_alloc_set_minimum_alignment(phys_addr_t align) static void *memalign_early(size_t alignment, size_t sz) { - static bool warned = false; phys_addr_t align = (phys_addr_t)alignment; phys_addr_t size = (phys_addr_t)sz; phys_addr_t size_orig = size; @@ -70,50 +55,36 @@ static void *memalign_early(size_t alignment, size_t sz) assert(align && !(align & (align - 1))); top_safe = top; - if (sizeof(long) == 4) top_safe = MIN(top_safe, 1ULL << 32); + assert(used < top_safe); - assert(base < top_safe); if (align < align_min) align = align_min; - addr = ALIGN(base, align); - size += addr - base; + addr = ALIGN(used, align); + size += addr - used; - if ((top_safe - base) < size) { + if (size > top_safe - used) { printf("phys_alloc: requested=%#" PRIx64 " (align=%#" PRIx64 "), " "need=%#" PRIx64 ", but free=%#" PRIx64 ". " "top=%#" PRIx64 ", top_safe=%#" PRIx64 "\n", (u64)size_orig, (u64)align, (u64)size, - (u64)(top_safe - base), (u64)top, (u64)top_safe); + (u64)(top_safe - used), (u64)top, (u64)top_safe); return NULL; } - base += size; - - if (nr_regions < PHYS_ALLOC_NR_REGIONS) { - regions[nr_regions].base = addr; - regions[nr_regions].size = size_orig; - ++nr_regions; - } else if (!warned) { - printf("WARNING: phys_alloc: No free log entries, " - "can no longer log allocations...\n"); - warned = true; - } + used += size; return phys_to_virt(addr); } void phys_alloc_get_unused(phys_addr_t *p_base, phys_addr_t *p_top) { - *p_base = base; + *p_base = used; *p_top = top; - if (base == top) - return; - regions[nr_regions].base = base; - regions[nr_regions].size = top - base; - ++nr_regions; - base = top; + + /* Empty allocator. */ + used = top; } diff --git a/lib/alloc_phys.h b/lib/alloc_phys.h index 8049c340818d..4d350f010031 100644 --- a/lib/alloc_phys.h +++ b/lib/alloc_phys.h @@ -29,8 +29,9 @@ extern void phys_alloc_set_minimum_alignment(phys_addr_t align); /* * phys_alloc_show outputs all currently allocated regions with the - * following format - * <start_addr>-<end_addr> [<USED|FREE>] + * following format, where <end_addr> is non-inclusive: + * + * <start_addr>-<end_addr> [<USED|FREE>] */ extern void phys_alloc_show(void);
The page allocator has better allocation tracking and is used by all architectures, while the physical allocator is now never used for allocating memory. Simplify the physical allocator by removing allocation accounting. This accomplishes two things: 1. It makes the allocator more useful, as the warning that was displayed each allocation after the 256th is removed. 2. Together with the lock removal, the physical allocator becomes more appealing as a very early allocator, when using the page allocator might not be desirable or feasible. Also, phys_alloc_show() has received a slight change in the way it displays the use and free regions: the end of the region is now non-inclusive, to allow phys_alloc_show() to express that no memory has been used, or no memory is free, in which case the start and the end adresses are equal. Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- lib/alloc_phys.c | 65 ++++++++++++++---------------------------------- lib/alloc_phys.h | 5 ++-- 2 files changed, 21 insertions(+), 49 deletions(-)