[PATCH v1 1/2] cma: factor out minimum alignment requirement
From: David Hildenbrand
Date: Mon Feb 14 2022 - 12:42:06 EST
Let's factor out determining the minimum alignment requirement for CMA
and add a helpful comment.
No functional change intended.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
arch/powerpc/include/asm/fadump-internal.h | 5 -----
arch/powerpc/kernel/fadump.c | 2 +-
drivers/of/of_reserved_mem.c | 9 +++------
include/linux/cma.h | 9 +++++++++
kernel/dma/contiguous.c | 4 +---
mm/cma.c | 20 +++++---------------
6 files changed, 19 insertions(+), 30 deletions(-)
diff --git a/arch/powerpc/include/asm/fadump-internal.h b/arch/powerpc/include/asm/fadump-internal.h
index 52189928ec08..81bcb9abb371 100644
--- a/arch/powerpc/include/asm/fadump-internal.h
+++ b/arch/powerpc/include/asm/fadump-internal.h
@@ -19,11 +19,6 @@
#define memblock_num_regions(memblock_type) (memblock.memblock_type.cnt)
-/* Alignment per CMA requirement. */
-#define FADUMP_CMA_ALIGNMENT (PAGE_SIZE << \
- max_t(unsigned long, MAX_ORDER - 1, \
- pageblock_order))
-
/* FAD commands */
#define FADUMP_REGISTER 1
#define FADUMP_UNREGISTER 2
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index d03e488cfe9c..7eb67201ea41 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -544,7 +544,7 @@ int __init fadump_reserve_mem(void)
if (!fw_dump.nocma) {
fw_dump.boot_memory_size =
ALIGN(fw_dump.boot_memory_size,
- FADUMP_CMA_ALIGNMENT);
+ CMA_MIN_ALIGNMENT_BYTES);
}
#endif
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 9c0fb962c22b..75caa6f5d36f 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -22,6 +22,7 @@
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/kmemleak.h>
+#include <linux/cma.h>
#include "of_private.h"
@@ -116,12 +117,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
if (IS_ENABLED(CONFIG_CMA)
&& of_flat_dt_is_compatible(node, "shared-dma-pool")
&& of_get_flat_dt_prop(node, "reusable", NULL)
- && !nomap) {
- unsigned long order =
- max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
-
- align = max(align, (phys_addr_t)PAGE_SIZE << order);
- }
+ && !nomap)
+ align = max_t(phys_addr_t, align, CMA_MIN_ALIGNMENT_BYTES);
prop = of_get_flat_dt_prop(node, "alloc-ranges", &len);
if (prop) {
diff --git a/include/linux/cma.h b/include/linux/cma.h
index bd801023504b..75fe188ec4a1 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -20,6 +20,15 @@
#define CMA_MAX_NAME 64
+/*
+ * TODO: once the buddy -- especially pageblock merging and alloc_contig_range()
+ * -- can deal with only some pageblocks of a higher-order page being
+ * MIGRATE_CMA, we can use pageblock_nr_pages.
+ */
+#define CMA_MIN_ALIGNMENT_PAGES max_t(phys_addr_t, MAX_ORDER_NR_PAGES, \
+ pageblock_nr_pages)
+#define CMA_MIN_ALIGNMENT_BYTES (PAGE_SIZE * CMA_MIN_ALIGNMENT_PAGES)
+
struct cma;
extern unsigned long totalcma_pages;
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 3d63d91cba5c..6ea80ae42622 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -399,8 +399,6 @@ static const struct reserved_mem_ops rmem_cma_ops = {
static int __init rmem_cma_setup(struct reserved_mem *rmem)
{
- phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
- phys_addr_t mask = align - 1;
unsigned long node = rmem->fdt_node;
bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
struct cma *cma;
@@ -416,7 +414,7 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
of_get_flat_dt_prop(node, "no-map", NULL))
return -EINVAL;
- if ((rmem->base & mask) || (rmem->size & mask)) {
+ if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) {
pr_err("Reserved memory: incorrect alignment of CMA region\n");
return -EINVAL;
}
diff --git a/mm/cma.c b/mm/cma.c
index bc9ca8f3c487..5a2cd5851658 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -168,7 +168,6 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
struct cma **res_cma)
{
struct cma *cma;
- phys_addr_t alignment;
/* Sanity checks */
if (cma_area_count == ARRAY_SIZE(cma_areas)) {
@@ -179,15 +178,12 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
if (!size || !memblock_is_region_reserved(base, size))
return -EINVAL;
- /* ensure minimal alignment required by mm core */
- alignment = PAGE_SIZE <<
- max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
-
/* alignment should be aligned with order_per_bit */
- if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
+ if (!IS_ALIGNED(CMA_MIN_ALIGNMENT_PAGES, 1 << order_per_bit))
return -EINVAL;
- if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
+ /* ensure minimal alignment required by mm core */
+ if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
return -EINVAL;
/*
@@ -262,14 +258,8 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
if (alignment && !is_power_of_2(alignment))
return -EINVAL;
- /*
- * Sanitise input arguments.
- * Pages both ends in CMA area could be merged into adjacent unmovable
- * migratetype page by page allocator's buddy algorithm. In the case,
- * you couldn't get a contiguous memory, which is not what we want.
- */
- alignment = max(alignment, (phys_addr_t)PAGE_SIZE <<
- max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
+ /* Sanitise input arguments. */
+ alignment = max_t(phys_addr_t, alignment, CMA_MIN_ALIGNMENT_BYTES);
if (fixed && base & (alignment - 1)) {
ret = -EINVAL;
pr_err("Region at %pa must be aligned to %pa bytes\n",
--
2.34.1