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cma: add placement specifier for "cma=" kernel parameter 

Currently, "cma=" kernel parameter is used to specify the size of CMA,
but we can't specify where it is located.  We want to locate CMA below
4GB for devices only supporting 32-bit addressing on 64-bit systems
without iommu.

This enables to specify the placement of CMA by extending "cma=" kernel
parameter.

Examples:
 1. locate 64MB CMA below 4GB by "cma=64M@0-4G"
 2. locate 64MB CMA exact at 512MB by "cma=64M@512M"

Note that the DMA contiguous memory allocator on x86 assumes that
page_address() works for the pages to allocate.  So this change requires
to limit end address of contiguous memory area upto max_pfn_mapped to
prevent from locating it on highmem area by the argument of
dma_contiguous_reserve().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Akinobu Mita 2014-06-04 16:06:54 -07:00 committed by Linus Torvalds
parent 2bfc2862c4
commit 5ea3b1b2f8
4 changed files with 44 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Documentation/kernel-parameters.txt
View File

@ -630,8 +630,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Also note the kernel might malfunction if you disable
some critical bits.
cma=nn[MG] [ARM,KNL]
Sets the size of kernel global memory area for contiguous
cma=nn[MG]@[start[MG][-end[MG]]]
[ARM,X86,KNL]
Sets the size of kernel global memory area for
contiguous memory allocations and optionally the
placement constraint by the physical address range of
memory allocations. For more information, see
include/linux/dma-contiguous.h

2
arch/x86/kernel/setup.c
View File

@ -1119,7 +1119,7 @@ void __init setup_arch(char **cmdline_p)
setup_real_mode();
memblock_set_current_limit(get_max_mapped());
dma_contiguous_reserve(0);
dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
/*
* NOTE: On x86-32, only from this point on, fixmaps are ready for use.

42
drivers/base/dma-contiguous.c
View File

@ -60,11 +60,22 @@ struct cma *dma_contiguous_default_area;
*/
static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M;
static phys_addr_t size_cmdline = -1;
static phys_addr_t base_cmdline;
static phys_addr_t limit_cmdline;
static int __init early_cma(char *p)
{
pr_debug("%s(%s)\n", __func__, p);
size_cmdline = memparse(p, &p);
if (*p != '@')
return 0;
base_cmdline = memparse(p + 1, &p);
if (*p != '-') {
limit_cmdline = base_cmdline + size_cmdline;
return 0;
}
limit_cmdline = memparse(p + 1, &p);
return 0;
}
early_param("cma", early_cma);
@ -108,11 +119,18 @@ static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
void __init dma_contiguous_reserve(phys_addr_t limit)
{
phys_addr_t selected_size = 0;
phys_addr_t selected_base = 0;
phys_addr_t selected_limit = limit;
bool fixed = false;
pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
if (size_cmdline != -1) {
selected_size = size_cmdline;
selected_base = base_cmdline;
selected_limit = min_not_zero(limit_cmdline, limit);
if (base_cmdline + size_cmdline == limit_cmdline)
fixed = true;
} else {
#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
selected_size = size_bytes;
@ -129,10 +147,12 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
pr_debug("%s: reserving %ld MiB for global area\n", __func__,
(unsigned long)selected_size / SZ_1M);
dma_contiguous_reserve_area(selected_size, 0, limit,
&dma_contiguous_default_area);
dma_contiguous_reserve_area(selected_size, selected_base,
selected_limit,
&dma_contiguous_default_area,
fixed);
}
};
}
static DEFINE_MUTEX(cma_mutex);
@ -189,15 +209,20 @@ core_initcall(cma_init_reserved_areas);
* @base: Base address of the reserved area optional, use 0 for any
* @limit: End address of the reserved memory (optional, 0 for any).
* @res_cma: Pointer to store the created cma region.
* @fixed: hint about where to place the reserved area
*
* This function reserves memory from early allocator. It should be
* called by arch specific code once the early allocator (memblock or bootmem)
* has been activated and all other subsystems have already allocated/reserved
* memory. This function allows to create custom reserved areas for specific
* devices.
*
* If @fixed is true, reserve contiguous area at exactly @base. If false,
* reserve in range from @base to @limit.
*/
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma)
phys_addr_t limit, struct cma **res_cma,
bool fixed)
{
struct cma *cma = &cma_areas[cma_area_count];
phys_addr_t alignment;
@ -223,18 +248,15 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
limit &= ~(alignment - 1);
/* Reserve memory */
if (base) {
if (base && fixed) {
if (memblock_is_region_reserved(base, size) ||
memblock_reserve(base, size) < 0) {
ret = -EBUSY;
goto err;
}
} else {
/*
* Use __memblock_alloc_base() since
* memblock_alloc_base() panic()s.
*/
phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
phys_addr_t addr = memblock_alloc_range(size, alignment, base,
limit);
if (!addr) {
ret = -ENOMEM;
goto err;

9
include/linux/dma-contiguous.h
View File

@ -88,7 +88,8 @@ static inline void dma_contiguous_set_default(struct cma *cma)
void dma_contiguous_reserve(phys_addr_t addr_limit);
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma);
phys_addr_t limit, struct cma **res_cma,
bool fixed);
/**
* dma_declare_contiguous() - reserve area for contiguous memory handling
@ -108,7 +109,7 @@ static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
{
struct cma *cma;
int ret;
ret = dma_contiguous_reserve_area(size, base, limit, &cma);
ret = dma_contiguous_reserve_area(size, base, limit, &cma, true);
if (ret == 0)
dev_set_cma_area(dev, cma);
@ -136,7 +137,9 @@ static inline void dma_contiguous_set_default(struct cma *cma) { }
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma) {
phys_addr_t limit, struct cma **res_cma,
bool fixed)
{
return -ENOSYS;
}