kgsl_ioctl_gpumem_alloc
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static const struct kgsl_ioctl kgsl_ioctl_funcs[] =
...
// ioctl命令：IOCTL_KGSL_GPUMEM_ALLOC
// ioctl函数：kgsl_ioctl_gpumem_alloc
KGSL_IOCTL_FUNC(IOCTL_KGSL_GPUMEM_ALLOC,
kgsl_ioctl_gpumem_alloc),
...
1. kgsl_gpumem_alloc
struct kgsl_gpumem_alloc
// 返回值：GPU内存地址
unsigned long gpuaddr; /* output param */
// 申请的内存大小
__kernel_size_t size;
// 标志位
unsigned int flags;
;
// ioctl参数：kgsl_gpumem_alloc
#define IOCTL_KGSL_GPUMEM_ALLOC \\
_IOWR(KGSL_IOC_TYPE, 0x2f, struct kgsl_gpumem_alloc)
2. kgsl_ioctl_gpumem_alloc
long kgsl_ioctl_gpumem_alloc(struct kgsl_device_private *dev_priv,
unsigned int cmd, void *data)
struct kgsl_device *device = dev_priv->device;
// ioctl命令参数
struct kgsl_gpumem_alloc *param = data;
// kgsl_mem_entry用于描述用户空间的内存分配[见2.1节]
struct kgsl_mem_entry *entry;
uint64_t flags = param->flags;
/*
* On 64 bit kernel, secure memory region is expanded and
* moved to 64 bit address, 32 bit apps can not access it from
* this IOCTL.
*/
if ((param->flags & KGSL_MEMFLAGS_SECURE) && is_compat_task()
&& test_bit(KGSL_MMU_64BIT, &device->mmu.features))
return -EOPNOTSUPP;
/* Legacy functions doesn't support these advanced features */
flags &= ~((uint64_t) KGSL_MEMFLAGS_USE_CPU_MAP);
if (is_compat_task())
flags |= KGSL_MEMFLAGS_FORCE_32BIT;
// 创建kgsl_mem_entry[见2.2节]
entry = gpumem_alloc_entry(dev_priv, (uint64_t) param->size, flags);
if (IS_ERR(entry))
return PTR_ERR(entry);
// 更新参数
param->gpuaddr = (unsigned long) entry->memdesc.gpuaddr;
param->size = (size_t) entry->memdesc.size;
param->flags = (unsigned int) entry->memdesc.flags;
/* Put the extra ref from kgsl_mem_entry_create() */
// 减少引用计数, 如果引用计数减为0则通过kgsl_mem_entry_destroy释放kgsl_mem_entry
kgsl_mem_entry_put(entry);
return 0;
2.1 kgsl_mem_entry
/*
* struct kgsl_mem_entry - a userspace memory allocation
*/
struct kgsl_mem_entry
// Currently userspace can only hold a single reference count but the kernel may hold more
struct kref refcount;
// description of the memory[见2.1.1节]
struct kgsl_memdesc memdesc;
// type-specific data, such as the dma-buf attachment pointer
void *priv_data;
// rb_node for the gpu address lookup rb tree
struct rb_node node;
// idr index for this entry, can be used to find memory that does not have a valid GPU address
unsigned int id;
// 持有该内存的进程
struct kgsl_process_private *priv;
// if !0, userspace requested that his memory be freed, but there are still references to it
int pending_free;
// String containing user specified metadata for the entry
char metadata[KGSL_GPUOBJ_ALLOC_METADATA_MAX + 1];
// used to schedule a kgsl_mem_entry_put in atomic contexts
struct work_struct work;
/**
* @map_count: Count how many vmas this object is mapped in - used for
* debugfs accounting
*/
// 映射的VMA数量
atomic_t map_count;
;
2.1.1 kgsl_memdesc
/**
* struct kgsl_memdesc - GPU memory object descriptor
*/
struct kgsl_memdesc
// Pointer to the pagetable that the object is mapped in
struct kgsl_pagetable *pagetable;
// Kernel virtual address
void *hostptr;
// Number of threads using hostptr
unsigned int hostptr_count;
// GPU virtual address
uint64_t gpuaddr;
// Physical address of the memory object
phys_addr_t physaddr;
// Size of the memory object
uint64_t size;
// Internal flags and settings
unsigned int priv;
struct sg_table *sgt;
// Function hooks for the memdesc memory type[见2.1.2节]
const struct kgsl_memdesc_ops *ops;
// Flags set from userspace
uint64_t flags;
struct device *dev;
// dma attributes for this memory
unsigned long attrs;
// An array of pointers to allocated pages
struct page **pages;
// Total number of pages allocated
unsigned int page_count;
/*
* @lock: Spinlock to protect the gpuaddr from being accessed by
* multiple entities trying to map the same SVM region at once
*/
spinlock_t lock;
/** @shmem_filp: Pointer to the shmem file backing this memdesc */
// 共享内存的文件
struct file *shmem_filp;
/** @ranges: rbtree base for the interval list of vbo ranges */
struct rb_root_cached ranges;
/** @ranges_lock: Mutex to protect the range database */
struct mutex ranges_lock;
/** @gmuaddr: GMU VA if this is mapped in GMU */
u32 gmuaddr;
;
2.1.2 kgsl_memdesc_ops
struct kgsl_memdesc_ops
unsigned int vmflags;
vm_fault_t (*vmfault)(struct kgsl_memdesc *memdesc,
struct vm_area_struct *vma, struct vm_fault *vmf);
void (*free)(struct kgsl_memdesc *memdesc);
int (*map_kernel)(struct kgsl_memdesc *memdesc);
void (*unmap_kernel)(struct kgsl_memdesc *memdesc);
/**
* @put_gpuaddr: Put away the GPU address and unmap the memory
* descriptor
*/
void (*put_gpuaddr)(struct kgsl_memdesc *memdesc);
;
2.2 gpumem_alloc_entry
struct kgsl_mem_entry *gpumem_alloc_entry(
struct kgsl_device_private *dev_priv,
uint64_t size, uint64_t flags)
int ret;
struct kgsl_process_private *private = dev_priv->process_priv;
struct kgsl_mem_entry *entry;
struct kgsl_device *device = dev_priv->device;
u32 cachemode;
/* For 32-bit kernel world nothing to do with this flag */
if (BITS_PER_LONG == 32)
flags &= ~((uint64_t) KGSL_MEMFLAGS_FORCE_32BIT);
if (flags & KGSL_MEMFLAGS_VBO)
return gpumem_alloc_vbo_entry(dev_priv, size, flags);
flags &= KGSL_MEMFLAGS_GPUREADONLY
| KGSL_CACHEMODE_MASK
| KGSL_MEMTYPE_MASK
| KGSL_MEMALIGN_MASK
| KGSL_MEMFLAGS_USE_CPU_MAP
| KGSL_MEMFLAGS_SECURE
| KGSL_MEMFLAGS_FORCE_32BIT
| KGSL_MEMFLAGS_IOCOHERENT
| KGSL_MEMFLAGS_GUARD_PAGE;
/* Return not supported error if secure memory isn't enabled */
if ((flags & KGSL_MEMFLAGS_SECURE) && !check_and_warn_secured(device))
return ERR_PTR(-EOPNOTSUPP);
flags = cap_alignment(device, flags);
/* For now only allow allocations up to 4G */
if (size == 0 || size > UINT_MAX)
return ERR_PTR(-EINVAL);
// 更新缓存策略
flags = kgsl_filter_cachemode(flags);
// 前面主要完成标志位的校验和更新
// 这里开始创建kgsl_mem_entry[见2.2.1节]
entry = kgsl_mem_entry_create();
if (entry == NULL)
return ERR_PTR(-ENOMEM);
// 根据标志位判断是否是cached buffer
if (IS_ENABLED(CONFIG_QCOM_KGSL_IOCOHERENCY_DEFAULT) &&
kgsl_cachemode_is_cached(flags))
flags |= KGSL_MEMFLAGS_IOCOHERENT;
// 用户空间分配[2.2.2节]
ret = kgsl_allocate_user(device, &entry->memdesc,
size, flags, 0);
if (ret != 0)
goto err;
// 绑定映射[2.2.7节]
ret = kgsl_mem_entry_attach_and_map(device, private, entry);
if (ret != 0)
kgsl_sharedmem_free(&entry->memdesc);
goto err;
// 获取缓存模式
cachemode = kgsl_memdesc_get_cachemode(&entry->memdesc);
/*
* Secure buffers cannot be reclaimed. Avoid reclaim of cached buffers
* as we could get request for cache operations on these buffers when
* they are reclaimed.
*/
// 确认memdesc的pages是否能够直接回收
if (!(flags & KGSL_MEMFLAGS_SECURE) &&
!(cachemode == KGSL_CACHEMODE_WRITEBACK) &&
!(cachemode == KGSL_CACHEMODE_WRITETHROUGH))
entry->memdesc.priv |= KGSL_MEMDESC_CAN_RECLAIM;
// 首先确定kgsl_memdesc的buffer类型
// 然后将其大小统计进kgsl_process_private的stats数组
kgsl_process_add_stats(private,
kgsl_memdesc_usermem_type(&entry->memdesc),
entry->memdesc.size);
trace_kgsl_mem_alloc(entry);
// 将kgsl_mem_entry提交到kgsl_process_private, 以便其他操作也能够访问
kgsl_mem_entry_commit_process(entry);
return entry;
err:
kfree(entry);
return ERR_PTR(ret);
2.2.1 kgsl_mem_entry_create
static struct kgsl_mem_entry *kgsl_mem_entry_create(void)
// 创建kgsl_mem_entry
struct kgsl_mem_entry *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (entry != NULL)
// 初始化kgsl_mem_entry引用计数为1
kref_init(&entry->refcount);
/* put this ref in userspace memory alloc and map ioctls */
// 引用计数加1
kref_get(&entry->refcount);
// 初始化映射的VMA数量为0
atomic_set(&entry->map_count, 0);
return entry;
2.2.2 kgsl_allocate_user
enum kgsl_mmutype
// 支持IOMMU
KGSL_MMU_TYPE_IOMMU = 0,
KGSL_MMU_TYPE_NONE
;
int kgsl_allocate_user(struct kgsl_device *device, struct kgsl_memdesc *memdesc,
u64 size, u64 flags, u32 priv)
// 如果不支持IOMMU, 则需要分配连续内存
if (device->mmu.type == KGSL_MMU_TYPE_NONE)
return kgsl_alloc_contiguous(device, memdesc, size, flags,
priv);
else if (flags & KGSL_MEMFLAGS_SECURE)
return kgsl_allocate_secure(device, memdesc, size, flags, priv);
// 页面分配[见2.2.3节]
return kgsl_alloc_pages(device, memdesc, size, flags, priv);
2.2.3 kgsl_alloc_pages
static int kgsl_alloc_pages(struct kgsl_device *device,
struct kgsl_memdesc *memdesc, u64 size, u64 flags, u32 priv)
struct page **pages;
int count;
// size大小对齐
size = PAGE_ALIGN(size);
// 判断size大小有效性
if (!size || size > UINT_MAX)
return -EINVAL;
// 根据标志位初始化kgsl_memdesc[见2.2.4节]
kgsl_memdesc_init(device, memdesc, flags);
// 传入的priv为0
memdesc->priv |= priv;
// #define KGSL_MEMDESC_SYSMEM BIT(9)
if (priv & KGSL_MEMDESC_SYSMEM)
memdesc->ops = &kgsl_system_ops;
count = kgsl_system_alloc_pages(size, &pages, device->dev);
else
// 设置kgsl_memdesc的kgsl_memdesc_ops实现[2.2.5节]
memdesc->ops = &kgsl_page_ops;
// 分配页面并返回分配的page[2.2.6节]
count = _kgsl_alloc_pages(memdesc, size, &pages, device->dev);
if (count < 0)
return count;
// 页面指针
memdesc->pages = pages;
// 内存大小
memdesc->size = size;
// 页面数量
memdesc->page_count = count;
// 更新全局的kgsl的内存统计: 将申请的内存大小统计进kgsl_driver的stats结构体page_alloc成员
KGSL_STATS_ADD(size, &kgsl_driver.stats.page_alloc,
&kgsl_driver.stats.page_alloc_max);
return 0;
2.2.4 kgsl_memdesc_init
void kgsl_memdesc_init(struct kgsl_device *device,
struct kgsl_memdesc *memdesc, uint64_t flags)
struct kgsl_mmu *mmu = &device->mmu;
unsigned int align;
// 初始化kgsl_memdesc
memset(memdesc, 0, sizeof(*memdesc));
/* Turn off SVM if the system doesn't support it */
// 判断是否支持KGSL_MMU_IOPGTABLE
if (!kgsl_mmu_is_perprocess(mmu))
flags &= ~((uint64_t) KGSL_MEMFLAGS_USE_CPU_MAP);
/* Secure memory disables advanced addressing modes */
if (flags & KGSL_MEMFLAGS_SECURE)
flags &= ~((uint64_t) KGSL_MEMFLAGS_USE_CPU_MAP);
/* Disable IO coherence if it is not supported on the chip */
// 判断是否支持I/O coherency
if (!kgsl_mmu_has_feature(device, KGSL_MMU_IO_COHERENT))
flags &= ~((uint64_t) KGSL_MEMFLAGS_IOCOHERENT);
WARN_ONCE(IS_ENABLED(CONFIG_QCOM_KGSL_IOCOHERENCY_DEFAULT),
"I/O coherency is not supported on this target\\n");
else if (IS_ENABLED(CONFIG_QCOM_KGSL_IOCOHERENCY_DEFAULT))
flags |= KGSL_MEMFLAGS_IOCOHERENT;
/*
* We can't enable I/O coherency on uncached surfaces because of
* situations where hardware might snoop the cpu caches which can
* have stale data. This happens primarily due to the limitations
* of dma caching APIs available on arm64
*/
if (!kgsl_cachemode_is_cached(flags))
flags &= ~((u64) KGSL_MEMFLAGS_IOCOHERENT);
if (kgsl_mmu_has_feature(device, KGSL_MMU_NEED_GUARD_PAGE) ||
(flags & KGSL_MEMFLAGS_GUARD_PAGE))
memdesc->priv |= KGSL_MEMDESC_GUARD_PAGE;
if (flags & KGSL_MEMFLAGS_SECURE)
memdesc->priv |= KGSL_MEMDESC_SECURE;
// 设置标志位
memdesc->flags = flags;
// 设置持有该内存的device
memdesc->dev = &device->pdev->dev;
// 对齐
align = max_t(unsigned int,
kgsl_memdesc_get_align(memdesc), ilog2(PAGE_SIZE));
// 设置kgsl_memdesc的对齐标志位
kgsl_memdesc_set_align(memdesc, align);
spin_lock_init(&memdesc->lock);
2.2.5 kgsl_page_ops
static const struct kgsl_memdesc_ops kgsl_page_ops =
.free = kgsl_free_pages,
.vmflags = VM_DONTDUMP | VM_DONTEXPAND | VM_DONTCOPY | VM_MIXEDMAP,
.vmfault = kgsl_paged_vmfault,
.map_kernel = kgsl_paged_map_kernel,
.unmap_kernel = kgsl_paged_unmap_kernel,
.put_gpuaddr = kgsl_unmap_and_put_gpuaddr,
;
2.2.6 _kgsl_alloc_pages
static int _kgsl_alloc_pages(struct kgsl_memdesc *memdesc,
u64 size, struct page ***pages, struct device *dev)
int count = 0;
// 将内存大小转换为页面数量
int npages = size >> PAGE_SHIFT;
// attempt to allocate physically contiguous memory by kmalloc
// but upon failure, fall back to non-contiguous (vmalloc) allocation
struct page **local = kvcalloc(npages, sizeof(*local), GFP_KERNEL);
u32 page_size, align;
u64 len = size;
if (!local)
return -ENOMEM;
// 共享内存设置成功或者未配置CONFIG_QCOM_KGSL_USE_SHMEM则返回0[见2.2.6.1节]
count = kgsl_memdesc_file_setup(memdesc, size);
if (count)
kvfree(local);
return count;
/* Start with 1MB alignment to get the biggest page we can */
align = ilog2(SZ_1M);
// 根据内存大小计算页面大小
page_size = kgsl_get_page_size(len, align);
while (len)
// 调用kgsl_pool_alloc_page分配, 并将获取的page通过local数组返回
int ret = kgsl_alloc_page(&page_size, &local[count],
npages, &align, count, memdesc->shmem_filp, dev);
if (ret == -EAGAIN)
continue;
else if (ret <= 0)
int i;
for (i = 0; i < count; )
int n = 1 << compound_order(local[i]);
kgsl_free_page(local[i]);
i += n;
kvfree(local);
if (!kgsl_sharedmem_noretry_flag)
pr_err_ratelimited("kgsl: out of memory: only allocated %lldKb of %lldKb requested\\n",
(size - len) >> 10, size >> 10);
if (memdesc->shmem_filp)
fput(memdesc->shmem_filp);
return -ENOMEM;
count += ret;
npages -= ret;
len -= page_size;
page_size = kgsl_get_page_size(len, align);
// pages作为返回值
*pages = local;
return count;
2.2.6.1 kgsl_memdesc_file_setup
// 配置kgsl使用共享内存
#ifdef CONFIG_QCOM_KGSL_USE_SHMEM
static int kgsl_以上是关于kgsl_ioctl_gpumem_alloc的主要内容，如果未能解决你的问题，请参考以下文章