Re: [PATCH 14/14] staging: android: ion: Add UNMAPPED heap type and helper

[Andrew F. Davis]

On 1/15/19 1:11 PM, Laura Abbott wrote:
> On 1/15/19 10:43 AM, Laura Abbott wrote:
>> On 1/15/19 7:58 AM, Andrew F. Davis wrote:
>>> On 1/14/19 8:32 PM, Laura Abbott wrote:
>>>> On 1/11/19 10:05 AM, Andrew F. Davis wrote:
>>>>> The "unmapped" heap is very similar to the carveout heap except
>>>>> the backing memory is presumed to be unmappable by the host, in
>>>>> my specific case due to firewalls. This memory can still be
>>>>> allocated from and used by devices that do have access to the
>>>>> backing memory.
>>>>>
>>>>> Based originally on the secure/unmapped heap from Linaro for
>>>>> the OP-TEE SDP implementation, this was re-written to match
>>>>> the carveout heap helper code.
>>>>>
>>>>> Suggested-by: Etienne Carriere <etienne.carriere@xxxxxxxxxx>
>>>>> Signed-off-by: Andrew F. Davis <afd@xxxxxx>
>>>>> ---
>>>>> ÂÂ drivers/staging/android/ion/KconfigÂÂÂÂÂÂÂÂÂÂ |Â 10 ++
>>>>> ÂÂ drivers/staging/android/ion/MakefileÂÂÂÂÂÂÂÂÂ |ÂÂ 1 +
>>>>> ÂÂ drivers/staging/android/ion/ion.hÂÂÂÂÂÂÂÂÂÂÂÂ |Â 16 +++
>>>>> ÂÂ .../staging/android/ion/ion_unmapped_heap.cÂÂ | 123
>>>>> ++++++++++++++++++
>>>>> ÂÂ drivers/staging/android/uapi/ion.hÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 3 +
>>>>> ÂÂ 5 files changed, 153 insertions(+)
>>>>> ÂÂ create mode 100644 drivers/staging/android/ion/ion_unmapped_heap.c
>>>>>
>>>>> diff --git a/drivers/staging/android/ion/Kconfig
>>>>> b/drivers/staging/android/ion/Kconfig
>>>>> index 0fdda6f62953..a117b8b91b14 100644
>>>>> --- a/drivers/staging/android/ion/Kconfig
>>>>> +++ b/drivers/staging/android/ion/Kconfig
>>>>> @@ -42,3 +42,13 @@ config ION_CMA_HEAP
>>>>> ÂÂÂÂÂÂÂÂ Choose this option to enable CMA heaps with Ion. This heap is
>>>>> backed
>>>>> ÂÂÂÂÂÂÂÂ by the Contiguous Memory Allocator (CMA). If your system has
>>>>> these
>>>>> ÂÂÂÂÂÂÂÂ regions, you should say Y here.
>>>>> +
>>>>> +config ION_UNMAPPED_HEAP
>>>>> +ÂÂÂ bool "ION unmapped heap support"
>>>>> +ÂÂÂ depends on ION
>>>>> +ÂÂÂ help
>>>>> +ÂÂÂÂÂ Choose this option to enable UNMAPPED heaps with Ion. This
>>>>> heap is
>>>>> +ÂÂÂÂÂ backed in specific memory pools, carveout from the Linux
>>>>> memory.
>>>>> +ÂÂÂÂÂ Unlike carveout heaps these are assumed to be not mappable by
>>>>> +ÂÂÂÂÂ kernel or user-space.
>>>>> +ÂÂÂÂÂ Unless you know your system has these regions, you should say N
>>>>> here.
>>>>> diff --git a/drivers/staging/android/ion/Makefile
>>>>> b/drivers/staging/android/ion/Makefile
>>>>> index 17f3a7569e3d..c71a1f3de581 100644
>>>>> --- a/drivers/staging/android/ion/Makefile
>>>>> +++ b/drivers/staging/android/ion/Makefile
>>>>> @@ -4,3 +4,4 @@ obj-$(CONFIG_ION_SYSTEM_HEAP) += ion_system_heap.o
>>>>> ion_page_pool.o
>>>>> ÂÂ obj-$(CONFIG_ION_CARVEOUT_HEAP) += ion_carveout_heap.o
>>>>> ÂÂ obj-$(CONFIG_ION_CHUNK_HEAP) += ion_chunk_heap.o
>>>>> ÂÂ obj-$(CONFIG_ION_CMA_HEAP) += ion_cma_heap.o
>>>>> +obj-$(CONFIG_ION_UNMAPPED_HEAP) += ion_unmapped_heap.o
>>>>> diff --git a/drivers/staging/android/ion/ion.h
>>>>> b/drivers/staging/android/ion/ion.h
>>>>> index 97b2876b165a..ce74332018ba 100644
>>>>> --- a/drivers/staging/android/ion/ion.h
>>>>> +++ b/drivers/staging/android/ion/ion.h
>>>>> @@ -341,4 +341,20 @@ static inline struct ion_heap
>>>>> *ion_chunk_heap_create(phys_addr_t base, size_t si
>>>>> ÂÂ }
>>>>> ÂÂ #endif
>>>>> ÂÂ +#ifdef CONFIG_ION_UNMAPPED_HEAP
>>>>> +/**
>>>>> + * ion_unmapped_heap_create
>>>>> + * @base:ÂÂÂÂÂÂÂ base address of carveout memory
>>>>> + * @size:ÂÂÂÂÂÂÂ size of carveout memory region
>>>>> + *
>>>>> + * Creates an unmapped ion_heap using the passed in data
>>>>> + */
>>>>> +struct ion_heap *ion_unmapped_heap_create(phys_addr_t base, size_t
>>>>> size);
>>>>> +#else
>>>>> +struct ion_heap *ion_unmapped_heap_create(phys_addr_t base, size_t
>>>>> size)
>>>>> +{
>>>>> +ÂÂÂ return ERR_PTR(-ENODEV);
>>>>> +}
>>>>> +#endif
>>>>> +
>>>>> ÂÂ #endif /* _ION_H */
>>>>> diff --git a/drivers/staging/android/ion/ion_unmapped_heap.c
>>>>> b/drivers/staging/android/ion/ion_unmapped_heap.c
>>>>> new file mode 100644
>>>>> index 000000000000..7602b659c2ec
>>>>> --- /dev/null
>>>>> +++ b/drivers/staging/android/ion/ion_unmapped_heap.c
>>>>> @@ -0,0 +1,123 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>> +/*
>>>>> + * ION Memory Allocator unmapped heap helper
>>>>> + *
>>>>> + * Copyright (C) 2015-2016 Texas Instruments Incorporated -
>>>>> http://www.ti.com/
>>>>> + *ÂÂÂ Andrew F. Davis <afd@xxxxxx>
>>>>> + *
>>>>> + * ION "unmapped" heaps are physical memory heaps not by default
>>>>> mapped into
>>>>> + * a virtual address space. The buffer owner can explicitly request
>>>>> kernel
>>>>> + * space mappings but the underlying memory may still not be
>>>>> accessible for
>>>>> + * various reasons, such as firewalls.
>>>>> + */
>>>>> +
>>>>> +#include <linux/err.h>
>>>>> +#include <linux/genalloc.h>
>>>>> +#include <linux/scatterlist.h>
>>>>> +#include <linux/slab.h>
>>>>> +
>>>>> +#include "ion.h"
>>>>> +
>>>>> +#define ION_UNMAPPED_ALLOCATE_FAIL -1
>>>>> +
>>>>> +struct ion_unmapped_heap {
>>>>> +ÂÂÂ struct ion_heap heap;
>>>>> +ÂÂÂ struct gen_pool *pool;
>>>>> +};
>>>>> +
>>>>> +static phys_addr_t ion_unmapped_allocate(struct ion_heap *heap,
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long size)
>>>>> +{
>>>>> +ÂÂÂ struct ion_unmapped_heap *unmapped_heap =
>>>>> +ÂÂÂÂÂÂÂ container_of(heap, struct ion_unmapped_heap, heap);
>>>>> +ÂÂÂ unsigned long offset;
>>>>> +
>>>>> +ÂÂÂ offset = gen_pool_alloc(unmapped_heap->pool, size);
>>>>> +ÂÂÂ if (!offset)
>>>>> +ÂÂÂÂÂÂÂ return ION_UNMAPPED_ALLOCATE_FAIL;
>>>>> +
>>>>> +ÂÂÂ return offset;
>>>>> +}
>>>>> +
>>>>> +static void ion_unmapped_free(struct ion_heap *heap, phys_addr_t
>>>>> addr,
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long size)
>>>>> +{
>>>>> +ÂÂÂ struct ion_unmapped_heap *unmapped_heap =
>>>>> +ÂÂÂÂÂÂÂ container_of(heap, struct ion_unmapped_heap, heap);
>>>>> +
>>>>> +ÂÂÂ gen_pool_free(unmapped_heap->pool, addr, size);
>>>>> +}
>>>>> +
>>>>> +static int ion_unmapped_heap_allocate(struct ion_heap *heap,
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct ion_buffer *buffer,
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long size,
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long flags)
>>>>> +{
>>>>> +ÂÂÂ struct sg_table *table;
>>>>> +ÂÂÂ phys_addr_t paddr;
>>>>> +ÂÂÂ int ret;
>>>>> +
>>>>> +ÂÂÂ table = kmalloc(sizeof(*table), GFP_KERNEL);
>>>>> +ÂÂÂ if (!table)
>>>>> +ÂÂÂÂÂÂÂ return -ENOMEM;
>>>>> +ÂÂÂ ret = sg_alloc_table(table, 1, GFP_KERNEL);
>>>>> +ÂÂÂ if (ret)
>>>>> +ÂÂÂÂÂÂÂ goto err_free;
>>>>> +
>>>>> +ÂÂÂ paddr = ion_unmapped_allocate(heap, size);
>>>>> +ÂÂÂ if (paddr == ION_UNMAPPED_ALLOCATE_FAIL) {
>>>>> +ÂÂÂÂÂÂÂ ret = -ENOMEM;
>>>>> +ÂÂÂÂÂÂÂ goto err_free_table;
>>>>> +ÂÂÂ }
>>>>> +
>>>>> +ÂÂÂ sg_set_page(table->sgl, pfn_to_page(PFN_DOWN(paddr)), size, 0);
>>>>> +ÂÂÂ buffer->sg_table = table;
>>>>> +
>>>>
>>>>
>>>> If this memory is actually unmapped this is not going to work because
>>>> the struct page will not be valid.
>>>>
>>>
>>> If it will never get mapped then it doesn't need a valid struct page as
>>> far as I can tell. We only use it as a marker to where the start of
>>> backing memory is, and that is calculated based on the struct page
>>> pointer address, not its contents.
>>>
>>
>> You can't rely on pfn_to_page returning a valid page pointer if the
>> pfn doesn't point to reserved memory. Even if you aren't relying
>> on the contents, that's no guarantee you can use that to to get
>> the valid pfn back. You can get away with that sometimes but it's
>> not correct to rely on it all the time.
>>
> 
> I found https://lore.kernel.org/lkml/20190111181731.11782-1-hch@xxxxxx/T/#u
> which I think is closer to what we might want to be looking at.
> 

That does seem to be something that could be used, I'll have to try to
understand this for a bit how to bring that into use here.

>>>>> +ÂÂÂ return 0;
>>>>> +
>>>>> +err_free_table:
>>>>> +ÂÂÂ sg_free_table(table);
>>>>> +err_free:
>>>>> +ÂÂÂ kfree(table);
>>>>> +ÂÂÂ return ret;
>>>>> +}
>>>>> +
>>>>> +static void ion_unmapped_heap_free(struct ion_buffer *buffer)
>>>>> +{
>>>>> +ÂÂÂ struct ion_heap *heap = buffer->heap;
>>>>> +ÂÂÂ struct sg_table *table = buffer->sg_table;
>>>>> +ÂÂÂ struct page *page = sg_page(table->sgl);
>>>>> +ÂÂÂ phys_addr_t paddr = PFN_PHYS(page_to_pfn(page));
>>>>> +
>>>>> +ÂÂÂ ion_unmapped_free(heap, paddr, buffer->size);
>>>>> +ÂÂÂ sg_free_table(buffer->sg_table);
>>>>> +ÂÂÂ kfree(buffer->sg_table);
>>>>> +}
>>>>> +
>>>>> +static struct ion_heap_ops unmapped_heap_ops = {
>>>>> +ÂÂÂ .allocate = ion_unmapped_heap_allocate,
>>>>> +ÂÂÂ .free = ion_unmapped_heap_free,
>>>>> +ÂÂÂ /* no .map_user, user mapping of unmapped heaps not allowed */
>>>>> +ÂÂÂ .map_kernel = ion_heap_map_kernel,
>>>>> +ÂÂÂ .unmap_kernel = ion_heap_unmap_kernel,
>>>>> +};
>>>>> +
>>>>> +struct ion_heap *ion_unmapped_heap_create(phys_addr_t base, size_t
>>>>> size)
>>>>> +{
>>>>> +ÂÂÂ struct ion_unmapped_heap *unmapped_heap;
>>>>> +
>>>>> +ÂÂÂ unmapped_heap = kzalloc(sizeof(*unmapped_heap), GFP_KERNEL);
>>>>> +ÂÂÂ if (!unmapped_heap)
>>>>> +ÂÂÂÂÂÂÂ return ERR_PTR(-ENOMEM);
>>>>> +
>>>>> +ÂÂÂ unmapped_heap->pool = gen_pool_create(PAGE_SHIFT, -1);
>>>>> +ÂÂÂ if (!unmapped_heap->pool) {
>>>>> +ÂÂÂÂÂÂÂ kfree(unmapped_heap);
>>>>> +ÂÂÂÂÂÂÂ return ERR_PTR(-ENOMEM);
>>>>> +ÂÂÂ }
>>>>> +ÂÂÂ gen_pool_add(unmapped_heap->pool, base, size, -1);
>>>>> +ÂÂÂ unmapped_heap->heap.ops = &unmapped_heap_ops;
>>>>> +ÂÂÂ unmapped_heap->heap.type = ION_HEAP_TYPE_UNMAPPED;
>>>>> +
>>>>> +ÂÂÂ return &unmapped_heap->heap;
>>>>> +}
>>>>> diff --git a/drivers/staging/android/uapi/ion.h
>>>>> b/drivers/staging/android/uapi/ion.h
>>>>> index 5d7009884c13..d5f98bc5f340 100644
>>>>> --- a/drivers/staging/android/uapi/ion.h
>>>>> +++ b/drivers/staging/android/uapi/ion.h
>>>>> @@ -19,6 +19,8 @@
>>>>> ÂÂÂ *ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ carveout heap, allocations are physically
>>>>> ÂÂÂ *ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ contiguous
>>>>> ÂÂÂ * @ION_HEAP_TYPE_DMA:ÂÂÂÂÂÂÂÂ memory allocated via DMA API
>>>>> + * @ION_HEAP_TYPE_UNMAPPED:ÂÂÂÂ memory not intended to be mapped into
>>>>> the
>>>>> + *ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ linux address space unless for debug cases
>>>>> ÂÂÂ * @ION_NUM_HEAPS:ÂÂÂÂÂÂÂÂ helper for iterating over heaps, a
>>>>> bit mask
>>>>> ÂÂÂ *ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ is used to identify the heaps, so only 32
>>>>> ÂÂÂ *ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ total heap types are supported
>>>>> @@ -29,6 +31,7 @@ enum ion_heap_type {
>>>>> ÂÂÂÂÂÂ ION_HEAP_TYPE_CARVEOUT,
>>>>> ÂÂÂÂÂÂ ION_HEAP_TYPE_CHUNK,
>>>>> ÂÂÂÂÂÂ ION_HEAP_TYPE_DMA,
>>>>> +ÂÂÂ ION_HEAP_TYPE_UNMAPPED,
>>>>> ÂÂÂÂÂÂ ION_HEAP_TYPE_CUSTOM, /*
>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ * must be last so device specific heaps always
>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ * are at the end of this enum
>>>>>
>>>>
>>>> Overall this seems way too similar to the carveout heap
>>>> to justify adding another heap type. It also still missing
>>>> the part of where exactly you call ion_unmapped_heap_create.
>>>> Figuring that out is one of the blocking items for moving
>>>> Ion out of staging.
>>>>
>>>
>>> I agree with this being almost a 1:1 copy of the carveout heap, I'm just
>>> not sure of a good way to do this without a new heap type. Adding flags
>>> to the existing carveout type seem a bit messy. Plus then those flags
>>> should be valid for other heap types, gets complicated quickly..
>>>
>>> I'll reply to the second part in your other top level response.
>>>
>>> Andrew
>>>
>>>> Thanks,
>>>> Laura
>>
>