Re: [PATCH 1/2] efi: Add efi_memmap_free() to free EFI memory map

[Yunfeng Ye <yeyunfeng@huawei.com>]

On 2019/9/25 23:29, Ard Biesheuvel wrote:
> On Wed, 25 Sep 2019 at 11:17, Yunfeng Ye <yeyunfeng@huawei.com> wrote:
>>
>> In efi_fake_memmap(), the commit 20b1e22d01a4 ("x86/efi: Don't allocate
>> memmap through memblock after mm_init()") replace memblock_alloc() with
>> efi_memmap_alloc(), but there is no matching modification of
>> memblock_free() when early_memremap() fail.
>>
>> Fix this by adding efi_memmap_free() to instead of memblock_free().
>>
>> Fixes: 20b1e22d01a4 ("x86/efi: Don't allocate memmap through memblock after mm_init()")
>> Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
> 
> What happens if you try to call efi_memmap_free() /after/ slab has
> become available on an allocation that was created before?
> 
I didn't met the failure path in efi_fake_memmap(), just looked at the code and
found that the memory allocation using efi_memmap_free(), but free memory using
memblock_free(), I think it's not correct.

Also another series patch "[PATCH 2/2] x86/efi: Fix memory leak for EFI memmap
reservations", using efi_memmap_free() for fixing the memory leak in the failure
path.

thanks.

>> ---
>>  drivers/firmware/efi/fake_mem.c |  2 +-
>>  drivers/firmware/efi/memmap.c   | 34 ++++++++++++++++++++++++++++++++++
>>  include/linux/efi.h             |  1 +
>>  3 files changed, 36 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
>> index 9501edc..c2f69f6 100644
>> --- a/drivers/firmware/efi/fake_mem.c
>> +++ b/drivers/firmware/efi/fake_mem.c
>> @@ -65,7 +65,7 @@ void __init efi_fake_memmap(void)
>>         new_memmap = early_memremap(new_memmap_phy,
>>                                     efi.memmap.desc_size * new_nr_map);
>>         if (!new_memmap) {
>> -               memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
>> +               efi_memmap_free(new_memmap_phy, new_nr_map);
>>                 return;
>>         }
>>
>> diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
>> index 38b686c..35dc189 100644
>> --- a/drivers/firmware/efi/memmap.c
>> +++ b/drivers/firmware/efi/memmap.c
>> @@ -18,6 +18,11 @@ static phys_addr_t __init __efi_memmap_alloc_early(unsigned long size)
>>         return memblock_phys_alloc(size, SMP_CACHE_BYTES);
>>  }
>>
>> +static void __init __efi_memmap_free_early(phys_addr_t addr, unsigned long size)
>> +{
>> +       memblock_free(addr, size);
>> +}
>> +
>>  static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
>>  {
>>         unsigned int order = get_order(size);
>> @@ -29,6 +34,15 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
>>         return PFN_PHYS(page_to_pfn(p));
>>  }
>>
>> +static void __init __efi_memmap_free_late(phys_addr_t addr, unsigned long size)
>> +{
>> +       unsigned int order = get_order(size);
>> +       struct page *p = pfn_to_page(PHYS_PFN(addr));
>> +
>> +       if (p)
>> +               __free_pages(p, order);
>> +}
>> +
>>  /**
>>   * efi_memmap_alloc - Allocate memory for the EFI memory map
>>   * @num_entries: Number of entries in the allocated map.
>> @@ -50,6 +64,26 @@ phys_addr_t __init efi_memmap_alloc(unsigned int num_entries)
>>  }
>>
>>  /**
>> + * efi_memmap_free - Free memory for the EFI memory map
>> + * @addr: Physical address of the EFI memory map to be freed.
>> + * @num_entries: Number of the EFI memory map entries.
>> + *
>> + * Depending on whether mm_init() has already been invoked or not,
>> + * either memblock or "normal" page free is used.
>> + */
>> +void __init efi_memmap_free(phys_addr_t addr, unsigned int num_entries)
>> +{
>> +       unsigned long size = num_entries * efi.memmap.desc_size;
>> +
>> +       if (slab_is_available()) {
>> +               __efi_memmap_free_late(addr, size);
>> +
>> +               return;
>> +       }
>> +       __efi_memmap_free_early(addr, size);
>> +}
>> +
>> +/**
>>   * __efi_memmap_init - Common code for mapping the EFI memory map
>>   * @data: EFI memory map data
>>   * @late: Use early or late mapping function?
>> diff --git a/include/linux/efi.h b/include/linux/efi.h
>> index bd38370..8bb741a 100644
>> --- a/include/linux/efi.h
>> +++ b/include/linux/efi.h
>> @@ -1057,6 +1057,7 @@ static inline efi_status_t efi_query_variable_store(u32 attributes,
>>  extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
>>
>>  extern phys_addr_t __init efi_memmap_alloc(unsigned int num_entries);
>> +extern void __init efi_memmap_free(phys_addr_t addr, unsigned int num_entries);
>>  extern int __init efi_memmap_init_early(struct efi_memory_map_data *data);
>>  extern int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size);
>>  extern void __init efi_memmap_unmap(void);
>> --
>> 1.8.3.1
>>
> 
> .
>