[PATCH] arm64/efi: add missing call to early_ioremap_reset()

[Ard Biesheuvel]

> On 8 jan. 2015, at 11:36, Will Deacon <will.deacon at arm.com> wrote:
> 
>> On Thu, Jan 08, 2015 at 09:54:58AM +0000, Ard Biesheuvel wrote:
>> The early ioremap support introduced by patch bf4b558eba92
>> ("arm64: add early_ioremap support") failed to add a call to
>> early_ioremap_reset() at an appropriate time. Without this call,
>> invocations of early_ioremap etc. that are done too late will go
>> unnoticed and may cause corruption.
>> 
>> This is exactly what happened when the first user of this feature
>> was added in patch f84d02755f5a ("arm64: add EFI runtime services").
>> The early mapping of the EFI memory map is unmapped during an early
>> initcall, at which time the early ioremap support is long gone.
>> 
>> Fix by adding the missing call to early_ioremap_reset() to
>> setup_arch(), and move the offending early_memunmap() to right after
>> the point where the early mapping of the EFI memory map is last used.
>> 
>> Fixes: f84d02755f5a ("arm64: add EFI runtime services")
>> Cc: <stable at vger.kernel.org>
>> Signed-off-by: Leif Lindholm <leif.lindholm at linaro.org>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> ---
>> 
>> After discussing off-list between Mark Salter, Leif and myself, this is the
>> bare minimum to fix the early ioremap issue in kernels up to 3.19, combined
>> into a single patch. Considering that the early_ioremap support was added in
>> 3.15 (eol), but not used until EFI runtime services support was added in 3.16,
>> there is no reason to split this up. Also, we have work underway to drastically
>> change the way runtime services etc are mapped during early boot [which we hope
>> will make it into 3.20] so it makes sense to do the bare minimum here and handle
>> any fallout in terms of style etc later.
> 
> Ok, so this replaces the two patch series sent earlier by Leif and should be
> appied for 3.19?
> 

yes, please.
@leif: please confirm on-list

> Will
> 
>> arch/arm64/kernel/efi.c   | 2 +-
>> arch/arm64/kernel/setup.c | 1 +
>> 2 files changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
>> index 6fac253bc783..2bb4347d0edf 100644
>> --- a/arch/arm64/kernel/efi.c
>> +++ b/arch/arm64/kernel/efi.c
>> @@ -326,6 +326,7 @@ void __init efi_idmap_init(void)
>> 
>>    /* boot time idmap_pg_dir is incomplete, so fill in missing parts */
>>    efi_setup_idmap();
>> +    early_memunmap(memmap.map, memmap.map_end - memmap.map);
>> }
>> 
>> static int __init remap_region(efi_memory_desc_t *md, void **new)
>> @@ -380,7 +381,6 @@ static int __init arm64_enter_virtual_mode(void)
>>    }
>> 
>>    mapsize = memmap.map_end - memmap.map;
>> -    early_memunmap(memmap.map, mapsize);
>> 
>>    if (efi_runtime_disabled()) {
>>        pr_info("EFI runtime services will be disabled.\n");
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index b80991166754..20fe2932ad0c 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -402,6 +402,7 @@ void __init setup_arch(char **cmdline_p)
>>    request_standard_resources();
>> 
>>    efi_idmap_init();
>> +    early_ioremap_reset();
>> 
>>    unflatten_device_tree();
>> 
>> -- 
>> 1.8.3.2
>> 
>>