Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking

[Julien Thierry <julien.thierry@arm.com>]

Hi Ard,

On 14/12/2018 16:40, Julien Thierry wrote:
> 
> 
> On 14/12/2018 15:49, Ard Biesheuvel wrote:
>> On Fri, 14 Dec 2018 at 16:23, Julien Thierry <julien.thierry@arm.com> wrote:
>>>
>>> Hi,
>>>
>>> On 13/12/2018 15:03, Julien Thierry wrote:
>>>>
>>>> Argh, not as simple as I had expected.
>>>>
>>>> Turns out include/linux/efi.h does not include asm/efi.h (including it
>>>> at the beginning of the file breaks the build because asm/efi.h misses
>>>> the efi type definitions.
>>>>
>>>> So a thing like:
>>>>
>>>> #ifndef efi_get_irqflags
>>>> #define efi_get_irqflags(flags) local_save_flags(flags)
>>>> #endif
>>>>
>>>> in include/linux/efi.h cannot be overridden.
>>>>
>>>> Either I would need to introduce the definitions arm, arm64 and x86 (I
>>>> don't think there are other arch supporting EFI right now) or I'll need
>>>> to come up with another solution.
>>>>
>>>
>>
>> It might be a bit nasty, but can we put the #ifndef above in
>> runtime-wrappers.c directly? The only reference in linux/efi.h is a
>> macro, so that shouldn't matter afaict.
>>
> 
> Sadly, in arch/x86/platform/uv/bios_uv.c, uv_bios_call() has a reference
> to the macro efi_call_virt_pointer() which wouldn't be able to see the
> definition in runtime-wrappers.c
> 
> Otherwise, we could've moved efi_call_virt_pointer() and
> __efi_call_virt_pointer in runtime-wrappers.c and things would not have
> been as nasty.
> 
> But no, I don't think we can do that without breaking some x86 build :( .
> 

Since the above does not work, would the solution with the
HAVE_GENERIC_EFI_FLAGS below be acceptable to you? Or would you rather I
defined helpers in <asm/efi.h> for all arm/arm64/x86?

Or neither and I shall find another way?

Thanks,

Julien

>>
>>> Would the following patch be acceptable for the EFI generic side?
>>>
>>> If it is, I'll add it to the next iteration of this series.
>>>
>>> Thanks,
>>>
>>> Julien
>>>
>>> -->
>>>
>>> From 7acaa8e17142263addafb18ae10bd5d2d49cfb39 Mon Sep 17 00:00:00 2001
>>> From: Julien Thierry <julien.thierry@arm.com>
>>> Date: Fri, 14 Dec 2018 14:20:13 +0000
>>> Subject: [RFC] efi: Let architectures decide the flags that should be
>>>  saved/restored
>>>
>>> Currently, irqflags are saved before calling runtime services and
>>> checked for mismatch on return.
>>>
>>> Add a config option to let architectures define a set of flags to be
>>> checked and (if needed) restored when coming back from runtime services.
>>> This allows to use check flags that are not necesarly related to
>>> irqflags.
>>>
>>> Signed-off-by: Julien Thierry <julien.thierry@arm.com>
>>> ---
>>>  arch/Kconfig                            |  8 ++++++++
>>>  drivers/firmware/efi/runtime-wrappers.c |  4 ++--
>>>  include/linux/efi.h                     | 12 ++++++++++--
>>>  3 files changed, 20 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/Kconfig b/arch/Kconfig
>>> index e1e540f..cbec325 100644
>>> --- a/arch/Kconfig
>>> +++ b/arch/Kconfig
>>> @@ -695,6 +695,14 @@ config HAVE_ARCH_HASH
>>>           file which provides platform-specific implementations of some
>>>           functions in <linux/hash.h> or fs/namei.c.
>>>
>>> +config HAVE_GENERIC_EFI_FLAGS
>>> +       bool
>>> +       default n
>>> +       help
>>> +         Architecture defines a set of flags that EFI runtime services
>>> +         should take care to restore when returning to the OS.
>>> +         If this is not set, the set of flags defaults to the arch irqflags.
>>> +
>>>  config ISA_BUS_API
>>>         def_bool ISA
>>>
>>> diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
>>> index 8903b9c..6dafa04 100644
>>> --- a/drivers/firmware/efi/runtime-wrappers.c
>>> +++ b/drivers/firmware/efi/runtime-wrappers.c
>>> @@ -93,7 +93,7 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)
>>>  {
>>>         unsigned long cur_flags, mismatch;
>>>
>>> -       local_save_flags(cur_flags);
>>> +       efi_save_flags(cur_flags);
>>>
>>>         mismatch = flags ^ cur_flags;
>>>         if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
>>> @@ -102,7 +102,7 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)
>>>         add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
>>>         pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
>>>                            flags, cur_flags, call);
>>> -       local_irq_restore(flags);
>>> +       efi_restore_flags(flags);
>>>  }
>>>
>>>  /*
>>> diff --git a/include/linux/efi.h b/include/linux/efi.h
>>> index 100ce4a..41c110a 100644
>>> --- a/include/linux/efi.h
>>> +++ b/include/linux/efi.h
>>> @@ -1594,6 +1594,14 @@ enum efi_secureboot_mode {
>>>
>>>  void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
>>>
>>> +#ifdef CONFIG_HAVE_GENERIC_EFI_FLAGS
>>> +#define efi_save_flags(state_flags)    arch_efi_save_flags(state_flags)
>>> +#define efi_restore_flags(state_flags) arch_efi_restore_flags(state_flags)
>>> +#else
>>> +#define efi_save_flags(state_flags)    local_save_flags(state_flags)
>>> +#define efi_restore_flags(state_flags) local_irq_restore(state_flags)
>>> +#endif
>>> +
>>>  /*
>>>   * Arch code can implement the following three template macros, avoiding
>>>   * reptition for the void/non-void return cases of {__,}efi_call_virt():
>>> @@ -1621,7 +1629,7 @@ enum efi_secureboot_mode {
>>>                                                                         \
>>>         arch_efi_call_virt_setup();                                     \
>>>                                                                         \
>>> -       local_save_flags(__flags);                                      \
>>> +       efi_save_flags(__flags);                                        \
>>>         __s = arch_efi_call_virt(p, f, args);                           \
>>>         efi_call_virt_check_flags(__flags, __stringify(f));             \
>>>                                                                         \
>>> @@ -1636,7 +1644,7 @@ enum efi_secureboot_mode {
>>>                                                                         \
>>>         arch_efi_call_virt_setup();                                     \
>>>                                                                         \
>>> -       local_save_flags(__flags);                                      \
>>> +       efi_save_flags(__flags);                                        \
>>>         arch_efi_call_virt(p, f, args);                                 \
>>>         efi_call_virt_check_flags(__flags, __stringify(f));             \
>>>                                                                         \
>>> --
>>> 1.9.1
>>>
>>>
>>>
>>>
>>> --
>>> Julien Thierry
> 

-- 
Julien Thierry

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