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

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

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 :( .

Thanks,

> 
>> 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