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Message-ID: <9c64a977-fdee-b2b2-d726-1e9744d229a7@arm.com>
Date: Fri, 14 Dec 2018 16:40:05 +0000
From: Julien Thierry <julien.thierry@....com>
To: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
joel@...lfernandes.org, Marc Zyngier <marc.zyngier@....com>,
Christoffer Dall <christoffer.dall@....com>,
James Morse <james.morse@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Mark Rutland <mark.rutland@....com>, oleg@...hat.com
Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt
masking
On 14/12/2018 15:49, Ard Biesheuvel wrote:
> On Fri, 14 Dec 2018 at 16:23, Julien Thierry <julien.thierry@....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@....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@....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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