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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Fri, 14 Dec 2018 16:49:29 +0100
Message-ID: <CAKv+Gu8CNmL8v=ePXSvQ0vEAzD2O2YAKutQW-b+E6JmyYBPTnA@mail.gmail.com>
Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking
To:     Julien Thierry <julien.thierry@arm.com>
Cc:     linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        joel@joelfernandes.org, Marc Zyngier <marc.zyngier@arm.com>,
        Christoffer Dall <christoffer.dall@arm.com>,
        James Morse <james.morse@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>, oleg@redhat.com
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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.


> 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