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From:   Andrew Jones <andrew.jones@linux.dev>
To:     Nadav Amit <nadav.amit@gmail.com>
Cc:     Nikos Nikoleris <nikos.nikoleris@arm.com>, kvm@vger.kernel.org,
        kvmarm@lists.linux.dev, Paolo Bonzini <pbonzini@redhat.com>,
        alexandru.elisei@arm.com, ricarkol@google.com, shahuang@redhat.com
Subject: Re: [kvm-unit-tests PATCH v6 00/32] EFI and ACPI support for arm64
Message-ID: <20230612-6e1f6fac1759f06309be3342@orel>
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 <CC2B570B-9EE0-4686-ADF3-82D1ECDD5D8A@gmail.com>
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On Sat, Jun 10, 2023 at 01:32:59AM -0700, Nadav Amit wrote:
> 
> > On May 30, 2023, at 9:08 AM, Nikos Nikoleris <nikos.nikoleris@arm.com> wrote:
> > 
> > Hello,
> > 
> > This series adds initial support for building arm64 tests as EFI
> > apps and running them under QEMU. Much like x86_64, we import external
> > dependencies from gnu-efi and adapt them to work with types and other
> > assumptions from kvm-unit-tests. In addition, this series adds support
> > for enumerating parts of the system using ACPI.
> 
> Just an issue I encountered, which I am not sure is arm64 specific:
> 
> All the printf’s in efi_main() are before current_thread_info() is
> initialized (or even memset’d to zero, as done in setup_efi).
> 
> But printf() calls puts() which checks if mmu_enabled(). And
> mmu_enabled() uses is_user() and current_thread_info()->cpu, both
> of which read uninitialized data from current_thread_info().
> 
> IOW: Any printf in efi_main() can cause a crash.
>

Nice catch, Nadav. Nikos, shouldn't we drop the memset() in setup_efi and
put a zero_range call, similar to the one in arm/cstart64.S which zero's
the thread-info area, in arm/efi/crt0-efi-aarch64.S?

Thanks,
drew