On 12/06/2023 08:52, Andrew Jones wrote:
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@xxxxxxx> 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?
While I haven't run into any problems with this in this series, I had in
a previous version and back then the solution was this patch:
993c37be - arm/arm64: Zero BSS and stack at startup
So I agree we should drop the memset and call some macro like zero_range
in arm/efi/crt0-efi-aarch64.S.
Let me know if you want me to send a patch for this.
Thanks,
Nikos
