Make the EFI runtime wrapper code more robust, by switching to a dedicated stack and dealing with sync exceptions occurring in firmware by unwinding it. While at it, move the backup copy of register X18 onto the base of that stack too so we can can restore it if needed without reloading it from the ordinary stack. Patch #2 is a v2 of a patch that got merged and reverted again in v6.1-rc. This supersedes 'arm64: efi: Move runtime services asm wrapper out of .text' Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Ard Biesheuvel (2): arm64: efi: Execute runtime services from a dedicated stack arm64: efi: Recover from synchronous exceptions occurring in firmware arch/arm64/include/asm/efi.h | 11 +++++ arch/arm64/kernel/efi-rt-wrapper.S | 38 ++++++++++++++-- arch/arm64/kernel/efi.c | 47 ++++++++++++++++++++ arch/arm64/mm/fault.c | 4 ++ drivers/firmware/efi/runtime-wrappers.c | 1 + 5 files changed, 98 insertions(+), 3 deletions(-) -- 2.35.1
