On Thu, Dec 26, 2019 at 7:16 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > The efi_call() wrapper used to invoke EFI runtime services serves > a number of purposes: > - realign the stack to 16 bytes > - preserve FP register state > - translate from SysV to MS calling convention. > > Preserving the FP register state is redundant in most cases, since > efi_call() is almost always used from within the scope of a pair of > kernel_fpu_begin()/_end() calls, with the exception of the early > call to SetVirtualAddressMap() and the SGI UV support code. So let's > add a pair of kernel_fpu_begin()/_end() calls there as well, and > remove the unnecessary code from the assembly implementation of > efi_call(), and only keep the pieces that deal with the stack > alignment and the ABI translation. FWIW, you also removed the CR0 save/restore. This ought to be fine, but it might be worth mentioning in the changelog. (At one point, CR0.TS was dynamic on Linux, but these days it's always cleared, so that part was presumably just a historical wart.) Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxx> --Andy
