From: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
Test that:
- "syscall" in a FRED system doesn't clobber %rcx and %r11.
- "syscall" in a non-FRED system sets %rcx=%rip and %r11=%rflags.
Test them out with a trivial system call like __NR_getppid and friends
which are extremely likely to return with SYSRET on an IDT system.
Link: https://lore.kernel.org/lkml/25b96960-a07e-a952-5c23-786b55054126@xxxxxxxxx
Co-developed-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Acked-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>