On Mon, Mar 18, 2024 at 11:33 PM Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > On 03/18, Andrii Nakryiko wrote: > > > > > + "syscall\n" > > > > oh, btw, do we need to save flags register as well or it's handled > > somehow? I think according to manual syscall instruction does > > something to rflags register. So do we need pushfq before syscall? > > The comment above entry_SYSCALL_64() says > > 64-bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11 > > then entry_SYSCALL_64 does > > pushq %r11 /* pt_regs->flags */ > > which should be restored on return to userspace. So I think that > only X86_EFLAGS_RF can be lost, we probably do not care. > Cool, thanks for elaborating! > Oleg. >
