Re: [PATCH RFC bpf-next 1/3] uprobe: Add uretprobe syscall to speed up return probe

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.

Oleg.





[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux