On Wed, Mar 25, 2015 at 07:20:28PM +0100, Denys Vlasenko wrote:
> A named label "ret_from_sys_call" implies that there are jumps
> to this location from elsewhere, as happens with many other labels
> in this file.
> But this label is used only by the JMP a few insns above.
> To make that obvious, use local numeric label instead.
>
> Do the same in the second copy of the syscall table dispatch code,
> it has a similar JMP which skips the CALL.
>
> Improve comments:
>
> "and return regs->ax" isn't too informative. We always return regs->ax.
>
> The comment suggesting that it'd be cool to use rip relative addressing for
> CALL
> is deleted. It's unclear why that would be an improvement - we aren't striving
> to use position-independent code here. PIC code here would require something
> like
> LEA sys_call_table(%rip),reg + CALL *(reg,%rax*8)...
>
> "iret frame is also incomplete" is no longer true, fix that too.
>
> Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
> CC: Linus Torvalds <torva...@linux-foundation.org>
> CC: Steven Rostedt <rost...@goodmis.org>
> CC: Ingo Molnar <mi...@kernel.org>
> CC: Borislav Petkov <b...@alien8.de>
> CC: "H. Peter Anvin" <h...@zytor.com>
> CC: Andy Lutomirski <l...@amacapital.net>
> CC: Oleg Nesterov <o...@redhat.com>
> CC: Frederic Weisbecker <fweis...@gmail.com>
> CC: Alexei Starovoitov <a...@plumgrid.com>
> CC: Will Drewry <w...@chromium.org>
> CC: Kees Cook <keesc...@chromium.org>
> CC: x...@kernel.org
> CC: linux-kernel@vger.kernel.org
> ---
>
> Changes in v2: gave "jmp 1f" treatment to the second jump.
>
> arch/x86/kernel/entry_64.S | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
Acked-by: Borislav Petkov <b...@suse.de>
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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