Hi Matthew,
> -----Original Message-----
> From: Matthew Malcomson <[email protected]>
> Sent: 24 July 2020 17:03
> To: Kyrylo Tkachov <[email protected]>; [email protected]
> Cc: Richard Earnshaw <[email protected]>; Ross Burton
> <[email protected]>; Richard Sandiford <[email protected]>
> Subject: Re: SLS Mitigation patches backported for GCC9
>
> On 24/07/2020 12:01, Kyrylo Tkachov wrote:
> > Hi Matthew,
> >
> >> -----Original Message-----
> >> From: Matthew Malcomson <[email protected]>
> >> Sent: 21 July 2020 16:16
> >> To: [email protected]
> >> Cc: Richard Earnshaw <[email protected]>; Kyrylo Tkachov
> >> <[email protected]>; Ross Burton <[email protected]>
> >> Subject: SLS Mitigation patches backported for GCC9
> >>
> >> Hello,
> >>
> >> Eventually we will want to backport the SLS patches to older branches.
> >>
> >> When the GCC10 release is unfrozen we will work on getting the same
> >> patches
> >> already posted backported to that branch. The patches already posted on
> >> the
> >> mailing list apply cleanly to the current releases/gcc-10 branch.
> >>
> >> I've heard interest in having the GCC 9 patches, so I'm posting the
> modified
> >> versions upstream sooner than otherwise.
> >
> > I'd say let's go ahead with the GCC 10 patches (assuming testing works out
> well on there).
> > For the GCC 9 patches it would be useful if you included a bit of text of
> > how
> they differ from the GCC 10/11 patches.
> > This would speed up the technical review.
> > Thanks,
> > Kyrill
> >
> >>
> >> Cheers,
> >> Matthew
> >>
> >> Entire patch series attached to cover letter.
>
> Below were the only two "interesting" hunks that failed to apply after
> `patch -p1`.
>
> The differences causing these were:
> - in GCC-9 the `retab` instruction wasn't in the "do_return" pattern.
> - `simple_return` had "aarch64_use_simple_return_insn_p ()" as a
> condition.
>
>
Thanks, the backports to GCC 10 and GCC 9 are okay, let's go ahead with them.
Kyrill
>
>
> --- gcc/config/aarch64/aarch64.md
> +++ gcc/config/aarch64/aarch64.md
> @@ -863,18 +882,23 @@
> [(return)]
> ""
> {
> + const char *ret = NULL;
> if (aarch64_return_address_signing_enabled ()
> && TARGET_ARMV8_3
> && !crtl->calls_eh_return)
> {
> if (aarch64_ra_sign_key == AARCH64_KEY_B)
> - return "retab";
> + ret = "retab";
> else
> - return "retaa";
> + ret = "retaa";
> }
> - return "ret";
> + else
> + ret = "ret";
> + output_asm_insn (ret, operands);
> + return aarch64_sls_barrier (aarch64_harden_sls_retbr_p ());
> }
> - [(set_attr "type" "branch")]
> + [(set_attr "type" "branch")
> + (set_attr "sls_length" "retbr")]
> )
>
> (define_expand "return"
> @@ -886,8 +910,12 @@
> (define_insn "simple_return"
> [(simple_return)]
> ""
> - "ret"
> - [(set_attr "type" "branch")]
> + {
> + output_asm_insn ("ret", operands);
> + return aarch64_sls_barrier (aarch64_harden_sls_retbr_p ());
> + }
> + [(set_attr "type" "branch")
> + (set_attr "sls_length" "retbr")]
> )
>
> (define_insn "*cb<optab><mode>1"
