On Wed, May 11, 2022 at 1:52 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> When -fcf-protection=branch is used, the compiler will generate jump
> tables for switch statements where the indirect jump is prefixed with
> the NOTRACK prefix, so it can jump to non-ENDBR targets. Since the
> indirect jump targets are generated by the compiler, they are always
> valid.
>
> Document -mcet-switch to generate jump tables for switch statements with
> ENDBR and skip the NOTRACK prefix for indirect jump. This option should
> be used when the NOTRACK prefix is disabled.
>
> PR target/104816
> * config/i386/i386.opt: Remove Undocumented.
> * doc/invoke.texi: Document -mcet-switch.
> ---
> gcc/config/i386/i386.opt | 2 +-
> gcc/doc/invoke.texi | 8 +++++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> index a6b0e28f238..0dbaacb57ed 100644
> --- a/gcc/config/i386/i386.opt
> +++ b/gcc/config/i386/i386.opt
> @@ -1047,7 +1047,7 @@ Enable shadow stack built-in functions from
> Control-flow Enforcement
> Technology (CET).
>
> mcet-switch
> -Target Undocumented Var(flag_cet_switch) Init(0)
> +Target Var(flag_cet_switch) Init(0)
> Turn on CET instrumentation for switch statements that use a jump table and
> an indirect jump.
>
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index 7a35d9613a4..968853690f9 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -1420,7 +1420,8 @@ See RS/6000 and PowerPC Options.
> -msse4a -m3dnow -m3dnowa -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop @gol
> -madx -mlzcnt -mbmi2 -mfxsr -mxsave -mxsaveopt -mrtm -mhle -mlwp @gol
> -mmwaitx -mclzero -mpku -mthreads -mgfni -mvaes -mwaitpkg @gol
> --mshstk -mmanual-endbr -mforce-indirect-call -mavx512vbmi2 -mavx512bf16
> -menqcmd @gol
> +-mshstk -mmanual-endbr -mcet-switch -mforce-indirect-call @gol
> +-mavx512vbmi2 -mavx512bf16 -menqcmd @gol
> -mvpclmulqdq -mavx512bitalg -mmovdiri -mmovdir64b -mavx512vpopcntdq @gol
> -mavx5124fmaps -mavx512vnni -mavx5124vnniw -mprfchw -mrdpid @gol
> -mrdseed -msgx -mavx512vp2intersect -mserialize -mtsxldtrk@gol
> @@ -32641,6 +32642,11 @@ function attribute. This is useful when used with
> the option
> @option{-fcf-protection=branch} to control ENDBR insertion at the
> function entry.
>
> +@item -mcet-switch
> +@opindex mcet-switch
> +Turn on CET instrumentation for switch statements that use a jump table
> +and an indirect jump.
> +
> @item -mcall-ms2sysv-xlogues
> @opindex mcall-ms2sysv-xlogues
> @opindex mno-call-ms2sysv-xlogues
> --
> 2.35.1
>
Any comments?
Thanks.
--
H.J.
