Re: [PATCH 0/4] tcg/aarch64: Enable BTI within the JIT

[Richard Henderson]

Ping.  Patch 3 still missing review.

On 8/16/23 07:25, Richard Henderson wrote:
> Patch 1 is cherry-picked from
>
> [PATCH v3 02/14] tcg: Add tcg_out_tb_start backend hook
> https://lore.kernel.org/qemu-devel/20230815195741.8325-3-richard.henderson@linaro.org/T/#u
>
> here used for a different application.
>
> There are not as many landing pads as I had imagined, so the
> overhead here is really quite minimal.
>
> The architecture enables the check only when the PTE for the
> jump target is marked "guarded".  Linux implements this by
> adding a PROT_BTI bit for mmap and mprotect.  I have isolated
> this within a host_prot_read_exec() local function, which
> seems clean enough.  So far, as far as I can tell, Linux it
> the only OS to support BTI.
>
>
> r~
>
>
> Richard Henderson (4):
>    tcg: Add tcg_out_tb_start backend hook
>    util/cpuinfo-aarch64: Add CPUINFO_BTI
>    tcg/aarch64: Emit BTI insns at jump landing pads
>    tcg: Map code_gen_buffer with PROT_BTI
>
>   host/include/aarch64/host/cpuinfo.h |  1 +
>   tcg/region.c                        | 39 ++++++++++++++++------
>   tcg/tcg.c                           |  3 ++
>   util/cpuinfo-aarch64.c              |  4 +++
>   tcg/aarch64/tcg-target.c.inc        | 52 +++++++++++++++++++++--------
>   tcg/arm/tcg-target.c.inc            |  5 +++
>   tcg/i386/tcg-target.c.inc           |  5 +++
>   tcg/loongarch64/tcg-target.c.inc    |  5 +++
>   tcg/mips/tcg-target.c.inc           |  5 +++
>   tcg/ppc/tcg-target.c.inc            |  5 +++
>   tcg/riscv/tcg-target.c.inc          |  5 +++
>   tcg/s390x/tcg-target.c.inc          |  5 +++
>   tcg/sparc64/tcg-target.c.inc        |  5 +++
>   tcg/tci/tcg-target.c.inc            |  5 +++
>   14 files changed, 119 insertions(+), 25 deletions(-)