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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Mon, 21 Oct 2019 08:21:48 +0200
Message-ID: <CAKv+Gu-88USO+fbjBgj35B4fUQ7A_t9nHO_swyN=T1q1G2wViA@mail.gmail.com>
Subject: Re: [PATCH 16/18] arm64: kprobes: fix kprobes without CONFIG_KRETPROBES
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Dave Martin <Dave.Martin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Laura Abbott <labbott@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, 18 Oct 2019 at 18:11, Sami Tolvanen <samitolvanen@google.com> wrote:
>
> This allows CONFIG_KRETPROBES to be disabled without disabling
> kprobes entirely.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Can we make kretprobes work with the shadow call stack instead?

> ---
>  arch/arm64/kernel/probes/kprobes.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index c4452827419b..98230ae979ca 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -551,6 +551,7 @@ void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
>         return (void *)orig_ret_address;
>  }
>
> +#ifdef CONFIG_KRETPROBES
>  void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
>                                       struct pt_regs *regs)
>  {
> @@ -564,6 +565,7 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p)
>  {
>         return 0;
>  }
> +#endif
>
>  int __init arch_init_kprobes(void)
>  {
> --
> 2.23.0.866.gb869b98d4c-goog
>