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From:   Song Liu <song@kernel.org>
Date:   Fri, 16 Jun 2023 13:09:45 -0700
Message-ID: <CAPhsuW6TmwsBmP4NQroE5OEFsaHh+S9zweXa4Fs_ZeJURguqAg@mail.gmail.com>
Subject: Re: [PATCH v2 09/12] powerpc: extend execmem_params for kprobes allocations
To:     Mike Rapoport <rppt@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        "David S. Miller" <davem@davemloft.net>,
        Dinh Nguyen <dinguyen@kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>,
        Helge Deller <deller@gmx.de>,
        Huacai Chen <chenhuacai@kernel.org>,
        Kent Overstreet <kent.overstreet@linux.dev>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nadav Amit <nadav.amit@gmail.com>,
        "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Puranjay Mohan <puranjay12@gmail.com>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
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On Fri, Jun 16, 2023 at 1:52=E2=80=AFAM Mike Rapoport <rppt@kernel.org> wro=
te:
>
> From: "Mike Rapoport (IBM)" <rppt@kernel.org>
>
> powerpc overrides kprobes::alloc_insn_page() to remove writable
> permissions when STRICT_MODULE_RWX is on.
>
> Add definition of jit area to execmem_params to allow using the generic
> kprobes::alloc_insn_page() with the desired permissions.
>
> As powerpc uses breakpoint instructions to inject kprobes, it does not
> need to constrain kprobe allocations to the modules area and can use the
> entire vmalloc address space.
>
> Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>

Acked-by: Song Liu <song@kernel.org>


> ---
>  arch/powerpc/kernel/kprobes.c | 14 --------------
>  arch/powerpc/kernel/module.c  | 13 +++++++++++++
>  2 files changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.=
c
> index 5db8df5e3657..14c5ddec3056 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -126,20 +126,6 @@ kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned lo=
ng addr, unsigned long offse
>         return (kprobe_opcode_t *)(addr + offset);
>  }
>
> -void *alloc_insn_page(void)
> -{
> -       void *page;
> -
> -       page =3D jit_text_alloc(PAGE_SIZE);
> -       if (!page)
> -               return NULL;
> -
> -       if (strict_module_rwx_enabled())
> -               set_memory_rox((unsigned long)page, 1);
> -
> -       return page;
> -}
> -
>  int arch_prepare_kprobe(struct kprobe *p)
>  {
>         int ret =3D 0;
> diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
> index 4c6c15bf3947..8e5b379d6da1 100644
> --- a/arch/powerpc/kernel/module.c
> +++ b/arch/powerpc/kernel/module.c
> @@ -96,6 +96,11 @@ static struct execmem_params execmem_params =3D {
>                         .alignment =3D 1,
>                 },
>         },
> +       .jit =3D {
> +               .text =3D {
> +                       .alignment =3D 1,
> +               },
> +       },
>  };
>
>
> @@ -131,5 +136,13 @@ struct execmem_params __init *execmem_arch_params(vo=
id)
>
>         execmem_params.modules.text.pgprot =3D prot;
>
> +       execmem_params.jit.text.start =3D VMALLOC_START;
> +       execmem_params.jit.text.end =3D VMALLOC_END;
> +
> +       if (strict_module_rwx_enabled())
> +               execmem_params.jit.text.pgprot =3D PAGE_KERNEL_ROX;
> +       else
> +               execmem_params.jit.text.pgprot =3D PAGE_KERNEL_EXEC;
> +
>         return &execmem_params;
>  }
> --
> 2.35.1
>