Re: [PATCH v2 09/12] powerpc: extend execmem_params for kprobes allocations

Song Liu
2023-06-16T20:10:02Z

On Fri, Jun 16, 2023 at 1:52 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> 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 long addr, unsigned long offse
> return (kprobe_opcode_t *)(addr + offset);
> }
>
> -void *alloc_insn_page(void)
> -{
> - void *page;
> -
> - page = 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 = 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 = {
> .alignment = 1,
> },
> },
> + .jit = {
> + .text = {
> + .alignment = 1,
> + },
> + },
> };
>
>
> @@ -131,5 +136,13 @@ struct execmem_params __init *execmem_arch_params(void)
>
> execmem_params.modules.text.pgprot = prot;
>
> + execmem_params.jit.text.start = VMALLOC_START;
> + execmem_params.jit.text.end = VMALLOC_END;
> +
> + if (strict_module_rwx_enabled())
> + execmem_params.jit.text.pgprot = PAGE_KERNEL_ROX;
> + else
> + execmem_params.jit.text.pgprot = PAGE_KERNEL_EXEC;
> +
> return &execmem_params;
> }
> --
> 2.35.1
>