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SubjectRe: [PATCH v4 2/8] riscv/kprobe: Allocate detour buffer from module area
On Sun,  6 Nov 2022 18:03:10 +0800
Chen Guokai <chenguokai17@mails.ucas.ac.cn> wrote:

> @@ -84,6 +85,30 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
> }
>
> #ifdef CONFIG_MMU
> +#if defined(CONFIG_OPTPROBES) && defined(CONFIG_64BIT)
> +void *alloc_optinsn_page(void)
> +{
> + void *page;
> +
> + page = __vmalloc_node_range(PAGE_SIZE, 1, MODULES_VADDR,
> + MODULES_END, GFP_KERNEL,
> + PAGE_KERNEL, 0, NUMA_NO_NODE,
> + __builtin_return_address(0));
> + if (!page)
> + return NULL;
> +
> + set_vm_flush_reset_perms(page);
> + /*
> + * First make the page read-only, and only then make it executable to
> + * prevent it from being W+X in between.
> + */
> + set_memory_ro((unsigned long)page, 1);
> + set_memory_x((unsigned long)page, 1);

FYI, the above combination is going to be going away:

https://lore.kernel.org/all/Y10OyLCLAAS6rsZv@hirez.programming.kicks-ass.net/

-- Steve


> +
> + return page;
> +}
> +#endif
> +

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