Re: [PATCH 2/3] arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2020-06-21 02:16:22
Also in:
linux-mm, lkml
On Thu, 18 Jun 2020 08:43:06 +0200 Christoph Hellwig [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Use PAGE_KERNEL_ROX directly instead of allocating RWX and setting the page read-only just after the allocation.--- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c@@ -120,15 +120,9 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) void *alloc_insn_page(void) { - void *page; - - page = vmalloc_exec(PAGE_SIZE); - if (page) { - set_memory_ro((unsigned long)page, 1); - set_vm_flush_reset_perms(page); - } - - return page; + return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END, + GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS, + NUMA_NO_NODE, __func__); } /* arm kprobe: install breakpoint in text */
But why. I think this is just a cleanup, doesn't address any runtime issue?