Re: [PATCH 2/3] arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page
From: Peter Zijlstra <peterz@infradead.org>
Date: 2020-06-18 09:28:11
Also in:
linux-arm-kernel, linux-mm, lkml
On Thu, Jun 18, 2020 at 08:43:06AM +0200, Christoph Hellwig 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. Signed-off-by: Christoph Hellwig <hch@lst.de> --- arch/arm64/kernel/probes/kprobes.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index d1c95dcf1d7833..cbe49cd117cfec 100644 --- 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__); }
I think this has the exact same range issue as the x86 user. But it might be less fatal if their PLT magic can cover the full range.