Thread (19 messages) 19 messages, 7 authors, 2020-06-27

Re: [PATCH 2/3] arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page

From: Ard Biesheuvel <ardb@kernel.org>
Date: 2020-06-27 07:34:57
Also in: linux-arm-kernel, linux-mm, lkml

On Thu, 18 Jun 2020 at 08:44, 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.

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__);
Why is this passing a string for the 'caller' argument, and not the
address of the caller?

 }

 /* arm kprobe: install breakpoint in text */
--
2.26.2


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