Hi Klara,

On Fri, May 17, 2024 at 01:00:31AM +0200, Klara Modin wrote:

quoted

This does not seem to work entirely. If build with BPF_JIT without module
support for my Raspberry Pi 3 B I get warnings in my kernel log (easiest way
to trigger it seems to be trying to ssh into it, which fails).

Thanks for the report. I was able to reproduce this using QEMU and it
looks like the problem is because bpf_arch_text_copy() silently fails
to write to the read-only area as a result of patch_map() faulting and
the resulting -EFAULT being chucked away.

Please can you try the diff below?

Will

--->8

diff --git a/arch/arm64/kernel/patching.c b/arch/arm64/kernel/patching.c
index 255534930368..94b9fea65aca 100644
--- a/arch/arm64/kernel/patching.c
+++ b/arch/arm64/kernel/patching.c

@@ -36,7 +36,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
  
         if (image)
                 page = phys_to_page(__pa_symbol(addr));
-       else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+       else if (IS_ENABLED(CONFIG_EXECMEM))
                 page = vmalloc_to_page(addr);
         else
                 return addr;