On Wed, Jun 26, 2024 at 12:18:30PM -0700, Yang Shi wrote:
@@ -568,6 +596,12 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
if (!vma)
goto lock_mmap;
+ if ((vm_flags & VM_READ) && (vma->vm_flags & VM_WRITE) &&
+ is_el0_atomic_instr(regs)) {
+ vm_flags = VM_WRITE;
+ mm_flags |= FAULT_FLAG_WRITE;
+ }
The patch looks fine now and AFAICT there's no ABI change.
However, before deciding whether to merge this patch, I'd like to
understand why OpenJDK cannot use madvise(MADV_POPULATE_WRITE). This
would be the portable (Linux) solution that works better on
architectures without such atomic instructions (e.g. arm64 without LSE
atomics). So fixing user-space would be my preferred solution.