Re: [PATCH v2] arm64: mm: fix pass user prot to ioremap_prot in generic_access_phys

On Tue, 27 Jan 2026 17:01:29 +0800 Jinjiang Tu [off-list ref] wrote:

The root cause is that generic_access_phys() passes a user pte to
ioremap_prot(), the user pte sets PTE_USER and PTE_NG bits.  Consequently,
any subsequent kernel-mode access to the remapped address raises a fault.

To fix it, define arch_mk_kernel_prot() to convert user prot to kernel
prot for arm64, and call arch_mk_kernel_prot() in generic_access_phys(),
so that a user prot is passed to ioremap_prot().

MM changes are Reviewed-by: Andrew Morton [off-list ref]

Thanks.  I assume the arm maintainers will process this.

Fixes: 893dea9ccd08 ("arm64: Add HAVE_IOREMAP_PROT support")

huh, three years.