Hi Carlos,
see
[PATCH 0/5] uprobes: transition from kmap_atomic to kmap_local_page
https://lore.kernel.org/all/[email protected]/
already in tip/perf/core
Oleg.
On 02/05, Carlos López wrote:
>
> kmap_atomic() has been deprecated for a few years, and kmap_local_page()
> should be used instead, so replace it. Since the uprobes code relied on
> kmap_atomic() disabling page faults to access user pages, add the
> required calls to keep the existing behavior.
>
> Signed-off-by: Carlos López <[email protected]>
> ---
> kernel/events/uprobes.c | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index d546d32390a8..38898435acfe 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -179,16 +179,24 @@ bool __weak is_trap_insn(uprobe_opcode_t *insn)
>
> void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void
> *dst, int len)
> {
> - void *kaddr = kmap_atomic(page);
> + void *kaddr = kmap_local_page(page);
> +
> + pagefault_disable();
> memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
> - kunmap_atomic(kaddr);
> + pagefault_enable();
> +
> + kunmap_local(kaddr);
> }
>
> static void copy_to_page(struct page *page, unsigned long vaddr, const void
> *src, int len)
> {
> - void *kaddr = kmap_atomic(page);
> + void *kaddr = kmap_local_page(page);
> +
> + pagefault_disable();
> memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
> - kunmap_atomic(kaddr);
> + pagefault_enable();
> +
> + kunmap_local(kaddr);
> }
>
> static int verify_opcode(struct page *page, unsigned long vaddr,
> uprobe_opcode_t *insn,
> @@ -323,9 +331,10 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long
> vaddr, short d)
> return ret == 0 ? -EBUSY : ret;
> }
>
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ptr = kaddr + (vaddr & ~PAGE_MASK);
>
> + pagefault_disable();
> if (unlikely(*ptr + d < 0)) {
> pr_warn("ref_ctr going negative. vaddr: 0x%lx, "
> "curr val: %d, delta: %d\n", vaddr, *ptr, d);
> @@ -336,7 +345,8 @@ __update_ref_ctr(struct mm_struct *mm, unsigned long
> vaddr, short d)
> *ptr += d;
> ret = 0;
> out:
> - kunmap_atomic(kaddr);
> + pagefault_enable();
> + kunmap_local(kaddr);
> put_page(page);
> return ret;
> }
>
> base-commit: f14faaf3a1fb3b9e4cf2e56269711fb85fba9458
> --
> 2.51.0
>
