On Thu, 5 Jun 2025 15:23:31 +0200
Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> Adding uprobe_write function that does what uprobe_write_opcode did
> so far, but allows to pass verify callback function that checks the
> memory location before writing the opcode.
>
> It will be used in following changes to implement specific checking
> logic for instruction update.
>
> The uprobe_write_opcode now calls uprobe_write with verify_opcode as
> the verify callback.
>
Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Thanks,
> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> include/linux/uprobes.h | 5 +++++
> kernel/events/uprobes.c | 14 ++++++++++----
> 2 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index 7447e15559b8..e13382054435 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -187,6 +187,9 @@ struct uprobes_state {
> struct xol_area *xol_area;
> };
>
> +typedef int (*uprobe_write_verify_t)(struct page *page, unsigned long vaddr,
> + uprobe_opcode_t *opcode);
> +
> extern void __init uprobes_init(void);
> extern int set_swbp(struct arch_uprobe *aup, struct vm_area_struct *vma, unsigned long vaddr);
> extern int set_orig_insn(struct arch_uprobe *aup, struct vm_area_struct *vma, unsigned long vaddr);
> @@ -195,6 +198,8 @@ extern bool is_trap_insn(uprobe_opcode_t *insn);
> extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
> extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
> extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma, unsigned long vaddr, uprobe_opcode_t);
> +extern int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma, const unsigned long opcode_vaddr,
> + uprobe_opcode_t opcode, uprobe_write_verify_t verify);
> extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
> extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
> extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc);
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 37d3a3f6e48a..777de9b95dd7 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -399,7 +399,7 @@ static bool orig_page_is_identical(struct vm_area_struct *vma,
> return identical;
> }
>
> -static int __uprobe_write_opcode(struct vm_area_struct *vma,
> +static int __uprobe_write(struct vm_area_struct *vma,
> struct folio_walk *fw, struct folio *folio,
> unsigned long opcode_vaddr, uprobe_opcode_t opcode)
> {
> @@ -488,6 +488,12 @@ static int __uprobe_write_opcode(struct vm_area_struct *vma,
> */
> int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
> const unsigned long opcode_vaddr, uprobe_opcode_t opcode)
> +{
> + return uprobe_write(auprobe, vma, opcode_vaddr, opcode, verify_opcode);
> +}
> +
> +int uprobe_write(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
> + const unsigned long opcode_vaddr, uprobe_opcode_t opcode, uprobe_write_verify_t verify)
> {
> const unsigned long vaddr = opcode_vaddr & PAGE_MASK;
> struct mm_struct *mm = vma->vm_mm;
> @@ -510,7 +516,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
> * page that we can safely modify. Use FOLL_WRITE to trigger a write
> * fault if required. When unregistering, we might be lucky and the
> * anon page is already gone. So defer write faults until really
> - * required. Use FOLL_SPLIT_PMD, because __uprobe_write_opcode()
> + * required. Use FOLL_SPLIT_PMD, because __uprobe_write()
> * cannot deal with PMDs yet.
> */
> if (is_register)
> @@ -522,7 +528,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
> goto out;
> folio = page_folio(page);
>
> - ret = verify_opcode(page, opcode_vaddr, &opcode);
> + ret = verify(page, opcode_vaddr, &opcode);
> if (ret <= 0) {
> folio_put(folio);
> goto out;
> @@ -561,7 +567,7 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
> /* Walk the page tables again, to perform the actual update. */
> if (folio_walk_start(&fw, vma, vaddr, 0)) {
> if (fw.page == page)
> - ret = __uprobe_write_opcode(vma, &fw, folio, opcode_vaddr, opcode);
> + ret = __uprobe_write(vma, &fw, folio, opcode_vaddr, opcode);
> folio_walk_end(&fw, vma);
> }
>
> --
> 2.49.0
>
--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
