Re: [PATCH RFCv3 06/23] uprobes: Add orig argument to uprobe_write and uprobe_write_opcode

[Andrii Nakryiko]

On Thu, Mar 20, 2025 at 4:43 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> The uprobe_write has special path to restore the original page when
> we write original instruction back.
>
> This happens when uprobe_write detects that we want to write anything
> else but breakpoint instruction.
>
> In following changes we want to use uprobe_write function for multiple
> updates, so adding new function argument to denote that this is the
> original instruction update. This way uprobe_write can make appropriate
> checks and restore the original page when possible.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
>  arch/arm/probes/uprobes/core.c |  2 +-
>  include/linux/uprobes.h        |  5 +++--
>  kernel/events/uprobes.c        | 22 ++++++++++------------
>  3 files changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c
> index f5f790c6e5f8..54a90b565285 100644
> --- a/arch/arm/probes/uprobes/core.c
> +++ b/arch/arm/probes/uprobes/core.c
> @@ -30,7 +30,7 @@ int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
>              unsigned long vaddr)
>  {
>         return uprobe_write_opcode(auprobe, mm, vaddr,
> -                  __opcode_to_mem_arm(auprobe->bpinsn));
> +                  __opcode_to_mem_arm(auprobe->bpinsn), false);
>  }
>
>  bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index c69a05775394..1b6a4e2b5464 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -196,9 +196,10 @@ extern bool is_swbp_insn(uprobe_opcode_t *insn);
>  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 mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
> +extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr,
> +                              uprobe_opcode_t, bool);

add arg names for humans?..

>  extern int uprobe_write(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr,
> -                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify);
> +                       uprobe_opcode_t *insn, int nbytes, uprobe_write_verify_t verify, bool orig);
>  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);

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