linux-kernel - Re: [RFC perf/core 02/11] uprobes: Make copy_from

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Message-ID: <CAEf4BzaqbBPmCvW5m8VCpxoKMu8B=1yYxAJ64m9gtS=Tg5Rz7g@mail.gmail.com>
Date: Thu, 14 Nov 2024 15:40:58 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
	Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org, Song Liu <songliubraving@...com>, 
	Yonghong Song <yhs@...com>, John Fastabend <john.fastabend@...il.com>, Hao Luo <haoluo@...gle.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Alan Maguire <alan.maguire@...cle.com>, linux-kernel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org
Subject: Re: [RFC perf/core 02/11] uprobes: Make copy_from_page global

On Tue, Nov 5, 2024 at 5:34 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> Making copy_from_page global and adding uprobe prefix.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  include/linux/uprobes.h |  1 +
>  kernel/events/uprobes.c | 10 +++++-----
>  2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index 2f500bc97263..28068f9fcdc1 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -213,6 +213,7 @@ extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
>  extern void uprobe_handle_trampoline(struct pt_regs *regs);
>  extern void *arch_uretprobe_trampoline(unsigned long *psize);
>  extern unsigned long uprobe_get_trampoline_vaddr(void);
> +extern void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len);
>  #else /* !CONFIG_UPROBES */
>  struct uprobes_state {
>  };
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 0b04c051d712..e9308649bba3 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -250,7 +250,7 @@ bool __weak is_trap_insn(uprobe_opcode_t *insn)
>         return is_swbp_insn(insn);
>  }
>
> -static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
> +void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
>  {
>         void *kaddr = kmap_atomic(page);
>         memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
> @@ -278,7 +278,7 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t
>          * is a trap variant; uprobes always wins over any other (gdb)
>          * breakpoint.
>          */
> -       copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
> +       uprobe_copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
>         is_swbp = is_swbp_insn(&old_opcode);
>
>         if (is_swbp_insn(new_opcode)) {
> @@ -1027,7 +1027,7 @@ static int __copy_insn(struct address_space *mapping, struct file *filp,
>         if (IS_ERR(page))
>                 return PTR_ERR(page);
>
> -       copy_from_page(page, offset, insn, nbytes);
> +       uprobe_copy_from_page(page, offset, insn, nbytes);
>         put_page(page);
>
>         return 0;
> @@ -1368,7 +1368,7 @@ struct uprobe *uprobe_register(struct inode *inode,
>                 return ERR_PTR(-EINVAL);
>
>         /*
> -        * This ensures that copy_from_page(), copy_to_page() and
> +        * This ensures that uprobe_copy_from_page(), copy_to_page() and

rename copy_to_page() for symmetry?


>          * __update_ref_ctr() can't cross page boundary.
>          */
>         if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
> @@ -2288,7 +2288,7 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
>         if (result < 0)
>                 return result;
>
> -       copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
> +       uprobe_copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
>         put_page(page);
>   out:
>         /* This needs to return true for any variant of the trap insn */
> --
> 2.47.0
>