Re: [PATCH v1 4/9] uretprobes/ppc: Hijack return address

[Ananth N Mavinakayanahalli]

On Wed, Apr 03, 2013 at 06:00:34PM +0200, Anton Arapov wrote:
> Hijack the return address and replace it with a trampoline address.
> PowerPC implementation.
> 
> Signed-off-by: Anton Arapov <anton@xxxxxxxxxx>

Acked-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>

> ---
>  arch/powerpc/include/asm/uprobes.h |  1 +
>  arch/powerpc/kernel/uprobes.c      | 13 +++++++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/uprobes.h b/arch/powerpc/include/asm/uprobes.h
> index b532060..2301602 100644
> --- a/arch/powerpc/include/asm/uprobes.h
> +++ b/arch/powerpc/include/asm/uprobes.h
> @@ -51,4 +51,5 @@ extern int  arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
>  extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
>  extern int  arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
>  extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
> +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
>  #endif	/* _ASM_UPROBES_H */
> diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
> index bc77834..567b975 100644
> --- a/arch/powerpc/kernel/uprobes.c
> +++ b/arch/powerpc/kernel/uprobes.c
> @@ -188,3 +188,16 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
> 
>  	return false;
>  }
> +
> +unsigned long
> +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs)
> +{
> +	unsigned long orig_ret_vaddr;
> +
> +	orig_ret_vaddr = regs->link;
> +
> +	/* Replace the return addr with trampoline addr */
> +	regs->link = trampoline_vaddr;
> +
> +	return orig_ret_vaddr;
> +}
> -- 
> 1.8.1.4

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