Re: [PATCH -tip v8 08/13] arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline

From: Ingo Molnar
Date: Mon Jul 05 2021 - 04:04:47 EST



* Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Change kretprobe_trampoline to make a space for regs->ARM_pc so that
> kretprobe_trampoline_handler can call instruction_pointer_set()
> safely.

The idiom is "make space", but in any case, what does this mean?

Was the stack frame set up in kretprobe_trampoline() and calling
trampoline_handler() buggy?

If yes, then explain the bad effects of the bug, and make all of this clear
in the title & changelog.

Thanks,

Ingo