Re: [PATCH 4.19 078/191] ia64: kprobes: Use generic kretprobe trampoline handler

From: Pavel Machek
Date: Thu Nov 05 2020 - 14:35:39 EST


Hi!

> From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
>
> [ Upstream commit e792ff804f49720ce003b3e4c618b5d996256a18 ]
>
> Use the generic kretprobe trampoline handler. Don't use
> framepointer verification.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/159870606883.1229682.12331813108378725668.stgit@devnote2
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

There's no explanation here why this is good idea for -stable.

Plus, this seems to depend on commit
66ada2ccae4ed4dd07ba91df3b5fdb4c11335bd1 which is not present in
stable, so this will likely not build due to lack of
__kretprobe_trampoline_handler symbol. (I don't have ia64 to verify):

$ grep -ri __kretprobe_trampoline_handler .
./arch/ia64/kernel/kprobes.c: regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);
$

I believe it should be dropped.

Best regards,
Pavel
...
> - hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
> - hlist_del(&ri->hlist);
> - kfree(ri);
> - }
> + regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);

--
http://www.livejournal.com/~pavelmachek

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