linux-kernel - Re: [PATCH] arm64/module-plts: Consider the special case where plt_max

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Date:   Wed, 8 Jul 2020 09:25:20 +0100
From:   Will Deacon <will@...nel.org>
To:     Peng Hao <richard.peng@...o.com>
Cc:     catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, ardb@...nel.org
Subject: Re: [PATCH] arm64/module-plts: Consider the special case where
 plt_max_entries is 0

[+Ard]

On Tue, Jul 07, 2020 at 07:46:08AM -0400, Peng Hao wrote:
> If plt_max_entries is 0, a warning is triggered.
> WARNING: CPU: 200 PID: 3000 at arch/arm64/kernel/module-plts.c:97 module_emit_plt_entry+0xa4/0x150

Which kernel are you seeing this with? There is a PLT-related change in
for-next/core, and I'd like to rule if out if possible.

> Signed-off-by: Peng Hao <richard.peng@...o.com>
> ---
>  arch/arm64/kernel/module-plts.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c
> index 65b08a74aec6..1868c9ac13f2 100644
> --- a/arch/arm64/kernel/module-plts.c
> +++ b/arch/arm64/kernel/module-plts.c
> @@ -79,7 +79,8 @@ u64 module_emit_plt_entry(struct module *mod, Elf64_Shdr *sechdrs,
>  	int i = pltsec->plt_num_entries;
>  	int j = i - 1;
>  	u64 val = sym->st_value + rela->r_addend;
> -
> +	if (pltsec->plt_max_entries == 0)
> +		return 0;

Hmm, but if there aren't any PLTs then how do we end up here?

Will