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

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Message-ID: <HKAPR02MB4291B970192A023778445B1BE0670@HKAPR02MB4291.apcprd02.prod.outlook.com>
Date:   Wed, 8 Jul 2020 10:03:28 +0000
From:   彭浩(Richard) <richard.peng@...o.com>
To:     Will Deacon <will@...nel.org>
CC:     "catalin.marinas@....com" <catalin.marinas@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "ardb@...nel.org" <ardb@...nel.org>
Subject: Re: [PATCH] arm64/module-plts: Consider the special case where
 plt_max_entries is 0


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.
>
5.6.0-rc3+
>> 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?
>
We also returned 0 when warning was triggered.
>Will