linux-kernel - Re: [RFC PATCH v2 12/20] objtool: Warn about non __ro_after

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Message-ID: <xhsmh5y60s50v.mognet@vschneid.remote.csb>
Date:   Mon, 31 Jul 2023 12:18:40 +0100
From:   Valentin Schneider <vschneid@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
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Subject: Re: [RFC PATCH v2 12/20] objtool: Warn about non __ro_after_init
 static key usage in .noinstr

On 28/07/23 10:35, Josh Poimboeuf wrote:
> On Thu, Jul 20, 2023 at 05:30:48PM +0100, Valentin Schneider wrote:
>> +static int validate_static_key(struct instruction *insn, struct insn_state *state)
>> +{
>> +	if (state->noinstr && state->instr <= 0) {
>> +		if ((strcmp(insn->key_sym->sec->name, ".data..ro_after_init"))) {
>> +			WARN_INSN(insn,
>> +				  "Non __ro_after_init static key \"%s\" in .noinstr section",
>
> For consistency with other warnings, this should start with a lowercase
> "n" and the string literal should be on the same line as the WARN_INSN,
> like
>
>                       WARN_INSN(insn, "non __ro_after_init static key \"%s\" in .noinstr section",
>                                 ...
>
>> diff --git a/tools/objtool/special.c b/tools/objtool/special.c
>> index 91b1950f5bd8a..1f76cfd815bf3 100644
>> --- a/tools/objtool/special.c
>> +++ b/tools/objtool/special.c
>> @@ -127,6 +127,9 @@ static int get_alt_entry(struct elf *elf, const struct special_entry *entry,
>>                      return -1;
>>              }
>>              alt->key_addend = reloc_addend(key_reloc);
>> +
>> +		reloc_to_sec_off(key_reloc, &sec, &offset);
>> +		alt->key_sym = find_symbol_by_offset(sec, offset & ~2);
>
> Bits 0 and 1 can both store data, should be ~3?
>

Quite so, that needs to be the same as jump_entry_key().

> --
> Josh