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SubjectRe: Problems with commit 'kallsyms: add support for relative offsets in kallsyms address table' (in mmotm)
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> On 24 jan. 2016, at 19:01, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 01/24/2016 09:20 AM, Ard Biesheuvel wrote:
> [ ... ]
>>>> OK, there's an additional issue in my latest version: the
>>>> kallsyms_relative_base value itself is not relocated.
>>>>
>>>> If you have more time to burn on this, could you try the following on
>>>> top? (If not, that is also fine, I will look into it myself on Monday)
>>>>
>>>> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
>>>> index 5ab13394dfd9..0f43f0751d47 100644
>>>> --- a/scripts/kallsyms.c
>>>> +++ b/scripts/kallsyms.c
>>>> @@ -137,8 +137,10 @@ static int read_symbol(FILE *in, struct sym_entry *s)
>>>> sym++;
>>>>
>>>> /* Ignore most absolute/undefined (?) symbols. */
>>>> - if (strcmp(sym, "_text") == 0)
>>>> + if (strcmp(sym, "_text") == 0) {
>>>> _text = s->addr;
>>>> + stype = 'T';
>>>> + }
>>>> else if (check_symbol_range(sym, s->addr, text_ranges,
>>>> ARRAY_SIZE(text_ranges)) == 0)
>>>> /* nothing to do */;
>>>> @@ -406,7 +408,7 @@ static void write_src(void)
>>>>
>>>> if (base_relative) {
>>>> output_label("kallsyms_relative_base");
>>>> - printf("\tPTR\t%#llx\n", relative_base);
>>>> + printf("\tPTR\t_text - %#llx\n", _text - relative_base);
>>>> printf("\n");
>>>> }
>>>
>>> Does not help.
>>>
>>
>> For x86? Or none of them?
>>
>
> I tested sparc32 and x86_64/nosmp. Doesn't help for any of them.
> sparc32 has the following absolute symbols.
>
> f035a420 A _etext
> f03d9000 A _sdata
> f03de8c4 A jiffies
> f03f8860 A _edata
> f03fc000 A __init_begin
> f041bdc8 A __init_text_end
> f0423000 A __bss_start
> f0423000 A __init_end
> f044457d A __bss_stop
> f044457d A _end
>

Any clue why these don't get dropped? Am I missing something? Afaict A symbols get dropped unless they are whitelisted (i.e., the few ia64 ones)

> This results in:
>
> kallsyms failure: absolute symbol value 0xf035a420 out of range in relative mode
>
> This is with binutils 2.22. I didn't test with binutils 2.25 for sparc, or re-test mips.
>
>
> Looks like I'll need to add more test cases with binutils 2.22 vs. 2.25 for various
> architectures, as well as more SMP vs. !SMP builds.
>

Thanks once again

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