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Date:   Thu, 14 Sep 2023 18:40:23 +0200
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Subject: Re: [PATCH] LoongArch: Fix lockdep static memory detection
To:     Huacai Chen <chenhuacai@kernel.org>, loongarch@lists.linux.dev,
        WANG Xuerui <kernel@xen0n.name>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-kernel@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>
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 <9d0cb447-2556-4609-a96f-13875ddeeda3@roeck-us.net>
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From:   Helge Deller <deller@gmx.de>
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Precedence: bulk

PING to Loongarch maintainers!

Without this patch, lockdep is broken on LoongArch on kernel v6.1 and abov=
e.
(patch below wrongly mentions kernel 6.4, but actually it needs backport t=
o v6.1 too).

Helge

On 9/12/23 22:31, Guenter Roeck wrote:
> On Tue, Sep 12, 2023 at 09:18:37PM +0200, Helge Deller wrote:
>> Since commit 0a6b58c5cd0d ("lockdep: fix static memory detection even
>> more") the lockdep code uses is_kernel_core_data(), is_kernel_rodata()
>> and init_section_contains() to verify if a lock is located inside a
>> kernel static data section.
>>
>> This change triggers a failure on LoongArch, for which the vmlinux.lds.=
S
>> script misses to put the locks (as part of in the .data.rel symbols)
>> into the Linux data section.
>> This patch fixes the lockdep problem by moving *(.data.rel*) symbols
>> into the kernel data section (from _sdata to _edata).
>>
>> Additionally, move other wrongly assigned symbols too:
>> - altinstructions into the _initdata section,
>> - PLT symbols behind the read-only section, and
>> - *(.la_abs) into the data section.
>>
>> Signed-off-by: Helge Deller <deller@gmx.de>
>> Reported-by: Guenter Roeck <linux@roeck-us.net>
>> Fixes: 0a6b58c5cd0d ("lockdep: fix static memory detection even more")
>> Cc: stable <stable@kernel.org> # v6.4+
>
> Tested-by: Guenter Roeck <linux@roeck-us.net>
>
>>
>> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kerne=
l/vmlinux.lds.S
>> index b1686afcf876..bb2ec86f37a8 100644
>> --- a/arch/loongarch/kernel/vmlinux.lds.S
>> +++ b/arch/loongarch/kernel/vmlinux.lds.S
>> @@ -53,33 +53,6 @@ SECTIONS
>>   	. =3D ALIGN(PECOFF_SEGMENT_ALIGN);
>>   	_etext =3D .;
>>
>> -	/*
>> -	 * struct alt_inst entries. From the header (alternative.h):
>> -	 * "Alternative instructions for different CPU types or capabilities"
>> -	 * Think locking instructions on spinlocks.
>> -	 */
>> -	. =3D ALIGN(4);
>> -	.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
>> -		__alt_instructions =3D .;
>> -		*(.altinstructions)
>> -		__alt_instructions_end =3D .;
>> -	}
>> -
>> -#ifdef CONFIG_RELOCATABLE
>> -	. =3D ALIGN(8);
>> -	.la_abs : AT(ADDR(.la_abs) - LOAD_OFFSET) {
>> -		__la_abs_begin =3D .;
>> -		*(.la_abs)
>> -		__la_abs_end =3D .;
>> -	}
>> -#endif
>> -
>> -	.got : ALIGN(16) { *(.got) }
>> -	.plt : ALIGN(16) { *(.plt) }
>> -	.got.plt : ALIGN(16) { *(.got.plt) }
>> -
>> -	.data.rel : { *(.data.rel*) }
>> -
>>   	. =3D ALIGN(PECOFF_SEGMENT_ALIGN);
>>   	__init_begin =3D .;
>>   	__inittext_begin =3D .;
>> @@ -94,6 +67,18 @@ SECTIONS
>>
>>   	__initdata_begin =3D .;
>>
>> +	/*
>> +	 * struct alt_inst entries. From the header (alternative.h):
>> +	 * "Alternative instructions for different CPU types or capabilities"
>> +	 * Think locking instructions on spinlocks.
>> +	 */
>> +	. =3D ALIGN(4);
>> +	.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
>> +		__alt_instructions =3D .;
>> +		*(.altinstructions)
>> +		__alt_instructions_end =3D .;
>> +	}
>> +
>>   	INIT_DATA_SECTION(16)
>>   	.exit.data : {
>>   		EXIT_DATA
>> @@ -113,6 +98,11 @@ SECTIONS
>>
>>   	_sdata =3D .;
>>   	RO_DATA(4096)
>> +
>> +	.got : ALIGN(16) { *(.got) }
>> +	.plt : ALIGN(16) { *(.plt) }
>> +	.got.plt : ALIGN(16) { *(.got.plt) }
>> +
>>   	RW_DATA(1 << CONFIG_L1_CACHE_SHIFT, PAGE_SIZE, THREAD_SIZE)
>>
>>   	.rela.dyn : ALIGN(8) {
>> @@ -121,6 +111,17 @@ SECTIONS
>>   		__rela_dyn_end =3D .;
>>   	}
>>
>> +	.data.rel : { *(.data.rel*) }
>> +
>> +#ifdef CONFIG_RELOCATABLE
>> +	. =3D ALIGN(8);
>> +	.la_abs : AT(ADDR(.la_abs) - LOAD_OFFSET) {
>> +		__la_abs_begin =3D .;
>> +		*(.la_abs)
>> +		__la_abs_end =3D .;
>> +	}
>> +#endif
>> +
>>   	.sdata : {
>>   		*(.sdata)
>>   	}