linux-kernel - Re: [PATCH] LoongArch: Fix lockdep static memory detection

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Date:   Thu, 14 Sep 2023 18:40:23 +0200
From:   Helge Deller <deller@....de>
To:     Huacai Chen <chenhuacai@...nel.org>, loongarch@...ts.linux.dev,
        WANG Xuerui <kernel@...0n.name>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH] LoongArch: Fix lockdep static memory detection

PING to Loongarch maintainers!

Without this patch, lockdep is broken on LoongArch on kernel v6.1 and above.
(patch below wrongly mentions kernel 6.4, but actually it needs backport to 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@....de>
>> Reported-by: Guenter Roeck <linux@...ck-us.net>
>> Fixes: 0a6b58c5cd0d ("lockdep: fix static memory detection even more")
>> Cc: stable <stable@...nel.org> # v6.4+
>
> Tested-by: Guenter Roeck <linux@...ck-us.net>
>
>>
>> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/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
>>   	. = ALIGN(PECOFF_SEGMENT_ALIGN);
>>   	_etext = .;
>>
>> -	/*
>> -	 * struct alt_inst entries. From the header (alternative.h):
>> -	 * "Alternative instructions for different CPU types or capabilities"
>> -	 * Think locking instructions on spinlocks.
>> -	 */
>> -	. = ALIGN(4);
>> -	.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
>> -		__alt_instructions = .;
>> -		*(.altinstructions)
>> -		__alt_instructions_end = .;
>> -	}
>> -
>> -#ifdef CONFIG_RELOCATABLE
>> -	. = ALIGN(8);
>> -	.la_abs : AT(ADDR(.la_abs) - LOAD_OFFSET) {
>> -		__la_abs_begin = .;
>> -		*(.la_abs)
>> -		__la_abs_end = .;
>> -	}
>> -#endif
>> -
>> -	.got : ALIGN(16) { *(.got) }
>> -	.plt : ALIGN(16) { *(.plt) }
>> -	.got.plt : ALIGN(16) { *(.got.plt) }
>> -
>> -	.data.rel : { *(.data.rel*) }
>> -
>>   	. = ALIGN(PECOFF_SEGMENT_ALIGN);
>>   	__init_begin = .;
>>   	__inittext_begin = .;
>> @@ -94,6 +67,18 @@ SECTIONS
>>
>>   	__initdata_begin = .;
>>
>> +	/*
>> +	 * struct alt_inst entries. From the header (alternative.h):
>> +	 * "Alternative instructions for different CPU types or capabilities"
>> +	 * Think locking instructions on spinlocks.
>> +	 */
>> +	. = ALIGN(4);
>> +	.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
>> +		__alt_instructions = .;
>> +		*(.altinstructions)
>> +		__alt_instructions_end = .;
>> +	}
>> +
>>   	INIT_DATA_SECTION(16)
>>   	.exit.data : {
>>   		EXIT_DATA
>> @@ -113,6 +98,11 @@ SECTIONS
>>
>>   	_sdata = .;
>>   	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 = .;
>>   	}
>>
>> +	.data.rel : { *(.data.rel*) }
>> +
>> +#ifdef CONFIG_RELOCATABLE
>> +	. = ALIGN(8);
>> +	.la_abs : AT(ADDR(.la_abs) - LOAD_OFFSET) {
>> +		__la_abs_begin = .;
>> +		*(.la_abs)
>> +		__la_abs_end = .;
>> +	}
>> +#endif
>> +
>>   	.sdata : {
>>   		*(.sdata)
>>   	}