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SubjectRe: [PATCH] LoongArch: Fix lockdep static memory detection
From
On 9/15/23 05:22, Huacai Chen wrote:
> Hi Helge,
>
> On Wed, Sep 13, 2023 at 3:18 AM Helge Deller <deller@gmx.de> 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,

> I think altinstructions cannot be put into _initdata because it will
> be used by modules.

No.
arch/loongarch/kernel/vmlinux.lds.S is used for the static parts of the kernel
and altinstructions are replaced before modules are loaded.
For altinstructions in modules the linker script scripts/module.lds.S is used.

Helge


>> - 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+
>>
>> 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)
>> }

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