Re: [PATCH] LoongArch: Fix lockdep static memory detection

[Huacai Chen]

Hi Helge,

On Wed, Sep 13, 2023 at 3:18 AM Helge Deller <deller@xxxxxx> 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.

Huacai

> - PLT symbols behind the read-only section, and
> - *(.la_abs) into the data section.
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Fixes: 0a6b58c5cd0d ("lockdep: fix static memory detection even more")
> Cc: stable <stable@xxxxxxxxxx> # 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)
>         }