linux-kernel - Re: [PATCH v3 1/8] LoongArch: Calculate various sizes in the linker script

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Message-ID: <CAAhV-H5hBes5R30mFBW7asX8wPWeSQ+J-=GypnoMoO=-CR3cNg@mail.gmail.com>
Date:   Wed, 28 Jun 2023 17:33:31 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     WANG Xuerui <kernel@...0n.name>
Cc:     WANG Rui <wangrui@...ngson.cn>, Xi Ruoyao <xry111@...111.site>,
        loongarch@...ts.linux.dev, linux-kbuild@...r.kernel.org,
        llvm@...ts.linux.dev, linux-kernel@...r.kernel.org,
        WANG Xuerui <git@...0n.name>
Subject: Re: [PATCH v3 1/8] LoongArch: Calculate various sizes in the linker script

On Sun, Jun 25, 2023 at 5:57 PM WANG Xuerui <kernel@...0n.name> wrote:
>
> From: WANG Rui <wangrui@...ngson.cn>
>
> Taking the address delta between symbols in different sections is not
> supported by the LLVM IAS. Instead, do this in the linker script, so
> the same data can be properly referenced in assembly.
>
> Signed-off-by: WANG Rui <wangrui@...ngson.cn>
> Signed-off-by: WANG Xuerui <git@...0n.name>
> ---
>  arch/loongarch/kernel/efi-header.S  | 6 +++---
>  arch/loongarch/kernel/head.S        | 8 ++++----
>  arch/loongarch/kernel/vmlinux.lds.S | 7 +++++++
>  3 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/arch/loongarch/kernel/efi-header.S b/arch/loongarch/kernel/efi-header.S
> index 8c1d229a2afa..5f23b85d78ca 100644
> --- a/arch/loongarch/kernel/efi-header.S
> +++ b/arch/loongarch/kernel/efi-header.S
> @@ -24,7 +24,7 @@
>         .byte   0x02                                    /* MajorLinkerVersion */
>         .byte   0x14                                    /* MinorLinkerVersion */
>         .long   __inittext_end - .Lefi_header_end       /* SizeOfCode */
> -       .long   _end - __initdata_begin                 /* SizeOfInitializedData */
> +       .long   _kernel_vsize                           /* SizeOfInitializedData */
>         .long   0                                       /* SizeOfUninitializedData */
>         .long   __efistub_efi_pe_entry - _head          /* AddressOfEntryPoint */
>         .long   .Lefi_header_end - _head                /* BaseOfCode */
> @@ -79,9 +79,9 @@
>                 IMAGE_SCN_MEM_EXECUTE                   /* Characteristics */
>
>         .ascii  ".data\0\0\0"
> -       .long   _end - __initdata_begin                 /* VirtualSize */
> +       .long   _kernel_vsize                           /* VirtualSize */
>         .long   __initdata_begin - _head                /* VirtualAddress */
> -       .long   _edata - __initdata_begin               /* SizeOfRawData */
> +       .long   _kernel_rsize                           /* SizeOfRawData */
>         .long   __initdata_begin - _head                /* PointerToRawData */
>
>         .long   0                                       /* PointerToRelocations */
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 0d8180153ec0..53b883db0786 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -23,7 +23,7 @@ _head:
>         .word   MZ_MAGIC                /* "MZ", MS-DOS header */
>         .org    0x8
>         .dword  kernel_entry            /* Kernel entry point */
> -       .dword  _end - _text            /* Kernel image effective size */
> +       .dword  _kernel_asize           /* Kernel image effective size */
>         .quad   PHYS_LINK_KADDR         /* Kernel image load offset from start of RAM */
>         .org    0x38                    /* 0x20 ~ 0x37 reserved */
>         .long   LINUX_PE_MAGIC
> @@ -32,9 +32,9 @@ _head:
>  pe_header:
>         __EFI_PE_HEADER
>
> -SYM_DATA(kernel_asize, .long _end - _text);
> -SYM_DATA(kernel_fsize, .long _edata - _text);
> -SYM_DATA(kernel_offset, .long kernel_offset - _text);
> +SYM_DATA(kernel_asize, .long _kernel_asize);
> +SYM_DATA(kernel_fsize, .long _kernel_fsize);
> +SYM_DATA(kernel_offset, .long _kernel_offset);
>
>  #endif
>
> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
> index 0c7b041be9d8..79f238df029e 100644
> --- a/arch/loongarch/kernel/vmlinux.lds.S
> +++ b/arch/loongarch/kernel/vmlinux.lds.S
> @@ -136,6 +136,13 @@ SECTIONS
>         DWARF_DEBUG
>         ELF_DETAILS
>
> +       /* header symbols */
> +       _kernel_asize = _end - _text;
> +       _kernel_fsize = _edata - _text;
> +       _kernel_offset = kernel_offset - _text;
When !CONFIG_EFI_STUB there is a build error, I fixed it when I applied.

Huacai
> +       _kernel_vsize = _end - __initdata_begin;
> +       _kernel_rsize = _edata - __initdata_begin;
> +
>         .gptab.sdata : {
>                 *(.gptab.data)
>                 *(.gptab.sdata)
> --
> 2.40.0
>
>