linux-kernel - Re: [PATCH v4 1/5] LoongArch: Use la.pcrel instead of la.abs when it's trivially possible

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Date:   Fri, 10 Feb 2023 17:04:55 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Youling Tang <tangyouling@...ngson.cn>
Cc:     Xi Ruoyao <xry111@...111.site>, Jinyang He <hejinyang@...ngson.cn>,
        Xuerui Wang <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] LoongArch: Use la.pcrel instead of la.abs when
 it's trivially possible

Hi, Youling,

On Fri, Feb 10, 2023 at 4:47 PM Youling Tang <tangyouling@...ngson.cn> wrote:
>
> From: Xi Ruoyao <xry111@...111.site>
>
> Let's start to kill la.abs inpreparation for the subsequent support of the
> PIE kernel.
>
> Signed-off-by: Xi Ruoyao <xry111@...111.site>
> ---
>  arch/loongarch/include/asm/stackframe.h | 2 +-
>  arch/loongarch/include/asm/uaccess.h    | 1 -
>  arch/loongarch/kernel/entry.S           | 2 +-
>  arch/loongarch/kernel/head.S            | 2 +-
>  arch/loongarch/mm/tlbex.S               | 3 +--
>  5 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
> index 4ca953062b5b..7deb043ce387 100644
> --- a/arch/loongarch/include/asm/stackframe.h
> +++ b/arch/loongarch/include/asm/stackframe.h
> @@ -90,7 +90,7 @@
>         .endm
>
>         .macro  set_saved_sp stackp temp temp2
> -       la.abs    \temp, kernelsp
> +       la.pcrel  \temp, kernelsp
>  #ifdef CONFIG_SMP
>         LONG_ADD  \temp, \temp, u0
>  #endif
> diff --git a/arch/loongarch/include/asm/uaccess.h b/arch/loongarch/include/asm/uaccess.h
> index 255899d4a7c3..0d22991ae430 100644
> --- a/arch/loongarch/include/asm/uaccess.h
> +++ b/arch/loongarch/include/asm/uaccess.h
> @@ -22,7 +22,6 @@
>  extern u64 __ua_limit;
>
>  #define __UA_ADDR      ".dword"
> -#define __UA_LA                "la.abs"
>  #define __UA_LIMIT     __ua_limit
>
>  /*
> diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
> index d53b631c9022..2566977f2f68 100644
> --- a/arch/loongarch/kernel/entry.S
> +++ b/arch/loongarch/kernel/entry.S
> @@ -20,7 +20,7 @@
>         .align  5
>  SYM_FUNC_START(handle_syscall)
>         csrrd   t0, PERCPU_BASE_KS
> -       la.abs  t1, kernelsp
> +       la.pcrel        t1, kernelsp
Retab the whole function to align the first parameter, please.

Huacai
>         add.d   t1, t1, t0
>         move    t2, sp
>         ld.d    sp, t1, 0
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 57bada6b4e93..aa6181714ec3 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -117,7 +117,7 @@ SYM_CODE_START(smpboot_entry)
>         li.w            t0, 0x00                # FPE=0, SXE=0, ASXE=0, BTE=0
>         csrwr           t0, LOONGARCH_CSR_EUEN
>
> -       la.abs          t0, cpuboot_data
> +       la.pcrel        t0, cpuboot_data
>         ld.d            sp, t0, CPU_BOOT_STACK
>         ld.d            tp, t0, CPU_BOOT_TINFO
>
> diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
> index 58781c6e4191..3dd2a9615cd9 100644
> --- a/arch/loongarch/mm/tlbex.S
> +++ b/arch/loongarch/mm/tlbex.S
> @@ -24,8 +24,7 @@
>         move            a0, sp
>         REG_S           a2, sp, PT_BVADDR
>         li.w            a1, \write
> -       la.abs          t0, do_page_fault
> -       jirl            ra, t0, 0
> +       bl              do_page_fault
>         RESTORE_ALL_AND_RET
>         SYM_FUNC_END(tlb_do_page_fault_\write)
>         .endm
> --
> 2.37.3
>
>