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References: <20220430090518.3127980-1-chenhuacai@loongson.cn> <20220430090518.3127980-18-chenhuacai@loongson.cn>
In-Reply-To: <20220430090518.3127980-18-chenhuacai@loongson.cn>
From:   Guo Ren <guoren@kernel.org>
Date:   Sun, 1 May 2022 18:55:57 +0800
Message-ID: <CAJF2gTQ7D_3+V9U=BTPDE-gqxuP5+gLwM9C8_Rxna0GGJ1Yn9A@mail.gmail.com>
Subject: Re: [PATCH V9 17/24] LoongArch: Add some library functions
To:     Huacai Chen <chenhuacai@loongson.cn>
Cc:     Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Airlie <airlied@linux.ie>,
        Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Yanteng Si <siyanteng@loongson.cn>,
        Huacai Chen <chenhuacai@gmail.com>,
        Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Sat, Apr 30, 2022 at 5:23 PM Huacai Chen <chenhuacai@loongson.cn> wrote:
>
> This patch adds some library functions for LoongArch, including: delay,
> memset, memcpy, memmove, copy_user, strncpy_user, strnlen_user and tlb
> dump functions.
>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>  arch/loongarch/include/asm/delay.h  |  26 +++++++
>  arch/loongarch/include/asm/string.h |  17 +++++
>  arch/loongarch/lib/clear_user.S     |  43 +++++++++++
>  arch/loongarch/lib/copy_user.S      |  47 ++++++++++++
>  arch/loongarch/lib/delay.c          |  43 +++++++++++
>  arch/loongarch/lib/dump_tlb.c       | 111 ++++++++++++++++++++++++++++
>  arch/loongarch/lib/memcpy.S         |  32 ++++++++
>  arch/loongarch/lib/memmove.S        |  45 +++++++++++
>  arch/loongarch/lib/memset.S         |  30 ++++++++
>  9 files changed, 394 insertions(+)
>  create mode 100644 arch/loongarch/include/asm/delay.h
>  create mode 100644 arch/loongarch/include/asm/string.h
>  create mode 100644 arch/loongarch/lib/clear_user.S
>  create mode 100644 arch/loongarch/lib/copy_user.S
>  create mode 100644 arch/loongarch/lib/delay.c
>  create mode 100644 arch/loongarch/lib/dump_tlb.c
>  create mode 100644 arch/loongarch/lib/memcpy.S
>  create mode 100644 arch/loongarch/lib/memmove.S
>  create mode 100644 arch/loongarch/lib/memset.S
>
> diff --git a/arch/loongarch/include/asm/delay.h b/arch/loongarch/include/asm/delay.h
> new file mode 100644
> index 000000000000..016b3aca65cb
> --- /dev/null
> +++ b/arch/loongarch/include/asm/delay.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef _ASM_DELAY_H
> +#define _ASM_DELAY_H
> +
> +#include <linux/param.h>
> +
> +extern void __delay(unsigned long loops);
> +extern void __ndelay(unsigned long ns);
> +extern void __udelay(unsigned long us);
> +
> +#define ndelay(ns) __ndelay(ns)
> +#define udelay(us) __udelay(us)
> +
> +/* make sure "usecs *= ..." in udelay do not overflow. */
> +#if HZ >= 1000
> +#define MAX_UDELAY_MS  1
> +#elif HZ <= 200
> +#define MAX_UDELAY_MS  5
> +#else
> +#define MAX_UDELAY_MS  (1000 / HZ)
> +#endif
> +
> +#endif /* _ASM_DELAY_H */
> diff --git a/arch/loongarch/include/asm/string.h b/arch/loongarch/include/asm/string.h
> new file mode 100644
> index 000000000000..7b29cc9c70aa
> --- /dev/null
> +++ b/arch/loongarch/include/asm/string.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef _ASM_STRING_H
> +#define _ASM_STRING_H
> +
> +#define __HAVE_ARCH_MEMSET
> +extern void *memset(void *__s, int __c, size_t __count);
> +
> +#define __HAVE_ARCH_MEMCPY
> +extern void *memcpy(void *__to, __const__ void *__from, size_t __n);
> +
> +#define __HAVE_ARCH_MEMMOVE
> +extern void *memmove(void *__dest, __const__ void *__src, size_t __n);
> +
> +#endif /* _ASM_STRING_H */
> diff --git a/arch/loongarch/lib/clear_user.S b/arch/loongarch/lib/clear_user.S
> new file mode 100644
> index 000000000000..b8168d22ac80
> --- /dev/null
> +++ b/arch/loongarch/lib/clear_user.S
> @@ -0,0 +1,43 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/asm.h>
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +.macro fixup_ex from, to, offset, fix
> +.if \fix
> +       .section .fixup, "ax"
> +\to:   addi.d  v0, a1, \offset
> +       jr      ra
> +       .previous
> +.endif
> +       .section __ex_table, "a"
> +       PTR     \from\()b, \to\()b
> +       .previous
> +.endm
> +
> +/*
> + * unsigned long __clear_user(void *addr, size_t size)
> + *
> + * a0: addr
> + * a1: size
> + */
> +SYM_FUNC_START(__clear_user)
> +       beqz    a1, 2f
> +
> +1:     st.b    zero, a0, 0
> +       addi.d  a0, a0, 1
> +       addi.d  a1, a1, -1
> +       bgt     a1, zero, 1b
> +
> +2:     move    v0, a1
> +       jr      ra
> +
> +       fixup_ex 1, 3, 0, 1
> +SYM_FUNC_END(__clear_user)
> +
> +EXPORT_SYMBOL(__clear_user)
> diff --git a/arch/loongarch/lib/copy_user.S b/arch/loongarch/lib/copy_user.S
> new file mode 100644
> index 000000000000..43ed26304954
> --- /dev/null
> +++ b/arch/loongarch/lib/copy_user.S
> @@ -0,0 +1,47 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/asm.h>
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +.macro fixup_ex from, to, offset, fix
> +.if \fix
> +       .section .fixup, "ax"
> +\to:   addi.d  v0, a2, \offset
> +       jr      ra
> +       .previous
> +.endif
> +       .section __ex_table, "a"
> +       PTR     \from\()b, \to\()b
> +       .previous
> +.endm
> +
> +/*
> + * unsigned long __copy_user(void *to, const void *from, size_t n)
> + *
> + * a0: to
> + * a1: from
> + * a2: n
> + */
> +SYM_FUNC_START(__copy_user)
> +       beqz    a2, 3f
> +
> +1:     ld.b    t0, a1, 0
> +2:     st.b    t0, a0, 0
> +       addi.d  a0, a0, 1
> +       addi.d  a1, a1, 1
> +       addi.d  a2, a2, -1
> +       bgt     a2, zero, 1b
> +
> +3:     move    v0, a2
> +       jr      ra
> +
> +       fixup_ex 1, 4, 0, 1
> +       fixup_ex 2, 4, 0, 0
> +SYM_FUNC_END(__copy_user)
> +
> +EXPORT_SYMBOL(__copy_user)
> diff --git a/arch/loongarch/lib/delay.c b/arch/loongarch/lib/delay.c
> new file mode 100644
> index 000000000000..5d856694fcfe
> --- /dev/null
> +++ b/arch/loongarch/lib/delay.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#include <linux/delay.h>
> +#include <linux/export.h>
> +#include <linux/smp.h>
> +#include <linux/timex.h>
> +
> +#include <asm/compiler.h>
> +#include <asm/processor.h>
> +
> +void __delay(unsigned long cycles)
> +{
> +       u64 t0 = get_cycles();
> +
> +       while ((unsigned long)(get_cycles() - t0) < cycles)
> +               cpu_relax();
> +}
> +EXPORT_SYMBOL(__delay);
> +
> +/*
> + * Division by multiplication: you don't have to worry about
> + * loss of precision.
> + *
> + * Use only for very small delays ( < 1 msec). Should probably use a
> + * lookup table, really, as the multiplications take much too long with
> + * short delays.  This is a "reasonable" implementation, though (and the
> + * first constant multiplications gets optimized away if the delay is
> + * a constant)
> + */
> +
> +void __udelay(unsigned long us)
> +{
> +       __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32);
> +}
> +EXPORT_SYMBOL(__udelay);
> +
> +void __ndelay(unsigned long ns)
> +{
> +       __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32);
> +}
> +EXPORT_SYMBOL(__ndelay);
> diff --git a/arch/loongarch/lib/dump_tlb.c b/arch/loongarch/lib/dump_tlb.c
> new file mode 100644
> index 000000000000..cda2c6bc7f09
> --- /dev/null
> +++ b/arch/loongarch/lib/dump_tlb.c
> @@ -0,0 +1,111 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + *
> + * Derived from MIPS:
> + * Copyright (C) 1994, 1995 by Waldorf Electronics, written by Ralf Baechle.
> + * Copyright (C) 1999 by Silicon Graphics, Inc.
> + */
> +#include <linux/kernel.h>
> +#include <linux/mm.h>
> +
> +#include <asm/loongarch.h>
> +#include <asm/page.h>
> +#include <asm/pgtable.h>
> +#include <asm/tlb.h>
> +
> +void dump_tlb_regs(void)
> +{
> +       const int field = 2 * sizeof(unsigned long);
> +
> +       pr_info("Index    : %0x\n", read_csr_tlbidx());
> +       pr_info("PageSize : %0x\n", read_csr_pagesize());
> +       pr_info("EntryHi  : %0*llx\n", field, read_csr_entryhi());
> +       pr_info("EntryLo0 : %0*llx\n", field, read_csr_entrylo0());
> +       pr_info("EntryLo1 : %0*llx\n", field, read_csr_entrylo1());
> +}
> +
> +static void dump_tlb(int first, int last)
> +{
> +       unsigned long s_entryhi, entryhi, asid;
> +       unsigned long long entrylo0, entrylo1, pa;
> +       unsigned int index;
> +       unsigned int s_index, s_asid;
> +       unsigned int pagesize, c0, c1, i;
> +       unsigned long asidmask = cpu_asid_mask(&current_cpu_data);
> +       int pwidth = 11;
> +       int vwidth = 11;
> +       int asidwidth = DIV_ROUND_UP(ilog2(asidmask) + 1, 4);
> +
> +       s_entryhi = read_csr_entryhi();
> +       s_index = read_csr_tlbidx();
> +       s_asid = read_csr_asid();
> +
> +       for (i = first; i <= last; i++) {
> +               write_csr_index(i);
> +               tlb_read();
> +               pagesize = read_csr_pagesize();
> +               entryhi  = read_csr_entryhi();
> +               entrylo0 = read_csr_entrylo0();
> +               entrylo1 = read_csr_entrylo1();
> +               index = read_csr_tlbidx();
> +               asid = read_csr_asid();
> +
> +               /* EHINV bit marks entire entry as invalid */
> +               if (index & CSR_TLBIDX_EHINV)
> +                       continue;
> +               /*
> +                * ASID takes effect in absence of G (global) bit.
> +                */
> +               if (!((entrylo0 | entrylo1) & ENTRYLO_G) &&
> +                   asid != s_asid)
> +                       continue;
> +
> +               /*
> +                * Only print entries in use
> +                */
> +               pr_info("Index: %2d pgsize=%x ", i, (1 << pagesize));
> +
> +               c0 = (entrylo0 & ENTRYLO_C) >> ENTRYLO_C_SHIFT;
> +               c1 = (entrylo1 & ENTRYLO_C) >> ENTRYLO_C_SHIFT;
> +
> +               pr_cont("va=%0*lx asid=%0*lx",
> +                       vwidth, (entryhi & ~0x1fffUL), asidwidth, asid & asidmask);
> +
> +               /* NR/NX are in awkward places, so mask them off separately */
> +               pa = entrylo0 & ~(ENTRYLO_NR | ENTRYLO_NX);
> +               pa = pa & PAGE_MASK;
> +               pr_cont("\n\t[");
> +               pr_cont("ri=%d xi=%d ",
> +                       (entrylo0 & ENTRYLO_NR) ? 1 : 0,
> +                       (entrylo0 & ENTRYLO_NX) ? 1 : 0);
> +               pr_cont("pa=%0*llx c=%d d=%d v=%d g=%d plv=%lld] [",
> +                       pwidth, pa, c0,
> +                       (entrylo0 & ENTRYLO_D) ? 1 : 0,
> +                       (entrylo0 & ENTRYLO_V) ? 1 : 0,
> +                       (entrylo0 & ENTRYLO_G) ? 1 : 0,
> +                       (entrylo0 & ENTRYLO_PLV) >> ENTRYLO_PLV_SHIFT);
> +               /* NR/NX are in awkward places, so mask them off separately */
> +               pa = entrylo1 & ~(ENTRYLO_NR | ENTRYLO_NX);
> +               pa = pa & PAGE_MASK;
> +               pr_cont("ri=%d xi=%d ",
> +                       (entrylo1 & ENTRYLO_NR) ? 1 : 0,
> +                       (entrylo1 & ENTRYLO_NX) ? 1 : 0);
> +               pr_cont("pa=%0*llx c=%d d=%d v=%d g=%d plv=%lld]\n",
> +                       pwidth, pa, c1,
> +                       (entrylo1 & ENTRYLO_D) ? 1 : 0,
> +                       (entrylo1 & ENTRYLO_V) ? 1 : 0,
> +                       (entrylo1 & ENTRYLO_G) ? 1 : 0,
> +                       (entrylo1 & ENTRYLO_PLV) >> ENTRYLO_PLV_SHIFT);
> +       }
> +       pr_info("\n");
> +
> +       write_csr_entryhi(s_entryhi);
> +       write_csr_tlbidx(s_index);
> +       write_csr_asid(s_asid);
> +}
> +
> +void dump_tlb_all(void)
> +{
> +       dump_tlb(0, current_cpu_data.tlbsize - 1);
> +}
> diff --git a/arch/loongarch/lib/memcpy.S b/arch/loongarch/lib/memcpy.S
> new file mode 100644
> index 000000000000..d53f1148d26b
> --- /dev/null
> +++ b/arch/loongarch/lib/memcpy.S
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +/*
> + * void *memcpy(void *dst, const void *src, size_t n)
> + *
> + * a0: dst
> + * a1: src
> + * a2: n
> + */
> +SYM_FUNC_START(memcpy)
> +       move    a3, a0
> +       beqz    a2, 2f
> +
> +1:     ld.b    t0, a1, 0
> +       st.b    t0, a0, 0
> +       addi.d  a0, a0, 1
> +       addi.d  a1, a1, 1
> +       addi.d  a2, a2, -1
> +       bgt     a2, zero, 1b
> +
> +2:     move    v0, a3
> +       jr      ra
> +SYM_FUNC_END(memcpy)
> +
> +EXPORT_SYMBOL(memcpy)
> diff --git a/arch/loongarch/lib/memmove.S b/arch/loongarch/lib/memmove.S
> new file mode 100644
> index 000000000000..18907d83a83b
> --- /dev/null
> +++ b/arch/loongarch/lib/memmove.S
> @@ -0,0 +1,45 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +/*
> + * void *rmemcpy(void *dst, const void *src, size_t n)
> + *
> + * a0: dst
> + * a1: src
> + * a2: n
> + */
> +SYM_FUNC_START(rmemcpy)
> +       move    a3, a0
> +       beqz    a2, 2f
> +
> +       add.d   a0, a0, a2
> +       add.d   a1, a1, a2
> +
> +1:     ld.b    t0, a1, -1
> +       st.b    t0, a0, -1
> +       addi.d  a0, a0, -1
> +       addi.d  a1, a1, -1
> +       addi.d  a2, a2, -1
> +       bgt     a2, zero, 1b
> +
> +2:     move    v0, a3
> +       jr      ra
> +SYM_FUNC_END(rmemcpy)
Why not directly use:

lib/string.c:
#ifndef __HAVE_ARCH_MEMCPY
/**
 * memcpy - Copy one area of memory to another
 * @dest: Where to copy to
 * @src: Where to copy from
 * @count: The size of the area.
 *
 * You should not use this function to access IO space, use memcpy_toio()
 * or memcpy_fromio() instead.
 */
void *memcpy(void *dest, const void *src, size_t count)
{
        char *tmp = dest;
        const char *s = src;

        while (count--)
                *tmp++ = *s++;
        return dest;
}
EXPORT_SYMBOL(memcpy);
#endif

Do you want to try a C's string implementation?
https://lore.kernel.org/linux-csky/202204051450.UN2k1raL-lkp@intel.com/T/#Z2e.:..:20220404142354.2792428-1-guoren::40kernel.org:1arch:csky:lib:string.c

> +
> +SYM_FUNC_START(memmove)
> +       blt     a0, a1, 1f      /* dst < src, memcpy */
> +       blt     a1, a0, 2f      /* src < dst, rmemcpy */
> +       jr      ra              /* dst == src, return */
> +
> +1:     b       memcpy
> +
> +2:     b       rmemcpy
> +SYM_FUNC_END(memmove)
> +
> +EXPORT_SYMBOL(memmove)
> diff --git a/arch/loongarch/lib/memset.S b/arch/loongarch/lib/memset.S
> new file mode 100644
> index 000000000000..3fc3e7da5263
> --- /dev/null
> +++ b/arch/loongarch/lib/memset.S
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/asmmacro.h>
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +
> +/*
> + * void *memset(void *s, int c, size_t n)
> + *
> + * a0: s
> + * a1: c
> + * a2: n
> + */
> +SYM_FUNC_START(memset)
> +       move    a3, a0
> +       beqz    a2, 2f
> +
> +1:     st.b    a1, a0, 0
> +       addi.d  a0, a0, 1
> +       addi.d  a2, a2, -1
> +       bgt     a2, zero, 1b
> +
> +2:     move    v0, a3
> +       jr      ra
> +SYM_FUNC_END(memset)
> +
> +EXPORT_SYMBOL(memset)
> --
> 2.27.0
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/