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From: "Heiko Stübner" <heiko@sntech.de>
To: Conor Dooley <conor@kernel.org>
Cc: linux-riscv@lists.infradead.org, palmer@dabbelt.com,
	christoph.muellner@vrull.eu, philipp.tomsich@vrull.eu,
	ajones@ventanamicro.com, jszhang@kernel.org
Subject: Re: [PATCH v4 4/5] RISC-V: add infrastructure to allow different str* implementations
Date: Tue, 10 Jan 2023 00:31:30 +0100	[thread overview]
Message-ID: <2059459.3VsfAaAtOV@diego> (raw)
In-Reply-To: <Y7yXOfIAKj9ct1SD@spud>

Am Montag, 9. Januar 2023, 23:37:45 CET schrieb Conor Dooley:
> On Mon, Jan 09, 2023 at 07:17:54PM +0100, Heiko Stuebner wrote:
> > From: Heiko Stuebner <heiko.stuebner@vrull.eu>
> > 
> > Depending on supported extensions on specific RISC-V cores,
> > optimized str* functions might make sense.
> > 
> > This adds basic infrastructure to allow patching the function calls
> > via alternatives later on.
> > 
> > The Linux kernel provides standard implementations for string functions
> > but when architectures want to extend them, they need to provide their
> > own.
> > 
> > The added generic string functions are done in assembler (taken from
> > disassembling the main-kernel functions for now) to allow us to control
> > the used registers and extend them with optimized variants.
> > 
> > Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
> 
> asm looks the same as what I previously provided a review for, but I
> assume you dropped cos of the EFI stub stuff? You can have it back I
> suppose..
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

That was the

| Technically patch4 got a review from Andrew, but that was still with
| the inline approach, so I didn't bring it over to v4.

part in the cover-letter, thanks for bringing the rb back :-)


Heiko

> > ---
> >  arch/riscv/include/asm/string.h | 10 +++++++++
> >  arch/riscv/kernel/riscv_ksyms.c |  3 +++
> >  arch/riscv/lib/Makefile         |  3 +++
> >  arch/riscv/lib/strcmp.S         | 37 ++++++++++++++++++++++++++++++
> >  arch/riscv/lib/strlen.S         | 28 +++++++++++++++++++++++
> >  arch/riscv/lib/strncmp.S        | 40 +++++++++++++++++++++++++++++++++
> >  arch/riscv/purgatory/Makefile   | 13 +++++++++++
> >  7 files changed, 134 insertions(+)
> >  create mode 100644 arch/riscv/lib/strcmp.S
> >  create mode 100644 arch/riscv/lib/strlen.S
> >  create mode 100644 arch/riscv/lib/strncmp.S
> > 
> > diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h
> > index 909049366555..a96b1fea24fe 100644
> > --- a/arch/riscv/include/asm/string.h
> > +++ b/arch/riscv/include/asm/string.h
> > @@ -18,6 +18,16 @@ extern asmlinkage void *__memcpy(void *, const void *, size_t);
> >  #define __HAVE_ARCH_MEMMOVE
> >  extern asmlinkage void *memmove(void *, const void *, size_t);
> >  extern asmlinkage void *__memmove(void *, const void *, size_t);
> > +
> > +#define __HAVE_ARCH_STRCMP
> > +extern asmlinkage int strcmp(const char *cs, const char *ct);
> > +
> > +#define __HAVE_ARCH_STRLEN
> > +extern asmlinkage __kernel_size_t strlen(const char *);
> > +
> > +#define __HAVE_ARCH_STRNCMP
> > +extern asmlinkage int strncmp(const char *cs, const char *ct, size_t count);
> > +
> >  /* For those files which don't want to check by kasan. */
> >  #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> >  #define memcpy(dst, src, len) __memcpy(dst, src, len)
> > diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ksyms.c
> > index 5ab1c7e1a6ed..a72879b4249a 100644
> > --- a/arch/riscv/kernel/riscv_ksyms.c
> > +++ b/arch/riscv/kernel/riscv_ksyms.c
> > @@ -12,6 +12,9 @@
> >  EXPORT_SYMBOL(memset);
> >  EXPORT_SYMBOL(memcpy);
> >  EXPORT_SYMBOL(memmove);
> > +EXPORT_SYMBOL(strcmp);
> > +EXPORT_SYMBOL(strlen);
> > +EXPORT_SYMBOL(strncmp);
> >  EXPORT_SYMBOL(__memset);
> >  EXPORT_SYMBOL(__memcpy);
> >  EXPORT_SYMBOL(__memmove);
> > diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
> > index 25d5c9664e57..6c74b0bedd60 100644
> > --- a/arch/riscv/lib/Makefile
> > +++ b/arch/riscv/lib/Makefile
> > @@ -3,6 +3,9 @@ lib-y			+= delay.o
> >  lib-y			+= memcpy.o
> >  lib-y			+= memset.o
> >  lib-y			+= memmove.o
> > +lib-y			+= strcmp.o
> > +lib-y			+= strlen.o
> > +lib-y			+= strncmp.o
> >  lib-$(CONFIG_MMU)	+= uaccess.o
> >  lib-$(CONFIG_64BIT)	+= tishift.o
> >  
> > diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S
> > new file mode 100644
> > index 000000000000..94440fb8390c
> > --- /dev/null
> > +++ b/arch/riscv/lib/strcmp.S
> > @@ -0,0 +1,37 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/asm.h>
> > +#include <asm-generic/export.h>
> > +
> > +/* int strcmp(const char *cs, const char *ct) */
> > +SYM_FUNC_START(strcmp)
> > +	/*
> > +	 * Returns
> > +	 *   a0 - comparison result, value like strcmp
> > +	 *
> > +	 * Parameters
> > +	 *   a0 - string1
> > +	 *   a1 - string2
> > +	 *
> > +	 * Clobbers
> > +	 *   t0, t1, t2
> > +	 */
> > +	mv	t2, a1
> > +1:
> > +	lbu	t1, 0(a0)
> > +	lbu	t0, 0(a1)
> > +	addi	a0, a0, 1
> > +	addi	a1, a1, 1
> > +	beq	t1, t0, 3f
> > +	li	a0, 1
> > +	bgeu	t1, t0, 2f
> > +	li	a0, -1
> > +2:
> > +	mv	a1, t2
> > +	ret
> > +3:
> > +	bnez	t1, 1b
> > +	li	a0, 0
> > +	j	2b
> > +SYM_FUNC_END(strcmp)
> > diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S
> > new file mode 100644
> > index 000000000000..09a7aaff26c8
> > --- /dev/null
> > +++ b/arch/riscv/lib/strlen.S
> > @@ -0,0 +1,28 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/asm.h>
> > +#include <asm-generic/export.h>
> > +
> > +/* int strlen(const char *s) */
> > +SYM_FUNC_START(strlen)
> > +	/*
> > +	 * Returns
> > +	 *   a0 - string length
> > +	 *
> > +	 * Parameters
> > +	 *   a0 - String to measure
> > +	 *
> > +	 * Clobbers:
> > +	 *   t0, t1
> > +	 */
> > +	mv	t1, a0
> > +1:
> > +	lbu	t0, 0(t1)
> > +	bnez	t0, 2f
> > +	sub	a0, t1, a0
> > +	ret
> > +2:
> > +	addi	t1, t1, 1
> > +	j	1b
> > +SYM_FUNC_END(strlen)
> > diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S
> > new file mode 100644
> > index 000000000000..493ab6febcb2
> > --- /dev/null
> > +++ b/arch/riscv/lib/strncmp.S
> > @@ -0,0 +1,40 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/asm.h>
> > +#include <asm-generic/export.h>
> > +
> > +/* int strncmp(const char *cs, const char *ct, size_t count) */
> > +SYM_FUNC_START(strncmp)
> > +	/*
> > +	 * Returns
> > +	 *   a0 - comparison result, value like strncmp
> > +	 *
> > +	 * Parameters
> > +	 *   a0 - string1
> > +	 *   a1 - string2
> > +	 *   a2 - number of characters to compare
> > +	 *
> > +	 * Clobbers
> > +	 *   t0, t1, t2
> > +	 */
> > +	li	t0, 0
> > +1:
> > +	beq	a2, t0, 4f
> > +	add	t1, a0, t0
> > +	add	t2, a1, t0
> > +	lbu	t1, 0(t1)
> > +	lbu	t2, 0(t2)
> > +	beq	t1, t2, 3f
> > +	li	a0, 1
> > +	bgeu	t1, t2, 2f
> > +	li	a0, -1
> > +2:
> > +	ret
> > +3:
> > +	addi	t0, t0, 1
> > +	bnez	t1, 1b
> > +4:
> > +	li	a0, 0
> > +	j	2b
> > +SYM_FUNC_END(strncmp)
> > diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
> > index dd58e1d99397..d16bf715a586 100644
> > --- a/arch/riscv/purgatory/Makefile
> > +++ b/arch/riscv/purgatory/Makefile
> > @@ -2,6 +2,7 @@
> >  OBJECT_FILES_NON_STANDARD := y
> >  
> >  purgatory-y := purgatory.o sha256.o entry.o string.o ctype.o memcpy.o memset.o
> > +purgatory-y += strcmp.o strlen.o strncmp.o
> >  
> >  targets += $(purgatory-y)
> >  PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
> > @@ -18,6 +19,15 @@ $(obj)/memcpy.o: $(srctree)/arch/riscv/lib/memcpy.S FORCE
> >  $(obj)/memset.o: $(srctree)/arch/riscv/lib/memset.S FORCE
> >  	$(call if_changed_rule,as_o_S)
> >  
> > +$(obj)/strcmp.o: $(srctree)/arch/riscv/lib/strcmp.S FORCE
> > +	$(call if_changed_rule,as_o_S)
> > +
> > +$(obj)/strlen.o: $(srctree)/arch/riscv/lib/strlen.S FORCE
> > +	$(call if_changed_rule,as_o_S)
> > +
> > +$(obj)/strncmp.o: $(srctree)/arch/riscv/lib/strncmp.S FORCE
> > +	$(call if_changed_rule,as_o_S)
> > +
> >  $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
> >  	$(call if_changed_rule,cc_o_c)
> >  
> > @@ -77,6 +87,9 @@ CFLAGS_ctype.o			+= $(PURGATORY_CFLAGS)
> >  AFLAGS_REMOVE_entry.o		+= -Wa,-gdwarf-2
> >  AFLAGS_REMOVE_memcpy.o		+= -Wa,-gdwarf-2
> >  AFLAGS_REMOVE_memset.o		+= -Wa,-gdwarf-2
> > +AFLAGS_REMOVE_strcmp.o		+= -Wa,-gdwarf-2
> > +AFLAGS_REMOVE_strlen.o		+= -Wa,-gdwarf-2
> > +AFLAGS_REMOVE_strncmp.o		+= -Wa,-gdwarf-2
> >  
> >  $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
> >  		$(call if_changed,ld)
> 





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  reply	other threads:[~2023-01-09 23:31 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-09 18:17 [PATCH v4 0/5] Zbb string optimizations and call support in alternatives Heiko Stuebner
2023-01-09 18:17 ` [PATCH v4 1/5] RISC-V: move some stray __RISCV_INSN_FUNCS definitions from kprobes Heiko Stuebner
2023-01-09 20:53   ` Conor Dooley
2023-01-11 15:14     ` Heiko Stübner
2023-01-10  8:32   ` Andrew Jones
2023-01-09 18:17 ` [PATCH v4 2/5] RISC-V: add helpers for J-type immediate handling Heiko Stuebner
2023-01-09 22:22   ` Conor Dooley
2023-01-10  8:44   ` Andrew Jones
2023-01-10  8:54     ` Conor Dooley
2023-01-11 14:43       ` Jisheng Zhang
2023-01-09 18:17 ` [PATCH v4 3/5] RISC-V: fix jal addresses in patched alternatives Heiko Stuebner
2023-01-10  9:28   ` Andrew Jones
2023-01-11 17:15     ` Jisheng Zhang
2023-01-11 13:18   ` Jisheng Zhang
2023-01-11 13:53     ` Heiko Stübner
2023-01-11 14:15     ` Andrew Jones
2023-01-11 14:44       ` Jisheng Zhang
2023-01-09 18:17 ` [PATCH v4 4/5] RISC-V: add infrastructure to allow different str* implementations Heiko Stuebner
2023-01-09 22:37   ` Conor Dooley
2023-01-09 23:31     ` Heiko Stübner [this message]
2023-01-10  9:39   ` Andrew Jones
2023-01-10 10:46     ` Heiko Stübner
2023-01-10 11:16       ` Andrew Jones
2023-01-11 12:34         ` Andrew Jones
     [not found]           ` <CAEg0e7gJgpoiGjfLeedba0-r=dCE1Z_qkU53w_+-cVjsuqaC3A@mail.gmail.com>
2023-01-11 13:42             ` Philipp Tomsich
2023-01-11 13:47             ` Andrew Jones
2023-01-10 12:13   ` Andrew Jones
2023-01-11 12:30     ` Andrew Jones
2023-01-12 16:05     ` Heiko Stübner
2023-01-09 18:17 ` [PATCH v4 5/5] RISC-V: add zbb support to string functions Heiko Stuebner
2023-01-09 20:39   ` Conor Dooley
2023-01-10  9:57   ` Andrew Jones
2023-01-10 10:14     ` Conor Dooley
2023-01-12 11:21       ` Heiko Stübner
2023-01-12 12:06         ` Conor Dooley
2023-01-12 12:28           ` Heiko Stübner
2023-01-11 12:24   ` Andrew Jones
2023-01-11 14:27     ` Christoph Müllner
2023-01-11 15:16       ` Andrew Jones
2023-01-11 15:22       ` Jeff Law
2023-01-12 22:05     ` Heiko Stübner
2023-01-11 13:24 ` [PATCH v4 0/5] Zbb string optimizations and call support in alternatives Jisheng Zhang

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