Re: [PATCH] LoongArch: Add jump-label implementation

[Youling Tang <tangyouling@xxxxxxxxxxx>]

On 05/09/2023 03:29 PM, Youling Tang wrote:
> Add jump-label implementation based on the ARM64 version.
>
> Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
> ---
>  .../core/jump-labels/arch-support.txt         |  2 +-
>  arch/loongarch/Kconfig                        |  2 +
>  arch/loongarch/configs/loongson3_defconfig    |  1 +
>  arch/loongarch/include/asm/jump_label.h       | 52 +++++++++++++++++++
>  arch/loongarch/kernel/Makefile                |  2 +
>  arch/loongarch/kernel/jump_label.c            | 23 ++++++++
>  6 files changed, 81 insertions(+), 1 deletion(-)
>  create mode 100644 arch/loongarch/include/asm/jump_label.h
>  create mode 100644 arch/loongarch/kernel/jump_label.c
>
> diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> index 2328eada3a49..94d9dece580f 100644
> --- a/Documentation/features/core/jump-labels/arch-support.txt
> +++ b/Documentation/features/core/jump-labels/arch-support.txt
> @@ -13,7 +13,7 @@
>      |        csky: |  ok  |
>      |     hexagon: | TODO |
>      |        ia64: | TODO |
> -    |   loongarch: | TODO |
> +    |   loongarch: |  ok  |
>      |        m68k: | TODO |
>      |  microblaze: | TODO |
>      |        mips: |  ok  |
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index d38b066fc931..193a959a5611 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -83,6 +83,8 @@ config LOONGARCH
>  	select GPIOLIB
>  	select HAS_IOPORT
>  	select HAVE_ARCH_AUDITSYSCALL
> +	select HAVE_ARCH_JUMP_LABEL
> +	select HAVE_ARCH_JUMP_LABEL_RELATIVE
>  	select HAVE_ARCH_MMAP_RND_BITS if MMU
>  	select HAVE_ARCH_SECCOMP_FILTER
>  	select HAVE_ARCH_TRACEHOOK
> diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
> index 6cd26dd3c134..33a0f5f742f6 100644
> --- a/arch/loongarch/configs/loongson3_defconfig
> +++ b/arch/loongarch/configs/loongson3_defconfig
> @@ -63,6 +63,7 @@ CONFIG_EFI_ZBOOT=y
>  CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER=y
>  CONFIG_EFI_CAPSULE_LOADER=m
>  CONFIG_EFI_TEST=m
> +CONFIG_JUMP_LABEL=y
>  CONFIG_MODULES=y
>  CONFIG_MODULE_FORCE_LOAD=y
>  CONFIG_MODULE_UNLOAD=y
> diff --git a/arch/loongarch/include/asm/jump_label.h b/arch/loongarch/include/asm/jump_label.h
> new file mode 100644
> index 000000000000..453a0cd3ddf0
> --- /dev/null
> +++ b/arch/loongarch/include/asm/jump_label.h
> @@ -0,0 +1,52 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2023 Loongson Technology Corporation Limited
> + *
> + * Based on arch/arm64/include/asm/jump_label.h
> + */
> +#ifndef __ASM_JUMP_LABEL_H
> +#define __ASM_JUMP_LABEL_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/types.h>
> +#include <asm/inst.h>
> +
> +#define JUMP_LABEL_NOP_SIZE		LOONGARCH_INSN_SIZE
> +
> +static __always_inline bool arch_static_branch(struct static_key * const key,
> +					       const bool branch)
> +{
> +	asm_volatile_goto(
> +		"1:	nop					\n\t"
> +		 "	.pushsection	__jump_table, \"aw\"	\n\t"
> +		 "	.align		3			\n\t"
> +		 "	.long		1b - ., %l[l_yes] - .	\n\t"
> +		 "	.quad		%0 - .			\n\t"
> +		 "	.popsection				\n\t"
> +		 :  :  "i"(&((char *)key)[branch]) :  : l_yes);
> +
> +	return false;
> +l_yes:
> +	return true;
> +}
> +
> +static __always_inline bool arch_static_branch_jump(struct static_key * const key,
> +						    const bool branch)
> +{
> +	asm_volatile_goto(
> +		"1:	b		%l[l_yes]		\n\t"
> +		 "	.pushsection	__jump_table, \"aw\"	\n\t"
> +		 "	.align		3			\n\t"
> +		 "	.long		1b - ., %l[l_yes] - .	\n\t"
> +		 "	.quad		%0 - .			\n\t"
> +		 "	.popsection				\n\t"
> +		 :  :  "i"(&((char *)key)[branch]) :  : l_yes);
> +
> +	return false;
> +l_yes:
> +	return true;
> +}
> +
> +#endif  /* __ASSEMBLY__ */
> +#endif	/* __ASM_JUMP_LABEL_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 9a72d91cd104..64ea76f60e2c 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -54,4 +54,6 @@ obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
>
>  obj-$(CONFIG_KPROBES)		+= kprobes.o kprobes_trampoline.o
>
> +obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
> +
>  CPPFLAGS_vmlinux.lds		:= $(KBUILD_CFLAGS)
> diff --git a/arch/loongarch/kernel/jump_label.c b/arch/loongarch/kernel/jump_label.c
> new file mode 100644
> index 000000000000..c3ebaa4cf1e5
> --- /dev/null
> +++ b/arch/loongarch/kernel/jump_label.c
> @@ -0,0 +1,23 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2023 Loongson Technology Corporation Limited
> + *
> + * Based on arch/arm64/include/asm/jump_label.h
Sorry, this should be changed to,
Based on arch/arm64/kernel/jump_label.c

> + */
> +#include <linux/jump_label.h>
> +#include <linux/kernel.h>
> +#include <asm/inst.h>
> +
> +void arch_jump_label_transform(struct jump_entry *entry,
> +			       enum jump_label_type type)
> +{
> +	void *addr = (void *)jump_entry_code(entry);
> +	u32 insn;
> +
> +	if (type == JUMP_LABEL_JMP)
> +		insn = larch_insn_gen_b(jump_entry_code(entry), jump_entry_target(entry));
> +	else
> +		insn = larch_insn_gen_nop();
> +
> +	larch_insn_patch_text(addr, insn);
> +}