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Message-ID: <CAKxVwgcW9+3XBRp1LJ5KAVCTROLtHaf6ABK+wbt8S1SEm_Djqw@mail.gmail.com>
Date: Sun, 10 Aug 2025 23:09:19 +0800
From: Miao Chen <chenmiao.ku@...il.com>
To: Stafford Horne <shorne@...il.com>
Cc: Linux Kernel <linux-kernel@...r.kernel.org>,
Linux OpenRISC <linux-openrisc@...r.kernel.org>, Jonathan Corbet <corbet@....net>,
Jonas Bonn <jonas@...thpole.se>,
Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>, Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...nel.org>, Jason Baron <jbaron@...mai.com>,
Steven Rostedt <rostedt@...dmis.org>, Ard Biesheuvel <ardb@...nel.org>,
Masahiro Yamada <masahiroy@...nel.org>, Sahil Siddiq <sahilcdq0@...il.com>,
Nicolas Schier <nicolas.schier@...ux.dev>, Johannes Berg <johannes@...solutions.net>,
linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] openrisc: Add jump label support
Stafford Horne <shorne@...il.com> 于2025年8月9日周六 16:37写道：
>
> On Wed, Aug 06, 2025 at 02:05:04AM +0000, ChenMiao wrote:
> > From: chenmiao <chenmiao.ku@...il.com>
> >
> > Implemented the full functionality of jump_label, of course,
> > with text patching supported by just one API.
> >
> > By the way, add new macro OPENRISC_INSN_NOP in insn-def.h to use.
> >
> > - V2: using the patch_insn_write(void *addr, u32 insn) not the
> > const void *insn.
> >
> > Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t
> >
> > Signed-off-by: chenmiao <chenmiao.ku@...il.com>
> > ---
> > .../core/jump-labels/arch-support.txt | 2 +-
> > arch/openrisc/Kconfig | 2 +
> > arch/openrisc/configs/or1ksim_defconfig | 19 ++----
> > arch/openrisc/configs/virt_defconfig | 1 +
> > arch/openrisc/include/asm/insn-def.h | 3 +
> > arch/openrisc/include/asm/jump_label.h | 68 +++++++++++++++++++
> > arch/openrisc/kernel/Makefile | 1 +
> > arch/openrisc/kernel/jump_label.c | 53 +++++++++++++++
> > arch/openrisc/kernel/setup.c | 2 +
> > 9 files changed, 138 insertions(+), 13 deletions(-)
> > create mode 100644 arch/openrisc/include/asm/jump_label.h
> > create mode 100644 arch/openrisc/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 ccada815569f..683de7c15058 100644
> > --- a/Documentation/features/core/jump-labels/arch-support.txt
> > +++ b/Documentation/features/core/jump-labels/arch-support.txt
> > @@ -17,7 +17,7 @@
> > | microblaze: | TODO |
> > | mips: | ok |
> > | nios2: | TODO |
> > - | openrisc: | TODO |
> > + | openrisc: | ok |
> > | parisc: | ok |
> > | powerpc: | ok |
> > | riscv: | ok |
> > diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
> > index b38fee299bc4..9156635dd264 100644
> > --- a/arch/openrisc/Kconfig
> > +++ b/arch/openrisc/Kconfig
> > @@ -24,6 +24,8 @@ config OPENRISC
> > select GENERIC_PCI_IOMAP
> > select GENERIC_IOREMAP
> > select GENERIC_CPU_DEVICES
> > + select HAVE_ARCH_JUMP_LABEL
> > + select HAVE_ARCH_JUMP_LABEL_RELATIVE
> > select HAVE_PCI
> > select HAVE_UID16
> > select HAVE_PAGE_SIZE_8KB
> > diff --git a/arch/openrisc/configs/or1ksim_defconfig b/arch/openrisc/configs/or1ksim_defconfig
> > index 59fe33cefba2..769705ac24d5 100644
> > --- a/arch/openrisc/configs/or1ksim_defconfig
> > +++ b/arch/openrisc/configs/or1ksim_defconfig
> > @@ -3,26 +3,23 @@ CONFIG_LOG_BUF_SHIFT=14
> > CONFIG_BLK_DEV_INITRD=y
> > # CONFIG_RD_GZIP is not set
> > CONFIG_EXPERT=y
> > -# CONFIG_KALLSYMS is not set
> > # CONFIG_EPOLL is not set
> > # CONFIG_TIMERFD is not set
> > # CONFIG_EVENTFD is not set
> > # CONFIG_AIO is not set
> > -# CONFIG_VM_EVENT_COUNTERS is not set
> > -# CONFIG_COMPAT_BRK is not set
> > -CONFIG_SLUB=y
> > -CONFIG_SLUB_TINY=y
> > -CONFIG_MODULES=y
> > -# CONFIG_BLOCK is not set
> > +# CONFIG_KALLSYMS is not set
> > CONFIG_BUILTIN_DTB_NAME="or1ksim"
> > CONFIG_HZ_100=y
> > +CONFIG_JUMP_LABEL=y
> > +CONFIG_MODULES=y
> > +# CONFIG_BLOCK is not set
> > +CONFIG_SLUB_TINY=y
> > +# CONFIG_COMPAT_BRK is not set
> > +# CONFIG_VM_EVENT_COUNTERS is not set
> > CONFIG_NET=y
> > CONFIG_PACKET=y
> > CONFIG_UNIX=y
> > CONFIG_INET=y
> > -# CONFIG_INET_XFRM_MODE_TRANSPORT is not set
> > -# CONFIG_INET_XFRM_MODE_TUNNEL is not set
> > -# CONFIG_INET_XFRM_MODE_BEET is not set
> > # CONFIG_INET_DIAG is not set
> > CONFIG_TCP_CONG_ADVANCED=y
> > # CONFIG_TCP_CONG_BIC is not set
> > @@ -35,7 +32,6 @@ CONFIG_DEVTMPFS=y
> > CONFIG_DEVTMPFS_MOUNT=y
> > # CONFIG_PREVENT_FIRMWARE_BUILD is not set
> > # CONFIG_FW_LOADER is not set
> > -CONFIG_PROC_DEVICETREE=y
> > CONFIG_NETDEVICES=y
> > CONFIG_ETHOC=y
> > CONFIG_MICREL_PHY=y
> > @@ -53,4 +49,3 @@ CONFIG_SERIAL_OF_PLATFORM=y
> > # CONFIG_DNOTIFY is not set
> > CONFIG_TMPFS=y
> > CONFIG_NFS_FS=y
> > -# CONFIG_ENABLE_MUST_CHECK is not set
> > diff --git a/arch/openrisc/configs/virt_defconfig b/arch/openrisc/configs/virt_defconfig
> > index c1b69166c500..4a80c5794877 100644
> > --- a/arch/openrisc/configs/virt_defconfig
> > +++ b/arch/openrisc/configs/virt_defconfig
> > @@ -12,6 +12,7 @@ CONFIG_NR_CPUS=8
> > CONFIG_SMP=y
> > CONFIG_HZ_100=y
> > # CONFIG_OPENRISC_NO_SPR_SR_DSX is not set
> > +CONFIG_JUMP_LABEL=y
> > # CONFIG_COMPAT_BRK is not set
> > CONFIG_NET=y
> > CONFIG_PACKET=y
>
> The defconfig updates look quite different. Did you use savedefconfig for both
> of them?
Sure, it will do in the next version.
>
> > diff --git a/arch/openrisc/include/asm/insn-def.h b/arch/openrisc/include/asm/insn-def.h
> > index dc8d16db1579..2ccdbb37c27c 100644
> > --- a/arch/openrisc/include/asm/insn-def.h
> > +++ b/arch/openrisc/include/asm/insn-def.h
> > @@ -9,4 +9,7 @@
> > /* or1k instructions are always 32 bits. */
> > #define OPENRISC_INSN_SIZE 4
> >
> > +/* or1k nop instruction code */
> > +#define OPENRISC_INSN_NOP 0x15000000U
>
> I see you use this header again here, note that in
> arch/openrisc/kernel/signal.c. We write instructions to memory too for the
> sigreturn trampoline.
>
> Also, you use OPENRISC_INSN_SIZE below. Could you move this header to this
> patch completely? I don't think its needed in the patching patch.
>
maybe... this patch we no need this header, but I think this header is
meaningful, we can do this in another patch? modify the hard code insn
to macro.
> > #endif /* __ASM_INSN_DEF_H */
> > diff --git a/arch/openrisc/include/asm/jump_label.h b/arch/openrisc/include/asm/jump_label.h
> > new file mode 100644
> > index 000000000000..03afca9c3a1f
> > --- /dev/null
> > +++ b/arch/openrisc/include/asm/jump_label.h
> > @@ -0,0 +1,68 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2025 Chen Miao
> > + *
> > + * Based on arch/arm/include/asm/jump_label.h
> > + */
> > +#ifndef __ASM_JUMP_LABEL_H
> > +#define __ASM_JUMP_LABEL_H
>
> Can this be __ASM_OPENRISC_JUMP_LABEL_H?
>
> > +#ifndef __ASSEMBLY__
>
> Note upstream this is now __ASSEMBLER__.
copy that.
>
> > +#include <linux/types.h>
> > +#include <asm/insn-def.h>
> > +
> > +#define HAVE_JUMP_LABEL_BATCH
> > +
> > +#define JUMP_LABEL_NOP_SIZE OPENRISC_INSN_SIZE
> > +
> > +/*
> > + * should aligned 4
> > + * for jump_label relative
> > + * entry.code = nop.addr - . -> return false
> > + * entry.target = l_yes - . -> return true
> > + * entry.key = key - .
> > + */
> > +#define JUMP_TABLE_ENTRY(key, label) \
> > + ".pushsection __jump_table, \"aw\" \n\t" \
> > + ".align 4 \n\t" \
> > + ".long 1b - ., " label " - . \n\t" \
> > + ".long " key " - . \n\t" \
> > + ".popsection \n\t"
> > +
> > +#define ARCH_STATIC_BRANCH_ASM(key, label) \
> > + ".align 4 \n\t" \
> > + "1: l.nop \n\t" \
> > + " l.nop \n\t" \
> > + JUMP_TABLE_ENTRY(key, label)
> > +
> > +static __always_inline bool arch_static_branch(struct static_key *const key,
> > + const bool branch)
> > +{
> > + asm goto (ARCH_STATIC_BRANCH_ASM("%0", "%l[l_yes]")
> > + ::"i"(&((char *)key)[branch])::l_yes);
> > +
> > + return false;
> > +l_yes:
> > + return true;
> > +}
> > +
> > +#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \
> > + ".align 4 \n\t" \
> > + "1: l.j " label " \n\t" \
> > + " l.nop \n\t" \
> > + JUMP_TABLE_ENTRY(key, label)
> > +
> > +static __always_inline bool
> > +arch_static_branch_jump(struct static_key *const key, const bool branch)
> > +{
> > + asm goto (ARCH_STATIC_BRANCH_JUMP_ASM("%0", "%l[l_yes]")
> > + ::"i"(&((char *)key)[branch])::l_yes);
> > +
> > + return false;
> > +l_yes:
> > + return true;
> > +}
> > +
> > +#endif /* __ASSEMBLY__ */
> > +#endif /* __ASM_JUMP_LABEL_H */
> > diff --git a/arch/openrisc/kernel/Makefile b/arch/openrisc/kernel/Makefile
> > index f0957ce16d6b..19e0eb94f2eb 100644
> > --- a/arch/openrisc/kernel/Makefile
> > +++ b/arch/openrisc/kernel/Makefile
> > @@ -9,6 +9,7 @@ obj-y := head.o setup.o or32_ksyms.o process.o dma.o \
> > traps.o time.o irq.o entry.o ptrace.o signal.o \
> > sys_call_table.o unwinder.o cacheinfo.o
> >
> > +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> > obj-$(CONFIG_SMP) += smp.o sync-timer.o
> > obj-$(CONFIG_STACKTRACE) += stacktrace.o
> > obj-$(CONFIG_MODULES) += module.o
> > diff --git a/arch/openrisc/kernel/jump_label.c b/arch/openrisc/kernel/jump_label.c
> > new file mode 100644
> > index 000000000000..ce259ba30258
> > --- /dev/null
> > +++ b/arch/openrisc/kernel/jump_label.c
> > @@ -0,0 +1,53 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2025 Chen Miao
> > + *
> > + * Based on arch/arm/kernel/jump_label.c
> > + */
> > +#include <linux/jump_label.h>
> > +#include <linux/kernel.h>
> > +#include <linux/memory.h>
> > +#include <asm/bug.h>
> > +#include <asm/cacheflush.h>
> > +#include <asm/text-patching.h>
> > +
> > +bool arch_jump_label_transform_queue(struct jump_entry *entry,
> > + enum jump_label_type type)
> > +{
> > + void *addr = (void *)jump_entry_code(entry);
> > + u32 insn;
> > +
> > + if (type == JUMP_LABEL_JMP) {
> > + long offset;
> > +
> > + offset = jump_entry_target(entry) - jump_entry_code(entry);
> > + /*
> > + * The actual maximum range of the l.j instruction's offset is -134,217,728
> > + * ~ 134,217,724 (sign 26-bit imm).
> > + * For the original jump range, we need to right-shift N by 2 to obtain the
> > + * instruction's offset.
> > + */
> > + if (unlikely(offset < -134217728 || offset > 134217724)) {
> > + WARN_ON_ONCE(true);
> > + }
> > + /* 26bit imm mask */
> > + offset = (offset >> 2) & 0x03ffffff;
> > +
> > + insn = offset;
> > + } else {
> > + insn = OPENRISC_INSN_NOP;
> > + }
> > +
> > + if (early_boot_irqs_disabled) {
> > + copy_to_kernel_nofault(addr, &insn, sizeof(insn));
> > + } else {
> > + patch_insn_write(addr, insn);
> > + }
> > + return true;
> > +}
> > +
> > +void arch_jump_label_transform_apply(void)
> > +{
> > + // flush
>
> Could you use the /* */ comment style? Is this really flushing?
sure, really flushing.
>
> > + kick_all_cpus_sync();
> > +}
> > diff --git a/arch/openrisc/kernel/setup.c b/arch/openrisc/kernel/setup.c
> > index a9fb9cc6779e..000a9cc10e6f 100644
> > --- a/arch/openrisc/kernel/setup.c
> > +++ b/arch/openrisc/kernel/setup.c
> > @@ -249,6 +249,8 @@ void __init setup_arch(char **cmdline_p)
> > initrd_below_start_ok = 1;
> > }
> > #endif
> > + /* perform jump_table sorting before paging_init locks down read only memory */
> > + jump_label_init();
> >
> > /* paging_init() sets up the MMU and marks all pages as reserved */
> > paging_init();
> > --
> > 2.45.2
> >
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