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Date: Mon, 20 Sep 2010 22:32:26 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Jason Baron <jbaron@...hat.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu,
mathieu.desnoyers@...ymtl.ca, hpa@...or.com, tglx@...utronix.de,
andi@...stfloor.org, roland@...hat.com, rth@...hat.com,
mhiramat@...hat.com, fweisbec@...il.com, avi@...hat.com,
davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org,
tony@...eyournoodle.com
Subject: Re: [PATCH 08/10] jump label v11: x86 support
I'm starting to play with this. I just updated my distcc to gcc 4.5.1 so
that I can.
On Fri, 2010-09-17 at 11:09 -0400, Jason Baron wrote:
> add x86 support for jump label. I'm keeping this patch separate so its clear to
> arch maintainers what was required for x86 support this new feature. hopefully,
> it wouldn't be too painful for other arches.
>
> Signed-off-by: Jason Baron <jbaron@...hat.com>
> ---
> arch/x86/Kconfig | 1 +
> arch/x86/include/asm/jump_label.h | 47 +++++++++++++++++++++++++++++++++++
> arch/x86/kernel/Makefile | 2 +-
> arch/x86/kernel/jump_label.c | 49 +++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/module.c | 3 ++
> 5 files changed, 101 insertions(+), 1 deletions(-)
> create mode 100644 arch/x86/include/asm/jump_label.h
> create mode 100644 arch/x86/kernel/jump_label.c
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 0c14369..a986079 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -60,6 +60,7 @@ config X86
> select ANON_INODES
> select HAVE_ARCH_KMEMCHECK
> select HAVE_USER_RETURN_NOTIFIER
> + select HAVE_ARCH_JUMP_LABEL if !CC_OPTIMIZE_FOR_SIZE
>
> config INSTRUCTION_DECODER
> def_bool (KPROBES || PERF_EVENTS)
> diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
> new file mode 100644
> index 0000000..b4a2cb4
> --- /dev/null
> +++ b/arch/x86/include/asm/jump_label.h
> @@ -0,0 +1,47 @@
> +#ifndef _ASM_X86_JUMP_LABEL_H
> +#define _ASM_X86_JUMP_LABEL_H
> +
> +#ifdef __KERNEL__
> +
> +#include <linux/types.h>
> +#include <asm/nops.h>
> +
> +#define JUMP_LABEL_NOP_SIZE 5
> +
> +# define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
> +
> +# define JUMP_LABEL(key, label) \
> + do { \
> + asm goto("1:" \
> + JUMP_LABEL_INITIAL_NOP \
> + ".pushsection __jump_table, \"a\" \n\t"\
> + _ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
> + ".popsection \n\t" \
> + : : "i" (key) : : label); \
> + } while (0)
> +
> +#endif /* __KERNEL__ */
> +
> +#ifdef CONFIG_X86_64
> +
> +typedef u64 jump_label_t;
> +
> +struct jump_entry {
> + jump_label_t code;
> + jump_label_t target;
> + jump_label_t key;
> +};
> +
> +#else
> +
> +typedef u32 jump_label_t;
> +
> +struct jump_entry {
> + jump_label_t code;
> + jump_label_t target;
> + jump_label_t key;
> +};
> +
> +#endif
Why duplicate the structure? You typedef'd jump_label_t and used that in
the structure twice!
-- Steve
> +
> +#endif
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 11a9925..dfa1443 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -32,7 +32,7 @@ GCOV_PROFILE_paravirt.o := n
> obj-y := process_$(BITS).o signal.o entry_$(BITS).o
> obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
> obj-y += time.o ioport.o ldt.o dumpstack.o
> -obj-y += setup.o x86_init.o i8259.o irqinit.o
> +obj-y += setup.o x86_init.o i8259.o irqinit.o jump_label.o
> obj-$(CONFIG_X86_VISWS) += visws_quirks.o
> obj-$(CONFIG_X86_32) += probe_roms_32.o
> obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o
> diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
> new file mode 100644
> index 0000000..b3c0f37
> --- /dev/null
> +++ b/arch/x86/kernel/jump_label.c
> @@ -0,0 +1,49 @@
> +/*
> + * jump label x86 support
> + *
> + * Copyright (C) 2009 Jason Baron <jbaron@...hat.com>
> + *
> + */
> +#include <linux/jump_label.h>
> +#include <linux/memory.h>
> +#include <linux/uaccess.h>
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/jhash.h>
> +#include <linux/cpu.h>
> +#include <asm/kprobes.h>
> +#include <asm/alternative.h>
> +
> +#ifdef HAVE_JUMP_LABEL
> +
> +union jump_code_union {
> + char code[JUMP_LABEL_NOP_SIZE];
> + struct {
> + char jump;
> + int offset;
> + } __attribute__((packed));
> +};
> +
> +void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type)
> +{
> + union jump_code_union code;
> +
> + if (type == JUMP_LABEL_ENABLE) {
> + code.jump = 0xe9;
> + code.offset = entry->target -
> + (entry->code + JUMP_LABEL_NOP_SIZE);
> + } else
> + memcpy(&code, ideal_nop5, JUMP_LABEL_NOP_SIZE);
> + get_online_cpus();
> + mutex_lock(&text_mutex);
> + text_poke_smp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
> + mutex_unlock(&text_mutex);
> + put_online_cpus();
> +}
> +
> +void arch_jump_label_text_poke_early(jump_label_t addr)
> +{
> + text_poke_early((void *)addr, ideal_nop5, JUMP_LABEL_NOP_SIZE);
> +}
> +
> +#endif
> diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
> index e0bc186..5399f58 100644
> --- a/arch/x86/kernel/module.c
> +++ b/arch/x86/kernel/module.c
> @@ -239,6 +239,9 @@ int module_finalize(const Elf_Ehdr *hdr,
> apply_paravirt(pseg, pseg + para->sh_size);
> }
>
> + /* make jump label nops */
> + jump_label_apply_nops(me);
> +
> return module_bug_finalize(hdr, sechdrs, me);
> }
>
--
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