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Re: [PATCH] jump label: Add MIPS support.

To: David Daney <ddaney@caviumnetworks.com>
Subject: Re: [PATCH] jump label: Add MIPS support.
From: Steven Rostedt <rostedt@goodmis.org>
Date: Fri, 01 Oct 2010 17:49:46 -0400
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org, linux-kernel@vger.kernel.org, jbaron@redhat.com
In-reply-to: <1285697432-29244-1-git-send-email-ddaney@caviumnetworks.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1285697432-29244-1-git-send-email-ddaney@caviumnetworks.com>
Sender: linux-mips-bounce@linux-mips.org
On Tue, 2010-09-28 at 11:10 -0700, David Daney wrote:
> When in Rome...
> 
> In order not to be left behind, we add jump label support for MIPS.
> 
> Tested on 64-bit big endian (Octeon), and 32-bit little endian
> (malta/qemu).
> 
> Signed-off-by: David Daney <ddaney@caviumnetworks.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Jason Baron <jbaron@redhat.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>

I can pull this into tip with an Acked-by from Ralf. He was just in
Tokyo with me, and I don't know when he'll be available to do so.

-- Steve

> ---
>  arch/mips/Kconfig                  |    1 +
>  arch/mips/include/asm/jump_label.h |   48 ++++++++++++++++++++++++++++
>  arch/mips/kernel/Makefile          |    3 +-
>  arch/mips/kernel/jump_label.c      |   60 
> ++++++++++++++++++++++++++++++++++++
>  arch/mips/kernel/module.c          |    5 +++
>  5 files changed, 116 insertions(+), 1 deletions(-)
>  create mode 100644 arch/mips/include/asm/jump_label.h
>  create mode 100644 arch/mips/kernel/jump_label.c
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 3ad59dd..6b3bdb5 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -13,6 +13,7 @@ config MIPS
>       select HAVE_KPROBES
>       select HAVE_KRETPROBES
>       select RTC_LIB if !MACH_LOONGSON
> +     select HAVE_ARCH_JUMP_LABEL
>  
>  mainmenu "Linux/MIPS Kernel Configuration"
>  
> diff --git a/arch/mips/include/asm/jump_label.h 
> b/arch/mips/include/asm/jump_label.h
> new file mode 100644
> index 0000000..7622ccf
> --- /dev/null
> +++ b/arch/mips/include/asm/jump_label.h
> @@ -0,0 +1,48 @@
> +/*
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + *
> + * Copyright (c) 2010 Cavium Networks, Inc.
> + */
> +#ifndef _ASM_MIPS_JUMP_LABEL_H
> +#define _ASM_MIPS_JUMP_LABEL_H
> +
> +#include <linux/types.h>
> +
> +#ifdef __KERNEL__
> +
> +#define JUMP_LABEL_NOP_SIZE 4
> +
> +#ifdef CONFIG_64BIT
> +#define WORD_INSN ".dword"
> +#else
> +#define WORD_INSN ".word"
> +#endif
> +
> +#define JUMP_LABEL(key, label)                                               
> \
> +     do {                                                            \
> +             asm goto("1:\tnop\n\t"                                  \
> +                     "nop\n\t"                                       \
> +                     ".pushsection __jump_table,  \"a\"\n\t"         \
> +                     WORD_INSN " 1b, %l[" #label "], %0\n\t"         \
> +                     ".popsection\n\t"                               \
> +                     : :  "i" (key) :  : label);                     \
> +     } while (0)
> +
> +
> +#endif /* __KERNEL__ */
> +
> +#ifdef CONFIG_64BIT
> +typedef u64 jump_label_t;
> +#else
> +typedef u32 jump_label_t;
> +#endif
> +
> +struct jump_entry {
> +     jump_label_t code;
> +     jump_label_t target;
> +     jump_label_t key;
> +};
> +
> +#endif /* _ASM_MIPS_JUMP_LABEL_H */
> diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> index 06f8482..db4feb9 100644
> --- a/arch/mips/kernel/Makefile
> +++ b/arch/mips/kernel/Makefile
> @@ -6,7 +6,8 @@ extra-y               := head.o init_task.o vmlinux.lds
>  
>  obj-y                += cpu-probe.o branch.o entry.o genex.o irq.o process.o 
> \
>                  ptrace.o reset.o setup.o signal.o syscall.o \
> -                time.o topology.o traps.o unaligned.o watch.o vdso.o
> +                time.o topology.o traps.o unaligned.o watch.o vdso.o \
> +                jump_label.o
>  
>  ifdef CONFIG_FUNCTION_TRACER
>  CFLAGS_REMOVE_ftrace.o = -pg
> diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c
> new file mode 100644
> index 0000000..3c145a8
> --- /dev/null
> +++ b/arch/mips/kernel/jump_label.c
> @@ -0,0 +1,60 @@
> +/*
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + *
> + * Copyright (c) 2010 Cavium Networks, Inc.
> + */
> +
> +#include <linux/jump_label.h>
> +#include <linux/kernel.h>
> +#include <linux/memory.h>
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +#include <linux/cpu.h>
> +
> +#include <asm/cacheflush.h>
> +#include <asm/inst.h>
> +
> +#define J_RANGE_MASK ((1ul << 28) - 1)
> +
> +void arch_jump_label_transform(struct jump_entry *e,
> +                            enum jump_label_type type)
> +{
> +     union mips_instruction insn;
> +     union mips_instruction *insn_p =
> +             (union mips_instruction *)(unsigned long)e->code;
> +
> +     /* Jump only works within a 256MB aligned region. */
> +     BUG_ON((e->target & ~J_RANGE_MASK) != (e->code & ~J_RANGE_MASK));
> +
> +     /* Target must have 4 byte alignment. */
> +     BUG_ON((e->target & 3) != 0);
> +
> +     if (type == JUMP_LABEL_ENABLE) {
> +             insn.j_format.opcode = j_op;
> +             insn.j_format.target = (e->target & J_RANGE_MASK) >> 2;
> +     } else {
> +             insn.word = 0; /* nop */
> +     }
> +
> +     get_online_cpus();
> +     mutex_lock(&text_mutex);
> +     *insn_p = insn;
> +
> +     flush_icache_range((unsigned long)insn_p,
> +                        (unsigned long)insn_p + sizeof(*insn_p));
> +
> +     mutex_unlock(&text_mutex);
> +     put_online_cpus();
> +}
> +
> +void arch_jump_label_text_poke_early(jump_label_t addr)
> +{
> +     union mips_instruction *insn_p =
> +             (union mips_instruction *)(unsigned long)addr;
> +
> +     insn_p->word = 0; /* nop */
> +     flush_icache_range((unsigned long)insn_p,
> +                        (unsigned long)insn_p + sizeof(*insn_p));
> +}
> diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
> index 6f51dda..bb9cde4 100644
> --- a/arch/mips/kernel/module.c
> +++ b/arch/mips/kernel/module.c
> @@ -30,6 +30,8 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/spinlock.h>
> +#include <linux/jump_label.h>
> +
>  #include <asm/pgtable.h>     /* MODULE_START */
>  
>  struct mips_hi16 {
> @@ -390,6 +392,9 @@ int module_finalize(const Elf_Ehdr *hdr,
>       const Elf_Shdr *s;
>       char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
>  
> +     /* Make jump label nops. */
> +     jump_label_apply_nops(me);
> +
>       INIT_LIST_HEAD(&me->arch.dbe_list);
>       for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
>               if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)



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