Re: [PATCH 2/5] jump label: constify lookup functions

[Steven Rostedt]

This should have been Cc'd to linux-arch.

-- Steve


On Wed, 2013-01-09 at 18:09 -0500, Sasha Levin wrote:
> Modify the parameters of all the lookup and the bookkeeping functions which
> should be const to const.
> 
> For example, jump_label_text_reserved() doesn't modify the memory it works on,
> it just checks whether there are any jump labels there.
> 
> Note I couldn't test the non-x86 architectures, but the changes are rather
> trivial.
> 
> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> ---
>  arch/arm/include/asm/jump_label.h     |  2 +-
>  arch/arm/kernel/jump_label.c          |  6 +++---
>  arch/mips/include/asm/jump_label.h    |  2 +-
>  arch/mips/kernel/jump_label.c         |  2 +-
>  arch/powerpc/include/asm/jump_label.h |  2 +-
>  arch/powerpc/kernel/jump_label.c      |  2 +-
>  arch/s390/include/asm/jump_label.h    |  2 +-
>  arch/s390/kernel/jump_label.c         |  8 ++++----
>  arch/sparc/include/asm/jump_label.h   |  2 +-
>  arch/sparc/kernel/jump_label.c        |  2 +-
>  arch/x86/include/asm/jump_label.h     |  2 +-
>  arch/x86/kernel/jump_label.c          |  6 +++---
>  include/linux/jump_label.h            | 24 ++++++++++++------------
>  kernel/jump_label.c                   | 27 +++++++++++++++------------
>  14 files changed, 46 insertions(+), 43 deletions(-)
> 
> diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
> index bfc198c..f4ee633 100644
> --- a/arch/arm/include/asm/jump_label.h
> +++ b/arch/arm/include/asm/jump_label.h
> @@ -14,7 +14,7 @@
>  #define JUMP_LABEL_NOP	"nop"
>  #endif
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  	asm goto("1:\n\t"
>  		 JUMP_LABEL_NOP "\n\t"
> diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c
> index 4ce4f78..9686fce 100644
> --- a/arch/arm/kernel/jump_label.c
> +++ b/arch/arm/kernel/jump_label.c
> @@ -6,7 +6,7 @@
>  
>  #ifdef HAVE_JUMP_LABEL
>  
> -static void __arch_jump_label_transform(struct jump_entry *entry,
> +static void __arch_jump_label_transform(const struct jump_entry *entry,
>  					enum jump_label_type type,
>  					bool is_static)
>  {
> @@ -24,13 +24,13 @@ static void __arch_jump_label_transform(struct jump_entry *entry,
>  		patch_text(addr, insn);
>  }
>  
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void arch_jump_label_transform(const struct jump_entry *entry,
>  			       enum jump_label_type type)
>  {
>  	__arch_jump_label_transform(entry, type, false);
>  }
>  
> -void arch_jump_label_transform_static(struct jump_entry *entry,
> +void arch_jump_label_transform_static(const struct jump_entry *entry,
>  				      enum jump_label_type type)
>  {
>  	__arch_jump_label_transform(entry, type, true);
> diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
> index 4d6d77e..a95ddf5 100644
> --- a/arch/mips/include/asm/jump_label.h
> +++ b/arch/mips/include/asm/jump_label.h
> @@ -20,7 +20,7 @@
>  #define WORD_INSN ".word"
>  #endif
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  	asm goto("1:\tnop\n\t"
>  		"nop\n\t"
> diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c
> index 6001610..bfba488 100644
> --- a/arch/mips/kernel/jump_label.c
> +++ b/arch/mips/kernel/jump_label.c
> @@ -20,7 +20,7 @@
>  
>  #define J_RANGE_MASK ((1ul << 28) - 1)
>  
> -void arch_jump_label_transform(struct jump_entry *e,
> +void arch_jump_label_transform(const struct jump_entry *e,
>  			       enum jump_label_type type)
>  {
>  	union mips_instruction insn;
> diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
> index ae098c4..c00b303 100644
> --- a/arch/powerpc/include/asm/jump_label.h
> +++ b/arch/powerpc/include/asm/jump_label.h
> @@ -17,7 +17,7 @@
>  #define JUMP_ENTRY_TYPE		stringify_in_c(FTR_ENTRY_LONG)
>  #define JUMP_LABEL_NOP_SIZE	4
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  	asm goto("1:\n\t"
>  		 "nop\n\t"
> diff --git a/arch/powerpc/kernel/jump_label.c b/arch/powerpc/kernel/jump_label.c
> index a1ed8a8..f9626ec 100644
> --- a/arch/powerpc/kernel/jump_label.c
> +++ b/arch/powerpc/kernel/jump_label.c
> @@ -12,7 +12,7 @@
>  #include <asm/code-patching.h>
>  
>  #ifdef HAVE_JUMP_LABEL
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void arch_jump_label_transform(const struct jump_entry *entry,
>  			       enum jump_label_type type)
>  {
>  	u32 *addr = (u32 *)(unsigned long)entry->code;
> diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
> index 6c32190..96adb78 100644
> --- a/arch/s390/include/asm/jump_label.h
> +++ b/arch/s390/include/asm/jump_label.h
> @@ -13,7 +13,7 @@
>  #define ASM_ALIGN ".balign 4"
>  #endif
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  	asm goto("0:	brcl 0,0\n"
>  		".pushsection __jump_table, \"aw\"\n"
> diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c
> index b987ab2..85fa643 100644
> --- a/arch/s390/kernel/jump_label.c
> +++ b/arch/s390/kernel/jump_label.c
> @@ -22,7 +22,7 @@ struct insn_args {
>  	enum jump_label_type type;
>  };
>  
> -static void __jump_label_transform(struct jump_entry *entry,
> +static void __jump_label_transform(const struct jump_entry *entry,
>  				   enum jump_label_type type)
>  {
>  	struct insn insn;
> @@ -44,13 +44,13 @@ static void __jump_label_transform(struct jump_entry *entry,
>  
>  static int __sm_arch_jump_label_transform(void *data)
>  {
> -	struct insn_args *args = data;
> +	const struct insn_args *args = data;
>  
>  	__jump_label_transform(args->entry, args->type);
>  	return 0;
>  }
>  
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void arch_jump_label_transform(const struct jump_entry *entry,
>  			       enum jump_label_type type)
>  {
>  	struct insn_args args;
> @@ -61,7 +61,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
>  	stop_machine(__sm_arch_jump_label_transform, &args, NULL);
>  }
>  
> -void arch_jump_label_transform_static(struct jump_entry *entry,
> +void arch_jump_label_transform_static(const struct jump_entry *entry,
>  				      enum jump_label_type type)
>  {
>  	__jump_label_transform(entry, type);
> diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
> index 5080d16..44cb914 100644
> --- a/arch/sparc/include/asm/jump_label.h
> +++ b/arch/sparc/include/asm/jump_label.h
> @@ -7,7 +7,7 @@
>  
>  #define JUMP_LABEL_NOP_SIZE 4
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  		asm goto("1:\n\t"
>  			 "nop\n\t"
> diff --git a/arch/sparc/kernel/jump_label.c b/arch/sparc/kernel/jump_label.c
> index 48565c1..231c10e 100644
> --- a/arch/sparc/kernel/jump_label.c
> +++ b/arch/sparc/kernel/jump_label.c
> @@ -10,7 +10,7 @@
>  
>  #ifdef HAVE_JUMP_LABEL
>  
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void arch_jump_label_transform(const struct jump_entry *entry,
>  			       enum jump_label_type type)
>  {
>  	u32 val;
> diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
> index 3a16c14..6b6e976 100644
> --- a/arch/x86/include/asm/jump_label.h
> +++ b/arch/x86/include/asm/jump_label.h
> @@ -11,7 +11,7 @@
>  
>  #define STATIC_KEY_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
>  
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(const struct static_key *key)
>  {
>  	asm goto("1:"
>  		STATIC_KEY_INITIAL_NOP
> diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
> index 2889b3d..a7d2c5a 100644
> --- a/arch/x86/kernel/jump_label.c
> +++ b/arch/x86/kernel/jump_label.c
> @@ -24,7 +24,7 @@ union jump_code_union {
>  	} __attribute__((packed));
>  };
>  
> -static void __jump_label_transform(struct jump_entry *entry,
> +static void __jump_label_transform(const struct jump_entry *entry,
>  				   enum jump_label_type type,
>  				   void *(*poker)(void *, const void *, size_t))
>  {
> @@ -40,7 +40,7 @@ static void __jump_label_transform(struct jump_entry *entry,
>  	(*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
>  }
>  
> -void arch_jump_label_transform(struct jump_entry *entry,
> +void arch_jump_label_transform(const struct jump_entry *entry,
>  			       enum jump_label_type type)
>  {
>  	get_online_cpus();
> @@ -50,7 +50,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
>  	put_online_cpus();
>  }
>  
> -__init_or_module void arch_jump_label_transform_static(struct jump_entry *entry,
> +__init_or_module void arch_jump_label_transform_static(const struct jump_entry *entry,
>  				      enum jump_label_type type)
>  {
>  	__jump_label_transform(entry, type, text_poke_early);
> diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
> index 0976fc4..7c33d29 100644
> --- a/include/linux/jump_label.h
> +++ b/include/linux/jump_label.h
> @@ -89,19 +89,19 @@ inline struct jump_entry *jump_label_get_entries(struct static_key *key)
>  						& ~JUMP_LABEL_TRUE_BRANCH);
>  }
>  
> -static inline bool jump_label_get_branch_default(struct static_key *key)
> +static inline bool jump_label_get_branch_default(const struct static_key *key)
>  {
>  	if ((unsigned long)key->entries & JUMP_LABEL_TRUE_BRANCH)
>  		return true;
>  	return false;
>  }
>  
> -static __always_inline bool static_key_false(struct static_key *key)
> +static __always_inline bool static_key_false(const struct static_key *key)
>  {
>  	return arch_static_branch(key);
>  }
>  
> -static __always_inline bool static_key_true(struct static_key *key)
> +static __always_inline bool static_key_true(const struct static_key *key)
>  {
>  	return !static_key_false(key);
>  }
> @@ -112,15 +112,15 @@ extern struct jump_entry __stop___jump_table[];
>  extern void jump_label_init(void);
>  extern void jump_label_lock(void);
>  extern void jump_label_unlock(void);
> -extern void arch_jump_label_transform(struct jump_entry *entry,
> +extern void arch_jump_label_transform(const struct jump_entry *entry,
>  				      enum jump_label_type type);
> -extern void arch_jump_label_transform_static(struct jump_entry *entry,
> +extern void arch_jump_label_transform_static(const struct jump_entry *entry,
>  					     enum jump_label_type type);
> -extern int jump_label_text_reserved(void *start, void *end);
> +extern int jump_label_text_reserved(const void *start, const void *end);
>  extern void static_key_slow_inc(struct static_key *key);
>  extern void static_key_slow_dec(struct static_key *key);
>  extern void static_key_slow_dec_deferred(struct static_key_deferred *key);
> -extern void jump_label_apply_nops(struct module *mod);
> +extern void jump_label_apply_nops(const struct module *mod);
>  extern void
>  jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl);
>  
> @@ -145,14 +145,14 @@ struct static_key_deferred {
>  	struct static_key  key;
>  };
>  
> -static __always_inline bool static_key_false(struct static_key *key)
> +static __always_inline bool static_key_false(const struct static_key *key)
>  {
>  	if (unlikely(atomic_read(&key->enabled)) > 0)
>  		return true;
>  	return false;
>  }
>  
> -static __always_inline bool static_key_true(struct static_key *key)
> +static __always_inline bool static_key_true(const struct static_key *key)
>  {
>  	if (likely(atomic_read(&key->enabled)) > 0)
>  		return true;
> @@ -174,7 +174,7 @@ static inline void static_key_slow_dec_deferred(struct static_key_deferred *key)
>  	static_key_slow_dec(&key->key);
>  }
>  
> -static inline int jump_label_text_reserved(void *start, void *end)
> +static inline int jump_label_text_reserved(const void *start, const void *end)
>  {
>  	return 0;
>  }
> @@ -182,7 +182,7 @@ static inline int jump_label_text_reserved(void *start, void *end)
>  static inline void jump_label_lock(void) {}
>  static inline void jump_label_unlock(void) {}
>  
> -static inline int jump_label_apply_nops(struct module *mod)
> +static inline int jump_label_apply_nops(const struct module *mod)
>  {
>  	return 0;
>  }
> @@ -203,7 +203,7 @@ jump_label_rate_limit(struct static_key_deferred *key,
>  #define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
>  #define jump_label_enabled static_key_enabled
>  
> -static inline bool static_key_enabled(struct static_key *key)
> +static inline bool static_key_enabled(const struct static_key *key)
>  {
>  	return (atomic_read(&key->enabled) > 0);
>  }
> diff --git a/kernel/jump_label.c b/kernel/jump_label.c
> index 60f48fa..ba2fa54 100644
> --- a/kernel/jump_label.c
> +++ b/kernel/jump_label.c
> @@ -120,7 +120,8 @@ void jump_label_rate_limit(struct static_key_deferred *key,
>  }
>  EXPORT_SYMBOL_GPL(jump_label_rate_limit);
>  
> -static int addr_conflict(struct jump_entry *entry, void *start, void *end)
> +static int addr_conflict(const struct jump_entry *entry,
> +			const void *start, const void *end)
>  {
>  	if (entry->code <= (unsigned long)end &&
>  		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
> @@ -130,7 +131,8 @@ static int addr_conflict(struct jump_entry *entry, void *start, void *end)
>  }
>  
>  static int __jump_label_text_reserved(struct jump_entry *iter_start,
> -		struct jump_entry *iter_stop, void *start, void *end)
> +		struct jump_entry *iter_stop,
> +		const void *start, const void *end)
>  {
>  	struct jump_entry *iter;
>  
> @@ -150,7 +152,7 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
>   * running code can override this to make the non-live update case
>   * cheaper.
>   */
> -void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
> +void __weak __init_or_module arch_jump_label_transform_static(const struct jump_entry *entry,
>  					    enum jump_label_type type)
>  {
>  	arch_jump_label_transform(entry, type);	
> @@ -173,7 +175,7 @@ static void __jump_label_update(struct static_key *key,
>  	}
>  }
>  
> -static enum jump_label_type jump_label_type(struct static_key *key)
> +static enum jump_label_type jump_label_type(const struct static_key *key)
>  {
>  	bool true_branch = jump_label_get_branch_default(key);
>  	bool state = static_key_enabled(key);
> @@ -219,10 +221,11 @@ void __init jump_label_init(void)
>  struct static_key_mod {
>  	struct static_key_mod *next;
>  	struct jump_entry *entries;
> -	struct module *mod;
> +	const struct module *mod;
>  };
>  
> -static int __jump_label_mod_text_reserved(void *start, void *end)
> +static int __jump_label_mod_text_reserved(const void *start,
> +						const void *end)
>  {
>  	struct module *mod;
>  
> @@ -242,7 +245,7 @@ static void __jump_label_mod_update(struct static_key *key, int enable)
>  	struct static_key_mod *mod = key->next;
>  
>  	while (mod) {
> -		struct module *m = mod->mod;
> +		const struct module *m = mod->mod;
>  
>  		__jump_label_update(key, mod->entries,
>  				    m->jump_entries + m->num_jump_entries,
> @@ -259,7 +262,7 @@ static void __jump_label_mod_update(struct static_key *key, int enable)
>   * loads patch these with arch_get_jump_label_nop(), which is specified by
>   * the arch specific jump label code.
>   */
> -void jump_label_apply_nops(struct module *mod)
> +void jump_label_apply_nops(const struct module *mod)
>  {
>  	struct jump_entry *iter_start = mod->jump_entries;
>  	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
> @@ -274,7 +277,7 @@ void jump_label_apply_nops(struct module *mod)
>  	}
>  }
>  
> -static int jump_label_add_module(struct module *mod)
> +static int jump_label_add_module(const struct module *mod)
>  {
>  	struct jump_entry *iter_start = mod->jump_entries;
>  	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
> @@ -319,7 +322,7 @@ static int jump_label_add_module(struct module *mod)
>  	return 0;
>  }
>  
> -static void jump_label_del_module(struct module *mod)
> +static void jump_label_del_module(const struct module *mod)
>  {
>  	struct jump_entry *iter_start = mod->jump_entries;
>  	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
> @@ -351,7 +354,7 @@ static void jump_label_del_module(struct module *mod)
>  	}
>  }
>  
> -static void jump_label_invalidate_module_init(struct module *mod)
> +static void jump_label_invalidate_module_init(const struct module *mod)
>  {
>  	struct jump_entry *iter_start = mod->jump_entries;
>  	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
> @@ -419,7 +422,7 @@ early_initcall(jump_label_init_module);
>   *
>   * returns 1 if there is an overlap, 0 otherwise
>   */
> -int jump_label_text_reserved(void *start, void *end)
> +int jump_label_text_reserved(const void *start, const void *end)
>  {
>  	int ret = __jump_label_text_reserved(__start___jump_table,
>  			__stop___jump_table, start, end);


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