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    SubjectRe: [PATCH 2/5] jump label: constify lookup functions
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    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@oracle.com>
    > ---
    > 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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