From: Peter Zijlstra <peterz@infradead.org> mainline inclusion from mainline-v6.10-rc1 commit 91a1d97ef482c1e4c9d4c1c656a53b0f6b16d0ed category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBWQ24 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When a static_key is marked ro_after_init, its state will never change (after init), therefore jump_label_update() will never need to iterate the entries, and thus module load won't actually need to track this -- avoiding the static_key::next write. Therefore, mark these keys such that jump_label_add_module() might recognise them and avoid the modification. Use the special state: 'static_key_linked(key) && !static_key_mod(key)' to denote such keys. jump_label_add_module() does not exist under CONFIG_JUMP_LABEL=n, so the newly-introduced jump_label_init_ro() can be defined as a nop for that configuration. [ mingo: Renamed jump_label_ro() to jump_label_init_ro() ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Valentin Schneider <vschneid@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240313180106.2917308-2-vschneid@redhat.com Conflicts: init/main.c [Only context conflicts] Signed-off-by: Cai Xinchen <caixinchen1@huawei.com> --- include/asm-generic/sections.h | 5 ++++ include/linux/jump_label.h | 3 ++ init/main.c | 1 + kernel/jump_label.c | 53 ++++++++++++++++++++++++++++++++++ 4 files changed, 62 insertions(+) diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index db13bb620f52..c768de6f19a9 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -180,6 +180,11 @@ static inline bool is_kernel_rodata(unsigned long addr) addr < (unsigned long)__end_rodata; } +static inline bool is_kernel_ro_after_init(unsigned long addr) +{ + return addr >= (unsigned long)__start_ro_after_init && + addr < (unsigned long)__end_ro_after_init; +} /** * is_kernel_inittext - checks if the pointer address is located in the * .init.text section diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 39386db201a2..b43ceb20a689 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -216,6 +216,7 @@ extern struct jump_entry __start___jump_table[]; extern struct jump_entry __stop___jump_table[]; extern void jump_label_init(void); +extern void jump_label_init_ro(void); extern void jump_label_lock(void); extern void jump_label_unlock(void); extern void arch_jump_label_transform(struct jump_entry *entry, @@ -268,6 +269,8 @@ static __always_inline void jump_label_init(void) static_key_initialized = true; } +static __always_inline void jump_label_init_ro(void) { } + static __always_inline bool static_key_false(struct static_key *key) { if (unlikely_notrace(static_key_count(key) > 0)) diff --git a/init/main.c b/init/main.c index 02a2c5d9be67..afead48c58e4 100644 --- a/init/main.c +++ b/init/main.c @@ -1413,6 +1413,7 @@ static void mark_readonly(void) * insecure pages which are W+X. */ flush_module_init_free_work(); + jump_label_init_ro(); mark_rodata_ro(); rodata_test(); } else diff --git a/kernel/jump_label.c b/kernel/jump_label.c index ae29b818fd56..31c88eb5f936 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -565,6 +565,45 @@ void __init jump_label_init(void) cpus_read_unlock(); } +static inline bool static_key_sealed(struct static_key *key) +{ + return (key->type & JUMP_TYPE_LINKED) && !(key->type & ~JUMP_TYPE_MASK); +} + +static inline void static_key_seal(struct static_key *key) +{ + unsigned long type = key->type & JUMP_TYPE_TRUE; + key->type = JUMP_TYPE_LINKED | type; +} + +void jump_label_init_ro(void) +{ + struct jump_entry *iter_start = __start___jump_table; + struct jump_entry *iter_stop = __stop___jump_table; + struct jump_entry *iter; + + if (WARN_ON_ONCE(!static_key_initialized)) + return; + + cpus_read_lock(); + jump_label_lock(); + + for (iter = iter_start; iter < iter_stop; iter++) { + struct static_key *iterk = jump_entry_key(iter); + + if (!is_kernel_ro_after_init((unsigned long)iterk)) + continue; + + if (static_key_sealed(iterk)) + continue; + + static_key_seal(iterk); + } + + jump_label_unlock(); + cpus_read_unlock(); +} + #ifdef CONFIG_MODULES enum jump_label_type jump_label_init_type(struct jump_entry *entry) @@ -690,6 +729,15 @@ static int jump_label_add_module(struct module *mod) static_key_set_entries(key, iter); continue; } + + /* + * If the key was sealed at init, then there's no need to keep a + * reference to its module entries - just patch them now and be + * done with it. + */ + if (static_key_sealed(key)) + goto do_poke; + jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); if (!jlm) return -ENOMEM; @@ -715,6 +763,7 @@ static int jump_label_add_module(struct module *mod) static_key_set_linked(key); /* Only update if we've changed from our initial state */ +do_poke: if (jump_label_type(iter) != jump_label_init_type(iter)) __jump_label_update(key, iter, iter_stop, true); } @@ -744,6 +793,10 @@ static void jump_label_del_module(struct module *mod) if (within_module((unsigned long)key, mod)) continue; + /* No @jlm allocated because key was sealed at init. */ + if (static_key_sealed(key)) + continue; + /* No memory during module load */ if (WARN_ON(!static_key_linked(key))) continue; -- 2.18.0.huawei.25