Using single ftrace_ops for direct calls update instead of allocating ftrace_ops obejct for each trampoline.
At the moment we can enable this only on x86 arch, because arm relies on ftrace_ops object representing just single trampoline image (stored in ftrace_ops::direct_call). Adding HAVE_SINGLE_FTRACE_DIRECT_OPS config option to be enabled on each arch that supports this. Signed-off-by: Jiri Olsa <[email protected]> --- arch/x86/Kconfig | 1 + kernel/bpf/trampoline.c | 85 +++++++++++++++++++++++++++++++++++------ kernel/trace/Kconfig | 3 ++ kernel/trace/ftrace.c | 15 +++++++- 4 files changed, 92 insertions(+), 12 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 52c8910ba2ef..bfc9115baa6f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -330,6 +330,7 @@ config X86 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE select ARCH_SUPPORTS_PT_RECLAIM if X86_64 + select HAVE_SINGLE_FTRACE_DIRECT_OPS if X86_64 && DYNAMIC_FTRACE_WITH_DIRECT_CALLS config INSTRUCTION_DECODER def_bool y diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 3464859189a2..e3b721773dfb 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -33,12 +33,40 @@ static DEFINE_MUTEX(trampoline_mutex); #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex); +#ifdef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS +static struct bpf_trampoline *direct_ops_ip_lookup(struct ftrace_ops *ops, unsigned long ip) +{ + struct hlist_head *head_ip; + struct bpf_trampoline *tr; + + mutex_lock(&trampoline_mutex); + head_ip = &trampoline_ip_table[hash_64(ip, TRAMPOLINE_HASH_BITS)]; + hlist_for_each_entry(tr, head_ip, hlist_ip) { + if (tr->func.addr == (void *) ip) + goto out; + } + tr = NULL; +out: + mutex_unlock(&trampoline_mutex); + return tr; +} +#else +static struct bpf_trampoline *direct_ops_ip_lookup(struct ftrace_ops *ops, unsigned long ip) +{ + return ops->private; +} +#endif /* CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS */ + static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, unsigned long ip, enum ftrace_ops_cmd cmd) { - struct bpf_trampoline *tr = ops->private; + struct bpf_trampoline *tr; int ret = 0; + tr = direct_ops_ip_lookup(ops, ip); + if (!tr) + return -EINVAL; + if (cmd == FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF) { /* This is called inside register_ftrace_direct_multi(), so * tr->mutex is already locked. @@ -137,6 +165,48 @@ void bpf_image_ksym_del(struct bpf_ksym *ksym) PAGE_SIZE, true, ksym->name); } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +#ifdef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS +struct ftrace_ops direct_ops = { + .ops_func = bpf_tramp_ftrace_ops_func, +}; + +static int direct_ops_get(struct bpf_trampoline *tr) +{ + tr->fops = &direct_ops; + return 0; +} +static void direct_ops_clear(struct bpf_trampoline *tr) { } +static void direct_ops_free(struct bpf_trampoline *tr) { } +#else +static int direct_ops_get(struct bpf_trampoline *tr) +{ + tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL); + if (!tr->fops) + return -1; + tr->fops->private = tr; + tr->fops->ops_func = bpf_tramp_ftrace_ops_func; + return 0; +} + +static void direct_ops_clear(struct bpf_trampoline *tr) +{ + tr->fops->func = NULL; + tr->fops->trampoline = 0; +} + +static void direct_ops_free(struct bpf_trampoline *tr) +{ + if (tr->fops) { + ftrace_free_filter(tr->fops); + kfree(tr->fops); + } +} +#endif /* CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS */ +#else +static void direct_ops_free(struct bpf_trampoline *tr) { } +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ + static struct bpf_trampoline *bpf_trampoline_lookup(u64 key, unsigned long ip) { struct bpf_trampoline *tr; @@ -155,14 +225,11 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key, unsigned long ip) if (!tr) goto out; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS - tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL); - if (!tr->fops) { + if (direct_ops_get(tr)) { kfree(tr); tr = NULL; goto out; } - tr->fops->private = tr; - tr->fops->ops_func = bpf_tramp_ftrace_ops_func; #endif tr->key = key; @@ -482,8 +549,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut * trampoline again, and retry register. */ /* reset fops->func and fops->trampoline for re-register */ - tr->fops->func = NULL; - tr->fops->trampoline = 0; + direct_ops_clear(tr); /* free im memory and reallocate later */ bpf_tramp_image_free(im); @@ -864,10 +930,7 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) */ hlist_del(&tr->hlist_key); hlist_del(&tr->hlist_ip); - if (tr->fops) { - ftrace_free_filter(tr->fops); - kfree(tr->fops); - } + direct_ops_free(tr); kfree(tr); out: mutex_unlock(&trampoline_mutex); diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index d2c79da81e4f..4bf5beb04a5b 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -50,6 +50,9 @@ config HAVE_DYNAMIC_FTRACE_WITH_REGS config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS bool +config HAVE_SINGLE_FTRACE_DIRECT_OPS + bool + config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS bool diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2af1304d1a83..c4b969fb1010 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2592,8 +2592,13 @@ unsigned long ftrace_find_rec_direct(unsigned long ip) static void call_direct_funcs(unsigned long ip, unsigned long pip, struct ftrace_ops *ops, struct ftrace_regs *fregs) { - unsigned long addr = READ_ONCE(ops->direct_call); + unsigned long addr; +#ifdef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS + addr = ftrace_find_rec_direct(ip); +#else + addr = READ_ONCE(ops->direct_call); +#endif if (!addr) return; @@ -5986,6 +5991,10 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long ip, unsigned lo if (!hash) return -ENOMEM; +#ifndef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS + ops->direct_call = addr; +#endif + err = register_ftrace_direct_hash(ops, hash); free_ftrace_hash(hash); return err; @@ -6050,6 +6059,10 @@ int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long ip, unsigned long return -ENOMEM; err = modify_ftrace_direct_hash(ops, hash, lock_direct_mutex); +#ifndef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS + if (!err) + ops->direct_call = addr; +#endif free_ftrace_hash(hash); return err; } -- 2.51.0
