From 4be42c92220128b3128854a2d6b0f0ad0bcedbdb Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:02 +0100 Subject: ftrace,bpf: Remove FTRACE_OPS_FL_JMP ftrace_ops flag MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit At the moment the we allow the jmp attach only for ftrace_ops that has FTRACE_OPS_FL_JMP set. This conflicts with following changes where we use single ftrace_ops object for all direct call sites, so all could be be attached via just call or jmp. We already limit the jmp attach support with config option and bit (LSB) set on the trampoline address. It turns out that's actually enough to limit the jmp attach for architecture and only for chosen addresses (with LSB bit set). Each user of register_ftrace_direct or modify_ftrace_direct can set the trampoline bit (LSB) to indicate it has to be attached by jmp. The bpf trampoline generation code uses trampoline flags to generate jmp-attach specific code and ftrace inner code uses the trampoline bit (LSB) to handle return from jmp attachment, so there's no harm to remove the FTRACE_OPS_FL_JMP bit. The fexit/fmodret performance stays the same (did not drop), current code: fentry : 77.904 ± 0.546M/s fexit : 62.430 ± 0.554M/s fmodret : 66.503 ± 0.902M/s with this change: fentry : 80.472 ± 0.061M/s fexit : 63.995 ± 0.127M/s fmodret : 67.362 ± 0.175M/s Fixes: 25e4e3565d45 ("ftrace: Introduce FTRACE_OPS_FL_JMP") Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-2-jolsa@kernel.org --- include/linux/ftrace.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index a3a8989e3268..cc869c59c1a6 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -359,7 +359,6 @@ enum { FTRACE_OPS_FL_DIRECT = BIT(17), FTRACE_OPS_FL_SUBOP = BIT(18), FTRACE_OPS_FL_GRAPH = BIT(19), - FTRACE_OPS_FL_JMP = BIT(20), }; #ifndef CONFIG_DYNAMIC_FTRACE_WITH_ARGS -- cgit v1.2.3 From 0e860d07c29d70205d5ad48456ac7a133ccfb293 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:04 +0100 Subject: ftrace: Export some of hash related functions We are going to use these functions in following changes. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-4-jolsa@kernel.org --- include/linux/ftrace.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index cc869c59c1a6..a77b57a4aba2 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -82,6 +82,7 @@ static inline void early_trace_init(void) { } struct module; struct ftrace_hash; +struct ftrace_func_entry; #if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_MODULES) && \ defined(CONFIG_DYNAMIC_FTRACE) @@ -405,6 +406,14 @@ enum ftrace_ops_cmd { typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, enum ftrace_ops_cmd cmd); #ifdef CONFIG_DYNAMIC_FTRACE + +#define FTRACE_HASH_DEFAULT_BITS 10 + +struct ftrace_hash *alloc_ftrace_hash(int size_bits); +void free_ftrace_hash(struct ftrace_hash *hash); +struct ftrace_func_entry *add_ftrace_hash_entry_direct(struct ftrace_hash *hash, + unsigned long ip, unsigned long direct); + /* The hash used to know what functions callbacks trace */ struct ftrace_ops_hash { struct ftrace_hash __rcu *notrace_hash; -- cgit v1.2.3 From 05dc5e9c1fe156fd9dddc4c2f81e8fc6c7e50eb5 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:05 +0100 Subject: ftrace: Add update_ftrace_direct_add function Adding update_ftrace_direct_add function that adds all entries (ip -> addr) provided in hash argument to direct ftrace ops and updates its attachments. The difference to current register_ftrace_direct is - hash argument that allows to register multiple ip -> direct entries at once - we can call update_ftrace_direct_add multiple times on the same ftrace_ops object, becase after first registration with register_ftrace_function_nolock, it uses ftrace_update_ops to update the ftrace_ops object This change will allow us to have simple ftrace_ops for all bpf direct interface users in following changes. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-5-jolsa@kernel.org --- include/linux/ftrace.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index a77b57a4aba2..43a6cfaf5aae 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -543,6 +543,8 @@ int unregister_ftrace_direct(struct ftrace_ops *ops, unsigned long addr, int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr); int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr); +int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash); + void ftrace_stub_direct_tramp(void); #else @@ -569,6 +571,11 @@ static inline int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned l return -ENODEV; } +static inline int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash) +{ + return -ENODEV; +} + /* * This must be implemented by the architecture. * It is the way the ftrace direct_ops helper, when called -- cgit v1.2.3 From 8d2c1233f37149e4d1223d06ca7054a7f88c0a24 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:06 +0100 Subject: ftrace: Add update_ftrace_direct_del function Adding update_ftrace_direct_del function that removes all entries (ip -> addr) provided in hash argument to direct ftrace ops and updates its attachments. The difference to current unregister_ftrace_direct is - hash argument that allows to unregister multiple ip -> direct entries at once - we can call update_ftrace_direct_del multiple times on the same ftrace_ops object, becase we do not need to unregister all entries at once, we can do it gradualy with the help of ftrace_update_ops function This change will allow us to have simple ftrace_ops for all bpf direct interface users in following changes. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-6-jolsa@kernel.org --- include/linux/ftrace.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 43a6cfaf5aae..cfb957731433 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -544,6 +544,7 @@ int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr); int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr); int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash); +int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash); void ftrace_stub_direct_tramp(void); @@ -576,6 +577,11 @@ static inline int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace return -ENODEV; } +static inline int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash) +{ + return -ENODEV; +} + /* * This must be implemented by the architecture. * It is the way the ftrace direct_ops helper, when called -- cgit v1.2.3 From e93672f770d72f4c33d1dd9fb0633f95948c0cc9 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:07 +0100 Subject: ftrace: Add update_ftrace_direct_mod function Adding update_ftrace_direct_mod function that modifies all entries (ip -> direct) provided in hash argument to direct ftrace ops and updates its attachments. The difference to current modify_ftrace_direct is: - hash argument that allows to modify multiple ip -> direct entries at once This change will allow us to have simple ftrace_ops for all bpf direct interface users in following changes. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-7-jolsa@kernel.org --- include/linux/ftrace.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index cfb957731433..b8461e541b9d 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -545,6 +545,7 @@ int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr); int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash); int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash); +int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, bool do_direct_lock); void ftrace_stub_direct_tramp(void); @@ -582,6 +583,11 @@ static inline int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace return -ENODEV; } +static inline int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, bool do_direct_lock) +{ + return -ENODEV; +} + /* * This must be implemented by the architecture. * It is the way the ftrace direct_ops helper, when called -- cgit v1.2.3 From 7d0452497c292153e690652e6df218fead21185f Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:08 +0100 Subject: bpf: Add trampoline ip hash table Following changes need to lookup trampoline based on its ip address, adding hash table for that. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251230145010.103439-8-jolsa@kernel.org --- include/linux/bpf.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 9272a237cced..5524f9429e76 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1329,14 +1329,17 @@ struct bpf_tramp_image { }; struct bpf_trampoline { - /* hlist for trampoline_table */ - struct hlist_node hlist; + /* hlist for trampoline_key_table */ + struct hlist_node hlist_key; + /* hlist for trampoline_ip_table */ + struct hlist_node hlist_ip; struct ftrace_ops *fops; /* serializes access to fields of this trampoline */ struct mutex mutex; refcount_t refcnt; u32 flags; u64 key; + unsigned long ip; struct { struct btf_func_model model; void *addr; -- cgit v1.2.3 From 956747efd82aa60e0ac3e6aef2b9a17adda6f3b1 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 30 Dec 2025 15:50:09 +0100 Subject: ftrace: Factor ftrace_ops ops_func interface We are going to remove "ftrace_ops->private == bpf_trampoline" setup in following changes. Adding ip argument to ftrace_ops_func_t callback function, so we can use it to look up the trampoline. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/bpf/20251230145010.103439-9-jolsa@kernel.org --- include/linux/ftrace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index b8461e541b9d..705db0a6d995 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -403,7 +403,7 @@ enum ftrace_ops_cmd { * Negative on failure. The return value is dependent on the * callback. */ -typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, enum ftrace_ops_cmd cmd); +typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, unsigned long ip, enum ftrace_ops_cmd cmd); #ifdef CONFIG_DYNAMIC_FTRACE -- cgit v1.2.3