[RFC PATCH 1/9] fprobe: Pass entry_data to handlers
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2022-11-08 15:49:40
Also in:
lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [tracing], library code, the rest, tracing · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Andrew Morton, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> Pass the private entry_data to the entry and exit handlers so that they can share the context data, something like saved function arguments etc. User must specify the private entry_data size by @entry_data_size field before registering the fprobe. Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- include/linux/fprobe.h | 8 ++++++-- kernel/trace/bpf_trace.c | 2 +- kernel/trace/fprobe.c | 21 ++++++++++++++------- lib/test_fprobe.c | 6 ++++-- samples/fprobe/fprobe_example.c | 6 ++++-- 5 files changed, 29 insertions(+), 14 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 1c2bde0ead73..e0d4e6136249 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h@@ -13,6 +13,7 @@ * @nmissed: The counter for missing events. * @flags: The status flag. * @rethook: The rethook data structure. (internal data) + * @entry_data_size: The private data storage size. * @entry_handler: The callback function for function entry. * @exit_handler: The callback function for function exit. */
@@ -29,9 +30,12 @@ struct fprobe { unsigned long nmissed; unsigned int flags; struct rethook *rethook; + size_t entry_data_size; - void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs); - void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs); + void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip, + struct pt_regs *regs, void *entry_data); + void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip, + struct pt_regs *regs, void *entry_data); }; /* This fprobe is soft-disabled. */
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 1ed08967fb97..68c369452680 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -2625,7 +2625,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, static void kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, - struct pt_regs *regs) + struct pt_regs *regs, void *data) { struct bpf_kprobe_multi_link *link;
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index e8143e368074..fa25d09c9d57 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c@@ -17,14 +17,16 @@ struct fprobe_rethook_node { struct rethook_node node; unsigned long entry_ip; + char data[]; }; static void fprobe_handler(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct ftrace_regs *fregs) { struct fprobe_rethook_node *fpr; - struct rethook_node *rh; + struct rethook_node *rh = NULL; struct fprobe *fp; + void *entry_data = NULL; int bit; fp = container_of(ops, struct fprobe, ops);
@@ -37,9 +39,6 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, return; } - if (fp->entry_handler) - fp->entry_handler(fp, ip, ftrace_get_regs(fregs)); - if (fp->exit_handler) { rh = rethook_try_get(fp->rethook); if (!rh) {
@@ -48,9 +47,16 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, } fpr = container_of(rh, struct fprobe_rethook_node, node); fpr->entry_ip = ip; - rethook_hook(rh, ftrace_get_regs(fregs), true); + if (fp->entry_data_size) + entry_data = fpr->data; } + if (fp->entry_handler) + fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data); + + if (rh) + rethook_hook(rh, ftrace_get_regs(fregs), true); + out: ftrace_test_recursion_unlock(bit); }
@@ -81,7 +87,8 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data, fpr = container_of(rh, struct fprobe_rethook_node, node); - fp->exit_handler(fp, fpr->entry_ip, regs); + fp->exit_handler(fp, fpr->entry_ip, regs, + fp->entry_data_size ? (void *)fpr->data : NULL); } NOKPROBE_SYMBOL(fprobe_exit_handler);
@@ -146,7 +153,7 @@ static int fprobe_init_rethook(struct fprobe *fp, int num) for (i = 0; i < size; i++) { struct fprobe_rethook_node *node; - node = kzalloc(sizeof(*node), GFP_KERNEL); + node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL); if (!node) { rethook_free(fp->rethook); fp->rethook = NULL;
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index e0381b3ec410..34fa5a5bbda1 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c@@ -30,7 +30,8 @@ static noinline u32 fprobe_selftest_target2(u32 value) return (value / div_factor) + 1; } -static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, + struct pt_regs *regs, void *data) { KUNIT_EXPECT_FALSE(current_test, preemptible()); /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
@@ -39,7 +40,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct entry_val = (rand1 / div_factor); } -static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, + struct pt_regs *regs, void *data) { unsigned long ret = regs_return_value(regs);
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index e22da8573116..dd794990ad7e 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c@@ -48,7 +48,8 @@ static void show_backtrace(void) stack_trace_print(stacks, len, 24); } -static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +static void sample_entry_handler(struct fprobe *fp, unsigned long ip, + struct pt_regs *regs, void *data) { if (use_trace) /*
@@ -63,7 +64,8 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_ show_backtrace(); } -static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) +static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs, + void *data) { unsigned long rip = instruction_pointer(regs);