From 76d0de5729c0569c4071e7f21fcab394e502f03a Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Thu, 2 Feb 2023 00:56:01 +0900 Subject: fprobe: Pass entry_data to handlers 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. Link: https://lkml.kernel.org/r/167526696173.433354.17408372048319432574.stgit@mhiramat.roam.corp.google.com Cc: Florent Revest Cc: Mark Rutland Cc: Will Deacon Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- samples/fprobe/fprobe_example.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'samples') 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); -- cgit v1.2.3 From 39d954200bf6ad503c722e44d0be80c7b826fa42 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Thu, 2 Feb 2023 00:56:38 +0900 Subject: fprobe: Skip exit_handler if entry_handler returns !0 Skip hooking function return and calling exit_handler if the entry_handler() returns !0. Link: https://lkml.kernel.org/r/167526699798.433354.10998365726830117303.stgit@mhiramat.roam.corp.google.com Cc: Florent Revest Cc: Mark Rutland Cc: Will Deacon Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- include/linux/fprobe.h | 4 ++-- kernel/trace/bpf_trace.c | 15 +++++++++++++-- kernel/trace/fprobe.c | 14 +++++++++----- lib/test_fprobe.c | 7 +++++-- samples/fprobe/fprobe_example.c | 5 +++-- 5 files changed, 32 insertions(+), 13 deletions(-) (limited to 'samples') diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h index 678f741a7b33..47fefc7f363b 100644 --- a/include/linux/fprobe.h +++ b/include/linux/fprobe.h @@ -34,8 +34,8 @@ struct fprobe { size_t entry_data_size; int nr_maxactive; - void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip, - struct pt_regs *regs, void *entry_data); + int (*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); }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index fa403c323501..d804172b709c 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2644,12 +2644,23 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, return err; } -static void +static int kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, struct pt_regs *regs, void *data) { struct bpf_kprobe_multi_link *link; + link = container_of(fp, struct bpf_kprobe_multi_link, fp); + kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs); + return 0; +} + +static void +kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip, + struct pt_regs *regs, void *data) +{ + struct bpf_kprobe_multi_link *link; + link = container_of(fp, struct bpf_kprobe_multi_link, fp); kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs); } @@ -2848,7 +2859,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error; if (flags & BPF_F_KPROBE_MULTI_RETURN) - link->fp.exit_handler = kprobe_multi_link_handler; + link->fp.exit_handler = kprobe_multi_link_exit_handler; else link->fp.entry_handler = kprobe_multi_link_handler; diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index f222848571f2..9abb3905bc8e 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -27,7 +27,7 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, struct rethook_node *rh = NULL; struct fprobe *fp; void *entry_data = NULL; - int bit; + int bit, ret; fp = container_of(ops, struct fprobe, ops); if (fprobe_disabled(fp)) @@ -52,11 +52,15 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, } 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); + ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data); + /* If entry_handler returns !0, nmissed is not counted. */ + if (rh) { + if (ret) + rethook_recycle(rh); + else + rethook_hook(rh, ftrace_get_regs(fregs), true); + } out: ftrace_test_recursion_unlock(bit); } diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c index 4b37d7022f35..9fa2ac9eda83 100644 --- a/lib/test_fprobe.c +++ b/lib/test_fprobe.c @@ -37,7 +37,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32)) return nest(value + 2); } -static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, +static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs, void *data) { KUNIT_EXPECT_FALSE(current_test, preemptible()); @@ -51,6 +51,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, *(u32 *)data = entry_val; } else KUNIT_EXPECT_NULL(current_test, data); + + return 0; } static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, @@ -74,10 +76,11 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, KUNIT_EXPECT_NULL(current_test, data); } -static notrace void nest_entry_handler(struct fprobe *fp, unsigned long ip, +static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs, void *data) { KUNIT_EXPECT_FALSE(current_test, preemptible()); + return 0; } static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip, diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c index dd794990ad7e..4efc8feb6277 100644 --- a/samples/fprobe/fprobe_example.c +++ b/samples/fprobe/fprobe_example.c @@ -48,8 +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, void *data) +static int sample_entry_handler(struct fprobe *fp, unsigned long ip, + struct pt_regs *regs, void *data) { if (use_trace) /* @@ -62,6 +62,7 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip, nhit++; if (stackdump) show_backtrace(); + return 0; } static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs, -- cgit v1.2.3 From 9211ddaa78261373b50711c84de978cff8e2bd17 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 28 Mar 2023 16:52:15 -0700 Subject: tracing/user_events: Use write ABI in example The ABI has changed to use a remote write approach. Update the example to show the expected use of this new ABI. Also remove debugfs path and use tracefs to ensure example works in more environments. Link: https://lkml.kernel.org/r/20230328235219.203-9-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- samples/user_events/example.c | 45 ++++++++----------------------------------- 1 file changed, 8 insertions(+), 37 deletions(-) (limited to 'samples') diff --git a/samples/user_events/example.c b/samples/user_events/example.c index 18e34c9d708e..28165a096697 100644 --- a/samples/user_events/example.c +++ b/samples/user_events/example.c @@ -9,51 +9,28 @@ #include #include #include +#include #include #include #include -#include -#include #include -#if __BITS_PER_LONG == 64 -#define endian_swap(x) htole64(x) -#else -#define endian_swap(x) htole32(x) -#endif - -/* Assumes debugfs is mounted */ const char *data_file = "/sys/kernel/tracing/user_events_data"; -const char *status_file = "/sys/kernel/tracing/user_events_status"; +int enabled = 0; -static int event_status(long **status) -{ - int fd = open(status_file, O_RDONLY); - - *status = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ, - MAP_SHARED, fd, 0); - - close(fd); - - if (*status == MAP_FAILED) - return -1; - - return 0; -} - -static int event_reg(int fd, const char *command, long *index, long *mask, - int *write) +static int event_reg(int fd, const char *command, int *write, int *enabled) { struct user_reg reg = {0}; reg.size = sizeof(reg); + reg.enable_bit = 31; + reg.enable_size = sizeof(*enabled); + reg.enable_addr = (__u64)enabled; reg.name_args = (__u64)command; if (ioctl(fd, DIAG_IOCSREG, ®) == -1) return -1; - *index = reg.status_bit / __BITS_PER_LONG; - *mask = endian_swap(1L << (reg.status_bit % __BITS_PER_LONG)); *write = reg.write_index; return 0; @@ -62,17 +39,12 @@ static int event_reg(int fd, const char *command, long *index, long *mask, int main(int argc, char **argv) { int data_fd, write; - long index, mask; - long *status_page; struct iovec io[2]; __u32 count = 0; - if (event_status(&status_page) == -1) - return errno; - data_fd = open(data_file, O_RDWR); - if (event_reg(data_fd, "test u32 count", &index, &mask, &write) == -1) + if (event_reg(data_fd, "test u32 count", &write, &enabled) == -1) return errno; /* Setup iovec */ @@ -80,13 +52,12 @@ int main(int argc, char **argv) io[0].iov_len = sizeof(write); io[1].iov_base = &count; io[1].iov_len = sizeof(count); - ask: printf("Press enter to check status...\n"); getchar(); /* Check if anyone is listening */ - if (status_page[index] & mask) { + if (enabled) { /* Yep, trace out our data */ writev(data_fd, (const struct iovec *)io, 2); -- cgit v1.2.3