From efe34e99fc41ad2b3fd3bbe79ecd3906620ec961 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Mon, 28 Mar 2022 15:32:25 -0700 Subject: tracing/user_events: Hold event_mutex during dyn_event_add Make sure the event_mutex is properly held during dyn_event_add call. This is required when adding dynamic events. Link: https://lkml.kernel.org/r/20220328223225.1992-1-beaub@linux.microsoft.com Reported-by: Mathieu Desnoyers Signed-off-by: Beau Belgrave Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 8b3d241a31c2..61d78d64bdf0 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -1165,11 +1165,11 @@ static int user_event_parse(char *name, char *args, char *flags, #endif mutex_lock(&event_mutex); + ret = user_event_trace_register(user); - mutex_unlock(&event_mutex); if (ret) - goto put_user; + goto put_user_lock; user->index = index; @@ -1181,8 +1181,12 @@ static int user_event_parse(char *name, char *args, char *flags, set_bit(user->index, page_bitmap); hash_add(register_table, &user->node, key); + mutex_unlock(&event_mutex); + *newuser = user; return 0; +put_user_lock: + mutex_unlock(&event_mutex); put_user: user_event_destroy_fields(user); user_event_destroy_validators(user); -- cgit From 768c1e7f1de03afd0b55e0e951efc272309eeb52 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Tue, 29 Mar 2022 10:30:51 -0700 Subject: tracing/user_events: Remove eBPF interfaces Remove eBPF interfaces within user_events to ensure they are fully reviewed. Link: https://lore.kernel.org/all/20220329165718.GA10381@kbox/ Link: https://lkml.kernel.org/r/20220329173051.10087-1-beaub@linux.microsoft.com Suggested-by: Alexei Starovoitov Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 73 +--------------------------------------- 1 file changed, 1 insertion(+), 72 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 61d78d64bdf0..846c27bc7aef 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -42,9 +42,6 @@ #define MAX_FIELD_ARRAY_SIZE 1024 #define MAX_FIELD_ARG_NAME 256 -#define MAX_BPF_COPY_SIZE PAGE_SIZE -#define MAX_STACK_BPF_DATA 512 - static char *register_page_data; static DEFINE_MUTEX(reg_mutex); @@ -405,19 +402,6 @@ parse: type[0] != 'u', FILTER_OTHER); } -static void user_event_parse_flags(struct user_event *user, char *flags) -{ - char *flag; - - if (flags == NULL) - return; - - while ((flag = strsep(&flags, ",")) != NULL) { - if (strcmp(flag, "BPF_ITER") == 0) - user->flags |= FLAG_BPF_ITER; - } -} - static int user_event_parse_fields(struct user_event *user, char *args) { char *field; @@ -713,64 +697,14 @@ discard: } #ifdef CONFIG_PERF_EVENTS -static void user_event_bpf(struct user_event *user, struct iov_iter *i) -{ - struct user_bpf_context context; - struct user_bpf_iter bpf_i; - char fast_data[MAX_STACK_BPF_DATA]; - void *temp = NULL; - - if ((user->flags & FLAG_BPF_ITER) && iter_is_iovec(i)) { - /* Raw iterator */ - context.data_type = USER_BPF_DATA_ITER; - context.data_len = i->count; - context.iter = &bpf_i; - - bpf_i.iov_offset = i->iov_offset; - bpf_i.iov = i->iov; - bpf_i.nr_segs = i->nr_segs; - } else if (i->nr_segs == 1 && iter_is_iovec(i)) { - /* Single buffer from user */ - context.data_type = USER_BPF_DATA_USER; - context.data_len = i->count; - context.udata = i->iov->iov_base + i->iov_offset; - } else { - /* Multi buffer from user */ - struct iov_iter copy = *i; - size_t copy_size = min_t(size_t, i->count, MAX_BPF_COPY_SIZE); - - context.data_type = USER_BPF_DATA_KERNEL; - context.kdata = fast_data; - - if (unlikely(copy_size > sizeof(fast_data))) { - temp = kmalloc(copy_size, GFP_NOWAIT); - - if (temp) - context.kdata = temp; - else - copy_size = sizeof(fast_data); - } - - context.data_len = copy_nofault(context.kdata, - copy_size, ©); - } - - trace_call_bpf(&user->call, &context); - - kfree(temp); -} - /* - * Writes the user supplied payload out to perf ring buffer or eBPF program. + * Writes the user supplied payload out to perf ring buffer. */ static void user_event_perf(struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted) { struct hlist_head *perf_head; - if (bpf_prog_array_valid(&user->call)) - user_event_bpf(user, i); - perf_head = this_cpu_ptr(user->call.perf_events); if (perf_head && !hlist_empty(perf_head)) { @@ -1136,8 +1070,6 @@ static int user_event_parse(char *name, char *args, char *flags, user->tracepoint.name = name; - user_event_parse_flags(user, flags); - ret = user_event_parse_fields(user, args); if (ret) @@ -1579,9 +1511,6 @@ static int user_seq_show(struct seq_file *m, void *p) busy++; } - if (flags & FLAG_BPF_ITER) - seq_puts(m, " FLAG:BPF_ITER"); - seq_puts(m, "\n"); active++; } -- cgit From fcbf591cedbd44d82d7765b3c7e261858108593f Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 30 Mar 2022 15:58:35 -0400 Subject: tracing: Set user_events to BROKEN After being merged, user_events become more visible to a wider audience that have concerns with the current API. It is too late to fix this for this release, but instead of a full revert, just mark it as BROKEN (which prevents it from being selected in make config). Then we can work finding a better API. If that fails, then it will need to be completely reverted. Link: https://lore.kernel.org/all/2059213643.196683.1648499088753.JavaMail.zimbra@efficios.com/ Link: https://lkml.kernel.org/r/20220330155835.5e1f6669@gandalf.local.home Signed-off-by: Steven Rostedt (Google) --- kernel/trace/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 16a52a71732d..f83d29adb375 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -741,6 +741,7 @@ config USER_EVENTS bool "User trace events" select TRACING select DYNAMIC_EVENTS + depends on BROKEN || COMPILE_TEST # API needs to be straighten out help User trace events are user-defined trace events that can be used like an existing kernel trace event. User trace -- cgit From 18bfee3216fa6f28d55ebf88d824a539d2bec3c7 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 30 Mar 2022 09:00:19 +0200 Subject: ftrace: Make ftrace_graph_is_dead() a static branch ftrace_graph_is_dead() is used on hot paths, it just reads a variable in memory and is not worth suffering function call constraints. For instance, at entry of prepare_ftrace_return(), inlining it avoids saving prepare_ftrace_return() parameters to stack and restoring them after calling ftrace_graph_is_dead(). While at it using a static branch is even more performant and is rather well adapted considering that the returned value will almost never change. Inline ftrace_graph_is_dead() and replace 'kill_ftrace_graph' bool by a static branch. The performance improvement is noticeable. Link: https://lkml.kernel.org/r/e0411a6a0ed3eafff0ad2bc9cd4b0e202b4617df.1648623570.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Signed-off-by: Steven Rostedt (Google) --- kernel/trace/fgraph.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 19028e072cdb..8f4fb328133a 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -7,6 +7,7 @@ * * Highly modified by Steven Rostedt (VMware). */ +#include #include #include #include @@ -23,24 +24,12 @@ #define ASSIGN_OPS_HASH(opsname, val) #endif -static bool kill_ftrace_graph; +DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); int ftrace_graph_active; /* Both enabled by default (can be cleared by function_graph tracer flags */ static bool fgraph_sleep_time = true; -/** - * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called - * - * ftrace_graph_stop() is called when a severe error is detected in - * the function graph tracing. This function is called by the critical - * paths of function graph to keep those paths from doing any more harm. - */ -bool ftrace_graph_is_dead(void) -{ - return kill_ftrace_graph; -} - /** * ftrace_graph_stop - set to permanently disable function graph tracing * @@ -51,7 +40,7 @@ bool ftrace_graph_is_dead(void) */ void ftrace_graph_stop(void) { - kill_ftrace_graph = true; + static_branch_enable(&kill_ftrace_graph); } /* Add a function return address to the trace stack on thread info.*/ -- cgit From 5cfff569cab8bf544bab62c911c5d6efd5af5e05 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Fri, 1 Apr 2022 14:39:03 -0400 Subject: tracing: Move user_events.h temporarily out of include/uapi While user_events API is under development and has been marked for broken to not let the API become fixed, move the header file out of the uapi directory. This is to prevent it from being installed, then later changed, and then have an old distro user space update with a new kernel, where applications see the user_events being available, but the old header is in place, and then they get compiled incorrectly. Also, surround the include with CONFIG_COMPILE_TEST to the current location, but when the BROKEN tag is taken off, it will use the uapi directory, and fail to compile. This is a good way to remind us to move the header back. Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com Link: https://lkml.kernel.org/r/20220401143903.188384f3@gandalf.local.home Suggested-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 846c27bc7aef..706e1686b5eb 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -18,7 +18,12 @@ #include #include #include +/* Reminder to move to uapi when everything works */ +#ifdef CONFIG_COMPILE_TEST +#include +#else #include +#endif #include "trace.h" #include "trace_dynevent.h" -- cgit