function_graph: Move graph depth stored data to shadow stack global var

The use of the task->trace_recursion for the logic used for the function
graph depth was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use that
instead.

Link: https://lore.kernel.org/linux-trace-kernel/171509106728.162236.2398372644430125344.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190823.634870264@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index 02e6afc6d7fe5845b06496a1796cb0cfc7c7b084..fdfb6f66718affafb56cf7581b8efe29aa32a239 100644 (file)
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -44,25 +44,6 @@ enum {
  */
        TRACE_IRQ_BIT,
 
-       /*
-        * In the very unlikely case that an interrupt came in
-        * at a start of graph tracing, and we want to trace
-        * the function in that interrupt, the depth can be greater
-        * than zero, because of the preempted start of a previous
-        * trace. In an even more unlikely case, depth could be 2
-        * if a softirq interrupted the start of graph tracing,
-        * followed by an interrupt preempting a start of graph
-        * tracing in the softirq, and depth can even be 3
-        * if an NMI came in at the start of an interrupt function
-        * that preempted a softirq start of a function that
-        * preempted normal context!!!! Luckily, it can't be
-        * greater than 3, so the next two bits are a mask
-        * of what the depth is when we set TRACE_GRAPH_FL
-        */
-
-       TRACE_GRAPH_DEPTH_START_BIT,
-       TRACE_GRAPH_DEPTH_END_BIT,
-
        /*
         * To implement set_graph_notrace, if this bit is set, we ignore
         * function graph tracing of called functions, until the return
@@ -78,16 +59,6 @@ enum {
 #define trace_recursion_clear(bit)     do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
 #define trace_recursion_test(bit)      ((current)->trace_recursion & (1<<(bit)))
 
-#define trace_recursion_depth() \
-       (((current)->trace_recursion >> TRACE_GRAPH_DEPTH_START_BIT) & 3)
-#define trace_recursion_set_depth(depth) \
-       do {                                                            \
-               current->trace_recursion &=                             \
-                       ~(3 << TRACE_GRAPH_DEPTH_START_BIT);            \
-               current->trace_recursion |=                             \
-                       ((depth) & 3) << TRACE_GRAPH_DEPTH_START_BIT;   \
-       } while (0)
-
 #define TRACE_CONTEXT_BITS     4
 
 #define TRACE_FTRACE_START     TRACE_FTRACE_BIT

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 73919129e57c76f69f9fe3e717831a4066fe94ed..82d879dc63ff8608fd8645037e84841846c02d8e 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -900,8 +900,38 @@ extern void free_fgraph_ops(struct trace_array *tr);
 
 enum {
        TRACE_GRAPH_FL          = 1,
+
+       /*
+        * In the very unlikely case that an interrupt came in
+        * at a start of graph tracing, and we want to trace
+        * the function in that interrupt, the depth can be greater
+        * than zero, because of the preempted start of a previous
+        * trace. In an even more unlikely case, depth could be 2
+        * if a softirq interrupted the start of graph tracing,
+        * followed by an interrupt preempting a start of graph
+        * tracing in the softirq, and depth can even be 3
+        * if an NMI came in at the start of an interrupt function
+        * that preempted a softirq start of a function that
+        * preempted normal context!!!! Luckily, it can't be
+        * greater than 3, so the next two bits are a mask
+        * of what the depth is when we set TRACE_GRAPH_FL
+        */
+
+       TRACE_GRAPH_DEPTH_START_BIT,
+       TRACE_GRAPH_DEPTH_END_BIT,
 };
 
+static inline unsigned long ftrace_graph_depth(unsigned long *task_var)
+{
+       return (*task_var >> TRACE_GRAPH_DEPTH_START_BIT) & 3;
+}
+
+static inline void ftrace_graph_set_depth(unsigned long *task_var, int depth)
+{
+       *task_var &= ~(3 << TRACE_GRAPH_DEPTH_START_BIT);
+       *task_var |= (depth & 3) << TRACE_GRAPH_DEPTH_START_BIT;
+}
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 extern struct ftrace_hash __rcu *ftrace_graph_hash;
 extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;
@@ -934,7 +964,7 @@ ftrace_graph_addr(unsigned long *task_var, struct ftrace_graph_ent *trace)
                 * when the depth is zero.
                 */
                *task_var |= TRACE_GRAPH_FL;
-               trace_recursion_set_depth(trace->depth);
+               ftrace_graph_set_depth(task_var, trace->depth);
 
                /*
                 * If no irqs are to be traced, but a set_graph_function
@@ -959,7 +989,7 @@ ftrace_graph_addr_finish(struct fgraph_ops *gops, struct ftrace_graph_ret *trace
        unsigned long *task_var = fgraph_get_task_var(gops);
 
        if ((*task_var & TRACE_GRAPH_FL) &&
-           trace->depth == trace_recursion_depth())
+           trace->depth == ftrace_graph_depth(task_var))
                *task_var &= ~TRACE_GRAPH_FL;
 }