Merge tag 'ftrace-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

torvalds · torvalds · commit 90a871f74b70 · 2025-07-30T16:04:10.000-07:00
Pull ftrace updates from Steven Rostedt:

 - Keep track of when fgraph_ops are registered or not

   Keep accounting of when fgraph_ops are registered as if a fgraph_ops
   is registered twice it can mess up the accounting and it will not
   work as expected later. Trigger a warning if something registers it
   twice as to catch bugs before they are found by things just not
   working as expected.

 - Make DYNAMIC_FTRACE always enabled for architectures that support it

   As static ftrace (where all functions are always traced) is very
   expensive and only exists to help architectures support ftrace, do
   not make it an option. As soon as an architecture supports
   DYNAMIC_FTRACE make it use it. This simplifies the code.

 - Remove redundant config HAVE_FTRACE_MCOUNT_RECORD

   The CONFIG_HAVE_FTRACE_MCOUNT was added to help simplify the
   DYNAMIC_FTRACE work, but now every architecture that implements
   DYNAMIC_FTRACE also has HAVE_FTRACE_MCOUNT set too, making it
   redundant with the HAVE_DYNAMIC_FTRACE.

 - Make pid_ptr string size match the comment

   In print_graph_proc() the pid_ptr string is of size 11, but the
   comment says /* sign + log10(MAX_INT) + '\0' */ which is actually 12.

* tag 'ftrace-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Remove redundant config HAVE_FTRACE_MCOUNT_RECORD
  ftrace: Make DYNAMIC_FTRACE always enabled for architectures that support it
  fgraph: Keep track of when fgraph_ops are registered or not
  fgraph: Make pid_str size match the comment
diff --git a/Documentation/trace/ftrace-design.rst b/Documentation/trace/ftrace-design.rst
@@ -238,19 +238,15 @@ You need very few things to get the syscalls tracing in an arch.
   - Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
 
 
-HAVE_FTRACE_MCOUNT_RECORD
--------------------------
+HAVE_DYNAMIC_FTRACE
+-------------------
 
 See scripts/recordmcount.pl for more info.  Just fill in the arch-specific
 details for how to locate the addresses of mcount call sites via objdump.
 This option doesn't make much sense without also implementing dynamic ftrace.
 
-
-HAVE_DYNAMIC_FTRACE
--------------------
-
-You will first need HAVE_FTRACE_MCOUNT_RECORD and HAVE_FUNCTION_TRACER, so
-scroll your reader back up if you got over eager.
+You will first need HAVE_FUNCTION_TRACER, so scroll your reader back up if you
+got over eager.
 
 Once those are out of the way, you will need to implement:
 	- asm/ftrace.h:
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
@@ -105,7 +105,6 @@ config ARM
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_EXIT_THREAD
 	select HAVE_GUP_FAST if ARM_LPAE
-	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
@@ -221,7 +221,6 @@ config ARM64
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_GUP_FAST
 	select HAVE_FTRACE_GRAPH_FUNC
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_FREGS
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
@@ -80,7 +80,6 @@ config CSKY
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_ERROR_INJECTION
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZO
 	select HAVE_KERNEL_LZMA
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
@@ -143,7 +143,6 @@ config LOONGARCH
 	select HAVE_EXIT_THREAD
 	select HAVE_GUP_FAST
 	select HAVE_FTRACE_GRAPH_FUNC
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_FREGS
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
@@ -28,7 +28,6 @@ config MICROBLAZE
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_PAGE_SIZE_4KB
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
@@ -73,7 +73,6 @@ config MIPS
 	select HAVE_EBPF_JIT if !CPU_MICROMIPS
 	select HAVE_EXIT_THREAD
 	select HAVE_GUP_FAST
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
@@ -81,7 +81,6 @@ config PARISC
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_DYNAMIC_FTRACE if $(cc-option,-fpatchable-function-entry=1,1)
-	select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
 	select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY if DYNAMIC_FTRACE
 	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
@@ -244,7 +244,6 @@ config PPC
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_GUP_FAST
 	select HAVE_FTRACE_GRAPH_FUNC
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select HAVE_FUNCTION_DESCRIPTORS	if PPC64_ELF_ABI_V1
 	select HAVE_FUNCTION_ERROR_INJECTION
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
@@ -157,7 +157,6 @@ config RISCV
 	select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS if (DYNAMIC_FTRACE_WITH_ARGS && !CFI_CLANG)
 	select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_GRAPH_FUNC
-	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_GRAPH_TRACER if HAVE_DYNAMIC_FTRACE_WITH_ARGS
 	select HAVE_FUNCTION_GRAPH_FREGS
 	select HAVE_FUNCTION_TRACER if !XIP_KERNEL && HAVE_DYNAMIC_FTRACE
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
@@ -198,7 +198,6 @@ config S390
 	select HAVE_GUP_FAST
 	select HAVE_FENTRY
 	select HAVE_FTRACE_GRAPH_FUNC
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_FREGS
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
@@ -40,7 +40,6 @@ config SUPERH
 	select HAVE_GUP_FAST if MMU
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_HW_BREAKPOINT
 	select HAVE_IOREMAP_PROT if MMU && !X2TLB
 	select HAVE_KERNEL_BZIP2
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
@@ -78,7 +78,6 @@ config SPARC64
 	select MMU_GATHER_NO_FLUSH_CACHE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_DYNAMIC_FTRACE
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_PAGE_SIZE_8KB
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_CONTEXT_TRACKING_USER
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
@@ -242,7 +242,6 @@ config X86
 	select HAVE_GUP_FAST
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE
 	select HAVE_FTRACE_GRAPH_FUNC		if HAVE_FUNCTION_GRAPH_TRACER
-	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_FREGS	if HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER	if X86_32 || (X86_64 && DYNAMIC_FTRACE)
 	select HAVE_FUNCTION_TRACER
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
@@ -167,7 +167,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
 #define FTRACE_STUB_HACK
 #endif
 
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+#ifdef CONFIG_DYNAMIC_FTRACE
 /*
  * The ftrace call sites are logged to a section whose name depends on the
  * compiler option used. A given kernel image will only use one, AKA
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
@@ -1108,7 +1108,7 @@ static __always_inline unsigned long get_lock_parent_ip(void)
 # define trace_preempt_off(a0, a1) do { } while (0)
 #endif
 
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+#ifdef CONFIG_DYNAMIC_FTRACE
 extern void ftrace_init(void);
 #ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
 #define FTRACE_CALLSITE_SECTION	"__patchable_function_entries"
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
@@ -373,9 +373,9 @@ ftrace_vprintk(const char *fmt, va_list ap)
 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 #endif /* CONFIG_TRACING */
 
-/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
-# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
+/* Rebuild everything on CONFIG_DYNAMIC_FTRACE */
+#ifdef CONFIG_DYNAMIC_FTRACE
+# define REBUILD_DUE_TO_DYNAMIC_FTRACE
 #endif
 
 /* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
diff --git a/include/linux/module.h b/include/linux/module.h
@@ -539,7 +539,7 @@ struct module {
 	struct trace_eval_map **trace_evals;
 	unsigned int num_trace_evals;
 #endif
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+#ifdef CONFIG_DYNAMIC_FTRACE
 	unsigned int num_ftrace_callsites;
 	unsigned long *ftrace_callsites;
 #endif
diff --git a/kernel/module/main.c b/kernel/module/main.c
@@ -2673,7 +2673,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 					 sizeof(*mod->trace_bprintk_fmt_start),
 					 &mod->num_trace_bprintk_fmt);
 #endif
-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+#ifdef CONFIG_DYNAMIC_FTRACE
 	/* sechdrs[0].sh_size is always zero */
 	mod->ftrace_callsites = section_objs(info, FTRACE_CALLSITE_SECTION,
 					     sizeof(*mod->ftrace_callsites),
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
@@ -74,11 +74,6 @@ config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
 	  If the architecture generates __patchable_function_entries sections
 	  but does not want them included in the ftrace locations.
 
-config HAVE_FTRACE_MCOUNT_RECORD
-	bool
-	help
-	  See Documentation/trace/ftrace-design.rst
-
 config HAVE_SYSCALL_TRACEPOINTS
 	bool
 	help
@@ -275,7 +270,7 @@ config FUNCTION_TRACE_ARGS
 	  funcgraph-args (for the function graph tracer)
 
 config DYNAMIC_FTRACE
-	bool "enable/disable function tracing dynamically"
+	bool
 	depends on FUNCTION_TRACER
 	depends on HAVE_DYNAMIC_FTRACE
 	default y
@@ -803,35 +798,30 @@ config BPF_KPROBE_OVERRIDE
 	 Allows BPF to override the execution of a probed function and
 	 set a different return value.  This is used for error injection.
 
-config FTRACE_MCOUNT_RECORD
-	def_bool y
-	depends on DYNAMIC_FTRACE
-	depends on HAVE_FTRACE_MCOUNT_RECORD
-
 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
 	bool
-	depends on FTRACE_MCOUNT_RECORD
+	depends on DYNAMIC_FTRACE
 
 config FTRACE_MCOUNT_USE_CC
 	def_bool y
 	depends on $(cc-option,-mrecord-mcount)
 	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
-	depends on FTRACE_MCOUNT_RECORD
+	depends on DYNAMIC_FTRACE
 
 config FTRACE_MCOUNT_USE_OBJTOOL
 	def_bool y
 	depends on HAVE_OBJTOOL_MCOUNT
 	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
 	depends on !FTRACE_MCOUNT_USE_CC
-	depends on FTRACE_MCOUNT_RECORD
+	depends on DYNAMIC_FTRACE
 	select OBJTOOL
 
 config FTRACE_MCOUNT_USE_RECORDMCOUNT
 	def_bool y
 	depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
 	depends on !FTRACE_MCOUNT_USE_CC
 	depends on !FTRACE_MCOUNT_USE_OBJTOOL
-	depends on FTRACE_MCOUNT_RECORD
+	depends on DYNAMIC_FTRACE
 
 config TRACING_MAP
 	bool
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
@@ -1325,6 +1325,10 @@ int register_ftrace_graph(struct fgraph_ops *gops)
 	int ret = 0;
 	int i = -1;
 
+	if (WARN_ONCE(gops->ops.flags & FTRACE_OPS_FL_GRAPH,
+		      "function graph ops registered again"))
+		return -EBUSY;
+
 	guard(mutex)(&ftrace_lock);
 
 	if (!fgraph_stack_cachep) {
@@ -1401,17 +1405,21 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
 {
 	int command = 0;
 
+	if (WARN_ONCE(!(gops->ops.flags & FTRACE_OPS_FL_GRAPH),
+		      "function graph ops unregistered without registering"))
+		return;
+
 	guard(mutex)(&ftrace_lock);
 
 	if (unlikely(!ftrace_graph_active))
-		return;
+		goto out;
 
 	if (unlikely(gops->idx < 0 || gops->idx >= FGRAPH_ARRAY_SIZE ||
 		     fgraph_array[gops->idx] != gops))
-		return;
+		goto out;
 
 	if (fgraph_lru_release_index(gops->idx) < 0)
-		return;
+		goto out;
 
 	fgraph_array[gops->idx] = &fgraph_stub;
 
@@ -1434,4 +1442,6 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
 		unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
 	}
 	gops->saved_func = NULL;
+ out:
+	gops->ops.flags &= ~FTRACE_OPS_FL_GRAPH;
 }
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
@@ -1042,10 +1042,6 @@ static struct ftrace_ops *removed_ops;
  */
 static bool update_all_ops;
 
-#ifndef CONFIG_FTRACE_MCOUNT_RECORD
-# error Dynamic ftrace depends on MCOUNT_RECORD
-#endif
-
 struct ftrace_func_probe {
 	struct ftrace_probe_ops	*probe_ops;
 	struct ftrace_ops	ops;
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
@@ -513,7 +513,7 @@ static void print_graph_proc(struct trace_seq *s, pid_t pid)
 {
 	char comm[TASK_COMM_LEN];
 	/* sign + log10(MAX_INT) + '\0' */
-	char pid_str[11];
+	char pid_str[12];
 	int spaces = 0;
 	int len;
 	int i;
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
@@ -359,7 +359,7 @@
     $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_CKCORE_PCREL_JSR_IMM26BY2\\s+_mcount\$";
     $alignment = 2;
 } else {
-    die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
+    die "Arch $arch is not supported with CONFIG_DYNAMIC_FTRACE";
 }
 
 my $text_found = 0;
