Message-ID: <20250704104838.27a18690@gandalf.local.home>
Date: Fri, 4 Jul 2025 10:48:38 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, linux-arch@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Mark Rutland <mark.rutland@....com>,
 Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH] tracing: Remove redundant config HAVE_FTRACE_MCOUNT_RECORD

From: Steven Rostedt <rostedt@...dmis.org>

Ftrace is tightly coupled with architecture specific code because it
requires the use of trampolines written in assembly. This means that when
a new feature or optimization is made, it must be done for all
architectures. To simplify the approach, CONFIG_HAVE_FTRACE_* configs are
added to denote which architecture has the new enhancement so that other
architectures can still function until they too have been updated.

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.

Remove the HAVE_FTRACE_MCOUNT config and use DYNAMIC_FTRACE directly where
applicable.

Link: https://lore.kernel.org/all/20250703154916.48e3ada7@gandalf.local.home/

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
[
  I'm off today due to fireworks, but I noticed that this was
  ready to go out, so I'm posting it now.
]
 Documentation/trace/ftrace-design.rst | 12 ++++--------
 arch/arm/Kconfig                      |  1 -
 arch/arm64/Kconfig                    |  1 -
 arch/csky/Kconfig                     |  1 -
 arch/loongarch/Kconfig                |  1 -
 arch/microblaze/Kconfig               |  1 -
 arch/mips/Kconfig                     |  1 -
 arch/parisc/Kconfig                   |  1 -
 arch/powerpc/Kconfig                  |  1 -
 arch/riscv/Kconfig                    |  1 -
 arch/s390/Kconfig                     |  1 -
 arch/sh/Kconfig                       |  1 -
 arch/sparc/Kconfig                    |  1 -
 arch/x86/Kconfig                      |  1 -
 include/asm-generic/vmlinux.lds.h     |  2 +-
 include/linux/ftrace.h                |  2 +-
 include/linux/kernel.h                |  6 +++---
 include/linux/module.h                |  2 +-
 kernel/module/main.c                  |  2 +-
 kernel/trace/Kconfig                  | 18 ++++--------------
 kernel/trace/ftrace.c                 |  4 ----
 scripts/recordmcount.pl               |  2 +-
 22 files changed, 16 insertions(+), 47 deletions(-)

diff --git a/Documentation/trace/ftrace-design.rst b/Documentation/trace/ftrace-design.rst
index dc82d64b3a44..8f4fab3f9324 100644
--- 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
index 3072731fe09c..33cc9dbb7f68 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -107,7 +107,6 @@ 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
index 55fc331af337..f943a07db139 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -223,7 +223,6 @@ 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
index acc431c331b0..4331313a42ff 100644
--- 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
index 4b19f93379a1..bead8266dc5c 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -144,7 +144,6 @@ 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
index f18ec02ddeb2..484ebb3baedf 100644
--- 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
index 1e48184ecf1e..268730824f75 100644
--- 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
index fcc5973f7519..2efa4b08b7b8 100644
--- 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
index c3e0cc83f120..cb4fb8d73300 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -246,7 +246,6 @@ 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
index 36061f4732b7..cd1cec255015 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -158,7 +158,6 @@ 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
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0c16dc443e2f..d956e85f0465 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -199,7 +199,6 @@ 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
index 89185af7bcc9..d5795067befa 100644
--- 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
index 0f88123925a4..f307e730446c 100644
--- 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
index 71019b3b54ea..eb07f236ce53 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -244,7 +244,6 @@ 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
index fa5f19b8d53a..ae2d2359b79e 100644
--- 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
index b672ca15f265..7ded7df6e9b5 100644
--- 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
index 1cce1f6410a9..989315dabb86 100644
--- 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
index 5faa1fb1f4b4..800e6fde9bf7 100644
--- 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
index 413ac6ea3702..58d36f8cef0d 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2639,7 +2639,7 @@ 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
index a3f35c7d83b6..c2ce834313a9 100644
--- 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
@@ -803,27 +798,22 @@ 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
@@ -831,7 +821,7 @@ config FTRACE_MCOUNT_USE_RECORDMCOUNT
 	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/ftrace.c b/kernel/trace/ftrace.c
index 4203fad56b6c..00b76d450a89 100644
--- 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/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 0871b2e92584..861b56dda64e 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -359,7 +359,7 @@ if ($arch eq "x86_64") {
     $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;
-- 
2.47.2

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