linux-kernel - [PATCH v7 13/16] x86/ftrace: enable dynamic ftrace without CONFIG

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Message-ID: <20240429121620.1186447-14-rppt@kernel.org>
Date: Mon, 29 Apr 2024 15:16:17 +0300
From: Mike Rapoport <rppt@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
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Subject: [PATCH v7 13/16] x86/ftrace: enable dynamic ftrace without CONFIG_MODULES

From: "Mike Rapoport (IBM)" <rppt@...nel.org>

Dynamic ftrace must allocate memory for code and this was impossible
without CONFIG_MODULES.

With execmem separated from the modules code, execmem_text_alloc() is
available regardless of CONFIG_MODULES.

Remove dependency of dynamic ftrace on CONFIG_MODULES and make
CONFIG_DYNAMIC_FTRACE select CONFIG_EXECMEM in Kconfig.

Signed-off-by: Mike Rapoport (IBM) <rppt@...nel.org>
---
 arch/x86/Kconfig         |  1 +
 arch/x86/kernel/ftrace.c | 10 ----------
 2 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4474bf32d0a4..f2917ccf4fb4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -34,6 +34,7 @@ config X86_64
 	select SWIOTLB
 	select ARCH_HAS_ELFCORE_COMPAT
 	select ZONE_DMA32
+	select EXECMEM if DYNAMIC_FTRACE
 
 config FORCE_DYNAMIC_FTRACE
 	def_bool y
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index c8ddb7abda7c..8da0e66ca22d 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -261,8 +261,6 @@ void arch_ftrace_update_code(int command)
 /* Currently only x86_64 supports dynamic trampolines */
 #ifdef CONFIG_X86_64
 
-#ifdef CONFIG_MODULES
-/* Module allocation simplifies allocating memory for code */
 static inline void *alloc_tramp(unsigned long size)
 {
 	return execmem_alloc(EXECMEM_FTRACE, size);
@@ -271,14 +269,6 @@ static inline void tramp_free(void *tramp)
 {
 	execmem_free(tramp);
 }
-#else
-/* Trampolines can only be created if modules are supported */
-static inline void *alloc_tramp(unsigned long size)
-{
-	return NULL;
-}
-static inline void tramp_free(void *tramp) { }
-#endif
 
 /* Defined as markers to the end of the ftrace default trampolines */
 extern void ftrace_regs_caller_end(void);
-- 
2.43.0