netdev - [PATCH v2 11/12] x86/ftrace: enable dynamic ftrace without CONFIG

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Date: Fri, 16 Jun 2023 11:50:37 +0300
From: Mike Rapoport <rppt@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"David S. Miller" <davem@...emloft.net>,
	Dinh Nguyen <dinguyen@...nel.org>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Helge Deller <deller@....de>,
	Huacai Chen <chenhuacai@...nel.org>,
	Kent Overstreet <kent.overstreet@...ux.dev>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Mike Rapoport <rppt@...nel.org>,
	Nadav Amit <nadav.amit@...il.com>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Puranjay Mohan <puranjay12@...il.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Russell King <linux@...linux.org.uk>,
	Song Liu <song@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Will Deacon <will@...nel.org>,
	bpf@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mips@...r.kernel.org,
	linux-mm@...ck.org,
	linux-modules@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-s390@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	loongarch@...ts.linux.dev,
	netdev@...r.kernel.org,
	sparclinux@...r.kernel.org,
	x86@...nel.org
Subject: [PATCH v2 11/12] 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 53bab123a8ee..ab64bbef9e50 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -35,6 +35,7 @@ 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 f77c63bb3203..a824a5d3b129 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_text_alloc(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);
-- 
2.35.1