[PATCH v7 13/16] x86/ftrace: enable dynamic ftrace without CONFIG_MODULES

Mike Rapoport
2024-04-29T12:19:06Z

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@kernel.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