ftrace: Consolidate ftrace_regs accessor functions for archs using pt_regs

Most architectures use pt_regs within ftrace_regs making a lot of the
accessor functions just calls to the pt_regs internally. Instead of
duplication this effort, use a HAVE_ARCH_FTRACE_REGS for architectures
that have their own ftrace_regs that is not based on pt_regs and will
define all the accessor functions, and for the architectures that just use
pt_regs, it will leave it undefined, and the default accessor functions
will be used.

Note, this will also make it easier to add new accessor functions to
ftrace_regs as it will mean having to touch less architectures.

Cc: <linux-arch@vger.kernel.org>
Cc: "x86@kernel.org" <x86@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/20241010202114.2289f6fd@gandalf.local.home
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> # powerpc
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

2 files changed, 43 insertions, 25 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 66f10291a0b2..aa9ddd1e4bb6 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -113,6 +113,8 @@ static inline int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *val
 
 #ifdef CONFIG_FUNCTION_TRACER
 
+#include <linux/ftrace_regs.h>
+
 extern int ftrace_enabled;
 
 /**
@@ -150,14 +152,11 @@ struct ftrace_regs {
 #define ftrace_regs_size()	sizeof(struct __arch_ftrace_regs)
 
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
-
-struct __arch_ftrace_regs {
-	struct pt_regs		regs;
-};
-
-struct ftrace_regs;
-#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
-
+/*
+ * Architectures that define HAVE_DYNAMIC_FTRACE_WITH_ARGS must define their own
+ * arch_ftrace_get_regs() where it only returns pt_regs *if* it is fully
+ * populated. It should return NULL otherwise.
+ */
 static inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
 {
 	return &arch_ftrace_regs(fregs)->regs;
@@ -191,23 +190,6 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
 	return ftrace_get_regs(fregs) != NULL;
 }
 
-#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
-#define ftrace_regs_get_instruction_pointer(fregs) \
-	instruction_pointer(ftrace_get_regs(fregs))
-#define ftrace_regs_get_argument(fregs, n) \
-	regs_get_kernel_argument(ftrace_get_regs(fregs), n)
-#define ftrace_regs_get_stack_pointer(fregs) \
-	kernel_stack_pointer(ftrace_get_regs(fregs))
-#define ftrace_regs_return_value(fregs) \
-	regs_return_value(ftrace_get_regs(fregs))
-#define ftrace_regs_set_return_value(fregs, ret) \
-	regs_set_return_value(ftrace_get_regs(fregs), ret)
-#define ftrace_override_function_with_return(fregs) \
-	override_function_with_return(ftrace_get_regs(fregs))
-#define ftrace_regs_query_register_offset(name) \
-	regs_query_register_offset(name)
-#endif
-
 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
 			      struct ftrace_ops *op, struct ftrace_regs *fregs);
 
diff --git a/include/linux/ftrace_regs.h b/include/linux/ftrace_regs.h
new file mode 100644
index 000000000000..dea6a0851b74
--- /dev/null
+++ b/include/linux/ftrace_regs.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FTRACE_REGS_H
+#define _LINUX_FTRACE_REGS_H
+
+/*
+ * For archs that just copy pt_regs in ftrace regs, it can use this default.
+ * If an architecture does not use pt_regs, it must define all the below
+ * accessor functions.
+ */
+#ifndef HAVE_ARCH_FTRACE_REGS
+struct __arch_ftrace_regs {
+	struct pt_regs		regs;
+};
+
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+struct ftrace_regs;
+
+#define ftrace_regs_get_instruction_pointer(fregs) \
+	instruction_pointer(arch_ftrace_get_regs(fregs))
+#define ftrace_regs_get_argument(fregs, n) \
+	regs_get_kernel_argument(arch_ftrace_get_regs(fregs), n)
+#define ftrace_regs_get_stack_pointer(fregs) \
+	kernel_stack_pointer(arch_ftrace_get_regs(fregs))
+#define ftrace_regs_return_value(fregs) \
+	regs_return_value(arch_ftrace_get_regs(fregs))
+#define ftrace_regs_set_return_value(fregs, ret) \
+	regs_set_return_value(arch_ftrace_get_regs(fregs), ret)
+#define ftrace_override_function_with_return(fregs) \
+	override_function_with_return(arch_ftrace_get_regs(fregs))
+#define ftrace_regs_query_register_offset(name) \
+	regs_query_register_offset(name)
+
+#endif /* HAVE_ARCH_FTRACE_REGS */
+
+#endif /* _LINUX_FTRACE_REGS_H */