[PATCH 6.12 065/385] ftrace: Make ftrace_regs abstract from direct use

[Sasha Levin <sashal@kernel.org>]

From: Steven Rostedt <rostedt@goodmis.org>

[ Upstream commit 7888af4166d4ab07ba51234be6ba332b7807e901 ]

ftrace_regs was created to hold registers that store information to save
function parameters, return value and stack. Since it is a subset of
pt_regs, it should only be used by its accessor functions. But because
pt_regs can easily be taken from ftrace_regs (on most archs), it is
tempting to use it directly. But when running on other architectures, it
may fail to build or worse, build but crash the kernel!

Instead, make struct ftrace_regs an empty structure and have the
architectures define __arch_ftrace_regs and all the accessor functions
will typecast to it to get to the actual fields. This will help avoid
usage of ftrace_regs directly.

Link: https://lore.kernel.org/all/20241007171027.629bdafd@gandalf.local.home/

Cc: "linux-arch@vger.kernel.org" <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/20241008230628.958778821@goodmis.org
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: aea251799998 ("x86/fgraph,bpf: Switch kprobe_multi program stack unwind to hw_regs path")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm64/include/asm/ftrace.h          | 20 +++++++++--------
 arch/arm64/kernel/asm-offsets.c          | 22 +++++++++----------
 arch/arm64/kernel/ftrace.c               | 10 ++++-----
 arch/loongarch/include/asm/ftrace.h      | 22 ++++++++++---------
 arch/loongarch/kernel/ftrace_dyn.c       |  2 +-
 arch/powerpc/include/asm/ftrace.h        | 21 ++++++++++--------
 arch/powerpc/kernel/trace/ftrace.c       |  4 ++--
 arch/powerpc/kernel/trace/ftrace_64_pg.c |  2 +-
 arch/riscv/include/asm/ftrace.h          | 21 ++++++++++--------
 arch/riscv/kernel/asm-offsets.c          | 28 ++++++++++++------------
 arch/riscv/kernel/ftrace.c               |  2 +-
 arch/s390/include/asm/ftrace.h           | 23 ++++++++++---------
 arch/s390/kernel/asm-offsets.c           |  4 ++--
 arch/s390/kernel/ftrace.c                |  2 +-
 arch/s390/lib/test_unwind.c              |  4 ++--
 arch/x86/include/asm/ftrace.h            | 25 +++++++++++----------
 arch/x86/kernel/ftrace.c                 |  2 +-
 include/linux/ftrace.h                   | 21 +++++++++++++++---
 kernel/trace/ftrace.c                    |  2 +-
 19 files changed, 134 insertions(+), 103 deletions(-)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index dc9cf0bd2a4cb..bbb69c7751b99 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -56,6 +56,8 @@ unsigned long ftrace_call_adjust(unsigned long addr);
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
 struct dyn_ftrace;
 struct ftrace_ops;
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
 
 #define arch_ftrace_get_regs(regs) NULL
 
@@ -63,7 +65,7 @@ struct ftrace_ops;
  * Note: sizeof(struct ftrace_regs) must be a multiple of 16 to ensure correct
  * stack alignment
  */
-struct ftrace_regs {
+struct __arch_ftrace_regs {
 	/* x0 - x8 */
 	unsigned long regs[9];
 
@@ -83,47 +85,47 @@ struct ftrace_regs {
 static __always_inline unsigned long
 ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)
 {
-	return fregs->pc;
+	return arch_ftrace_regs(fregs)->pc;
 }
 
 static __always_inline void
 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
 				    unsigned long pc)
 {
-	fregs->pc = pc;
+	arch_ftrace_regs(fregs)->pc = pc;
 }
 
 static __always_inline unsigned long
 ftrace_regs_get_stack_pointer(const struct ftrace_regs *fregs)
 {
-	return fregs->sp;
+	return arch_ftrace_regs(fregs)->sp;
 }
 
 static __always_inline unsigned long
 ftrace_regs_get_argument(struct ftrace_regs *fregs, unsigned int n)
 {
 	if (n < 8)
-		return fregs->regs[n];
+		return arch_ftrace_regs(fregs)->regs[n];
 	return 0;
 }
 
 static __always_inline unsigned long
 ftrace_regs_get_return_value(const struct ftrace_regs *fregs)
 {
-	return fregs->regs[0];
+	return arch_ftrace_regs(fregs)->regs[0];
 }
 
 static __always_inline void
 ftrace_regs_set_return_value(struct ftrace_regs *fregs,
 			     unsigned long ret)
 {
-	fregs->regs[0] = ret;
+	arch_ftrace_regs(fregs)->regs[0] = ret;
 }
 
 static __always_inline void
 ftrace_override_function_with_return(struct ftrace_regs *fregs)
 {
-	fregs->pc = fregs->lr;
+	arch_ftrace_regs(fregs)->pc = arch_ftrace_regs(fregs)->lr;
 }
 
 int ftrace_regs_query_register_offset(const char *name);
@@ -143,7 +145,7 @@ static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs,
 	 * The ftrace trampoline will return to this address instead of the
 	 * instrumented function.
 	 */
-	fregs->direct_tramp = addr;
+	arch_ftrace_regs(fregs)->direct_tramp = addr;
 }
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 020e01181a0f1..1a1feca26515e 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -85,19 +85,19 @@ int main(void)
   DEFINE(PT_REGS_SIZE,		sizeof(struct pt_regs));
   BLANK();
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
-  DEFINE(FREGS_X0,		offsetof(struct ftrace_regs, regs[0]));
-  DEFINE(FREGS_X2,		offsetof(struct ftrace_regs, regs[2]));
-  DEFINE(FREGS_X4,		offsetof(struct ftrace_regs, regs[4]));
-  DEFINE(FREGS_X6,		offsetof(struct ftrace_regs, regs[6]));
-  DEFINE(FREGS_X8,		offsetof(struct ftrace_regs, regs[8]));
-  DEFINE(FREGS_FP,		offsetof(struct ftrace_regs, fp));
-  DEFINE(FREGS_LR,		offsetof(struct ftrace_regs, lr));
-  DEFINE(FREGS_SP,		offsetof(struct ftrace_regs, sp));
-  DEFINE(FREGS_PC,		offsetof(struct ftrace_regs, pc));
+  DEFINE(FREGS_X0,		offsetof(struct __arch_ftrace_regs, regs[0]));
+  DEFINE(FREGS_X2,		offsetof(struct __arch_ftrace_regs, regs[2]));
+  DEFINE(FREGS_X4,		offsetof(struct __arch_ftrace_regs, regs[4]));
+  DEFINE(FREGS_X6,		offsetof(struct __arch_ftrace_regs, regs[6]));
+  DEFINE(FREGS_X8,		offsetof(struct __arch_ftrace_regs, regs[8]));
+  DEFINE(FREGS_FP,		offsetof(struct __arch_ftrace_regs, fp));
+  DEFINE(FREGS_LR,		offsetof(struct __arch_ftrace_regs, lr));
+  DEFINE(FREGS_SP,		offsetof(struct __arch_ftrace_regs, sp));
+  DEFINE(FREGS_PC,		offsetof(struct __arch_ftrace_regs, pc));
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
-  DEFINE(FREGS_DIRECT_TRAMP,	offsetof(struct ftrace_regs, direct_tramp));
+  DEFINE(FREGS_DIRECT_TRAMP,	offsetof(struct __arch_ftrace_regs, direct_tramp));
 #endif
-  DEFINE(FREGS_SIZE,		sizeof(struct ftrace_regs));
+  DEFINE(FREGS_SIZE,		sizeof(struct __arch_ftrace_regs));
   BLANK();
 #endif
 #ifdef CONFIG_COMPAT
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index b657f058bf4d5..06017bc1a555f 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -23,10 +23,10 @@ struct fregs_offset {
 	int offset;
 };
 
-#define FREGS_OFFSET(n, field)				\
-{							\
-	.name = n,					\
-	.offset = offsetof(struct ftrace_regs, field),	\
+#define FREGS_OFFSET(n, field)					\
+{								\
+	.name = n,						\
+	.offset = offsetof(struct __arch_ftrace_regs, field),	\
 }
 
 static const struct fregs_offset fregs_offsets[] = {
@@ -488,7 +488,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
+	prepare_ftrace_return(ip, &arch_ftrace_regs(fregs)->lr, arch_ftrace_regs(fregs)->fp);
 }
 #else
 /*
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index c0a682808e070..0e15d36ce2512 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -43,38 +43,40 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent);
 
 #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 struct ftrace_ops;
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
 
-struct ftrace_regs {
+struct __arch_ftrace_regs {
 	struct pt_regs regs;
 };
 
 static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
 {
-	return &fregs->regs;
+	return &arch_ftrace_regs(fregs)->regs;
 }
 
 static __always_inline unsigned long
 ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)
 {
-	return instruction_pointer(&fregs->regs);
+	return instruction_pointer(&arch_ftrace_regs(fregs)->regs);
 }
 
 static __always_inline void
 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
 {
-	instruction_pointer_set(&fregs->regs, ip);
+	instruction_pointer_set(&arch_ftrace_regs(fregs)->regs, ip);
 }
 
 #define ftrace_regs_get_argument(fregs, n) \
-	regs_get_kernel_argument(&(fregs)->regs, n)
+	regs_get_kernel_argument(&arch_ftrace_regs(fregs)->regs, n)
 #define ftrace_regs_get_stack_pointer(fregs) \
-	kernel_stack_pointer(&(fregs)->regs)
+	kernel_stack_pointer(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_return_value(fregs) \
-	regs_return_value(&(fregs)->regs)
+	regs_return_value(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_set_return_value(fregs, ret) \
-	regs_set_return_value(&(fregs)->regs, ret)
+	regs_set_return_value(&arch_ftrace_regs(fregs)->regs, ret)
 #define ftrace_override_function_with_return(fregs) \
-	override_function_with_return(&(fregs)->regs)
+	override_function_with_return(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_query_register_offset(name) \
 	regs_query_register_offset(name)
 
@@ -90,7 +92,7 @@ __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
 }
 
 #define arch_ftrace_set_direct_caller(fregs, addr) \
-	__arch_ftrace_set_direct_caller(&(fregs)->regs, addr)
+	__arch_ftrace_set_direct_caller(&arch_ftrace_regs(fregs)->regs, addr)
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 #endif
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index bff058317062e..18056229e22e4 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -241,7 +241,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	struct pt_regs *regs = &fregs->regs;
+	struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs;
 	unsigned long *parent = (unsigned long *)&regs->regs[1];
 
 	prepare_ftrace_return(ip, (unsigned long *)parent);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 559560286e6d0..e299fd47d2014 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -32,39 +32,42 @@ struct dyn_arch_ftrace {
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #define ftrace_init_nop ftrace_init_nop
 
-struct ftrace_regs {
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+struct __arch_ftrace_regs {
 	struct pt_regs regs;
 };
 
 static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
 {
 	/* We clear regs.msr in ftrace_call */
-	return fregs->regs.msr ? &fregs->regs : NULL;
+	return arch_ftrace_regs(fregs)->regs.msr ? &arch_ftrace_regs(fregs)->regs : NULL;
 }
 
 static __always_inline void
 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
 				    unsigned long ip)
 {
-	regs_set_return_ip(&fregs->regs, ip);
+	regs_set_return_ip(&arch_ftrace_regs(fregs)->regs, ip);
 }
 
 static __always_inline unsigned long
 ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)
 {
-	return instruction_pointer(&fregs->regs);
+	return instruction_pointer(&arch_ftrace_regs(fregs)->regs);
 }
 
 #define ftrace_regs_get_argument(fregs, n) \
-	regs_get_kernel_argument(&(fregs)->regs, n)
+	regs_get_kernel_argument(&arch_ftrace_regs(fregs)->regs, n)
 #define ftrace_regs_get_stack_pointer(fregs) \
-	kernel_stack_pointer(&(fregs)->regs)
+	kernel_stack_pointer(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_return_value(fregs) \
-	regs_return_value(&(fregs)->regs)
+	regs_return_value(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_set_return_value(fregs, ret) \
-	regs_set_return_value(&(fregs)->regs, ret)
+	regs_set_return_value(&arch_ftrace_regs(fregs)->regs, ret)
 #define ftrace_override_function_with_return(fregs) \
-	override_function_with_return(&(fregs)->regs)
+	override_function_with_return(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_query_register_offset(name) \
 	regs_query_register_offset(name)
 
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index d8d6b4fd9a14c..df41f4a7c738b 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -421,7 +421,7 @@ int __init ftrace_dyn_arch_init(void)
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	unsigned long sp = fregs->regs.gpr[1];
+	unsigned long sp = arch_ftrace_regs(fregs)->regs.gpr[1];
 	int bit;
 
 	if (unlikely(ftrace_graph_is_dead()))
@@ -439,6 +439,6 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 
 	ftrace_test_recursion_unlock(bit);
 out:
-	fregs->regs.link = parent_ip;
+	arch_ftrace_regs(fregs)->regs.link = parent_ip;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 12fab1803bcf4..d3c5552e4984d 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -829,7 +829,7 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+	arch_ftrace_regs(fregs)->regs.link = __prepare_ftrace_return(parent_ip, ip, arch_ftrace_regs(fregs)->regs.gpr[1]);
 }
 #else
 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index f253c8dae878e..8a97ce5077e73 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -126,7 +126,10 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
 #define arch_ftrace_get_regs(regs) NULL
 struct ftrace_ops;
-struct ftrace_regs {
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+struct __arch_ftrace_regs {
 	unsigned long epc;
 	unsigned long ra;
 	unsigned long sp;
@@ -150,42 +153,42 @@ struct ftrace_regs {
 static __always_inline unsigned long ftrace_regs_get_instruction_pointer(const struct ftrace_regs
 									 *fregs)
 {
-	return fregs->epc;
+	return arch_ftrace_regs(fregs)->epc;
 }
 
 static __always_inline void ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
 								unsigned long pc)
 {
-	fregs->epc = pc;
+	arch_ftrace_regs(fregs)->epc = pc;
 }
 
 static __always_inline unsigned long ftrace_regs_get_stack_pointer(const struct ftrace_regs *fregs)
 {
-	return fregs->sp;
+	return arch_ftrace_regs(fregs)->sp;
 }
 
 static __always_inline unsigned long ftrace_regs_get_argument(struct ftrace_regs *fregs,
 							      unsigned int n)
 {
 	if (n < 8)
-		return fregs->args[n];
+		return arch_ftrace_regs(fregs)->args[n];
 	return 0;
 }
 
 static __always_inline unsigned long ftrace_regs_get_return_value(const struct ftrace_regs *fregs)
 {
-	return fregs->a0;
+	return arch_ftrace_regs(fregs)->a0;
 }
 
 static __always_inline void ftrace_regs_set_return_value(struct ftrace_regs *fregs,
 							 unsigned long ret)
 {
-	fregs->a0 = ret;
+	arch_ftrace_regs(fregs)->a0 = ret;
 }
 
 static __always_inline void ftrace_override_function_with_return(struct ftrace_regs *fregs)
 {
-	fregs->epc = fregs->ra;
+	arch_ftrace_regs(fregs)->epc = arch_ftrace_regs(fregs)->ra;
 }
 
 int ftrace_regs_query_register_offset(const char *name);
@@ -196,7 +199,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 
 static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs, unsigned long addr)
 {
-	fregs->t1 = addr;
+	arch_ftrace_regs(fregs)->t1 = addr;
 }
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */
 
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 05c6152a65310..dfed9986b45ed 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -497,19 +497,19 @@ void asm_offsets(void)
 	OFFSET(STACKFRAME_RA, stackframe, ra);
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
-	DEFINE(FREGS_SIZE_ON_STACK, ALIGN(sizeof(struct ftrace_regs), STACK_ALIGN));
-	DEFINE(FREGS_EPC,	    offsetof(struct ftrace_regs, epc));
-	DEFINE(FREGS_RA,	    offsetof(struct ftrace_regs, ra));
-	DEFINE(FREGS_SP,	    offsetof(struct ftrace_regs, sp));
-	DEFINE(FREGS_S0,	    offsetof(struct ftrace_regs, s0));
-	DEFINE(FREGS_T1,	    offsetof(struct ftrace_regs, t1));
-	DEFINE(FREGS_A0,	    offsetof(struct ftrace_regs, a0));
-	DEFINE(FREGS_A1,	    offsetof(struct ftrace_regs, a1));
-	DEFINE(FREGS_A2,	    offsetof(struct ftrace_regs, a2));
-	DEFINE(FREGS_A3,	    offsetof(struct ftrace_regs, a3));
-	DEFINE(FREGS_A4,	    offsetof(struct ftrace_regs, a4));
-	DEFINE(FREGS_A5,	    offsetof(struct ftrace_regs, a5));
-	DEFINE(FREGS_A6,	    offsetof(struct ftrace_regs, a6));
-	DEFINE(FREGS_A7,	    offsetof(struct ftrace_regs, a7));
+	DEFINE(FREGS_SIZE_ON_STACK, ALIGN(sizeof(struct __arch_ftrace_regs), STACK_ALIGN));
+	DEFINE(FREGS_EPC,	    offsetof(struct __arch_ftrace_regs, epc));
+	DEFINE(FREGS_RA,	    offsetof(struct __arch_ftrace_regs, ra));
+	DEFINE(FREGS_SP,	    offsetof(struct __arch_ftrace_regs, sp));
+	DEFINE(FREGS_S0,	    offsetof(struct __arch_ftrace_regs, s0));
+	DEFINE(FREGS_T1,	    offsetof(struct __arch_ftrace_regs, t1));
+	DEFINE(FREGS_A0,	    offsetof(struct __arch_ftrace_regs, a0));
+	DEFINE(FREGS_A1,	    offsetof(struct __arch_ftrace_regs, a1));
+	DEFINE(FREGS_A2,	    offsetof(struct __arch_ftrace_regs, a2));
+	DEFINE(FREGS_A3,	    offsetof(struct __arch_ftrace_regs, a3));
+	DEFINE(FREGS_A4,	    offsetof(struct __arch_ftrace_regs, a4));
+	DEFINE(FREGS_A5,	    offsetof(struct __arch_ftrace_regs, a5));
+	DEFINE(FREGS_A6,	    offsetof(struct __arch_ftrace_regs, a6));
+	DEFINE(FREGS_A7,	    offsetof(struct __arch_ftrace_regs, a7));
 #endif
 }
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 4b95c574fd045..5081ad886841f 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -214,7 +214,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	prepare_ftrace_return(&fregs->ra, ip, fregs->s0);
+	prepare_ftrace_return(&arch_ftrace_regs(fregs)->ra, ip, arch_ftrace_regs(fregs)->s0);
 }
 #else /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */
 extern void ftrace_graph_call(void);
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 406746666eb78..1498d0a9c7625 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -51,13 +51,16 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 	return addr;
 }
 
-struct ftrace_regs {
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+struct __arch_ftrace_regs {
 	struct pt_regs regs;
 };
 
 static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
 {
-	struct pt_regs *regs = &fregs->regs;
+	struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs;
 
 	if (test_pt_regs_flag(regs, PIF_FTRACE_FULL_REGS))
 		return regs;
@@ -84,26 +87,26 @@ static __always_inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph
 static __always_inline unsigned long
 ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)
 {
-	return fregs->regs.psw.addr;
+	return arch_ftrace_regs(fregs)->regs.psw.addr;
 }
 
 static __always_inline void
 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
 				    unsigned long ip)
 {
-	fregs->regs.psw.addr = ip;
+	arch_ftrace_regs(fregs)->regs.psw.addr = ip;
 }
 
 #define ftrace_regs_get_argument(fregs, n) \
-	regs_get_kernel_argument(&(fregs)->regs, n)
+	regs_get_kernel_argument(&arch_ftrace_regs(fregs)->regs, n)
 #define ftrace_regs_get_stack_pointer(fregs) \
-	kernel_stack_pointer(&(fregs)->regs)
+	kernel_stack_pointer(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_return_value(fregs) \
-	regs_return_value(&(fregs)->regs)
+	regs_return_value(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_set_return_value(fregs, ret) \
-	regs_set_return_value(&(fregs)->regs, ret)
+	regs_set_return_value(&arch_ftrace_regs(fregs)->regs, ret)
 #define ftrace_override_function_with_return(fregs) \
-	override_function_with_return(&(fregs)->regs)
+	override_function_with_return(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_query_register_offset(name) \
 	regs_query_register_offset(name)
 
@@ -117,7 +120,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
  */
 static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs, unsigned long addr)
 {
-	struct pt_regs *regs = &fregs->regs;
+	struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs;
 	regs->orig_gpr2 = addr;
 }
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 3cfc4939033c9..0bab4a9cdc768 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -185,8 +185,8 @@ int main(void)
 	OFFSET(__FGRAPH_RET_FP, fgraph_ret_regs, fp);
 	DEFINE(__FGRAPH_RET_SIZE, sizeof(struct fgraph_ret_regs));
 #endif
-	OFFSET(__FTRACE_REGS_PT_REGS, ftrace_regs, regs);
-	DEFINE(__FTRACE_REGS_SIZE, sizeof(struct ftrace_regs));
+	OFFSET(__FTRACE_REGS_PT_REGS, __arch_ftrace_regs, regs);
+	DEFINE(__FTRACE_REGS_SIZE, sizeof(struct __arch_ftrace_regs));
 
 	OFFSET(__PCPU_FLAGS, pcpu, flags);
 	return 0;
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 0b6e62d1d8b87..51439a71e392c 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -318,7 +318,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	if (bit < 0)
 		return;
 
-	kmsan_unpoison_memory(fregs, sizeof(*fregs));
+	kmsan_unpoison_memory(fregs, ftrace_regs_size());
 	regs = ftrace_get_regs(fregs);
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (!regs || unlikely(!p) || kprobe_disabled(p))
diff --git a/arch/s390/lib/test_unwind.c b/arch/s390/lib/test_unwind.c
index 8b7f981e6f347..6e42100875e75 100644
--- a/arch/s390/lib/test_unwind.c
+++ b/arch/s390/lib/test_unwind.c
@@ -270,9 +270,9 @@ static void notrace __used test_unwind_ftrace_handler(unsigned long ip,
 						      struct ftrace_ops *fops,
 						      struct ftrace_regs *fregs)
 {
-	struct unwindme *u = (struct unwindme *)fregs->regs.gprs[2];
+	struct unwindme *u = (struct unwindme *)arch_ftrace_regs(fregs)->regs.gprs[2];
 
-	u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? &fregs->regs : NULL,
+	u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? &arch_ftrace_regs(fregs)->regs : NULL,
 			     (u->flags & UWM_SP) ? u->sp : 0);
 }
 
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index b4d719de2c845..62fed5547c2e1 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -35,7 +35,10 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 }
 
 #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
-struct ftrace_regs {
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+struct __arch_ftrace_regs {
 	struct pt_regs		regs;
 };
 
@@ -43,27 +46,27 @@ static __always_inline struct pt_regs *
 arch_ftrace_get_regs(struct ftrace_regs *fregs)
 {
 	/* Only when FL_SAVE_REGS is set, cs will be non zero */
-	if (!fregs->regs.cs)
+	if (!arch_ftrace_regs(fregs)->regs.cs)
 		return NULL;
-	return &fregs->regs;
+	return &arch_ftrace_regs(fregs)->regs;
 }
 
 #define ftrace_regs_set_instruction_pointer(fregs, _ip)	\
-	do { (fregs)->regs.ip = (_ip); } while (0)
+	do { arch_ftrace_regs(fregs)->regs.ip = (_ip); } while (0)
 
 #define ftrace_regs_get_instruction_pointer(fregs) \
-	((fregs)->regs.ip)
+	arch_ftrace_regs(fregs)->regs.ip)
 
 #define ftrace_regs_get_argument(fregs, n) \
-	regs_get_kernel_argument(&(fregs)->regs, n)
+	regs_get_kernel_argument(&arch_ftrace_regs(fregs)->regs, n)
 #define ftrace_regs_get_stack_pointer(fregs) \
-	kernel_stack_pointer(&(fregs)->regs)
+	kernel_stack_pointer(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_return_value(fregs) \
-	regs_return_value(&(fregs)->regs)
+	regs_return_value(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_set_return_value(fregs, ret) \
-	regs_set_return_value(&(fregs)->regs, ret)
+	regs_set_return_value(&arch_ftrace_regs(fregs)->regs, ret)
 #define ftrace_override_function_with_return(fregs) \
-	override_function_with_return(&(fregs)->regs)
+	override_function_with_return(&arch_ftrace_regs(fregs)->regs)
 #define ftrace_regs_query_register_offset(name) \
 	regs_query_register_offset(name)
 
@@ -90,7 +93,7 @@ __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
 	regs->orig_ax = addr;
 }
 #define arch_ftrace_set_direct_caller(fregs, addr) \
-	__arch_ftrace_set_direct_caller(&(fregs)->regs, addr)
+	__arch_ftrace_set_direct_caller(&arch_ftrace_regs(fregs)->regs, addr)
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 #ifdef CONFIG_DYNAMIC_FTRACE
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index bfab966ea56e8..d3b14a9ad2edb 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -647,7 +647,7 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	struct pt_regs *regs = &fregs->regs;
+	struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs;
 	unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
 
 	prepare_ftrace_return(ip, (unsigned long *)stack, 0);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 42106b3de3961..fc76ce4bf0b7e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -115,8 +115,6 @@ static inline int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *val
 
 extern int ftrace_enabled;
 
-#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
-
 /**
  * ftrace_regs - ftrace partial/optimal register set
  *
@@ -142,11 +140,28 @@ extern int ftrace_enabled;
  *
  * NOTE: user *must not* access regs directly, only do it via APIs, because
  * the member can be changed according to the architecture.
+ * This is why the structure is empty here, so that nothing accesses
+ * the ftrace_regs directly.
  */
 struct ftrace_regs {
+	/* Nothing to see here, use the accessor functions! */
+};
+
+#define ftrace_regs_size()	sizeof(struct __arch_ftrace_regs)
+
+#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+
+struct __arch_ftrace_regs {
 	struct pt_regs		regs;
 };
-#define arch_ftrace_get_regs(fregs) (&(fregs)->regs)
+
+struct ftrace_regs;
+#define arch_ftrace_regs(fregs) ((struct __arch_ftrace_regs *)(fregs))
+
+static inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
+{
+	return &arch_ftrace_regs(fregs)->regs;
+}
 
 /*
  * ftrace_regs_set_instruction_pointer() is to be defined by the architecture
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b2442aabccfd0..27718845f86d8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -7973,7 +7973,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 			       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	kmsan_unpoison_memory(fregs, sizeof(*fregs));
+	kmsan_unpoison_memory(fregs, ftrace_regs_size());
 	__ftrace_ops_list_func(ip, parent_ip, NULL, fregs);
 }
 #else
-- 
2.51.0