[PATCH v20 02/19] fgraph: Replace fgraph_ret_regs with ftrace_regs

Masami Hiramatsu (Google)
2024-12-06T00:09:32Z

Use ftrace_regs instead of fgraph_ret_regs for tracing return value
on function_graph tracer because of simplifying the callback interface.

The CONFIG_HAVE_FUNCTION_GRAPH_RETVAL is also replaced by
CONFIG_HAVE_FUNCTION_GRAPH_FREGS.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Heiko Carstens <hca@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@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

---
Changes in v18:
- Use PTREGS_SIZE instead of redefining FRAME_SIZE on i386.
Changes in v17:
- Fixes s390 return_to_handler according to Heiko's advice.
Changes in v16:
- According to the recent ftrace_regs.h change, override
ftrace_regs_get_frame_pointer() if needed.
- s390: keep stack_frame on stack, just replace fgraph_ret_regs
with ftrace_regs.
Changes in v8:
- Newly added.
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/ftrace.h | 23 ++++++-----------------
arch/arm64/kernel/asm-offsets.c | 12 ------------
arch/arm64/kernel/entry-ftrace.S | 32 ++++++++++++++++++--------------
arch/loongarch/Kconfig | 2 +-
arch/loongarch/include/asm/ftrace.h | 26 ++++----------------------
arch/loongarch/kernel/asm-offsets.c | 12 ------------
arch/loongarch/kernel/mcount.S | 17 ++++++++++-------
arch/loongarch/kernel/mcount_dyn.S | 14 +++++++-------
arch/riscv/Kconfig | 2 +-
arch/riscv/include/asm/ftrace.h | 26 +++++---------------------
arch/riscv/kernel/mcount.S | 24 +++++++++++++-----------
arch/s390/Kconfig | 2 +-
arch/s390/include/asm/ftrace.h | 24 +++++++-----------------
arch/s390/kernel/asm-offsets.c | 6 ------
arch/s390/kernel/mcount.S | 12 ++++++------
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/ftrace.h | 20 --------------------
arch/x86/kernel/ftrace_32.S | 13 +++++++------
arch/x86/kernel/ftrace_64.S | 17 +++++++++--------
include/linux/ftrace.h | 12 +++++++++---
include/linux/ftrace_regs.h | 2 ++
kernel/trace/Kconfig | 4 ++--
kernel/trace/fgraph.c | 21 +++++++++------------
24 files changed, 119 insertions(+), 207 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 100570a048c5..5f086777dad9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -219,6 +219,7 @@ config ARM64
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_ERROR_INJECTION
+ select HAVE_FUNCTION_GRAPH_FREGS
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_RETVAL
select HAVE_GCC_PLUGINS
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 5ccff4de7f09..b5fa57b61378 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -129,6 +129,12 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
arch_ftrace_regs(fregs)->pc = arch_ftrace_regs(fregs)->lr;
}

+static __always_inline unsigned long
+ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)
+{
+ return arch_ftrace_regs(fregs)->fp;
+}
+
int ftrace_regs_query_register_offset(const char *name);

int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
@@ -186,23 +192,6 @@ static inline bool arch_syscall_match_sym_name(const char *sym,

#ifndef __ASSEMBLY__
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-struct fgraph_ret_regs {
- /* x0 - x7 */
- unsigned long regs[8];
-
- unsigned long fp;
- unsigned long __unused;
-};
-
-static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->regs[0];
-}
-
-static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->fp;
-}

void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
unsigned long frame_pointer);
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 29bf85dacffe..eb1a840e4110 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -179,18 +179,6 @@ int main(void)
DEFINE(FTRACE_OPS_FUNC, offsetof(struct ftrace_ops, func));
#endif
BLANK();
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- DEFINE(FGRET_REGS_X0, offsetof(struct fgraph_ret_regs, regs[0]));
- DEFINE(FGRET_REGS_X1, offsetof(struct fgraph_ret_regs, regs[1]));
- DEFINE(FGRET_REGS_X2, offsetof(struct fgraph_ret_regs, regs[2]));
- DEFINE(FGRET_REGS_X3, offsetof(struct fgraph_ret_regs, regs[3]));
- DEFINE(FGRET_REGS_X4, offsetof(struct fgraph_ret_regs, regs[4]));
- DEFINE(FGRET_REGS_X5, offsetof(struct fgraph_ret_regs, regs[5]));
- DEFINE(FGRET_REGS_X6, offsetof(struct fgraph_ret_regs, regs[6]));
- DEFINE(FGRET_REGS_X7, offsetof(struct fgraph_ret_regs, regs[7]));
- DEFINE(FGRET_REGS_FP, offsetof(struct fgraph_ret_regs, fp));
- DEFINE(FGRET_REGS_SIZE, sizeof(struct fgraph_ret_regs));
-#endif
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
DEFINE(FTRACE_OPS_DIRECT_CALL, offsetof(struct ftrace_ops, direct_call));
#endif
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index f0c16640ef21..169ccf600066 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -329,24 +329,28 @@ SYM_FUNC_END(ftrace_stub_graph)
* @fp is checked against the value passed by ftrace_graph_caller().
*/
SYM_CODE_START(return_to_handler)
- /* save return value regs */
- sub sp, sp, #FGRET_REGS_SIZE
- stp x0, x1, [sp, #FGRET_REGS_X0]
- stp x2, x3, [sp, #FGRET_REGS_X2]
- stp x4, x5, [sp, #FGRET_REGS_X4]
- stp x6, x7, [sp, #FGRET_REGS_X6]
- str x29, [sp, #FGRET_REGS_FP] // parent's fp
+ /* Make room for ftrace_regs */
+ sub sp, sp, #FREGS_SIZE
+
+ /* Save return value regs */
+ stp x0, x1, [sp, #FREGS_X0]
+ stp x2, x3, [sp, #FREGS_X2]
+ stp x4, x5, [sp, #FREGS_X4]
+ stp x6, x7, [sp, #FREGS_X6]
+
+ /* Save the callsite's FP */
+ str x29, [sp, #FREGS_FP]

mov x0, sp
- bl ftrace_return_to_handler // addr = ftrace_return_to_hander(regs);
+ bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs);
mov x30, x0 // restore the original return address

- /* restore return value regs */
- ldp x0, x1, [sp, #FGRET_REGS_X0]
- ldp x2, x3, [sp, #FGRET_REGS_X2]
- ldp x4, x5, [sp, #FGRET_REGS_X4]
- ldp x6, x7, [sp, #FGRET_REGS_X6]
- add sp, sp, #FGRET_REGS_SIZE
+ /* Restore return value regs */
+ ldp x0, x1, [sp, #FREGS_X0]
+ ldp x2, x3, [sp, #FREGS_X2]
+ ldp x4, x5, [sp, #FREGS_X4]
+ ldp x6, x7, [sp, #FREGS_X6]
+ add sp, sp, #FREGS_SIZE

ret
SYM_CODE_END(return_to_handler)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index dae3a9104ca6..49f5bfc00e5a 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -137,7 +137,7 @@ config LOONGARCH
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_FUNCTION_ERROR_INJECTION
- select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
+ select HAVE_FUNCTION_GRAPH_FREGS
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 8f13eaeaa325..ceb3e3d9c0d3 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -57,6 +57,10 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
instruction_pointer_set(&arch_ftrace_regs(fregs)->regs, ip);
}

+#undef ftrace_regs_get_frame_pointer
+#define ftrace_regs_get_frame_pointer(fregs) \
+ (arch_ftrace_regs(fregs)->regs.regs[22])
+
#define ftrace_graph_func ftrace_graph_func
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
@@ -78,26 +82,4 @@ __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)

#endif /* CONFIG_FUNCTION_TRACER */

-#ifndef __ASSEMBLY__
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-struct fgraph_ret_regs {
- /* a0 - a1 */
- unsigned long regs[2];
-
- unsigned long fp;
- unsigned long __unused;
-};
-
-static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->regs[0];
-}
-
-static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->fp;
-}
-#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
-#endif
-
#endif /* _ASM_LOONGARCH_FTRACE_H */
diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
index 049c5c3e370c..8be1c38ad8eb 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c
@@ -280,18 +280,6 @@ static void __used output_pbe_defines(void)
}
#endif

-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-static void __used output_fgraph_ret_regs_defines(void)
-{
- COMMENT("LoongArch fgraph_ret_regs offsets.");
- OFFSET(FGRET_REGS_A0, fgraph_ret_regs, regs[0]);
- OFFSET(FGRET_REGS_A1, fgraph_ret_regs, regs[1]);
- OFFSET(FGRET_REGS_FP, fgraph_ret_regs, fp);
- DEFINE(FGRET_REGS_SIZE, sizeof(struct fgraph_ret_regs));
- BLANK();
-}
-#endif
-
static void __used output_kvm_defines(void)
{
COMMENT("KVM/LoongArch Specific offsets.");
diff --git a/arch/loongarch/kernel/mcount.S b/arch/loongarch/kernel/mcount.S
index 3015896016a0..b6850503e061 100644
--- a/arch/loongarch/kernel/mcount.S
+++ b/arch/loongarch/kernel/mcount.S
@@ -79,10 +79,11 @@ SYM_FUNC_START(ftrace_graph_caller)
SYM_FUNC_END(ftrace_graph_caller)

SYM_FUNC_START(return_to_handler)
- PTR_ADDI sp, sp, -FGRET_REGS_SIZE
- PTR_S a0, sp, FGRET_REGS_A0
- PTR_S a1, sp, FGRET_REGS_A1
- PTR_S zero, sp, FGRET_REGS_FP
+ /* Save return value regs */
+ PTR_ADDI sp, sp, -PT_SIZE
+ PTR_S a0, sp, PT_R4
+ PTR_S a1, sp, PT_R5
+ PTR_S zero, sp, PT_R22

move a0, sp
bl ftrace_return_to_handler
@@ -90,9 +91,11 @@ SYM_FUNC_START(return_to_handler)
/* Restore the real parent address: a0 -> ra */
move ra, a0

- PTR_L a0, sp, FGRET_REGS_A0
- PTR_L a1, sp, FGRET_REGS_A1
- PTR_ADDI sp, sp, FGRET_REGS_SIZE
+ /* Restore return value regs */
+ PTR_L a0, sp, PT_R4
+ PTR_L a1, sp, PT_R5
+ PTR_ADDI sp, sp, PT_SIZE
+
jr ra
SYM_FUNC_END(return_to_handler)
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/loongarch/kernel/mcount_dyn.S b/arch/loongarch/kernel/mcount_dyn.S
index 0c65cf09110c..d6b474ad1d5e 100644
--- a/arch/loongarch/kernel/mcount_dyn.S
+++ b/arch/loongarch/kernel/mcount_dyn.S
@@ -140,19 +140,19 @@ SYM_CODE_END(ftrace_graph_caller)
SYM_CODE_START(return_to_handler)
UNWIND_HINT_UNDEFINED
/* Save return value regs */
- PTR_ADDI sp, sp, -FGRET_REGS_SIZE
- PTR_S a0, sp, FGRET_REGS_A0
- PTR_S a1, sp, FGRET_REGS_A1
- PTR_S zero, sp, FGRET_REGS_FP
+ PTR_ADDI sp, sp, -PT_SIZE
+ PTR_S a0, sp, PT_R4
+ PTR_S a1, sp, PT_R5
+ PTR_S zero, sp, PT_R22

move a0, sp
bl ftrace_return_to_handler
move ra, a0

/* Restore return value regs */
- PTR_L a0, sp, FGRET_REGS_A0
- PTR_L a1, sp, FGRET_REGS_A1
- PTR_ADDI sp, sp, FGRET_REGS_SIZE
+ PTR_L a0, sp, PT_R4
+ PTR_L a1, sp, PT_R5
+ PTR_ADDI sp, sp, PT_SIZE

jr ra
SYM_CODE_END(return_to_handler)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d4a7ca0388c0..1e807c61258f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -148,7 +148,7 @@ config RISCV
select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_GRAPH_TRACER
- select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
+ select HAVE_FUNCTION_GRAPH_FREGS
select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
select HAVE_EBPF_JIT if MMU
select HAVE_GUP_FAST if MMU
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 3d66437a1029..9372f8d7036f 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -168,6 +168,11 @@ static __always_inline unsigned long ftrace_regs_get_stack_pointer(const struct
return arch_ftrace_regs(fregs)->sp;
}

+static __always_inline unsigned long ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)
+{
+ return arch_ftrace_regs(fregs)->s0;
+}
+
static __always_inline unsigned long ftrace_regs_get_argument(struct ftrace_regs *fregs,
unsigned int n)
{
@@ -208,25 +213,4 @@ static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs, unsi

#endif /* CONFIG_DYNAMIC_FTRACE */

-#ifndef __ASSEMBLY__
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-struct fgraph_ret_regs {
- unsigned long a1;
- unsigned long a0;
- unsigned long s0;
- unsigned long ra;
-};
-
-static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->a0;
-}
-
-static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->s0;
-}
-#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
-#endif
-
#endif /* _ASM_RISCV_FTRACE_H */
diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S
index 3a42f6287909..068168046e0e 100644
--- a/arch/riscv/kernel/mcount.S
+++ b/arch/riscv/kernel/mcount.S
@@ -12,6 +12,8 @@
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>

+#define ABI_SIZE_ON_STACK 80
+
.text

.macro SAVE_ABI_STATE
@@ -26,12 +28,12 @@
* register if a0 was not saved.
*/
.macro SAVE_RET_ABI_STATE
- addi sp, sp, -4*SZREG
- REG_S s0, 2*SZREG(sp)
- REG_S ra, 3*SZREG(sp)
- REG_S a0, 1*SZREG(sp)
- REG_S a1, 0*SZREG(sp)
- addi s0, sp, 4*SZREG
+ addi sp, sp, -ABI_SIZE_ON_STACK
+ REG_S ra, 1*SZREG(sp)
+ REG_S s0, 8*SZREG(sp)
+ REG_S a0, 10*SZREG(sp)
+ REG_S a1, 11*SZREG(sp)
+ addi s0, sp, ABI_SIZE_ON_STACK
.endm

.macro RESTORE_ABI_STATE
@@ -41,11 +43,11 @@
.endm

.macro RESTORE_RET_ABI_STATE
- REG_L ra, 3*SZREG(sp)
- REG_L s0, 2*SZREG(sp)
- REG_L a0, 1*SZREG(sp)
- REG_L a1, 0*SZREG(sp)
- addi sp, sp, 4*SZREG
+ REG_L ra, 1*SZREG(sp)
+ REG_L s0, 8*SZREG(sp)
+ REG_L a0, 10*SZREG(sp)
+ REG_L a1, 11*SZREG(sp)
+ addi sp, sp, ABI_SIZE_ON_STACK
.endm

SYM_TYPED_FUNC_START(ftrace_stub)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0077969170e8..102029e56cf0 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -192,7 +192,7 @@ config S390
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_FUNCTION_ERROR_INJECTION
- select HAVE_FUNCTION_GRAPH_RETVAL
+ select HAVE_FUNCTION_GRAPH_FREGS
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index fc97d75dc752..5c94c1fc1bc1 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -62,23 +62,6 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *
return NULL;
}

-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-struct fgraph_ret_regs {
- unsigned long gpr2;
- unsigned long fp;
-};
-
-static __always_inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->gpr2;
-}
-
-static __always_inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->fp;
-}
-#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-
static __always_inline void
ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
unsigned long ip)
@@ -86,6 +69,13 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
arch_ftrace_regs(fregs)->regs.psw.addr = ip;
}

+#undef ftrace_regs_get_frame_pointer
+static __always_inline unsigned long
+ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
+{
+ return ftrace_regs_get_stack_pointer(fregs);
+}
+
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/*
* When an ftrace registered caller is tracing a function that is
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 862a9140528e..36709112ae7a 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -175,12 +175,6 @@ int main(void)
DEFINE(OLDMEM_SIZE, PARMAREA + offsetof(struct parmarea, oldmem_size));
DEFINE(COMMAND_LINE, PARMAREA + offsetof(struct parmarea, command_line));
DEFINE(MAX_COMMAND_LINE_SIZE, PARMAREA + offsetof(struct parmarea, max_command_line_size));
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- /* function graph return value tracing */
- OFFSET(__FGRAPH_RET_GPR2, fgraph_ret_regs, gpr2);
- OFFSET(__FGRAPH_RET_FP, fgraph_ret_regs, fp);
- DEFINE(__FGRAPH_RET_SIZE, sizeof(struct fgraph_ret_regs));
-#endif
OFFSET(__FTRACE_REGS_PT_REGS, __arch_ftrace_regs, regs);
DEFINE(__FTRACE_REGS_SIZE, sizeof(struct __arch_ftrace_regs));

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 7e267ef63a7f..2b628aa3d809 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -134,14 +134,14 @@ SYM_CODE_END(ftrace_common)
SYM_FUNC_START(return_to_handler)
stmg %r2,%r5,32(%r15)
lgr %r1,%r15
- aghi %r15,-(STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE)
+ # allocate ftrace_regs and stack frame for ftrace_return_to_handler
+ aghi %r15,-STACK_FRAME_SIZE_FREGS
stg %r1,__SF_BACKCHAIN(%r15)
- la %r3,STACK_FRAME_OVERHEAD(%r15)
- stg %r1,__FGRAPH_RET_FP(%r3)
- stg %r2,__FGRAPH_RET_GPR2(%r3)
- lgr %r2,%r3
+ stg %r2,(STACK_FREGS_PTREGS_GPRS+2*8)(%r15)
+ stg %r1,(STACK_FREGS_PTREGS_GPRS+15*8)(%r15)
+ la %r2,STACK_FRAME_OVERHEAD(%r15)
brasl %r14,ftrace_return_to_handler
- aghi %r15,STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE
+ aghi %r15,STACK_FRAME_SIZE_FREGS
lgr %r14,%r2
lmg %r2,%r5,32(%r15)
BR_EX %r14
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9d7bd0ae48c4..ff0d7e07c611 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -235,7 +235,7 @@ config X86
select HAVE_GUP_FAST
select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD
- select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
+ select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 6e8cf0fa48fc..d61407c680c2 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -134,24 +134,4 @@ static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
#endif /* !COMPILE_OFFSETS */
#endif /* !__ASSEMBLY__ */

-#ifndef __ASSEMBLY__
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-struct fgraph_ret_regs {
- unsigned long ax;
- unsigned long dx;
- unsigned long bp;
-};
-
-static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->ax;
-}
-
-static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
-{
- return ret_regs->bp;
-}
-#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
-#endif
-
#endif /* _ASM_X86_FTRACE_H */
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index 58d9ed50fe61..8e1a27d2c1eb 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -187,14 +187,15 @@ SYM_CODE_END(ftrace_graph_caller)

.globl return_to_handler
return_to_handler:
- pushl $0
- pushl %edx
- pushl %eax
+ subl $(PTREGS_SIZE), %esp
+ movl $0, PT_EBP(%esp)
+ movl %edx, PT_EDX(%esp)
+ movl %eax, PT_EAX(%esp)
movl %esp, %eax
call ftrace_return_to_handler
movl %eax, %ecx
- popl %eax
- popl %edx
- addl $4, %esp # skip ebp
+ movl %eax, PT_EAX(%esp)
+ movl %edx, PT_EDX(%esp)
+ addl $(PTREGS_SIZE), %esp
JMP_NOSPEC ecx
#endif
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 214f30e9f0c0..d51647228596 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -348,21 +348,22 @@ STACK_FRAME_NON_STANDARD_FP(__fentry__)
SYM_CODE_START(return_to_handler)
UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
- subq $24, %rsp

- /* Save the return values */
- movq %rax, (%rsp)
- movq %rdx, 8(%rsp)
- movq %rbp, 16(%rsp)
+ /* Save ftrace_regs for function exit context */
+ subq $(FRAME_SIZE), %rsp
+
+ movq %rax, RAX(%rsp)
+ movq %rdx, RDX(%rsp)
+ movq %rbp, RBP(%rsp)
movq %rsp, %rdi

call ftrace_return_to_handler

movq %rax, %rdi
- movq 8(%rsp), %rdx
- movq (%rsp), %rax
+ movq RDX(%rsp), %rdx
+ movq RAX(%rsp), %rax

- addq $24, %rsp
+ addq $(FRAME_SIZE), %rsp
/*
* Jump back to the old return address. This cannot be JMP_NOSPEC rdi
* since IBT would demand that contain ENDBR, which simply isn't so for
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c86ac786da3d..069f270bd7ae 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -43,9 +43,8 @@ struct dyn_ftrace;

char *arch_ftrace_match_adjust(char *str, const char *search);

-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
-struct fgraph_ret_regs;
-unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs);
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs);
#else
unsigned long ftrace_return_to_handler(unsigned long frame_pointer);
#endif
@@ -134,6 +133,13 @@ extern int ftrace_enabled;
* Also, architecture dependent fields can be used for internal process.
* (e.g. orig_ax on x86_64)
*
+ * Basically, ftrace_regs stores the registers related to the context.
+ * On function entry, registers for function parameters and hooking the
+ * function call are stored, and on function exit, registers for function
+ * return value and frame pointers are stored.
+ *
+ * And also, it dpends on the context that which registers are restored
+ * from the ftrace_regs.
* On the function entry, those registers will be restored except for
* the stack pointer, so that user can change the function parameters
* and instruction pointer (e.g. live patching.)
diff --git a/include/linux/ftrace_regs.h b/include/linux/ftrace_regs.h
index be1ed0c891d0..bbc1873ca6b8 100644
--- a/include/linux/ftrace_regs.h
+++ b/include/linux/ftrace_regs.h
@@ -30,6 +30,8 @@ struct ftrace_regs;
override_function_with_return(&arch_ftrace_regs(fregs)->regs)
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+ frame_pointer(&arch_ftrace_regs(fregs)->regs)

#endif /* HAVE_ARCH_FTRACE_REGS */

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 74c2b1d43bb9..c5ab2a561272 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -31,7 +31,7 @@ config HAVE_FUNCTION_GRAPH_TRACER
help
See Documentation/trace/ftrace-design.rst

-config HAVE_FUNCTION_GRAPH_RETVAL
+config HAVE_FUNCTION_GRAPH_FREGS
bool

config HAVE_DYNAMIC_FTRACE
@@ -232,7 +232,7 @@ config FUNCTION_GRAPH_TRACER

config FUNCTION_GRAPH_RETVAL
bool "Kernel Function Graph Return Value"
- depends on HAVE_FUNCTION_GRAPH_RETVAL
+ depends on HAVE_FUNCTION_GRAPH_FREGS
depends on FUNCTION_GRAPH_TRACER
default n
help
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index b2e3df6cce96..126671cd38e5 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -795,15 +795,12 @@ static struct notifier_block ftrace_suspend_notifier = {
.notifier_call = ftrace_suspend_notifier_call,
};

-/* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */
-struct fgraph_ret_regs;
-
/*
* Send the trace to the ring-buffer.
* @return the original return address.
*/
-static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs,
- unsigned long frame_pointer)
+static inline unsigned long
+__ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointer)
{
struct ftrace_ret_stack *ret_stack;
struct ftrace_graph_ret trace;
@@ -823,7 +820,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs

trace.rettime = trace_clock_local();
#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
- trace.retval = fgraph_ret_regs_return_value(ret_regs);
+ trace.retval = ftrace_regs_get_return_value(fregs);
#endif

bitmap = get_bitmap_bits(current, offset);
@@ -858,14 +855,14 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
}

/*
- * After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can
- * leave only ftrace_return_to_handler(ret_regs).
+ * After all architecures have selected HAVE_FUNCTION_GRAPH_FREGS, we can
+ * leave only ftrace_return_to_handler(fregs).
*/
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
-unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs)
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs)
{
- return __ftrace_return_to_handler(ret_regs,
- fgraph_ret_regs_frame_pointer(ret_regs));
+ return __ftrace_return_to_handler(fregs,
+ ftrace_regs_get_frame_pointer(fregs));
}
#else
unsigned long ftrace_return_to_handler(unsigned long frame_pointer)