[PATCH v9 22/36] function_graph: Replace fgraph_ret_regs with ftrace_regs

From: Masami Hiramatsu (Google)
Date: Mon Apr 15 2024 - 09:11:59 EST

From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

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@xxxxxxxxxx>
---
Changes in v8:
- Newly added.
---
arch/arm64/Kconfig | 2 +-
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 | 24 ++----------------------
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 | 21 ---------------------
arch/riscv/kernel/mcount.S | 24 +++++++++++++-----------
arch/s390/Kconfig | 2 +-
arch/s390/include/asm/ftrace.h | 26 +++++++++-----------------
arch/s390/kernel/asm-offsets.c | 6 ------
arch/s390/kernel/mcount.S | 9 +++++----
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/ftrace.h | 22 ++--------------------
arch/x86/kernel/ftrace_32.S | 15 +++++++++------
arch/x86/kernel/ftrace_64.S | 17 +++++++++--------
include/linux/ftrace.h | 14 +++++++++++---
kernel/trace/Kconfig | 4 ++--
kernel/trace/fgraph.c | 21 +++++++++------------
23 files changed, 117 insertions(+), 206 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b11c98b3e84..8d5047bc13bc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -209,7 +209,7 @@ config ARM64
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_TRACER
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_GCC_PLUGINS
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && \
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c..ac82dc43a57d 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -137,6 +137,12 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
fregs->pc = fregs->lr;
}

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

int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
@@ -194,23 +200,6 @@ 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 81496083c041..81bb6704ff5a 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -200,18 +200,6 @@ 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 a5f300ec6f28..da81053bfa6f 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -123,7 +123,7 @@ 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 b43acfc5776c..14a1576bf948 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -78,6 +78,8 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
override_function_with_return(&(fregs)->regs)
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+ ((fregs)->regs.regs[22])

#define ftrace_graph_func ftrace_graph_func
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
@@ -100,26 +102,4 @@ __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 bee9f7a3108f..714f5b5f1956 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c
@@ -279,18 +279,6 @@ 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 be09c8836d56..b58b8e81b510 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -129,7 +129,7 @@ config RISCV
select HAVE_DYNAMIC_FTRACE_WITH_REGS 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_FAST_GUP if MMU
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 1276d7d9ca8b..9500acf8e156 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -143,25 +143,4 @@ static inline void __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigne

#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 8f01ada6845e..1ed25b72eb47 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -179,7 +179,7 @@ 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 1912b598d1b8..9f8cc6d13bec 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -54,23 +54,6 @@ 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 unsigned long
ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)
{
@@ -97,6 +80,15 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)

+static __always_inline unsigned long
+ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
+{
+ unsigned long *sp;
+
+ sp = (void *)ftrace_regs_get_stack_pointer(fregs);
+ return sp[0]; /* return backchain */
+}
+
#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 fa5f6885c74a..73f8bcf0c873 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -178,12 +178,6 @@ 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, ftrace_regs, regs);
DEFINE(__FTRACE_REGS_SIZE, sizeof(struct ftrace_regs));
return 0;
diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index ae4d4fd9afcd..cda798b976de 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -133,14 +133,15 @@ 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 + backchain on the stack
+ 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)
+ stg %r2,(__SF_GPRS+2*8)(%r15)
+ stg %r15,(__SF_GPRS+15*8)(%r15)
lgr %r2,%r3
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 4fff6ed46e90..96c567714c6b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -224,7 +224,7 @@ config X86
select HAVE_FAST_GUP
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 c88bf47f46da..8d6db2b7d03a 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -72,6 +72,8 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
override_function_with_return(&(fregs)->regs)
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+ frame_pointer(&(fregs)->regs)

struct ftrace_ops;
#define ftrace_graph_func ftrace_graph_func
@@ -156,24 +158,4 @@ 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..4b265884d06c 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -23,6 +23,8 @@ SYM_FUNC_START(__fentry__)
SYM_FUNC_END(__fentry__)
EXPORT_SYMBOL(__fentry__)

+#define FRAME_SIZE PT_OLDSS+4
+
SYM_CODE_START(ftrace_caller)

#ifdef CONFIG_FRAME_POINTER
@@ -187,14 +189,15 @@ SYM_CODE_END(ftrace_graph_caller)

.globl return_to_handler
return_to_handler:
- pushl $0
- pushl %edx
- pushl %eax
+ subl $(FRAME_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 $(FRAME_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 087345ef0d72..0255b95f2d61 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
@@ -135,6 +134,13 @@ 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.)
@@ -192,6 +198,8 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
override_function_with_return(ftrace_get_regs(fregs))
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+ frame_pointer(&(fregs)->regs)
#endif

typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 61c541c36596..cb9c48a4f5bc 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 05845291c4bd..33be5af4801c 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -767,15 +767,12 @@ 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;
@@ -795,7 +792,7 @@ 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_fgraph_index_bitmap(current, index);
@@ -823,14 +820,14 @@ 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)