Re: [PATCH v8 7/8] LoongArch: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL
From: Donglin Peng
Date: Wed Mar 29 2023 - 00:31:33 EST
On 2023/3/29 12:08, Qing Zhang wrote:
Hi, Donglin
On 2023/3/28 下午9:43, Donglin Peng wrote:
The commit d4815c5d1bbd ("function_graph: Support recording and
printing the return value of function") laid the groundwork for the
for the funcgraph-retval, and this modification makes it available
on the LoongArch platform.
We introduce a new structure called fgraph_ret_regs for the LoongArch
platform to hold return registers and the frame pointer. We then fill
its content in the return_to_handler and pass its address to the
function ftrace_return_to_handler to record the return value.
Signed-off-by: Donglin Peng <pengdonglin@xxxxxxxxxxxxxx>
---
v8:
- Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
---
arch/loongarch/Kconfig | 1 +
arch/loongarch/include/asm/ftrace.h | 18 ++++++++++++++++++
arch/loongarch/kernel/mcount.S | 6 ++++--
arch/loongarch/kernel/mcount_dyn.S | 7 ++++---
4 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 7fd51257e0ed..4bf60132869b 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -99,6 +99,7 @@ config LOONGARCH
select HAVE_FAST_GUP
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_ARG_ACCESS_API
+ select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_GENERIC_VDSO
diff --git a/arch/loongarch/include/asm/ftrace.h
b/arch/loongarch/include/asm/ftrace.h
index 3418d32d4fc7..433c6218888b 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -63,4 +63,22 @@ void ftrace_graph_func(unsigned long ip, unsigned
long parent_ip,
#endif /* CONFIG_FUNCTION_TRACER */
+#ifndef __ASSEMBLY__
+struct fgraph_ret_regs {
+ unsigned long a0;
+ unsigned long a1;
+ unsigned long fp;
+};
This overall looks good, but some places need attention:
This will need to be padded to 16 bytes, as within the kernel,
loongarch requires the SP to be aligned to 16 bytes at all time.
Please can you add an `__unused/padding` field to ensure.
Thank you for pointing out this issue, and I will fix it.
+
+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->fp;
+}
+#endif
+
#endif /* _ASM_LOONGARCH_FTRACE_H */
diff --git a/arch/loongarch/kernel/mcount.S
b/arch/loongarch/kernel/mcount.S
index 8cdc1563cd33..3e405c0212c0 100644
--- a/arch/loongarch/kernel/mcount.S
+++ b/arch/loongarch/kernel/mcount.S
@@ -79,10 +79,12 @@ SYM_FUNC_START(ftrace_graph_caller)
SYM_FUNC_END(ftrace_graph_caller)
SYM_FUNC_START(return_to_handler)
- PTR_ADDI sp, sp, -2 * SZREG
+ PTR_ADDI sp, sp, -3 * SZREG
As above, this will need to be padded to keep the stack aligned to 16
bytes.
PTR_ADDI sp, sp, -4 * SZREG
Thanks.
PTR_S a0, sp, 0
PTR_S a1, sp, SZREG
+ PTR_S zero, sp, 2 * SZREG
+ move a0, sp
bl ftrace_return_to_handler
/* Restore the real parent address: a0 -> ra */
@@ -90,7 +92,7 @@ SYM_FUNC_START(return_to_handler)
PTR_L a0, sp, 0
PTR_L a1, sp, SZREG
- PTR_ADDI sp, sp, 2 * SZREG
+ PTR_ADDI sp, sp, 3 * SZREG
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 bbabf06244c2..ab85a953c6d3 100644
--- a/arch/loongarch/kernel/mcount_dyn.S
+++ b/arch/loongarch/kernel/mcount_dyn.S
@@ -131,18 +131,19 @@ SYM_CODE_END(ftrace_graph_caller)
SYM_CODE_START(return_to_handler)
/* Save return value regs */
- PTR_ADDI sp, sp, -2 * SZREG
+ PTR_ADDI sp, sp, -3 * SZREG
as above.
Thanks.
Thanks,
- Qing
PTR_S a0, sp, 0
PTR_S a1, sp, SZREG
+ PTR_S zero, sp, 2 * SZREG
- move a0, zero
+ move a0, sp
bl ftrace_return_to_handler
move ra, a0
/* Restore return value regs */
PTR_L a0, sp, 0
PTR_L a1, sp, SZREG
- PTR_ADDI sp, sp, 2 * SZREG
+ PTR_ADDI sp, sp, 3 * SZREG
jr ra
SYM_CODE_END(return_to_handler)