@@ -98,6 +98,7 @@ config ARM
select HAVE_FAST_GUP if ARM_LPAE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_ERROR_INJECTION
+ select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER if !XIP_KERNEL
select HAVE_GCC_PLUGINS
@@ -77,4 +77,26 @@ static inline bool arch_syscall_match_sym_name(const char *sym,
#endif /* ifndef __ASSEMBLY__ */
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
+struct fgraph_ret_regs {
+ unsigned long regs[4];
+ unsigned long fp;
+};
+
+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
+
+#endif
+
#endif /* _ASM_ARM_FTRACE */
@@ -257,11 +257,15 @@ ENDPROC(ftrace_graph_regs_caller)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
+ sub sp, sp, #4
stmdb sp!, {r0-r3}
- add r0, sp, #16 @ sp at exit of instrumented routine
+ add r0, sp, #20 @ sp at exit of instrumented routine
+ str r0, [sp, #16]
+ mov r0, sp
bl ftrace_return_to_handler
mov lr, r0 @ r0 has real ret addr
ldmia sp!, {r0-r3}
+ add sp, sp, #4 @ skip fp
ret lr
ENDPROC(return_to_handler)
#endif
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 ARM platform. We introduce a new structure called fgraph_ret_regs for the ARM 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@sangfor.com.cn> --- arch/arm/Kconfig | 1 + arch/arm/include/asm/ftrace.h | 22 ++++++++++++++++++++++ arch/arm/kernel/entry-ftrace.S | 6 +++++- 3 files changed, 28 insertions(+), 1 deletion(-)