Commit b97aec08 authored by Donglin Peng's avatar Donglin Peng Committed by Steven Rostedt (Google)
Browse files

riscv: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL 

The previous patch ("function_graph: Support recording and printing
the return value of function") has laid the groundwork for the for
the funcgraph-retval, and this modification makes it available on
the RISC-V platform.

We introduce a new structure called fgraph_ret_regs for the RISC-V
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.

Link: https://lore.kernel.org/linux-trace-kernel/a8d71b12259f90e7e63d0ea654fcac95b0232bbc.1680954589.git.pengdonglin@sangfor.com.cn



Signed-off-by: default avatarDonglin Peng <pengdonglin@sangfor.com.cn>
Acked-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 38638ffa

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ 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_TRACER if !XIP_KERNEL && !PREEMPTION



config CLANG_SUPPORTS_DYNAMIC_FTRACE

arch/riscv/include/asm/ftrace.h

+21 −0
Original line number Diff line number Diff line
@@ -111,4 +111,25 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); 


#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 */

arch/riscv/kernel/mcount.S

+1 −6
Original line number Diff line number Diff line
@@ -65,13 +65,8 @@ ENTRY(return_to_handler) 
 * So alternatively we check the *old* frame pointer position, that is, the

 * value stored in -16(s0) on entry, and the s0 on return.

 */

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	mv	t6, s0

#endif

	SAVE_RET_ABI_STATE

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	mv	a0, t6

#endif

	mv	a0, sp

	call	ftrace_return_to_handler

	mv	a2, a0

	RESTORE_RET_ABI_STATE