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riscv: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL

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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: Donglin Peng <pengdonglin@sangfor.com.cn>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Donglin Peng 2023-04-08 05:42:19 -07:00 committed by Steven Rostedt (Google)
parent 38638ffa60
commit b97aec082b
3 changed files with 23 additions and 6 deletions
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1
arch/riscv/Kconfig
View File

@ -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

21
arch/riscv/include/asm/ftrace.h
View File

@ -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 */

7
arch/riscv/kernel/mcount.S
View File

@ -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