Unverified Commit 35e61e88 authored by Song Shuai's avatar Song Shuai Committed by Palmer Dabbelt
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riscv: ftrace: Make function graph use ftrace directly 



Similar to commit 0c0593b4 ("x86/ftrace: Make function graph use
ftrace directly") and commit c4a0ebf8 ("arm64/ftrace: Make
function graph use ftrace directly"), RISC-V has no need for a special
graph tracer hook. The graph_ops::func function can be used to install
the return_hooker.

This cleanup only changes the FTRACE_WITH_REGS implementation, leaving
the mcount-based implementation is unaffected.

Perform the simplification, and also cleanup the register save/restore
macros.

Signed-off-by: default avatarSong Shuai <suagrfillet@gmail.com>
Tested-by: default avatarGuo Ren <guoren@kernel.org>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Acked-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20231130121531.1178502-3-bjorn@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent b546d636

arch/riscv/include/asm/ftrace.h

+10 −1
Original line number Diff line number Diff line
@@ -128,7 +128,16 @@ do { \ 
struct dyn_ftrace;

int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);

#define ftrace_init_nop ftrace_init_nop

#endif



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

struct ftrace_ops;

struct ftrace_regs;

void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

		       struct ftrace_ops *op, struct ftrace_regs *fregs);

#define ftrace_graph_func ftrace_graph_func

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */



#endif /* __ASSEMBLY__ */



#endif /* CONFIG_DYNAMIC_FTRACE */

arch/riscv/kernel/ftrace.c

+13 −17
Original line number Diff line number Diff line
@@ -178,32 +178,28 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
}



#ifdef CONFIG_DYNAMIC_FTRACE

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

		       struct ftrace_ops *op, struct ftrace_regs *fregs)

{

	struct pt_regs *regs = arch_ftrace_get_regs(fregs);

	unsigned long *parent = (unsigned long *)&regs->ra;



	prepare_ftrace_return(parent, ip, frame_pointer(regs));

}

#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */

extern void ftrace_graph_call(void);

extern void ftrace_graph_regs_call(void);

int ftrace_enable_ftrace_graph_caller(void)

{

	int ret;



	ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,

				    (unsigned long)&prepare_ftrace_return, true, true);

	if (ret)

		return ret;



	return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,

	return __ftrace_modify_call((unsigned long)&ftrace_graph_call,

				    (unsigned long)&prepare_ftrace_return, true, true);

}



int ftrace_disable_ftrace_graph_caller(void)

{

	int ret;



	ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,

				    (unsigned long)&prepare_ftrace_return, false, true);

	if (ret)

		return ret;



	return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,

	return __ftrace_modify_call((unsigned long)&ftrace_graph_call,

				    (unsigned long)&prepare_ftrace_return, false, true);

}

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */

#endif /* CONFIG_DYNAMIC_FTRACE */

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/riscv/kernel/mcount-dyn.S

+152 −38
Original line number Diff line number Diff line
@@ -57,31 +57,150 @@ 
	.endm



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

	.macro SAVE_ALL



/**

* SAVE_ABI_REGS - save regs against the pt_regs struct

*

* @all: tell if saving all the regs

*

* If all is set, all the regs will be saved, otherwise only ABI

* related regs (a0-a7,epc,ra and optional s0) will be saved.

*

* After the stack is established,

*

* 0(sp) stores the PC of the traced function which can be accessed

* by &(fregs)->regs->epc in tracing function. Note that the real

* function entry address should be computed with -FENTRY_RA_OFFSET.

*

* 8(sp) stores the function return address (i.e. parent IP) that

* can be accessed by &(fregs)->regs->ra in tracing function.

*

* The other regs are saved at the respective localtion and accessed

* by the respective pt_regs member.

*

* Here is the layout of stack for your reference.

*

* PT_SIZE_ON_STACK  ->  +++++++++

*                       + ..... +

*                       + t3-t6 +

*                       + s2-s11+

*                       + a0-a7 + --++++-> ftrace_caller saved

*                       + s1    +   +

*                       + s0    + --+

*                       + t0-t2 +   +

*                       + tp    +   +

*                       + gp    +   +

*                       + sp    +   +

*                       + ra    + --+ // parent IP

*               sp  ->  + epc   + --+ // PC

*                       +++++++++

**/

	.macro SAVE_ABI_REGS, all=0

	addi	sp, sp, -PT_SIZE_ON_STACK



	REG_S	t0,  PT_EPC(sp)

	REG_S	x1,  PT_RA(sp)



	// save the ABI regs



	REG_S	x10, PT_A0(sp)

	REG_S	x11, PT_A1(sp)

	REG_S	x12, PT_A2(sp)

	REG_S	x13, PT_A3(sp)

	REG_S	x14, PT_A4(sp)

	REG_S	x15, PT_A5(sp)

	REG_S	x16, PT_A6(sp)

	REG_S	x17, PT_A7(sp)



	// save the leftover regs



	.if \all == 1

	REG_S	x2, PT_SP(sp)

	REG_S	x3, PT_GP(sp)

	REG_S	x4, PT_TP(sp)

	REG_S	x5, PT_T0(sp)

	save_from_x6_to_x31

	REG_S	x6, PT_T1(sp)

	REG_S	x7, PT_T2(sp)

	REG_S	x8, PT_S0(sp)

	REG_S	x9, PT_S1(sp)

	REG_S	x18, PT_S2(sp)

	REG_S	x19, PT_S3(sp)

	REG_S	x20, PT_S4(sp)

	REG_S	x21, PT_S5(sp)

	REG_S	x22, PT_S6(sp)

	REG_S	x23, PT_S7(sp)

	REG_S	x24, PT_S8(sp)

	REG_S	x25, PT_S9(sp)

	REG_S	x26, PT_S10(sp)

	REG_S	x27, PT_S11(sp)

	REG_S	x28, PT_T3(sp)

	REG_S	x29, PT_T4(sp)

	REG_S	x30, PT_T5(sp)

	REG_S	x31, PT_T6(sp)



	// save s0 if FP_TEST defined



	.else

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	REG_S	x8, PT_S0(sp)

#endif

	.endif

	.endm



	.macro RESTORE_ALL

	.macro RESTORE_ABI_REGS, all=0

	REG_L	t0, PT_EPC(sp)

	REG_L	x1, PT_RA(sp)

	REG_L	x10, PT_A0(sp)

	REG_L	x11, PT_A1(sp)

	REG_L	x12, PT_A2(sp)

	REG_L	x13, PT_A3(sp)

	REG_L	x14, PT_A4(sp)

	REG_L	x15, PT_A5(sp)

	REG_L	x16, PT_A6(sp)

	REG_L	x17, PT_A7(sp)



	.if \all == 1

	REG_L	x2, PT_SP(sp)

	REG_L	x3, PT_GP(sp)

	REG_L	x4, PT_TP(sp)

	/* Restore t0 with PT_EPC */

	REG_L x5,  PT_EPC(sp)

	restore_from_x6_to_x31



	REG_L	x6, PT_T1(sp)

	REG_L	x7, PT_T2(sp)

	REG_L	x8, PT_S0(sp)

	REG_L	x9, PT_S1(sp)

	REG_L	x18, PT_S2(sp)

	REG_L	x19, PT_S3(sp)

	REG_L	x20, PT_S4(sp)

	REG_L	x21, PT_S5(sp)

	REG_L	x22, PT_S6(sp)

	REG_L	x23, PT_S7(sp)

	REG_L	x24, PT_S8(sp)

	REG_L	x25, PT_S9(sp)

	REG_L	x26, PT_S10(sp)

	REG_L	x27, PT_S11(sp)

	REG_L	x28, PT_T3(sp)

	REG_L	x29, PT_T4(sp)

	REG_L	x30, PT_T5(sp)

	REG_L	x31, PT_T6(sp)



	.else

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	REG_L	x8, PT_S0(sp)

#endif

	.endif

	addi	sp, sp, PT_SIZE_ON_STACK

	.endm



	.macro PREPARE_ARGS

	addi	a0, t0, -FENTRY_RA_OFFSET

	la	a1, function_trace_op

	REG_L	a2, 0(a1)

	mv	a1, ra

	mv	a3, sp

	.endm



#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */



#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS

SYM_FUNC_START(ftrace_caller)

	SAVE_ABI
@@ -108,31 +227,26 @@ SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) 
	jr	t0

SYM_FUNC_END(ftrace_caller)



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */

SYM_FUNC_START(ftrace_regs_caller)

	SAVE_ALL



	addi	a0, t0, -FENTRY_RA_OFFSET

	la	a1, function_trace_op

	REG_L	a2, 0(a1)

	mv	a1, ra

	mv	a3, sp

	SAVE_ABI_REGS 1

	PREPARE_ARGS



SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)

	call	ftrace_stub



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	addi	a0, sp, PT_RA

	REG_L	a1, PT_EPC(sp)

	addi	a1, a1, -FENTRY_RA_OFFSET

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	mv	a2, s0

#endif

SYM_INNER_LABEL(ftrace_graph_regs_call, SYM_L_GLOBAL)

	RESTORE_ABI_REGS 1

	jr	t0

SYM_FUNC_END(ftrace_regs_caller)



SYM_FUNC_START(ftrace_caller)

	SAVE_ABI_REGS 0

	PREPARE_ARGS



SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)

	call	ftrace_stub

#endif



	RESTORE_ALL

	RESTORE_ABI_REGS 0

	jr	t0

SYM_FUNC_END(ftrace_regs_caller)

SYM_FUNC_END(ftrace_caller)

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */