Commit d7a6aa35 authored by Xu Kuohai's avatar Xu Kuohai Committed by Pu Lehui
Browse files

arm64: ftrace: Add ftrace direct call support 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9FGRE



--------------------------------

Add ftrace direct support for arm64.

1. When there is custom trampoline only, patch fentry callsite to call
   the custom trampoline directly.

2. When ftrace caller and custom trampoline coexist, jump from fentry to
   ftrace caller first, then jump to custom trampoline when ftrace caller
   exits. As pt_regs->orig_x0 is currently unused by ftrace, its space
   is reused as an intermediary for jumping from ftrace caller to custom
   trampoline.

In short, this patch does the same thing as the x86 commit 562955fe
("ftrace/x86: Add register_ftrace_direct() for custom trampolines").

Signed-off-by: default avatarXu Kuohai <xukuohai@huawei.com>
Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
parent 5f63a133

arch/arm64/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -170,6 +170,8 @@ config ARM64 
	select HAVE_DYNAMIC_FTRACE

	select HAVE_DYNAMIC_FTRACE_WITH_REGS \

		if $(cc-option,-fpatchable-function-entry=2)

	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS \

		if DYNAMIC_FTRACE_WITH_REGS

	select HAVE_EFFICIENT_UNALIGNED_ACCESS

	select HAVE_FAST_GUP

	select HAVE_FTRACE_MCOUNT_RECORD

arch/arm64/include/asm/ftrace.h

+12 −0
Original line number Diff line number Diff line
@@ -56,6 +56,18 @@ extern void return_to_handler(void); 


unsigned long ftrace_call_adjust(unsigned long addr);



#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

static inline void arch_ftrace_set_direct_caller(struct pt_regs *regs,

						 unsigned long addr)

{

	/*

	 * Place custom trampoline address in regs->custom_tramp to let ftrace

	 * trampoline jump to it.

	 */

	regs->orig_x0 = addr;

}

#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS

struct dyn_ftrace;

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

arch/arm64/kernel/asm-offsets.c

+1 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ int main(void) 
  DEFINE(S_SDEI_TTBR1,		offsetof(struct pt_regs, sdei_ttbr1));

  DEFINE(S_PMR_SAVE,		offsetof(struct pt_regs, pmr_save));

  DEFINE(S_STACKFRAME,		offsetof(struct pt_regs, stackframe));

  DEFINE(S_ORIG_X0,		offsetof(struct pt_regs, orig_x0));

  DEFINE(S_FRAME_SIZE,		sizeof(struct pt_regs));

  BLANK();

#ifdef CONFIG_AARCH32_EL0

arch/arm64/kernel/entry-ftrace.S

+15 −3
Original line number Diff line number Diff line
@@ -62,6 +62,9 @@ 
	str	x29, [sp, #S_FP]

	.endif



	/* Set custom_tramp to zero  */

	str     xzr, [sp, #S_ORIG_X0]



	/* Save the callsite's SP and LR */

	add	x10, sp, #(S_FRAME_SIZE + 16)

	stp	x9, x10, [sp, #S_LR]
@@ -125,12 +128,21 @@ ftrace_common_return: 
	/* Restore the callsite's FP, LR, PC */

	ldr	x29, [sp, #S_FP]

	ldr	x30, [sp, #S_LR]

	ldr	x9, [sp, #S_PC]



	ldr	x10, [sp, #S_PC]



	ldr	x11, [sp, #S_ORIG_X0]

	cbz	x11, 1f

	/* Set x9 to parent ip before jump to custom trampoline */

	mov	x9,  x30

	/* Set lr to self ip */

	ldr	x30, [sp, #S_PC]

	/* Set x10 (used for return address) to custom trampoline */

	mov	x10, x11

1:

	/* Restore the callsite's SP */

	add	sp, sp, #S_FRAME_SIZE + 16



	ret	x9

	ret	x10

SYM_CODE_END(ftrace_common)



#ifdef CONFIG_FUNCTION_GRAPH_TRACER