Commit a5cd1177 authored by Xu Kuohai's avatar Xu Kuohai Committed by Pu Lehui
Browse files

arm64: ftrace: Support direct call for no literal module functions 

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



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

For kernel modules copmiled without DIRECT_CALL, there is no literal
space reserved on the function entry, this patch add support for these
functions.

Signed-off-by: default avatarXu Kuohai <xukuohai@huawei.com>
Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
parent d7a6aa35

arch/arm64/kernel/ftrace.c

+62 −12
Original line number Diff line number Diff line
@@ -117,6 +117,9 @@ enum ftrace_callsite_action { 


static unsigned long ftrace_literal_call_addr(struct dyn_ftrace *rec)

{

	if (rec->arch.func == 0UL)

		return 0UL;



	return rec->arch.func - 2 * AARCH64_INSN_SIZE;

}
@@ -125,6 +128,9 @@ static unsigned long ftrace_literal_addr(struct dyn_ftrace *rec) 
	unsigned long addr = 0;



	addr = ftrace_literal_call_addr(rec);

	if (addr == 0UL)

		return 0UL;



	if (addr % sizeof(long))

		addr -= 3 * AARCH64_INSN_SIZE;

	else
@@ -154,6 +160,9 @@ static int ftrace_init_literal(struct module *mod, struct dyn_ftrace *rec) 
	old = aarch64_insn_gen_nop();



	addr = ftrace_literal_addr(rec);

	if (addr == 0UL)

		return 0UL;



	ftrace_update_literal(addr, 0, FC_INIT);



	pc = ftrace_literal_call_addr(rec);
@@ -222,10 +231,12 @@ static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, 
		unsigned long literal_addr;



		literal_addr = ftrace_literal_addr(rec);

		if (literal_addr != 0UL) {

			ftrace_update_literal(literal_addr, *addr, action);

			*addr = ftrace_literal_call_addr(rec);

			return true;

		}

	}



	/*

	 * When the target is outside of the range of a 'BL' instruction, we
@@ -343,27 +354,51 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) 
}

#endif



static int ftrace_nop_count(unsigned long addr)

{

	u32 insn;

	u32 nop = aarch64_insn_gen_nop();

	int count = 0;



	for (;;) {

		if (aarch64_insn_read((void *)addr, &insn))

			return -1;



		if (insn != nop)

			break;



		count++;

		addr += AARCH64_INSN_SIZE;

	}



	return count;

}



unsigned long ftrace_call_adjust(unsigned long addr)

{

	if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS)) {

		u32 insn;

		u32 nop = aarch64_insn_gen_nop();

		int count = ftrace_nop_count(addr);



		if (count != 5 && count != 7 && count != 2)

			return 0;



		if (count == 5 || count == 7) {

			/* Skip the first 5 NOPS */

			addr += 5 * AARCH64_INSN_SIZE;



			/* Skip bti c */

			if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) {

				if (aarch64_insn_read((void *)addr, &insn))

					return 0;



		if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) {

			if (insn != nop) {

				if (insn != nop)

					addr += AARCH64_INSN_SIZE;

				if (aarch64_insn_read((void *)addr, &insn))

					return 0;

			}

		}



		if (WARN_ON_ONCE(insn != nop))

		if (ftrace_nop_count(addr) != 2)

			return 0;



		return addr + AARCH64_INSN_SIZE;
@@ -421,10 +456,25 @@ void arch_ftrace_update_code(int command) 
	ftrace_modify_all_code(command);

}



bool ftrace_directable(struct dyn_ftrace *rec)

{

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

	return rec->arch.func != 0UL;

#else

	return false;

#endif

}



void ftrace_rec_arch_init(struct dyn_ftrace *rec, unsigned long func)

{

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

	int count;



	count = ftrace_nop_count(func);

	if (count == 5 || count == 7)

		rec->arch.func = func + 5 * AARCH64_INSN_SIZE;

	else

		rec->arch.func = 0UL;

#endif

}

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -280,6 +280,8 @@ struct ftrace_func_entry { 


struct dyn_ftrace;



bool ftrace_directable(struct dyn_ftrace *rec);



#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

extern int ftrace_direct_func_count;

int register_ftrace_direct(unsigned long ip, unsigned long addr);

kernel/trace/ftrace.c

+8 −0
Original line number Diff line number Diff line
@@ -5092,6 +5092,11 @@ static struct ftrace_direct_func *ftrace_alloc_direct_func(unsigned long addr) 
	return direct;

}



bool __weak ftrace_directable(struct dyn_ftrace *rec)

{

	return true;

}



/**

 * register_ftrace_direct - Call a custom trampoline directly

 * @ip: The address of the nop at the beginning of a function
@@ -5133,6 +5138,9 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) 
	if (!rec)

		goto out_unlock;



	if (!ftrace_directable(rec))

		goto out_unlock;



	/*

	 * Check if the rec says it has a direct call but we didn't

	 * find one earlier?