Commit 24d4f527 authored by Youling Tang's avatar Youling Tang Committed by Huacai Chen
Browse files

LoongArch: ftrace: Implement ftrace_find_callable_addr() to simplify code 



In the module processing functions, the same logic can be reused by
implementing ftrace_find_callable_addr().

Signed-off-by: default avatarYouling Tang <tangyouling@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 819cf655

arch/loongarch/kernel/ftrace_dyn.c

+57 −59
Original line number Diff line number Diff line
@@ -31,16 +31,11 @@ static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate) 
}



#ifdef CONFIG_MODULES

static inline int __get_mod(struct module **mod, unsigned long addr)

static bool reachable_by_bl(unsigned long addr, unsigned long pc)

{

	preempt_disable();

	*mod = __module_text_address(addr);

	preempt_enable();



	if (WARN_ON(!(*mod)))

		return -EINVAL;

	long offset = (long)addr - (long)pc;



	return 0;

	return offset >= -SZ_128M && offset < SZ_128M;

}



static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
@@ -56,17 +51,58 @@ static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr) 
	return NULL;

}



static unsigned long get_plt_addr(struct module *mod, unsigned long addr)

/*

 * Find the address the callsite must branch to in order to reach '*addr'.

 *

 * Due to the limited range of 'bl' instruction, modules may be placed too far

 * away to branch directly and we must use a PLT.

 *

 * Returns true when '*addr' contains a reachable target address, or has been

 * modified to contain a PLT address. Returns false otherwise.

 */

static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod, unsigned long *addr)

{

	unsigned long pc = rec->ip + LOONGARCH_INSN_SIZE;

	struct plt_entry *plt;



	plt = get_ftrace_plt(mod, addr);

	/*

	 * When the target is within range of the 'bl' instruction, use 'addr'

	 * as-is and branch to that directly.

	 */

	if (reachable_by_bl(*addr, pc))

		return true;



	/*

	 * 'mod' is only set at module load time, but if we end up

	 * dealing with an out-of-range condition, we can assume it

	 * is due to a module being loaded far away from the kernel.

	 *

	 * NOTE: __module_text_address() must be called with preemption

	 * disabled, but we can rely on ftrace_lock to ensure that 'mod'

	 * retains its validity throughout the remainder of this code.

	 */

	if (!mod) {

		preempt_disable();

		mod = __module_text_address(pc);

		preempt_enable();

	}



	if (WARN_ON(!mod))

		return false;



	plt = get_ftrace_plt(mod, *addr);

	if (!plt) {

		pr_err("ftrace: no module PLT for %ps\n", (void *)addr);

		return -EINVAL;

		pr_err("ftrace: no module PLT for %ps\n", (void *)*addr);

		return false;

	}



	return (unsigned long)plt;

	*addr = (unsigned long)plt;

	return true;

}

#else /* !CONFIG_MODULES */

static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod, unsigned long *addr)

{

	return true;

}

#endif
@@ -75,26 +111,14 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned 
{

	u32 old, new;

	unsigned long pc;

	long offset __maybe_unused;



	pc = rec->ip + LOONGARCH_INSN_SIZE;



#ifdef CONFIG_MODULES

	offset = (long)pc - (long)addr;



	if (offset < -SZ_128M || offset >= SZ_128M) {

		int ret;

		struct module *mod;



		ret = __get_mod(&mod, pc);

		if (ret)

			return ret;



		addr = get_plt_addr(mod, addr);

	if (!ftrace_find_callable_addr(rec, NULL, &addr))

		return -EINVAL;



		old_addr = get_plt_addr(mod, old_addr);

	}

#endif

	if (!ftrace_find_callable_addr(rec, NULL, &old_addr))

		return -EINVAL;



	new = larch_insn_gen_bl(pc, addr);

	old = larch_insn_gen_bl(pc, old_addr);
@@ -151,24 +175,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
{

	u32 old, new;

	unsigned long pc;

	long offset __maybe_unused;



	pc = rec->ip + LOONGARCH_INSN_SIZE;



#ifdef CONFIG_MODULES

	offset = (long)pc - (long)addr;



	if (offset < -SZ_128M || offset >= SZ_128M) {

		int ret;

		struct module *mod;



		ret = __get_mod(&mod, pc);

		if (ret)

			return ret;



		addr = get_plt_addr(mod, addr);

	}

#endif

	if (!ftrace_find_callable_addr(rec, NULL, &addr))

		return -EINVAL;



	old = larch_insn_gen_nop();

	new = larch_insn_gen_bl(pc, addr);
@@ -180,24 +191,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long ad 
{

	u32 old, new;

	unsigned long pc;

	long offset __maybe_unused;



	pc = rec->ip + LOONGARCH_INSN_SIZE;



#ifdef CONFIG_MODULES

	offset = (long)pc - (long)addr;



	if (offset < -SZ_128M || offset >= SZ_128M) {

		int ret;

		struct module *mod;



		ret = __get_mod(&mod, pc);

		if (ret)

			return ret;



		addr = get_plt_addr(mod, addr);

	}

#endif

	if (!ftrace_find_callable_addr(rec, NULL, &addr))

		return -EINVAL;



	new = larch_insn_gen_nop();

	old = larch_insn_gen_bl(pc, addr);