Commit 17512892 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/code-patching: Use jump_label to check if poking_init() is done 



It's only during early startup that poking_init() is not done yet,
for instance when calling ftrace_init().

Once poking_init() has been called there must be a poking area, no
need to check it everytime patch_instruction() is called.

ftrace activation time is reduced by 7% with the change on an 8xx.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8d6088aca7b63247377b6d9e4897d08d935fbe93.1647962456.git.christophe.leroy@csgroup.eu
parent b0337678

arch/powerpc/lib/code-patching.c

+4 −1
Original line number Diff line number Diff line
@@ -79,6 +79,8 @@ static int text_area_cpu_down(unsigned int cpu) 
	return 0;

}



static __ro_after_init DEFINE_STATIC_KEY_FALSE(poking_init_done);



/*

 * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and

 * we judge it as being preferable to a kernel that will crash later when
@@ -89,6 +91,7 @@ void __init poking_init(void) 
	BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,

		"powerpc/text_poke:online", text_area_cpu_up,

		text_area_cpu_down));

	static_branch_enable(&poking_init_done);

}



/*
@@ -171,7 +174,7 @@ static int do_patch_instruction(u32 *addr, ppc_inst_t instr) 
	 * when text_poke_area is not ready, but we still need

	 * to allow patching. We just do the plain old patching

	 */

	if (!this_cpu_read(text_poke_area))

	if (!static_branch_likely(&poking_init_done))

		return raw_patch_instruction(addr, instr);



	local_irq_save(flags);