[PATCH v1 4/4] powerpc/code-patching: Use jump_label to check if poking_init() is done
From: Christophe Leroy <hidden>
Date: 2022-03-22 15:40:47
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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: Christophe Leroy <redacted> --- arch/powerpc/lib/code-patching.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index ab434c3853c9..8bd74bbe8b8d 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c@@ -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); } static unsigned long get_patch_pfn(void *addr)
@@ -176,7 +179,7 @@ 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);
--
2.35.1