Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [PATCH v1 4/4] powerpc/code-patching: Use jump_label to check if poking_init() is done | Date | Tue, 22 Mar 2022 16:40:21 +0100 |
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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 <christophe.leroy@csgroup.eu> --- 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
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