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

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8d6088aca7b63247377b6d9e4897d08d935fbe93.1647962456.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2022-03-22 16:40:21 +01:00 committed by Michael Ellerman
parent b033767848
commit 1751289268
1 changed files with 4 additions and 1 deletions
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5
arch/powerpc/lib/code-patching.c
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@ -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);