From 071c95c1acbd96e76bab8b25b5cad0d71a011f37 Mon Sep 17 00:00:00 2001 From: Benjamin Gray Date: Wed, 9 Nov 2022 15:51:05 +1100 Subject: [PATCH] powerpc/code-patching: Use WARN_ON and fix check in poking_init BUG_ON() when failing to initialise the code patching window is unnecessary, and use of BUG_ON is discouraged. We don't set poking_init_done in this case, so failure to init the boot CPU will result in a strict RWX error when a following patch_instruction uses raw_patch_instruction. If it only fails for later CPUs, they won't be onlined in the first place. The return value of cpuhp_setup_state() is also >= 0 on success, so check for < 0. Signed-off-by: Benjamin Gray Reviewed-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221109045112.187069-3-bgray@linux.ibm.com --- arch/powerpc/lib/code-patching.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index ad0cf3108dd09..3055eef7dcdcc 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -81,16 +81,17 @@ static int text_area_cpu_down(unsigned int cpu) 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 - * someone tries to use patch_instruction(). - */ 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)); + int ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "powerpc/text_poke:online", + text_area_cpu_up, + text_area_cpu_down); + + /* cpuhp_setup_state returns >= 0 on success */ + if (WARN_ON(ret < 0)) + return; + static_branch_enable(&poking_init_done); } -- 2.30.2