From 0b7a66a2c864859fbf9bb16229c03172eef02c05 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 5 Dec 2024 17:06:02 +0100 Subject: [PATCH] preempt: Move PREEMPT_RT before PREEMPT in vermagic. Since the dynamic preemption has been enabled for PREEMPT_RT we have now CONFIG_PREEMPT and CONFIG_PREEMPT_RT set simultaneously. This affects the vermagic strings which comes now PREEMPT with PREEMPT_RT enabled. The PREEMPT_RT module usually can not be loaded on a PREEMPT kernel because some symbols are missing. However if the symbols are fine then it continues and it crashes later. The problem is that the struct module has a different layout and the num_exentries or init members are at a different position leading to a crash later on. This is not necessary caught by the size check in elf_validity_cache_index_mod() because the mem member has an alignment requirement of __module_memory_align which is big enough keep the total size unchanged. Therefore we should keep the string accurate instead of removing it. Move the PREEMPT_RT check before the PREEMPT so that it takes precedence if both symbols are enabled. Fixes: 35772d627b55c ("sched: Enable PREEMPT_DYNAMIC for PREEMPT_RT") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Petr Pavlu Link: https://lore.kernel.org/r/20241205160602.3lIAsJRT@linutronix.de Signed-off-by: Petr Pavlu --- include/linux/vermagic.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h index a54046bf37e5..939ceabcaf06 100644 --- a/include/linux/vermagic.h +++ b/include/linux/vermagic.h @@ -15,10 +15,10 @@ #else #define MODULE_VERMAGIC_SMP "" #endif -#ifdef CONFIG_PREEMPT_BUILD -#define MODULE_VERMAGIC_PREEMPT "preempt " -#elif defined(CONFIG_PREEMPT_RT) +#ifdef CONFIG_PREEMPT_RT #define MODULE_VERMAGIC_PREEMPT "preempt_rt " +#elif defined(CONFIG_PREEMPT_BUILD) +#define MODULE_VERMAGIC_PREEMPT "preempt " #else #define MODULE_VERMAGIC_PREEMPT "" #endif