From: Peter Zijlstra <peterz@infradead.org> To: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: kernel test robot <lkp@intel.com>, Steven Rostedt <rostedt@goodmis.org>, LKML <linux-kernel@vger.kernel.org>, x86@kernel.org, lkp@lists.01.org, keescook@chromium.org, hjl.tools@gmail.com Subject: Re: [sched] c3a340f7e7: invalid_opcode:#[##] Date: Tue, 30 Jun 2020 16:11:32 +0200 [thread overview] Message-ID: <20200630141132.GH117543@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20200630140231.GW4817@hirez.programming.kicks-ass.net> On Tue, Jun 30, 2020 at 04:02:31PM +0200, Peter Zijlstra wrote: > On Tue, Jun 30, 2020 at 03:55:05PM +0200, Rasmus Villemoes wrote: > > > > Consistently so with GCC-4.9. Any other GCC I tried does the sane thing. > > > > Does that include gcc 4.8, or is it only "anything newer than 4.9"? > > It includes 4.8 :-) > > > so the section it was put in has an alignment of 64. The generated > > assembly is indeed > > > > .globl fair_sched_class > > .section __fair_sched_class,"a",@progbits > > .align 64 > > > > /me goes brew coffee > > Right.. so I now have the below patch, and with that I get: > > 62931: c1e62c20 0 NOTYPE GLOBAL DEFAULT 2 __begin_sched_classes > 65736: c1e62e40 128 OBJECT GLOBAL DEFAULT 2 stop_sched_class > 71813: c1e62cc0 128 OBJECT GLOBAL DEFAULT 2 fair_sched_class > 78689: c1e62c40 128 OBJECT GLOBAL DEFAULT 2 idle_sched_class > 78953: c1e62ec0 0 NOTYPE GLOBAL DEFAULT 2 __end_sched_classes > 79090: c1e62d40 128 OBJECT GLOBAL DEFAULT 2 rt_sched_class > 79431: c1e62dc0 128 OBJECT GLOBAL DEFAULT 2 dl_sched_class > > > Which has me stumped on __begin_sched_classes being on a 32byte edge > (and crashes differently due to that). > > Argh!! Steve suggested adding a dummy variable before the lot and this actually works... But this just cannot be right :-( --- diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 66fb84c3dc7ee..9c0ee5cf73a50 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -108,6 +108,17 @@ #define SBSS_MAIN .sbss #endif +/* + * Align to a 32 byte boundary equal to the + * alignment gcc 4.5 uses for a struct + */ +#if GCC_VERSION >= 40900 && GCC_VERSION < 50000 +#define STRUCT_ALIGNMENT 64 +#else +#define STRUCT_ALIGNMENT 32 +#endif +#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) + /* * The order of the sched class addresses are important, as they are * used to determine the order of the priority of each sched class in @@ -115,6 +126,7 @@ */ #define SCHED_DATA \ STRUCT_ALIGN(); \ + *(__dummy_sched_class) \ __begin_sched_classes = .; \ *(__idle_sched_class) \ *(__fair_sched_class) \ @@ -123,13 +135,6 @@ *(__stop_sched_class) \ __end_sched_classes = .; -/* - * Align to a 32 byte boundary equal to the - * alignment gcc 4.5 uses for a struct - */ -#define STRUCT_ALIGNMENT 32 -#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) - /* The actual configuration determine if the init/exit sections * are handled as text/data or they can be discarded (which * often happens at runtime) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 81640fe0eae8f..f8535a3438819 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6641,6 +6641,9 @@ static struct kmem_cache *task_group_cache __read_mostly; DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); +const struct sched_class dummy_sched_class + __attribute__((section("__dummy_sched_class"))); + void __init sched_init(void) { unsigned long ptr = 0; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4165c06d1d7bd..33251d0ab62e7 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -67,6 +67,7 @@ #include <linux/tsacct_kern.h> #include <asm/tlb.h> +#include <asm-generic/vmlinux.lds.h> #ifdef CONFIG_PARAVIRT # include <asm/paravirt.h> @@ -1811,7 +1812,7 @@ struct sched_class { #ifdef CONFIG_FAIR_GROUP_SCHED void (*task_change_group)(struct task_struct *p, int type); #endif -} __aligned(32); /* STRUCT_ALIGN(), vmlinux.lds.h */ +} __aligned(STRUCT_ALIGNMENT); /* STRUCT_ALIGN(), vmlinux.lds.h */ static inline void put_prev_task(struct rq *rq, struct task_struct *prev) {
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: lkp@lists.01.org Subject: Re: [sched] c3a340f7e7: invalid_opcode:#[##] Date: Tue, 30 Jun 2020 16:11:32 +0200 [thread overview] Message-ID: <20200630141132.GH117543@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20200630140231.GW4817@hirez.programming.kicks-ass.net> [-- Attachment #1: Type: text/plain, Size: 3921 bytes --] On Tue, Jun 30, 2020 at 04:02:31PM +0200, Peter Zijlstra wrote: > On Tue, Jun 30, 2020 at 03:55:05PM +0200, Rasmus Villemoes wrote: > > > > Consistently so with GCC-4.9. Any other GCC I tried does the sane thing. > > > > Does that include gcc 4.8, or is it only "anything newer than 4.9"? > > It includes 4.8 :-) > > > so the section it was put in has an alignment of 64. The generated > > assembly is indeed > > > > .globl fair_sched_class > > .section __fair_sched_class,"a",@progbits > > .align 64 > > > > /me goes brew coffee > > Right.. so I now have the below patch, and with that I get: > > 62931: c1e62c20 0 NOTYPE GLOBAL DEFAULT 2 __begin_sched_classes > 65736: c1e62e40 128 OBJECT GLOBAL DEFAULT 2 stop_sched_class > 71813: c1e62cc0 128 OBJECT GLOBAL DEFAULT 2 fair_sched_class > 78689: c1e62c40 128 OBJECT GLOBAL DEFAULT 2 idle_sched_class > 78953: c1e62ec0 0 NOTYPE GLOBAL DEFAULT 2 __end_sched_classes > 79090: c1e62d40 128 OBJECT GLOBAL DEFAULT 2 rt_sched_class > 79431: c1e62dc0 128 OBJECT GLOBAL DEFAULT 2 dl_sched_class > > > Which has me stumped on __begin_sched_classes being on a 32byte edge > (and crashes differently due to that). > > Argh!! Steve suggested adding a dummy variable before the lot and this actually works... But this just cannot be right :-( --- diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 66fb84c3dc7ee..9c0ee5cf73a50 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -108,6 +108,17 @@ #define SBSS_MAIN .sbss #endif +/* + * Align to a 32 byte boundary equal to the + * alignment gcc 4.5 uses for a struct + */ +#if GCC_VERSION >= 40900 && GCC_VERSION < 50000 +#define STRUCT_ALIGNMENT 64 +#else +#define STRUCT_ALIGNMENT 32 +#endif +#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) + /* * The order of the sched class addresses are important, as they are * used to determine the order of the priority of each sched class in @@ -115,6 +126,7 @@ */ #define SCHED_DATA \ STRUCT_ALIGN(); \ + *(__dummy_sched_class) \ __begin_sched_classes = .; \ *(__idle_sched_class) \ *(__fair_sched_class) \ @@ -123,13 +135,6 @@ *(__stop_sched_class) \ __end_sched_classes = .; -/* - * Align to a 32 byte boundary equal to the - * alignment gcc 4.5 uses for a struct - */ -#define STRUCT_ALIGNMENT 32 -#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) - /* The actual configuration determine if the init/exit sections * are handled as text/data or they can be discarded (which * often happens@runtime) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 81640fe0eae8f..f8535a3438819 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6641,6 +6641,9 @@ static struct kmem_cache *task_group_cache __read_mostly; DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); +const struct sched_class dummy_sched_class + __attribute__((section("__dummy_sched_class"))); + void __init sched_init(void) { unsigned long ptr = 0; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4165c06d1d7bd..33251d0ab62e7 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -67,6 +67,7 @@ #include <linux/tsacct_kern.h> #include <asm/tlb.h> +#include <asm-generic/vmlinux.lds.h> #ifdef CONFIG_PARAVIRT # include <asm/paravirt.h> @@ -1811,7 +1812,7 @@ struct sched_class { #ifdef CONFIG_FAIR_GROUP_SCHED void (*task_change_group)(struct task_struct *p, int type); #endif -} __aligned(32); /* STRUCT_ALIGN(), vmlinux.lds.h */ +} __aligned(STRUCT_ALIGNMENT); /* STRUCT_ALIGN(), vmlinux.lds.h */ static inline void put_prev_task(struct rq *rq, struct task_struct *prev) {
next prev parent reply other threads:[~2020-06-30 14:11 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-29 0:31 [sched] c3a340f7e7: invalid_opcode:#[##] kernel test robot 2020-06-29 0:31 ` kernel test robot 2020-06-30 12:46 ` Peter Zijlstra 2020-06-30 12:46 ` Peter Zijlstra 2020-06-30 13:55 ` Rasmus Villemoes 2020-06-30 13:55 ` Rasmus Villemoes 2020-06-30 14:02 ` Peter Zijlstra 2020-06-30 14:02 ` Peter Zijlstra 2020-06-30 14:11 ` Peter Zijlstra [this message] 2020-06-30 14:11 ` Peter Zijlstra 2020-06-30 14:35 ` Peter Zijlstra 2020-06-30 14:35 ` Peter Zijlstra 2020-06-30 14:49 ` Peter Zijlstra 2020-06-30 14:49 ` Peter Zijlstra 2020-07-09 8:45 ` [tip: sched/core] sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to 64 bytes for GCC-4.9 tip-bot2 for Peter Zijlstra 2020-10-20 23:39 ` [sched] c3a340f7e7: invalid_opcode:#[##] Florian Fainelli 2020-10-21 8:00 ` GCC section alignment, and GCC-4.9 being a weird one Peter Zijlstra 2020-10-21 13:18 ` Jakub Jelinek 2020-10-21 13:44 ` Peter Zijlstra 2020-10-21 17:42 ` Nick Desaulniers 2020-10-21 17:54 ` Miguel Ojeda 2020-10-21 18:35 ` Joe Perches 2020-10-21 18:35 ` [Linux-kernel-mentees] " Joe Perches 2020-10-21 19:27 ` Miguel Ojeda 2020-10-21 19:27 ` [Linux-kernel-mentees] " Miguel Ojeda 2020-10-22 7:38 ` Peter Zijlstra
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