From 18ed1c01a7dd3d7c780b06a49124da237a4c1790 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 18 Sep 2021 10:44:38 +0200 Subject: ARM: smp: Enable THREAD_INFO_IN_TASK Now that we no longer rely on thread_info living at the base of the task stack to be able to access the 'current' pointer, we can wire up the generic support for moving thread_info into the task struct itself. Note that this requires us to update the cpu field in thread_info explicitly, now that the core code no longer does so. Ideally, we would switch the percpu code to access the cpu field in task_struct instead, but this unleashes #include circular dependency hell. Co-developed-by: Keith Packard Signed-off-by: Keith Packard Signed-off-by: Ard Biesheuvel Reviewed-by: Linus Walleij Tested-by: Amit Daniel Kachhap --- arch/arm/include/asm/assembler.h | 5 +++++ arch/arm/include/asm/switch_to.h | 14 ++++++++++++++ arch/arm/include/asm/thread_info.h | 10 +++++++++- 3 files changed, 28 insertions(+), 1 deletion(-) (limited to 'arch/arm/include/asm') diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index c1551dee28be..7d23d4bb2168 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -227,10 +227,15 @@ * Get current thread_info. */ .macro get_thread_info, rd +#ifdef CONFIG_THREAD_INFO_IN_TASK + /* thread_info is the first member of struct task_struct */ + get_current \rd +#else ARM( mov \rd, sp, lsr #THREAD_SIZE_ORDER + PAGE_SHIFT ) THUMB( mov \rd, sp ) THUMB( lsr \rd, \rd, #THREAD_SIZE_ORDER + PAGE_SHIFT ) mov \rd, \rd, lsl #THREAD_SIZE_ORDER + PAGE_SHIFT +#endif .endm /* diff --git a/arch/arm/include/asm/switch_to.h b/arch/arm/include/asm/switch_to.h index 61e4a3c4ca6e..b55c7b2755e4 100644 --- a/arch/arm/include/asm/switch_to.h +++ b/arch/arm/include/asm/switch_to.h @@ -23,9 +23,23 @@ */ extern struct task_struct *__switch_to(struct task_struct *, struct thread_info *, struct thread_info *); +static inline void set_ti_cpu(struct task_struct *p) +{ +#ifdef CONFIG_THREAD_INFO_IN_TASK + /* + * The core code no longer maintains the thread_info::cpu field once + * CONFIG_THREAD_INFO_IN_TASK is in effect, but we rely on it for + * raw_smp_processor_id(), which cannot access struct task_struct* + * directly for reasons of circular #inclusion hell. + */ + task_thread_info(p)->cpu = task_cpu(p); +#endif +} + #define switch_to(prev,next,last) \ do { \ __complete_pending_tlbi(); \ + set_ti_cpu(next); \ if (IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO)) \ __this_cpu_write(__entry_task, next); \ last = __switch_to(prev,task_thread_info(prev), task_thread_info(next)); \ diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 76b6fbd5540c..787511396f3f 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -54,7 +54,9 @@ struct cpu_context_save { struct thread_info { unsigned long flags; /* low level flags */ int preempt_count; /* 0 => preemptable, <0 => bug */ +#ifndef CONFIG_THREAD_INFO_IN_TASK struct task_struct *task; /* main task structure */ +#endif __u32 cpu; /* cpu */ __u32 cpu_domain; /* cpu domain */ struct cpu_context_save cpu_context; /* cpu context */ @@ -70,11 +72,16 @@ struct thread_info { #define INIT_THREAD_INFO(tsk) \ { \ - .task = &tsk, \ + INIT_THREAD_INFO_TASK(tsk) \ .flags = 0, \ .preempt_count = INIT_PREEMPT_COUNT, \ } +#ifdef CONFIG_THREAD_INFO_IN_TASK +#define INIT_THREAD_INFO_TASK(tsk) +#else +#define INIT_THREAD_INFO_TASK(tsk) .task = &(tsk), + /* * how to get the thread information struct from C */ @@ -85,6 +92,7 @@ static inline struct thread_info *current_thread_info(void) return (struct thread_info *) (current_stack_pointer & ~(THREAD_SIZE - 1)); } +#endif #define thread_saved_pc(tsk) \ ((unsigned long)(task_thread_info(tsk)->cpu_context.pc)) -- cgit v1.2.3-59-g8ed1b