csky: Process management and Signal

This patch adds files related to task_switch, sigcontext, signal,
fpu context switch.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Eric W. Biederman <ebiederm@xmission.com>

5 files changed, 396 insertions, 0 deletions

diff --git a/arch/csky/include/asm/mmu_context.h b/arch/csky/include/asm/mmu_context.h
new file mode 100644
index 000000000000..c410aa4fff1a
--- /dev/null
+++ b/arch/csky/include/asm/mmu_context.h
@@ -0,0 +1,150 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_MMU_CONTEXT_H
+#define __ASM_CSKY_MMU_CONTEXT_H
+
+#include <asm-generic/mm_hooks.h>
+#include <asm/setup.h>
+#include <asm/page.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <abi/ckmmu.h>
+
+static inline void tlbmiss_handler_setup_pgd(unsigned long pgd, bool kernel)
+{
+	pgd &= ~(1<<31);
+	pgd += PHYS_OFFSET;
+	pgd |= 1;
+	setup_pgd(pgd, kernel);
+}
+
+#define TLBMISS_HANDLER_SETUP_PGD(pgd) \
+	tlbmiss_handler_setup_pgd((unsigned long)pgd, 0)
+#define TLBMISS_HANDLER_SETUP_PGD_KERNEL(pgd) \
+	tlbmiss_handler_setup_pgd((unsigned long)pgd, 1)
+
+static inline unsigned long tlb_get_pgd(void)
+{
+	return ((get_pgd()|(1<<31)) - PHYS_OFFSET) & ~1;
+}
+
+#define cpu_context(cpu, mm)	((mm)->context.asid[cpu])
+#define cpu_asid(cpu, mm)	(cpu_context((cpu), (mm)) & ASID_MASK)
+#define asid_cache(cpu)		(cpu_data[cpu].asid_cache)
+
+#define ASID_FIRST_VERSION	(1 << CONFIG_CPU_ASID_BITS)
+#define ASID_INC		0x1
+#define ASID_MASK		(ASID_FIRST_VERSION - 1)
+#define ASID_VERSION_MASK	~ASID_MASK
+
+#define destroy_context(mm)		do {} while (0)
+#define enter_lazy_tlb(mm, tsk)		do {} while (0)
+#define deactivate_mm(tsk, mm)		do {} while (0)
+
+/*
+ *  All unused by hardware upper bits will be considered
+ *  as a software asid extension.
+ */
+static inline void
+get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
+{
+	unsigned long asid = asid_cache(cpu);
+
+	asid += ASID_INC;
+	if (!(asid & ASID_MASK)) {
+		flush_tlb_all();	/* start new asid cycle */
+		if (!asid)		/* fix version if needed */
+			asid = ASID_FIRST_VERSION;
+	}
+	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
+}
+
+/*
+ * Initialize the context related info for a new mm_struct
+ * instance.
+ */
+static inline int
+init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+	int i;
+
+	for_each_online_cpu(i)
+		cpu_context(i, mm) = 0;
+	return 0;
+}
+
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+			struct task_struct *tsk)
+{
+	unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+
+	local_irq_save(flags);
+	/* Check if our ASID is of an older version and thus invalid */
+	if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & ASID_VERSION_MASK)
+		get_new_mmu_context(next, cpu);
+	write_mmu_entryhi(cpu_asid(cpu, next));
+	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
+
+	/*
+	 * Mark current->active_mm as not "active" anymore.
+	 * We don't want to mislead possible IPI tlb flush routines.
+	 */
+	cpumask_clear_cpu(cpu, mm_cpumask(prev));
+	cpumask_set_cpu(cpu, mm_cpumask(next));
+
+	local_irq_restore(flags);
+}
+
+/*
+ * After we have set current->mm to a new value, this activates
+ * the context for the new mm so we see the new mappings.
+ */
+static inline void
+activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+	unsigned long flags;
+	int cpu = smp_processor_id();
+
+	local_irq_save(flags);
+
+	/* Unconditionally get a new ASID.  */
+	get_new_mmu_context(next, cpu);
+
+	write_mmu_entryhi(cpu_asid(cpu, next));
+	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
+
+	/* mark mmu ownership change */
+	cpumask_clear_cpu(cpu, mm_cpumask(prev));
+	cpumask_set_cpu(cpu, mm_cpumask(next));
+
+	local_irq_restore(flags);
+}
+
+/*
+ * If mm is currently active_mm, we can't really drop it. Instead,
+ * we will get a new one for it.
+ */
+static inline void
+drop_mmu_context(struct mm_struct *mm, unsigned int cpu)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (cpumask_test_cpu(cpu, mm_cpumask(mm)))  {
+		get_new_mmu_context(mm, cpu);
+		write_mmu_entryhi(cpu_asid(cpu, mm));
+	} else {
+		/* will get a new context next time */
+		cpu_context(cpu, mm) = 0;
+	}
+
+	local_irq_restore(flags);
+}
+
+#endif /* __ASM_CSKY_MMU_CONTEXT_H */
diff --git a/arch/csky/include/asm/processor.h b/arch/csky/include/asm/processor.h
new file mode 100644
index 000000000000..5ad4f0b83092
--- /dev/null
+++ b/arch/csky/include/asm/processor.h
@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_PROCESSOR_H
+#define __ASM_CSKY_PROCESSOR_H
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+#define current_text_addr() ({ __label__ _l; _l: &&_l; })
+
+#include <linux/bitops.h>
+#include <asm/segment.h>
+#include <asm/ptrace.h>
+#include <asm/current.h>
+#include <asm/cache.h>
+#include <abi/reg_ops.h>
+#include <abi/regdef.h>
+#ifdef CONFIG_CPU_HAS_FPU
+#include <abi/fpu.h>
+#endif
+
+struct cpuinfo_csky {
+	unsigned long udelay_val;
+	unsigned long asid_cache;
+	/*
+	 * Capability and feature descriptor structure for CSKY CPU
+	 */
+	unsigned long options;
+	unsigned int processor_id[4];
+	unsigned int fpu_id;
+} __aligned(SMP_CACHE_BYTES);
+
+extern struct cpuinfo_csky cpu_data[];
+
+/*
+ * User space process size: 2GB. This is hardcoded into a few places,
+ * so don't change it unless you know what you are doing.  TASK_SIZE
+ * for a 64 bit kernel expandable to 8192EB, of which the current CSKY
+ * implementations will "only" be able to use 1TB ...
+ */
+#define TASK_SIZE       0x7fff8000UL
+
+#ifdef __KERNEL__
+#define STACK_TOP       TASK_SIZE
+#define STACK_TOP_MAX   STACK_TOP
+#endif
+
+/* This decides where the kernel will search for a free chunk of vm
+ * space during mmap's.
+ */
+#define TASK_UNMAPPED_BASE      (TASK_SIZE / 3)
+
+struct thread_struct {
+	unsigned long  ksp;       /* kernel stack pointer */
+	unsigned long  sr;        /* saved status register */
+	unsigned long  esp0;      /* points to SR of stack frame */
+	unsigned long  hi;
+	unsigned long  lo;
+
+	/* Other stuff associated with the thread. */
+	unsigned long address;      /* Last user fault */
+	unsigned long error_code;
+
+	/* FPU regs */
+	struct user_fp __aligned(16) user_fp;
+};
+
+#define INIT_THREAD  { \
+	.ksp = (unsigned long) init_thread_union.stack + THREAD_SIZE, \
+	.sr = DEFAULT_PSR_VALUE, \
+}
+
+/*
+ * Do necessary setup to start up a newly executed thread.
+ *
+ * pass the data segment into user programs if it exists,
+ * it can't hurt anything as far as I can tell
+ */
+#define start_thread(_regs, _pc, _usp)					\
+do {									\
+	set_fs(USER_DS); /* reads from user space */			\
+	(_regs)->pc = (_pc);						\
+	(_regs)->regs[1] = 0; /* ABIV1 is R7, uClibc_main rtdl arg */	\
+	(_regs)->regs[2] = 0;						\
+	(_regs)->regs[3] = 0; /* ABIV2 is R7, use it? */		\
+	(_regs)->sr &= ~PS_S;						\
+	(_regs)->usp = (_usp);						\
+} while (0)
+
+/* Forward declaration, a strange C thing */
+struct task_struct;
+
+/* Free all resources held by a thread. */
+static inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+/* Prepare to copy thread state - unlazy all lazy status */
+#define prepare_to_copy(tsk)    do { } while (0)
+
+extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+
+#define copy_segments(tsk, mm)		do { } while (0)
+#define release_segments(mm)		do { } while (0)
+#define forget_segments()		do { } while (0)
+
+extern unsigned long thread_saved_pc(struct task_struct *tsk);
+
+unsigned long get_wchan(struct task_struct *p);
+
+#define KSTK_EIP(tsk)		(task_pt_regs(tsk)->pc)
+#define KSTK_ESP(tsk)		(task_pt_regs(tsk)->usp)
+
+#define task_pt_regs(p) \
+	((struct pt_regs *)(THREAD_SIZE + p->stack) - 1)
+
+#define cpu_relax() barrier()
+
+#endif /* __ASM_CSKY_PROCESSOR_H */
diff --git a/arch/csky/include/asm/switch_to.h b/arch/csky/include/asm/switch_to.h
new file mode 100644
index 000000000000..35a39e88933d
--- /dev/null
+++ b/arch/csky/include/asm/switch_to.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_SWITCH_TO_H
+#define __ASM_CSKY_SWITCH_TO_H
+
+#include <linux/thread_info.h>
+#ifdef CONFIG_CPU_HAS_FPU
+#include <abi/fpu.h>
+static inline void __switch_to_fpu(struct task_struct *prev,
+				   struct task_struct *next)
+{
+	save_to_user_fp(&prev->thread.user_fp);
+	restore_from_user_fp(&next->thread.user_fp);
+}
+#else
+static inline void __switch_to_fpu(struct task_struct *prev,
+				   struct task_struct *next)
+{}
+#endif
+
+/*
+ * Context switching is now performed out-of-line in switch_to.S
+ */
+extern struct task_struct *__switch_to(struct task_struct *,
+				       struct task_struct *);
+
+#define switch_to(prev, next, last)					\
+	do {								\
+		struct task_struct *__prev = (prev);			\
+		struct task_struct *__next = (next);			\
+		__switch_to_fpu(__prev, __next);			\
+		((last) = __switch_to((prev), (next)));			\
+	} while (0)
+
+#endif /* __ASM_CSKY_SWITCH_TO_H */
diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
new file mode 100644
index 000000000000..a2c69a7836f7
--- /dev/null
+++ b/arch/csky/include/asm/thread_info.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef _ASM_CSKY_THREAD_INFO_H
+#define _ASM_CSKY_THREAD_INFO_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/version.h>
+#include <asm/types.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+
+struct thread_info {
+	struct task_struct	*task;
+	void			*dump_exec_domain;
+	unsigned long		flags;
+	int			preempt_count;
+	unsigned long		tp_value;
+	mm_segment_t		addr_limit;
+	struct restart_block	restart_block;
+	struct pt_regs		*regs;
+	unsigned int		cpu;
+};
+
+#define INIT_THREAD_INFO(tsk)			\
+{						\
+	.task		= &tsk,			\
+	.preempt_count  = INIT_PREEMPT_COUNT,	\
+	.addr_limit     = KERNEL_DS,		\
+	.cpu		= 0,			\
+	.restart_block = {			\
+		.fn = do_no_restart_syscall,	\
+	},					\
+}
+
+#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)
+
+static inline struct thread_info *current_thread_info(void)
+{
+	unsigned long sp;
+
+	asm volatile("mov %0, sp\n":"=r"(sp));
+
+	return (struct thread_info *)(sp & ~(THREAD_SIZE - 1));
+}
+
+#endif /* !__ASSEMBLY__ */
+
+/* entry.S relies on these definitions!
+ * bits 0-5 are tested at every exception exit
+ */
+#define TIF_SIGPENDING		0	/* signal pending */
+#define TIF_NOTIFY_RESUME	1       /* callback before returning to user */
+#define TIF_NEED_RESCHED	2	/* rescheduling necessary */
+#define TIF_SYSCALL_TRACE	5	/* syscall trace active */
+#define TIF_DELAYED_TRACE	14	/* single step a syscall */
+#define TIF_POLLING_NRFLAG	16	/* poll_idle() is TIF_NEED_RESCHED */
+#define TIF_MEMDIE		18      /* is terminating due to OOM killer */
+#define TIF_FREEZE		19	/* thread is freezing for suspend */
+#define TIF_RESTORE_SIGMASK	20	/* restore signal mask in do_signal() */
+#define TIF_SECCOMP		21	/* secure computing */
+
+#define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
+#define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
+#define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
+#define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
+#define _TIF_DELAYED_TRACE	(1 << TIF_DELAYED_TRACE)
+#define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
+#define _TIF_MEMDIE		(1 << TIF_MEMDIE)
+#define _TIF_FREEZE             (1 << TIF_FREEZE)
+#define _TIF_RESTORE_SIGMASK    (1 << TIF_RESTORE_SIGMASK)
+#define _TIF_SECCOMP            (1 << TIF_SECCOMP)
+
+#endif	/* _ASM_CSKY_THREAD_INFO_H */
diff --git a/arch/csky/include/uapi/asm/sigcontext.h b/arch/csky/include/uapi/asm/sigcontext.h
new file mode 100644
index 000000000000..e81e7ff11e36
--- /dev/null
+++ b/arch/csky/include/uapi/asm/sigcontext.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_SIGCONTEXT_H
+#define __ASM_CSKY_SIGCONTEXT_H
+
+#include <asm/ptrace.h>
+
+struct sigcontext {
+	struct pt_regs	sc_pt_regs;
+	struct user_fp	sc_user_fp;
+};
+
+#endif /* __ASM_CSKY_SIGCONTEXT_H */