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authorPalmer Dabbelt <palmer@dabbelt.com>2017-07-11 04:04:30 +0300
committerPalmer Dabbelt <palmer@dabbelt.com>2017-09-27 01:26:46 +0300
commit7db91e57a0acde126a162ababfb1e0ab190130cb (patch)
tree1bbfd887d30e00b25318389256fdcb722b1b4785 /arch/riscv/include
parent2129a235c098960c57d4b6ef23be842a98d97ac9 (diff)
downloadlinux-7db91e57a0acde126a162ababfb1e0ab190130cb.tar.xz
RISC-V: Task implementation
This patch contains the implementation of tasks on RISC-V, most of which is involved in task switching. Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Diffstat (limited to 'arch/riscv/include')
-rw-r--r--arch/riscv/include/asm/asm-offsets.h1
-rw-r--r--arch/riscv/include/asm/current.h45
-rw-r--r--arch/riscv/include/asm/kprobes.h22
-rw-r--r--arch/riscv/include/asm/processor.h97
-rw-r--r--arch/riscv/include/asm/switch_to.h69
-rw-r--r--arch/riscv/include/asm/thread_info.h94
6 files changed, 328 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/asm-offsets.h b/arch/riscv/include/asm/asm-offsets.h
new file mode 100644
index 000000000000..d370ee36a182
--- /dev/null
+++ b/arch/riscv/include/asm/asm-offsets.h
@@ -0,0 +1 @@
+#include <generated/asm-offsets.h>
diff --git a/arch/riscv/include/asm/current.h b/arch/riscv/include/asm/current.h
new file mode 100644
index 000000000000..2cf6336ef600
--- /dev/null
+++ b/arch/riscv/include/asm/current.h
@@ -0,0 +1,45 @@
+/*
+ * Based on arm/arm64/include/asm/current.h
+ *
+ * Copyright (C) 2016 ARM
+ * Copyright (C) 2017 SiFive
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+
+#ifndef __ASM_CURRENT_H
+#define __ASM_CURRENT_H
+
+#include <linux/bug.h>
+#include <linux/compiler.h>
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+
+/*
+ * This only works because "struct thread_info" is at offset 0 from "struct
+ * task_struct". This constraint seems to be necessary on other architectures
+ * as well, but __switch_to enforces it. We can't check TASK_TI here because
+ * <asm/asm-offsets.h> includes this, and I can't get the definition of "struct
+ * task_struct" here due to some header ordering problems.
+ */
+static __always_inline struct task_struct *get_current(void)
+{
+ register struct task_struct *tp __asm__("tp");
+ return tp;
+}
+
+#define current get_current()
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_CURRENT_H */
diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h
new file mode 100644
index 000000000000..c7eb010d1528
--- /dev/null
+++ b/arch/riscv/include/asm/kprobes.h
@@ -0,0 +1,22 @@
+/*
+ * Copied from arch/arm64/include/asm/kprobes.h
+ *
+ * Copyright (C) 2013 Linaro Limited
+ * Copyright (C) 2017 SiFive
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef _RISCV_KPROBES_H
+#define _RISCV_KPROBES_H
+
+#include <asm-generic/kprobes.h>
+
+#endif /* _RISCV_KPROBES_H */
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
new file mode 100644
index 000000000000..3fe4af8147d2
--- /dev/null
+++ b/arch/riscv/include/asm/processor.h
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RISCV_PROCESSOR_H
+#define _ASM_RISCV_PROCESSOR_H
+
+#include <linux/const.h>
+
+#include <asm/ptrace.h>
+
+/*
+ * This decides where the kernel will search for a free chunk of vm
+ * space during mmap's.
+ */
+#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE >> 1)
+
+#define STACK_TOP TASK_SIZE
+#define STACK_TOP_MAX STACK_TOP
+#define STACK_ALIGN 16
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+struct pt_regs;
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+#define current_text_addr() ({ __label__ _l; _l: &&_l; })
+
+/* CPU-specific state of a task */
+struct thread_struct {
+ /* Callee-saved registers */
+ unsigned long ra;
+ unsigned long sp; /* Kernel mode stack */
+ unsigned long s[12]; /* s[0]: frame pointer */
+ struct __riscv_d_ext_state fstate;
+};
+
+#define INIT_THREAD { \
+ .sp = sizeof(init_stack) + (long)&init_stack, \
+}
+
+#define task_pt_regs(tsk) \
+ ((struct pt_regs *)(task_stack_page(tsk) + THREAD_SIZE \
+ - ALIGN(sizeof(struct pt_regs), STACK_ALIGN)))
+
+#define KSTK_EIP(tsk) (task_pt_regs(tsk)->sepc)
+#define KSTK_ESP(tsk) (task_pt_regs(tsk)->sp)
+
+
+/* Do necessary setup to start up a newly executed thread. */
+extern void start_thread(struct pt_regs *regs,
+ unsigned long pc, unsigned long sp);
+
+/* Free all resources held by a thread. */
+static inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+extern unsigned long get_wchan(struct task_struct *p);
+
+
+static inline void cpu_relax(void)
+{
+#ifdef __riscv_muldiv
+ int dummy;
+ /* In lieu of a halt instruction, induce a long-latency stall. */
+ __asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy));
+#endif
+ barrier();
+}
+
+static inline void wait_for_interrupt(void)
+{
+ __asm__ __volatile__ ("wfi");
+}
+
+struct device_node;
+extern int riscv_of_processor_hart(struct device_node *node);
+
+extern void riscv_fill_hwcap(void);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_RISCV_PROCESSOR_H */
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
new file mode 100644
index 000000000000..dd6b05bff75b
--- /dev/null
+++ b/arch/riscv/include/asm/switch_to.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RISCV_SWITCH_TO_H
+#define _ASM_RISCV_SWITCH_TO_H
+
+#include <asm/processor.h>
+#include <asm/ptrace.h>
+#include <asm/csr.h>
+
+extern void __fstate_save(struct task_struct *save_to);
+extern void __fstate_restore(struct task_struct *restore_from);
+
+static inline void __fstate_clean(struct pt_regs *regs)
+{
+ regs->sstatus |= (regs->sstatus & ~(SR_FS)) | SR_FS_CLEAN;
+}
+
+static inline void fstate_save(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ if ((regs->sstatus & SR_FS) == SR_FS_DIRTY) {
+ __fstate_save(task);
+ __fstate_clean(regs);
+ }
+}
+
+static inline void fstate_restore(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ if ((regs->sstatus & SR_FS) != SR_FS_OFF) {
+ __fstate_restore(task);
+ __fstate_clean(regs);
+ }
+}
+
+static inline void __switch_to_aux(struct task_struct *prev,
+ struct task_struct *next)
+{
+ struct pt_regs *regs;
+
+ regs = task_pt_regs(prev);
+ if (unlikely(regs->sstatus & SR_SD))
+ fstate_save(prev, regs);
+ fstate_restore(next, task_pt_regs(next));
+}
+
+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_aux(__prev, __next); \
+ ((last) = __switch_to(__prev, __next)); \
+} while (0)
+
+#endif /* _ASM_RISCV_SWITCH_TO_H */
diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
new file mode 100644
index 000000000000..22c3536ed281
--- /dev/null
+++ b/arch/riscv/include/asm/thread_info.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2009 Chen Liqin <liqin.chen@sunplusct.com>
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_RISCV_THREAD_INFO_H
+#define _ASM_RISCV_THREAD_INFO_H
+
+#include <asm/page.h>
+#include <linux/const.h>
+
+/* thread information allocation */
+#define THREAD_SIZE_ORDER (1)
+#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
+
+#ifndef __ASSEMBLY__
+
+#include <asm/processor.h>
+#include <asm/csr.h>
+
+typedef unsigned long mm_segment_t;
+
+/*
+ * low level task data that entry.S needs immediate access to
+ * - this struct should fit entirely inside of one cache line
+ * - if the members of this struct changes, the assembly constants
+ * in asm-offsets.c must be updated accordingly
+ * - thread_info is included in task_struct at an offset of 0. This means that
+ * tp points to both thread_info and task_struct.
+ */
+struct thread_info {
+ unsigned long flags; /* low level flags */
+ int preempt_count; /* 0=>preemptible, <0=>BUG */
+ mm_segment_t addr_limit;
+ /*
+ * These stack pointers are overwritten on every system call or
+ * exception. SP is also saved to the stack it can be recovered when
+ * overwritten.
+ */
+ long kernel_sp; /* Kernel stack pointer */
+ long user_sp; /* User stack pointer */
+ int cpu;
+};
+
+/*
+ * macros/functions for gaining access to the thread information structure
+ *
+ * preempt_count needs to be 1 initially, until the scheduler is functional.
+ */
+#define INIT_THREAD_INFO(tsk) \
+{ \
+ .flags = 0, \
+ .preempt_count = INIT_PREEMPT_COUNT, \
+ .addr_limit = KERNEL_DS, \
+}
+
+#define init_stack (init_thread_union.stack)
+
+#endif /* !__ASSEMBLY__ */
+
+/*
+ * thread information flags
+ * - these are process state flags that various assembly files may need to
+ * access
+ * - pending work-to-be-done flags are in lowest half-word
+ * - other flags in upper half-word(s)
+ */
+#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
+#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
+#define TIF_SIGPENDING 2 /* signal pending */
+#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
+#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
+#define TIF_MEMDIE 5 /* is terminating due to OOM killer */
+#define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
+
+#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
+#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
+#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
+#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
+
+#define _TIF_WORK_MASK \
+ (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED)
+
+#endif /* _ASM_RISCV_THREAD_INFO_H */