This patch adds process management support for LoongArch, including:
thread info definition, context switch and process tracing.
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
arch/loongarch/include/asm/fpu.h | 129 +++++++
arch/loongarch/include/asm/idle.h | 9 +
arch/loongarch/include/asm/mmu.h | 16 +
arch/loongarch/include/asm/mmu_context.h | 152 ++++++++
arch/loongarch/include/asm/processor.h | 208 +++++++++++
arch/loongarch/include/asm/ptrace.h | 150 ++++++++
arch/loongarch/include/asm/switch_to.h | 37 ++
arch/loongarch/include/asm/thread_info.h | 116 ++++++
arch/loongarch/include/uapi/asm/ptrace.h | 50 +++
arch/loongarch/kernel/fpu.S | 264 ++++++++++++++
arch/loongarch/kernel/idle.c | 16 +
arch/loongarch/kernel/process.c | 260 ++++++++++++++
arch/loongarch/kernel/ptrace.c | 432 +++++++++++++++++++++++
arch/loongarch/kernel/switch.S | 35 ++
14 files changed, 1874 insertions(+)
create mode 100644 arch/loongarch/include/asm/fpu.h
create mode 100644 arch/loongarch/include/asm/idle.h
create mode 100644 arch/loongarch/include/asm/mmu.h
create mode 100644 arch/loongarch/include/asm/mmu_context.h
create mode 100644 arch/loongarch/include/asm/processor.h
create mode 100644 arch/loongarch/include/asm/ptrace.h
create mode 100644 arch/loongarch/include/asm/switch_to.h
create mode 100644 arch/loongarch/include/asm/thread_info.h
create mode 100644 arch/loongarch/include/uapi/asm/ptrace.h
create mode 100644 arch/loongarch/kernel/fpu.S
create mode 100644 arch/loongarch/kernel/idle.c
create mode 100644 arch/loongarch/kernel/process.c
create mode 100644 arch/loongarch/kernel/ptrace.c
create mode 100644 arch/loongarch/kernel/switch.S
diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h
new file mode 100644
index 000000000000..3e1c6f01aec5
--- /dev/null
+++ b/arch/loongarch/include/asm/fpu.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_FPU_H
+#define _ASM_FPU_H
+
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/ptrace.h>
+#include <linux/thread_info.h>
+#include <linux/bitops.h>
+
+#include <asm/cpu.h>
+#include <asm/cpu-features.h>
+#include <asm/current.h>
+#include <asm/loongarch.h>
+#include <asm/processor.h>
+#include <asm/ptrace.h>
+
+struct sigcontext;
+
+extern void _init_fpu(unsigned int);
+extern void _save_fp(struct loongarch_fpu *);
+extern void _restore_fp(struct loongarch_fpu *);
+
+/*
+ * Mask the FCSR Cause bits according to the Enable bits, observing
+ * that Unimplemented is always enabled.
+ */
+static inline unsigned long mask_fcsr_x(unsigned long fcsr)
+{
+ return fcsr & ((fcsr & FPU_CSR_ALL_E) <<
+ (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)));
+}
+
+static inline int is_fp_enabled(void)
+{
+ return (csr_readl(LOONGARCH_CSR_EUEN) & CSR_EUEN_FPEN) ?
+ 1 : 0;
+}
+
+#define enable_fpu() set_csr_euen(CSR_EUEN_FPEN)
+
+#define disable_fpu() clear_csr_euen(CSR_EUEN_FPEN)
+
+#define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
+
+static inline int is_fpu_owner(void)
+{
+ return test_thread_flag(TIF_USEDFPU);
+}
+
+static inline void __own_fpu(void)
+{
+ enable_fpu();
+ set_thread_flag(TIF_USEDFPU);
+ KSTK_EUEN(current) |= CSR_EUEN_FPEN;
+}
+
+static inline void own_fpu_inatomic(int restore)
+{
+ if (cpu_has_fpu && !is_fpu_owner()) {
+ __own_fpu();
+ if (restore)
+ _restore_fp(¤t->thread.fpu);
+ }
+}
+
+static inline void own_fpu(int restore)
+{
+ preempt_disable();
+ own_fpu_inatomic(restore);
+ preempt_enable();
+}
+
+static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
+{
+ if (is_fpu_owner()) {
+ if (save)
+ _save_fp(&tsk->thread.fpu);
+ disable_fpu();
+ clear_tsk_thread_flag(tsk, TIF_USEDFPU);
+ }
+ KSTK_EUEN(tsk) &= ~(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN);
+}
+
+static inline void lose_fpu(int save)
+{
+ preempt_disable();
+ lose_fpu_inatomic(save, current);
+ preempt_enable();
+}
+
+static inline void init_fpu(void)
+{
+ unsigned int fcsr = current->thread.fpu.fcsr;
+
+ __own_fpu();
+ _init_fpu(fcsr);
+ set_used_math();
+}
+
+static inline void save_fp(struct task_struct *tsk)
+{
+ if (cpu_has_fpu)
+ _save_fp(&tsk->thread.fpu);
+}
+
+static inline void restore_fp(struct task_struct *tsk)
+{
+ if (cpu_has_fpu)
+ _restore_fp(&tsk->thread.fpu);
+}
+
+static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
+{
+ if (tsk == current) {
+ preempt_disable();
+ if (is_fpu_owner())
+ _save_fp(¤t->thread.fpu);
+ preempt_enable();
+ }
+
+ return tsk->thread.fpu.fpr;
+}
+
+#endif /* _ASM_FPU_H */
diff --git a/arch/loongarch/include/asm/idle.h b/arch/loongarch/include/asm/idle.h
new file mode 100644
index 000000000000..f7f2b7dbf958
--- /dev/null
+++ b/arch/loongarch/include/asm/idle.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_IDLE_H
+#define __ASM_IDLE_H
+
+#include <linux/linkage.h>
+
+extern asmlinkage void __arch_cpu_idle(void);
+
+#endif /* __ASM_IDLE_H */
diff --git a/arch/loongarch/include/asm/mmu.h b/arch/loongarch/include/asm/mmu.h
new file mode 100644
index 000000000000..0cc2d0803537
--- /dev/null
+++ b/arch/loongarch/include/asm/mmu.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_MMU_H
+#define __ASM_MMU_H
+
+#include <linux/atomic.h>
+#include <linux/spinlock.h>
+
+typedef struct {
+ u64 asid[NR_CPUS];
+ void *vdso;
+} mm_context_t;
+
+#endif /* __ASM_MMU_H */
diff --git a/arch/loongarch/include/asm/mmu_context.h b/arch/loongarch/include/asm/mmu_context.h
new file mode 100644
index 000000000000..ccd3c8a47cad
--- /dev/null
+++ b/arch/loongarch/include/asm/mmu_context.h
@@ -0,0 +1,152 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Switch a MMU context.
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_MMU_CONTEXT_H
+#define _ASM_MMU_CONTEXT_H
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/mm_types.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm-generic/mm_hooks.h>
+
+/*
+ * All unused by hardware upper bits will be considered
+ * as a software asid extension.
+ */
+static inline u64 asid_version_mask(unsigned int cpu)
+{
+ return ~(u64)(cpu_asid_mask(&cpu_data[cpu]));
+}
+
+static inline u64 asid_first_version(unsigned int cpu)
+{
+ return cpu_asid_mask(&cpu_data[cpu]) + 1;
+}
+
+#define cpu_context(cpu, mm) ((mm)->context.asid[cpu])
+#define asid_cache(cpu) (cpu_data[cpu].asid_cache)
+#define cpu_asid(cpu, mm) (cpu_context((cpu), (mm)) & cpu_asid_mask(&cpu_data[cpu]))
+
+static inline int asid_valid(struct mm_struct *mm, unsigned int cpu)
+{
+ if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) & asid_version_mask(cpu))
+ return 0;
+
+ return 1;
+}
+
+static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+/* Normal, classic get_new_mmu_context */
+static inline void
+get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
+{
+ u64 asid = asid_cache(cpu);
+
+ if (!((++asid) & cpu_asid_mask(&cpu_data[cpu])))
+ local_flush_tlb_user(); /* start new asid cycle */
+
+ 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_possible_cpu(i)
+ cpu_context(i, mm) = 0;
+
+ return 0;
+}
+
+static inline void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ unsigned int cpu = smp_processor_id();
+
+ /* Check if our ASID is of an older version and thus invalid */
+ if (!asid_valid(next, cpu))
+ get_new_mmu_context(next, cpu);
+
+ write_csr_asid(cpu_asid(cpu, next));
+
+ if (next != &init_mm)
+ csr_writeq((unsigned long)next->pgd, LOONGARCH_CSR_PGDL);
+ else
+ csr_writeq((unsigned long)invalid_pg_dir, LOONGARCH_CSR_PGDL);
+
+ /*
+ * Mark current->active_mm as not "active" anymore.
+ * We don't want to mislead possible IPI tlb flush routines.
+ */
+ cpumask_set_cpu(cpu, mm_cpumask(next));
+}
+
+#define switch_mm_irqs_off switch_mm_irqs_off
+
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ switch_mm_irqs_off(prev, next, tsk);
+ local_irq_restore(flags);
+}
+
+/*
+ * Destroy context related info for an mm_struct that is about
+ * to be put to rest.
+ */
+static inline void destroy_context(struct mm_struct *mm)
+{
+}
+
+#define activate_mm(prev, next) switch_mm(prev, next, current)
+#define deactivate_mm(task, mm) do { } while (0)
+
+/*
+ * If mm is currently active, 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)
+{
+ int asid;
+ unsigned long flags;
+
+ local_irq_save(flags);
+
+ asid = read_csr_asid() & cpu_asid_mask(¤t_cpu_data);
+
+ if (asid == cpu_asid(cpu, mm)) {
+ if (!current->mm || (current->mm == mm)) {
+ get_new_mmu_context(mm, cpu);
+ write_csr_asid(cpu_asid(cpu, mm));
+ goto out;
+ }
+ }
+
+ /* Will get a new context next time */
+ cpu_context(cpu, mm) = 0;
+ cpumask_clear_cpu(cpu, mm_cpumask(mm));
+out:
+ local_irq_restore(flags);
+}
+
+#endif /* _ASM_MMU_CONTEXT_H */
diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
new file mode 100644
index 000000000000..5fc32cea8ec7
--- /dev/null
+++ b/arch/loongarch/include/asm/processor.h
@@ -0,0 +1,208 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_PROCESSOR_H
+#define _ASM_PROCESSOR_H
+
+#include <linux/atomic.h>
+#include <linux/cpumask.h>
+#include <linux/sizes.h>
+
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+#include <asm/loongarch.h>
+#include <asm/vdso/processor.h>
+#include <uapi/asm/ptrace.h>
+#include <uapi/asm/sigcontext.h>
+
+#ifdef CONFIG_32BIT
+#define TASK_SIZE 0x80000000UL
+#define STACK_TOP_MAX TASK_SIZE
+
+#define TASK_IS_32BIT_ADDR 1
+
+#endif
+
+#ifdef CONFIG_64BIT
+
+#define TASK_SIZE32 0x100000000UL
+
+#define TASK_SIZE64 (0x1UL << ((cpu_vabits > VA_BITS) ? VA_BITS : cpu_vabits))
+
+#define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64)
+
+#define STACK_TOP_MAX TASK_SIZE64
+
+#define TASK_SIZE_OF(tsk) \
+ (test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64)
+
+#define TASK_IS_32BIT_ADDR test_thread_flag(TIF_32BIT_ADDR)
+
+#endif
+
+#define VDSO_RANDOMIZE_SIZE (TASK_IS_32BIT_ADDR ? SZ_1M : SZ_64M)
+
+unsigned long stack_top(void);
+#define STACK_TOP stack_top()
+
+/*
+ * 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 / 3)
+
+#define FPU_REG_WIDTH 256
+#define FPU_ALIGN __attribute__((aligned(32)))
+
+union fpureg {
+ __u32 val32[FPU_REG_WIDTH / 32];
+ __u64 val64[FPU_REG_WIDTH / 64];
+};
+
+#define FPR_IDX(width, idx) (idx)
+
+#define BUILD_FPR_ACCESS(width) \
+static inline u##width get_fpr##width(union fpureg *fpr, unsigned idx) \
+{ \
+ return fpr->val##width[FPR_IDX(width, idx)]; \
+} \
+ \
+static inline void set_fpr##width(union fpureg *fpr, unsigned int idx, \
+ u##width val) \
+{ \
+ fpr->val##width[FPR_IDX(width, idx)] = val; \
+}
+
+BUILD_FPR_ACCESS(32)
+BUILD_FPR_ACCESS(64)
+
+struct loongarch_fpu {
+ unsigned int fcsr;
+ unsigned int vcsr;
+ uint64_t fcc; /* 8x8 */
+ union fpureg fpr[NUM_FPU_REGS];
+};
+
+#define INIT_CPUMASK { \
+ {0,} \
+}
+
+#define ARCH_MIN_TASKALIGN 32
+
+struct loongarch_vdso_info;
+
+/*
+ * If you change thread_struct remember to change the #defines below too!
+ */
+struct thread_struct {
+ /* Saved main processor registers. */
+ unsigned long reg01, reg03, reg22; /* ra sp fp */
+ unsigned long reg23, reg24, reg25, reg26; /* s0-s3 */
+ unsigned long reg27, reg28, reg29, reg30, reg31; /* s4-s8 */
+
+ /* Saved csr registers */
+ unsigned long csr_prmd;
+ unsigned long csr_crmd;
+ unsigned long csr_euen;
+ unsigned long csr_ecfg;
+ unsigned long csr_badvaddr; /* Last user fault */
+
+ /* Saved scratch registers */
+ unsigned long scr0;
+ unsigned long scr1;
+ unsigned long scr2;
+ unsigned long scr3;
+
+ /* Saved eflags register */
+ unsigned long eflags;
+
+ /* Other stuff associated with the thread. */
+ unsigned long trap_nr;
+ unsigned long error_code;
+ struct loongarch_vdso_info *vdso;
+
+ /*
+ * Saved fpu register stuff, must be at last because
+ * it is conditionally copied at fork.
+ */
+ struct loongarch_fpu fpu FPU_ALIGN;
+};
+
+#define INIT_THREAD { \
+ /* \
+ * Saved main processor registers \
+ */ \
+ .reg01 = 0, \
+ .reg03 = 0, \
+ .reg22 = 0, \
+ .reg23 = 0, \
+ .reg24 = 0, \
+ .reg25 = 0, \
+ .reg26 = 0, \
+ .reg27 = 0, \
+ .reg28 = 0, \
+ .reg29 = 0, \
+ .reg30 = 0, \
+ .reg31 = 0, \
+ .csr_crmd = 0, \
+ .csr_prmd = 0, \
+ .csr_euen = 0, \
+ .csr_ecfg = 0, \
+ .csr_badvaddr = 0, \
+ /* \
+ * Other stuff associated with the process \
+ */ \
+ .trap_nr = 0, \
+ .error_code = 0, \
+ /* \
+ * Saved fpu register stuff \
+ */ \
+ .fpu = { \
+ .fcsr = 0, \
+ .vcsr = 0, \
+ .fcc = 0, \
+ .fpr = {{{0,},},}, \
+ }, \
+}
+
+struct task_struct;
+
+/* Free all resources held by a thread. */
+#define release_thread(thread) do { } while (0)
+
+enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_HALT, IDLE_NOMWAIT, IDLE_POLL};
+
+extern unsigned long boot_option_idle_override;
+/*
+ * Do necessary setup to start up a newly executed thread.
+ */
+extern void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp);
+
+static inline void flush_thread(void)
+{
+}
+
+unsigned long __get_wchan(struct task_struct *p);
+
+#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
+ THREAD_SIZE - 32 - sizeof(struct pt_regs))
+#define task_pt_regs(tsk) ((struct pt_regs *)__KSTK_TOS(tsk))
+#define KSTK_EIP(tsk) (task_pt_regs(tsk)->csr_era)
+#define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[3])
+#define KSTK_EUEN(tsk) (task_pt_regs(tsk)->csr_euen)
+#define KSTK_ECFG(tsk) (task_pt_regs(tsk)->csr_ecfg)
+
+#define return_address() ({__asm__ __volatile__("":::"$1"); __builtin_return_address(0);})
+
+#ifdef CONFIG_CPU_HAS_PREFETCH
+
+#define ARCH_HAS_PREFETCH
+#define prefetch(x) __builtin_prefetch((x), 0, 1)
+
+#define ARCH_HAS_PREFETCHW
+#define prefetchw(x) __builtin_prefetch((x), 1, 1)
+
+#endif
+
+#endif /* _ASM_PROCESSOR_H */
diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/asm/ptrace.h
new file mode 100644
index 000000000000..1fd46d92bc89
--- /dev/null
+++ b/arch/loongarch/include/asm/ptrace.h
@@ -0,0 +1,150 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_PTRACE_H
+#define _ASM_PTRACE_H
+
+#include <asm/page.h>
+#include <asm/thread_info.h>
+#include <uapi/asm/ptrace.h>
+
+/*
+ * This struct defines the way the registers are stored on the stack during
+ * a system call/exception. If you add a register here, please also add it to
+ * regoffset_table[] in arch/loongarch/kernel/ptrace.c.
+ */
+struct pt_regs {
+ /* Saved main processor registers. */
+ unsigned long regs[32];
+
+ /* Saved special registers. */
+ unsigned long orig_a0;
+ unsigned long csr_era;
+ unsigned long csr_badvaddr;
+ unsigned long csr_crmd;
+ unsigned long csr_prmd;
+ unsigned long csr_euen;
+ unsigned long csr_ecfg;
+ unsigned long csr_estat;
+ unsigned long __last[0];
+} __aligned(8);
+
+static inline int regs_irqs_disabled(struct pt_regs *regs)
+{
+ return arch_irqs_disabled_flags(regs->csr_prmd);
+}
+
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+ return regs->regs[3];
+}
+
+/*
+ * Don't use asm-generic/ptrace.h it defines FP accessors that don't make
+ * sense on LoongArch. We rather want an error if they get invoked.
+ */
+
+static inline void instruction_pointer_set(struct pt_regs *regs, unsigned long val)
+{
+ regs->csr_era = val;
+}
+
+/* Query offset/name of register from its name/offset */
+extern int regs_query_register_offset(const char *name);
+#define MAX_REG_OFFSET (offsetof(struct pt_regs, __last))
+
+/**
+ * regs_get_register() - get register value from its offset
+ * @regs: pt_regs from which register value is gotten.
+ * @offset: offset number of the register.
+ *
+ * regs_get_register returns the value of a register. The @offset is the
+ * offset of the register in struct pt_regs address which specified by @regs.
+ * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
+ */
+static inline unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
+{
+ if (unlikely(offset > MAX_REG_OFFSET))
+ return 0;
+
+ return *(unsigned long *)((unsigned long)regs + offset);
+}
+
+/**
+ * regs_within_kernel_stack() - check the address in the stack
+ * @regs: pt_regs which contains kernel stack pointer.
+ * @addr: address which is checked.
+ *
+ * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
+ * If @addr is within the kernel stack, it returns true. If not, returns false.
+ */
+static inline int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
+{
+ return ((addr & ~(THREAD_SIZE - 1)) ==
+ (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
+}
+
+/**
+ * regs_get_kernel_stack_nth() - get Nth entry of the stack
+ * @regs: pt_regs which contains kernel stack pointer.
+ * @n: stack entry number.
+ *
+ * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
+ * is specified by @regs. If the @n th entry is NOT in the kernel stack,
+ * this returns 0.
+ */
+static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
+{
+ unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
+
+ addr += n;
+ if (regs_within_kernel_stack(regs, (unsigned long)addr))
+ return *addr;
+ else
+ return 0;
+}
+
+struct task_struct;
+
+/*
+ * Does the process account for user or for system time?
+ */
+#define user_mode(regs) (((regs)->csr_prmd & PLV_MASK) == PLV_USER)
+
+static inline long regs_return_value(struct pt_regs *regs)
+{
+ return regs->regs[4];
+}
+
+#define instruction_pointer(regs) ((regs)->csr_era)
+#define profile_pc(regs) instruction_pointer(regs)
+
+extern void die(const char *, struct pt_regs *) __noreturn;
+
+static inline void die_if_kernel(const char *str, struct pt_regs *regs)
+{
+ if (unlikely(!user_mode(regs)))
+ die(str, regs);
+}
+
+#define current_pt_regs() \
+({ \
+ unsigned long sp = (unsigned long)__builtin_frame_address(0); \
+ (struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1 - 32) - 1; \
+})
+
+/* Helpers for working with the user stack pointer */
+
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+ return regs->regs[3];
+}
+
+static inline void user_stack_pointer_set(struct pt_regs *regs,
+ unsigned long val)
+{
+ regs->regs[3] = val;
+}
+
+#endif /* _ASM_PTRACE_H */
diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h
new file mode 100644
index 000000000000..2a8d04375574
--- /dev/null
+++ b/arch/loongarch/include/asm/switch_to.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_SWITCH_TO_H
+#define _ASM_SWITCH_TO_H
+
+#include <asm/cpu-features.h>
+#include <asm/fpu.h>
+
+struct task_struct;
+
+/**
+ * __switch_to - switch execution of a task
+ * @prev: The task previously executed.
+ * @next: The task to begin executing.
+ * @next_ti: task_thread_info(next).
+ *
+ * This function is used whilst scheduling to save the context of prev & load
+ * the context of next. Returns prev.
+ */
+extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev,
+ struct task_struct *next, struct thread_info *next_ti);
+
+/*
+ * For newly created kernel threads switch_to() will return to
+ * ret_from_kernel_thread, newly created user threads to ret_from_fork.
+ * That is, everything following __switch_to() will be skipped for new threads.
+ * So everything that matters to new threads should be placed before __switch_to().
+ */
+#define switch_to(prev, next, last) \
+do { \
+ lose_fpu_inatomic(1, prev); \
+ (last) = __switch_to(prev, next, task_thread_info(next)); \
+} while (0)
+
+#endif /* _ASM_SWITCH_TO_H */
diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
new file mode 100644
index 000000000000..a6642b07a64e
--- /dev/null
+++ b/arch/loongarch/include/asm/thread_info.h
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * thread_info.h: LoongArch low-level thread information
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _ASM_THREAD_INFO_H
+#define _ASM_THREAD_INFO_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+
+#include <asm/processor.h>
+
+/*
+ * low level task data that entry.S needs immediate access to
+ * - this struct should fit entirely inside of one cache line
+ * - this struct shares the supervisor stack pages
+ * - if the contents of this structure are changed, the assembly constants
+ * must also be changed
+ */
+struct thread_info {
+ struct task_struct *task; /* main task structure */
+ unsigned long flags; /* low level flags */
+ unsigned long tp_value; /* thread pointer */
+ __u32 cpu; /* current CPU */
+ int preempt_count; /* 0 => preemptible, <0 => BUG */
+ struct pt_regs *regs;
+ unsigned long syscall; /* syscall number */
+ unsigned long syscall_work; /* SYSCALL_WORK_ flags */
+};
+
+/*
+ * macros/functions for gaining access to the thread information structure
+ */
+#define INIT_THREAD_INFO(tsk) \
+{ \
+ .task = &tsk, \
+ .flags = 0, \
+ .cpu = 0, \
+ .preempt_count = INIT_PREEMPT_COUNT, \
+}
+
+/* How to get the thread information struct from C. */
+register struct thread_info *__current_thread_info __asm__("$r2");
+
+static inline struct thread_info *current_thread_info(void)
+{
+ return __current_thread_info;
+}
+
+register unsigned long current_stack_pointer __asm__("$r3");
+
+#endif /* !__ASSEMBLY__ */
+
+/* thread information allocation */
+#ifdef CONFIG_PAGE_SIZE_4KB
+#define THREAD_SIZE_ORDER (2)
+#endif
+#ifdef CONFIG_PAGE_SIZE_16KB
+#define THREAD_SIZE_ORDER (0)
+#endif
+#ifdef CONFIG_PAGE_SIZE_64KB
+#define THREAD_SIZE_ORDER (0)
+#endif
+
+#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
+#define THREAD_MASK (THREAD_SIZE - 1UL)
+
+#define STACK_WARN (THREAD_SIZE / 8)
+
+/*
+ * thread information flags
+ * - these are process state flags that various assembly files may need to
+ * access
+ * - pending work-to-be-done flags are in LSW
+ * - other flags in MSW
+ */
+#define TIF_SIGPENDING 1 /* signal pending */
+#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
+#define TIF_NOTIFY_RESUME 3 /* callback before returning to user */
+#define TIF_NOTIFY_SIGNAL 4 /* signal notifications exist */
+#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
+#define TIF_NOHZ 6 /* in adaptive nohz mode */
+#define TIF_UPROBE 7 /* breakpointed or singlestepping */
+#define TIF_USEDFPU 8 /* FPU was used by this task this quantum (SMP) */
+#define TIF_USEDSIMD 9 /* SIMD has been used this quantum */
+#define TIF_MEMDIE 10 /* is terminating due to OOM killer */
+#define TIF_FIXADE 11 /* Fix address errors in software */
+#define TIF_LOGADE 12 /* Log address errors to syslog */
+#define TIF_32BIT_REGS 13 /* 32-bit general purpose registers */
+#define TIF_32BIT_ADDR 14 /* 32-bit address space */
+#define TIF_LOAD_WATCH 15 /* If set, load watch registers */
+#define TIF_LSX_CTX_LIVE 16 /* LSX context must be preserved */
+#define TIF_LASX_CTX_LIVE 17 /* LASX context must be preserved */
+
+#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
+#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
+#define _TIF_NOTIFY_SIGNAL (1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_NOHZ (1<<TIF_NOHZ)
+#define _TIF_UPROBE (1<<TIF_UPROBE)
+#define _TIF_USEDFPU (1<<TIF_USEDFPU)
+#define _TIF_USEDSIMD (1<<TIF_USEDSIMD)
+#define _TIF_FIXADE (1<<TIF_FIXADE)
+#define _TIF_LOGADE (1<<TIF_LOGADE)
+#define _TIF_32BIT_REGS (1<<TIF_32BIT_REGS)
+#define _TIF_32BIT_ADDR (1<<TIF_32BIT_ADDR)
+#define _TIF_LOAD_WATCH (1<<TIF_LOAD_WATCH)
+#define _TIF_LSX_CTX_LIVE (1<<TIF_LSX_CTX_LIVE)
+#define _TIF_LASX_CTX_LIVE (1<<TIF_LASX_CTX_LIVE)
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_THREAD_INFO_H */
diff --git a/arch/loongarch/include/uapi/asm/ptrace.h b/arch/loongarch/include/uapi/asm/ptrace.h
new file mode 100644
index 000000000000..23685624b108
--- /dev/null
+++ b/arch/loongarch/include/uapi/asm/ptrace.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _UAPI_ASM_PTRACE_H
+#define _UAPI_ASM_PTRACE_H
+
+#include <linux/types.h>
+
+#ifndef __KERNEL__
+#include <stdint.h>
+#endif
+
+/*
+ * For PTRACE_{POKE,PEEK}USR. 0 - 31 are GPRs,
+ * 32 is syscall's original ARG0, 33 is PC, 34 is BADVADDR.
+ */
+#define GPR_BASE 0
+#define GPR_NUM 32
+#define GPR_END (GPR_BASE + GPR_NUM - 1)
+#define ARG0 (GPR_END + 1)
+#define PC (GPR_END + 2)
+#define BADVADDR (GPR_END + 3)
+
+#define NUM_FPU_REGS 32
+
+struct user_pt_regs {
+ /* Saved main processor registers. */
+ unsigned long regs[32];
+
+ /* Saved special registers. */
+ unsigned long orig_a0;
+ unsigned long csr_era;
+ unsigned long csr_badv;
+ unsigned long reserved[10];
+} __attribute__((aligned(8)));
+
+struct user_fp_state {
+ uint64_t fpr[32];
+ uint64_t fcc;
+ uint32_t fcsr;
+};
+
+#define PTRACE_SYSEMU 0x1f
+#define PTRACE_SYSEMU_SINGLESTEP 0x20
+
+#endif /* _UAPI_ASM_PTRACE_H */
diff --git a/arch/loongarch/kernel/fpu.S b/arch/loongarch/kernel/fpu.S
new file mode 100644
index 000000000000..7ff9b91043b1
--- /dev/null
+++ b/arch/loongarch/kernel/fpu.S
@@ -0,0 +1,264 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Lu Zeng <zenglu@xxxxxxxxxxx>
+ * Pei Huang <huangpei@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/export.h>
+#include <asm/fpregdef.h>
+#include <asm/loongarch.h>
+#include <asm/regdef.h>
+
+#undef v0
+#undef v1
+
+#define FPU_REG_WIDTH 8
+#define LSX_REG_WIDTH 16
+#define LASX_REG_WIDTH 32
+
+ .macro EX insn, reg, src, offs
+.ex\@: \insn \reg, \src, \offs
+ .section __ex_table,"a"
+ PTR .ex\@, fault
+ .previous
+ .endm
+
+ .macro sc_save_fp base
+ EX fst.d $f0, \base, (0 * FPU_REG_WIDTH)
+ EX fst.d $f1, \base, (1 * FPU_REG_WIDTH)
+ EX fst.d $f2, \base, (2 * FPU_REG_WIDTH)
+ EX fst.d $f3, \base, (3 * FPU_REG_WIDTH)
+ EX fst.d $f4, \base, (4 * FPU_REG_WIDTH)
+ EX fst.d $f5, \base, (5 * FPU_REG_WIDTH)
+ EX fst.d $f6, \base, (6 * FPU_REG_WIDTH)
+ EX fst.d $f7, \base, (7 * FPU_REG_WIDTH)
+ EX fst.d $f8, \base, (8 * FPU_REG_WIDTH)
+ EX fst.d $f9, \base, (9 * FPU_REG_WIDTH)
+ EX fst.d $f10, \base, (10 * FPU_REG_WIDTH)
+ EX fst.d $f11, \base, (11 * FPU_REG_WIDTH)
+ EX fst.d $f12, \base, (12 * FPU_REG_WIDTH)
+ EX fst.d $f13, \base, (13 * FPU_REG_WIDTH)
+ EX fst.d $f14, \base, (14 * FPU_REG_WIDTH)
+ EX fst.d $f15, \base, (15 * FPU_REG_WIDTH)
+ EX fst.d $f16, \base, (16 * FPU_REG_WIDTH)
+ EX fst.d $f17, \base, (17 * FPU_REG_WIDTH)
+ EX fst.d $f18, \base, (18 * FPU_REG_WIDTH)
+ EX fst.d $f19, \base, (19 * FPU_REG_WIDTH)
+ EX fst.d $f20, \base, (20 * FPU_REG_WIDTH)
+ EX fst.d $f21, \base, (21 * FPU_REG_WIDTH)
+ EX fst.d $f22, \base, (22 * FPU_REG_WIDTH)
+ EX fst.d $f23, \base, (23 * FPU_REG_WIDTH)
+ EX fst.d $f24, \base, (24 * FPU_REG_WIDTH)
+ EX fst.d $f25, \base, (25 * FPU_REG_WIDTH)
+ EX fst.d $f26, \base, (26 * FPU_REG_WIDTH)
+ EX fst.d $f27, \base, (27 * FPU_REG_WIDTH)
+ EX fst.d $f28, \base, (28 * FPU_REG_WIDTH)
+ EX fst.d $f29, \base, (29 * FPU_REG_WIDTH)
+ EX fst.d $f30, \base, (30 * FPU_REG_WIDTH)
+ EX fst.d $f31, \base, (31 * FPU_REG_WIDTH)
+ .endm
+
+ .macro sc_restore_fp base
+ EX fld.d $f0, \base, (0 * FPU_REG_WIDTH)
+ EX fld.d $f1, \base, (1 * FPU_REG_WIDTH)
+ EX fld.d $f2, \base, (2 * FPU_REG_WIDTH)
+ EX fld.d $f3, \base, (3 * FPU_REG_WIDTH)
+ EX fld.d $f4, \base, (4 * FPU_REG_WIDTH)
+ EX fld.d $f5, \base, (5 * FPU_REG_WIDTH)
+ EX fld.d $f6, \base, (6 * FPU_REG_WIDTH)
+ EX fld.d $f7, \base, (7 * FPU_REG_WIDTH)
+ EX fld.d $f8, \base, (8 * FPU_REG_WIDTH)
+ EX fld.d $f9, \base, (9 * FPU_REG_WIDTH)
+ EX fld.d $f10, \base, (10 * FPU_REG_WIDTH)
+ EX fld.d $f11, \base, (11 * FPU_REG_WIDTH)
+ EX fld.d $f12, \base, (12 * FPU_REG_WIDTH)
+ EX fld.d $f13, \base, (13 * FPU_REG_WIDTH)
+ EX fld.d $f14, \base, (14 * FPU_REG_WIDTH)
+ EX fld.d $f15, \base, (15 * FPU_REG_WIDTH)
+ EX fld.d $f16, \base, (16 * FPU_REG_WIDTH)
+ EX fld.d $f17, \base, (17 * FPU_REG_WIDTH)
+ EX fld.d $f18, \base, (18 * FPU_REG_WIDTH)
+ EX fld.d $f19, \base, (19 * FPU_REG_WIDTH)
+ EX fld.d $f20, \base, (20 * FPU_REG_WIDTH)
+ EX fld.d $f21, \base, (21 * FPU_REG_WIDTH)
+ EX fld.d $f22, \base, (22 * FPU_REG_WIDTH)
+ EX fld.d $f23, \base, (23 * FPU_REG_WIDTH)
+ EX fld.d $f24, \base, (24 * FPU_REG_WIDTH)
+ EX fld.d $f25, \base, (25 * FPU_REG_WIDTH)
+ EX fld.d $f26, \base, (26 * FPU_REG_WIDTH)
+ EX fld.d $f27, \base, (27 * FPU_REG_WIDTH)
+ EX fld.d $f28, \base, (28 * FPU_REG_WIDTH)
+ EX fld.d $f29, \base, (29 * FPU_REG_WIDTH)
+ EX fld.d $f30, \base, (30 * FPU_REG_WIDTH)
+ EX fld.d $f31, \base, (31 * FPU_REG_WIDTH)
+ .endm
+
+ .macro sc_save_fcc base, tmp0, tmp1
+ movcf2gr \tmp0, $fcc0
+ move \tmp1, \tmp0
+ movcf2gr \tmp0, $fcc1
+ bstrins.d \tmp1, \tmp0, 15, 8
+ movcf2gr \tmp0, $fcc2
+ bstrins.d \tmp1, \tmp0, 23, 16
+ movcf2gr \tmp0, $fcc3
+ bstrins.d \tmp1, \tmp0, 31, 24
+ movcf2gr \tmp0, $fcc4
+ bstrins.d \tmp1, \tmp0, 39, 32
+ movcf2gr \tmp0, $fcc5
+ bstrins.d \tmp1, \tmp0, 47, 40
+ movcf2gr \tmp0, $fcc6
+ bstrins.d \tmp1, \tmp0, 55, 48
+ movcf2gr \tmp0, $fcc7
+ bstrins.d \tmp1, \tmp0, 63, 56
+ EX st.d \tmp1, \base, 0
+ .endm
+
+ .macro sc_restore_fcc base, tmp0, tmp1
+ EX ld.d \tmp0, \base, 0
+ bstrpick.d \tmp1, \tmp0, 7, 0
+ movgr2cf $fcc0, \tmp1
+ bstrpick.d \tmp1, \tmp0, 15, 8
+ movgr2cf $fcc1, \tmp1
+ bstrpick.d \tmp1, \tmp0, 23, 16
+ movgr2cf $fcc2, \tmp1
+ bstrpick.d \tmp1, \tmp0, 31, 24
+ movgr2cf $fcc3, \tmp1
+ bstrpick.d \tmp1, \tmp0, 39, 32
+ movgr2cf $fcc4, \tmp1
+ bstrpick.d \tmp1, \tmp0, 47, 40
+ movgr2cf $fcc5, \tmp1
+ bstrpick.d \tmp1, \tmp0, 55, 48
+ movgr2cf $fcc6, \tmp1
+ bstrpick.d \tmp1, \tmp0, 63, 56
+ movgr2cf $fcc7, \tmp1
+ .endm
+
+ .macro sc_save_fcsr base, tmp0
+ movfcsr2gr \tmp0, fcsr0
+ EX st.w \tmp0, \base, 0
+ .endm
+
+ .macro sc_restore_fcsr base, tmp0
+ EX ld.w \tmp0, \base, 0
+ movgr2fcsr fcsr0, \tmp0
+ .endm
+
+ .macro sc_save_vcsr base, tmp0
+ movfcsr2gr \tmp0, vcsr16
+ EX st.w \tmp0, \base, 0
+ .endm
+
+ .macro sc_restore_vcsr base, tmp0
+ EX ld.w \tmp0, \base, 0
+ movgr2fcsr vcsr16, \tmp0
+ .endm
+
+/*
+ * Save a thread's fp context.
+ */
+SYM_FUNC_START(_save_fp)
+ fpu_save_csr a0 t1
+ fpu_save_double a0 t1 # clobbers t1
+ fpu_save_cc a0 t1 t2 # clobbers t1, t2
+ jirl zero, ra, 0
+SYM_FUNC_END(_save_fp)
+EXPORT_SYMBOL(_save_fp)
+
+/*
+ * Restore a thread's fp context.
+ */
+SYM_FUNC_START(_restore_fp)
+ fpu_restore_double a0 t1 # clobbers t1
+ fpu_restore_csr a0 t1
+ fpu_restore_cc a0 t1 t2 # clobbers t1, t2
+ jirl zero, ra, 0
+SYM_FUNC_END(_restore_fp)
+
+/*
+ * Load the FPU with signalling NANS. This bit pattern we're using has
+ * the property that no matter whether considered as single or as double
+ * precision represents signaling NANS.
+ *
+ * The value to initialize fcsr0 to comes in $a0.
+ */
+
+SYM_FUNC_START(_init_fpu)
+ li.w t1, CSR_EUEN_FPEN
+ csrxchg t1, t1, LOONGARCH_CSR_EUEN
+
+ movgr2fcsr fcsr0, a0
+
+ li.w t1, -1 # SNaN
+
+ movgr2fr.d $f0, t1
+ movgr2fr.d $f1, t1
+ movgr2fr.d $f2, t1
+ movgr2fr.d $f3, t1
+ movgr2fr.d $f4, t1
+ movgr2fr.d $f5, t1
+ movgr2fr.d $f6, t1
+ movgr2fr.d $f7, t1
+ movgr2fr.d $f8, t1
+ movgr2fr.d $f9, t1
+ movgr2fr.d $f10, t1
+ movgr2fr.d $f11, t1
+ movgr2fr.d $f12, t1
+ movgr2fr.d $f13, t1
+ movgr2fr.d $f14, t1
+ movgr2fr.d $f15, t1
+ movgr2fr.d $f16, t1
+ movgr2fr.d $f17, t1
+ movgr2fr.d $f18, t1
+ movgr2fr.d $f19, t1
+ movgr2fr.d $f20, t1
+ movgr2fr.d $f21, t1
+ movgr2fr.d $f22, t1
+ movgr2fr.d $f23, t1
+ movgr2fr.d $f24, t1
+ movgr2fr.d $f25, t1
+ movgr2fr.d $f26, t1
+ movgr2fr.d $f27, t1
+ movgr2fr.d $f28, t1
+ movgr2fr.d $f29, t1
+ movgr2fr.d $f30, t1
+ movgr2fr.d $f31, t1
+
+ jirl zero, ra, 0
+SYM_FUNC_END(_init_fpu)
+
+/*
+ * a0: fpregs
+ * a1: fcc
+ * a2: fcsr
+ */
+SYM_FUNC_START(_save_fp_context)
+ sc_save_fcc a1 t1 t2
+ sc_save_fcsr a2 t1
+ sc_save_fp a0
+ li.w a0, 0 # success
+ jirl zero, ra, 0
+SYM_FUNC_END(_save_fp_context)
+
+/*
+ * a0: fpregs
+ * a1: fcc
+ * a2: fcsr
+ */
+SYM_FUNC_START(_restore_fp_context)
+ sc_restore_fp a0
+ sc_restore_fcc a1 t1 t2
+ sc_restore_fcsr a2 t1
+ li.w a0, 0 # success
+ jirl zero, ra, 0
+SYM_FUNC_END(_restore_fp_context)
+
+SYM_FUNC_START(fault)
+ li.w a0, -EFAULT # failure
+ jirl zero, ra, 0
+SYM_FUNC_END(fault)
diff --git a/arch/loongarch/kernel/idle.c b/arch/loongarch/kernel/idle.c
new file mode 100644
index 000000000000..1a65d0527d25
--- /dev/null
+++ b/arch/loongarch/kernel/idle.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * LoongArch idle loop support.
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <linux/cpu.h>
+#include <linux/irqflags.h>
+#include <asm/cpu.h>
+#include <asm/idle.h>
+
+void __cpuidle arch_cpu_idle(void)
+{
+ raw_local_irq_enable();
+ __arch_cpu_idle(); /* idle instruction needs irq enabled */
+}
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
new file mode 100644
index 000000000000..8ac0dcf18be3
--- /dev/null
+++ b/arch/loongarch/kernel/process.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ *
+ * Derived from MIPS:
+ * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
+ * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@xxxxxxxxxxxxxx)
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2004 Thiemo Seufer
+ * Copyright (C) 2013 Imagination Technologies Ltd.
+ */
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+#include <linux/mm.h>
+#include <linux/stddef.h>
+#include <linux/unistd.h>
+#include <linux/export.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/personality.h>
+#include <linux/sys.h>
+#include <linux/completion.h>
+#include <linux/kallsyms.h>
+#include <linux/random.h>
+#include <linux/prctl.h>
+#include <linux/nmi.h>
+
+#include <asm/asm.h>
+#include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/elf.h>
+#include <asm/fpu.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/irq_regs.h>
+#include <asm/loongarch.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/reg.h>
+#include <asm/vdso.h>
+
+/*
+ * Idle related variables and functions
+ */
+
+unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
+EXPORT_SYMBOL(boot_option_idle_override);
+
+asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
+
+void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
+{
+ unsigned long crmd;
+ unsigned long prmd;
+ unsigned long euen;
+
+ /* New thread loses kernel privileges. */
+ crmd = regs->csr_crmd & ~(PLV_MASK);
+ crmd |= PLV_USER;
+ regs->csr_crmd = crmd;
+
+ prmd = regs->csr_prmd & ~(PLV_MASK);
+ prmd |= PLV_USER;
+ regs->csr_prmd = prmd;
+
+ euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
+ regs->csr_euen = euen;
+ lose_fpu(0);
+
+ clear_thread_flag(TIF_LSX_CTX_LIVE);
+ clear_thread_flag(TIF_LASX_CTX_LIVE);
+ clear_used_math();
+ regs->csr_era = pc;
+ regs->regs[3] = sp;
+}
+
+void exit_thread(struct task_struct *tsk)
+{
+}
+
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
+{
+ /*
+ * Save any process state which is live in hardware registers to the
+ * parent context prior to duplication. This prevents the new child
+ * state becoming stale if the parent is preempted before copy_thread()
+ * gets a chance to save the parent's live hardware registers to the
+ * child context.
+ */
+ preempt_disable();
+
+ if (is_fpu_owner())
+ save_fp(current);
+
+ preempt_enable();
+
+ if (used_math())
+ memcpy(dst, src, sizeof(struct task_struct));
+ else
+ memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
+
+ return 0;
+}
+
+/*
+ * Copy architecture-specific thread state
+ */
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+ unsigned long kthread_arg, struct task_struct *p, unsigned long tls)
+{
+ unsigned long childksp;
+ struct pt_regs *childregs, *regs = current_pt_regs();
+
+ childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
+
+ /* set up new TSS. */
+ childregs = (struct pt_regs *) childksp - 1;
+ /* Put the stack after the struct pt_regs. */
+ childksp = (unsigned long) childregs;
+ p->thread.csr_euen = 0;
+ p->thread.csr_crmd = csr_readl(LOONGARCH_CSR_CRMD);
+ p->thread.csr_prmd = csr_readl(LOONGARCH_CSR_PRMD);
+ p->thread.csr_ecfg = csr_readl(LOONGARCH_CSR_ECFG);
+ if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ /* kernel thread */
+ p->thread.reg23 = usp; /* fn */
+ p->thread.reg24 = kthread_arg;
+ p->thread.reg03 = childksp;
+ p->thread.reg01 = (unsigned long) ret_from_kernel_thread;
+ memset(childregs, 0, sizeof(struct pt_regs));
+ childregs->csr_euen = p->thread.csr_euen;
+ childregs->csr_crmd = p->thread.csr_crmd;
+ childregs->csr_prmd = p->thread.csr_prmd;
+ childregs->csr_ecfg = p->thread.csr_ecfg;
+ return 0;
+ }
+
+ /* user thread */
+ *childregs = *regs;
+ childregs->regs[4] = 0; /* Child gets zero as return value */
+ if (usp)
+ childregs->regs[3] = usp;
+
+ p->thread.reg03 = (unsigned long) childregs;
+ p->thread.reg01 = (unsigned long) ret_from_fork;
+
+ /*
+ * New tasks lose permission to use the fpu. This accelerates context
+ * switching for most programs since they don't use the fpu.
+ */
+ childregs->csr_euen = 0;
+
+ clear_tsk_thread_flag(p, TIF_USEDFPU);
+ clear_tsk_thread_flag(p, TIF_USEDSIMD);
+ clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
+ clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
+
+ if (clone_flags & CLONE_SETTLS)
+ childregs->regs[2] = tls;
+
+ return 0;
+}
+
+unsigned long __get_wchan(struct task_struct *task)
+{
+ return 0;
+}
+
+unsigned long stack_top(void)
+{
+ unsigned long top = TASK_SIZE & PAGE_MASK;
+
+ /* Space for the VDSO & data page */
+ top -= PAGE_ALIGN(current->thread.vdso->size);
+ top -= PAGE_SIZE;
+
+ /* Space to randomize the VDSO base */
+ if (current->flags & PF_RANDOMIZE)
+ top -= VDSO_RANDOMIZE_SIZE;
+
+ return top;
+}
+
+/*
+ * Don't forget that the stack pointer must be aligned on a 8 bytes
+ * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
+ */
+unsigned long arch_align_stack(unsigned long sp)
+{
+ if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+ sp -= get_random_int() & ~PAGE_MASK;
+
+ return sp & ALMASK;
+}
+
+static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
+static struct cpumask backtrace_csd_busy;
+
+static void handle_backtrace(void *info)
+{
+ nmi_cpu_backtrace(get_irq_regs());
+ cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
+}
+
+static void raise_backtrace(cpumask_t *mask)
+{
+ call_single_data_t *csd;
+ int cpu;
+
+ for_each_cpu(cpu, mask) {
+ /*
+ * If we previously sent an IPI to the target CPU & it hasn't
+ * cleared its bit in the busy cpumask then it didn't handle
+ * our previous IPI & it's not safe for us to reuse the
+ * call_single_data_t.
+ */
+ if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
+ pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
+ cpu);
+ continue;
+ }
+
+ csd = &per_cpu(backtrace_csd, cpu);
+ csd->func = handle_backtrace;
+ smp_call_function_single_async(cpu, csd);
+ }
+}
+
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+ nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
+}
+
+#ifdef CONFIG_64BIT
+void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
+{
+ unsigned int i;
+
+ for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
+ uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
+ }
+
+ uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
+ uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
+ uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
+ uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
+ uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
+ uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
+ uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
+ uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
+}
+#endif /* CONFIG_64BIT */
diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
new file mode 100644
index 000000000000..40250fe9cc2d
--- /dev/null
+++ b/arch/loongarch/kernel/ptrace.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ *
+ * Derived from MIPS:
+ * Copyright (C) 1992 Ross Biro
+ * Copyright (C) Linus Torvalds
+ * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
+ * Copyright (C) 1996 David S. Miller
+ * Kevin D. Kissell, kevink@xxxxxxxx and Carsten Langgaard, carstenl@xxxxxxxx
+ * Copyright (C) 1999 MIPS Technologies, Inc.
+ * Copyright (C) 2000 Ulf Carlsson
+ */
+#include <linux/kernel.h>
+#include <linux/audit.h>
+#include <linux/compiler.h>
+#include <linux/context_tracking.h>
+#include <linux/elf.h>
+#include <linux/errno.h>
+#include <linux/ftrace.h>
+#include <linux/mm.h>
+#include <linux/ptrace.h>
+#include <linux/regset.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/security.h>
+#include <linux/smp.h>
+#include <linux/stddef.h>
+#include <linux/seccomp.h>
+#include <linux/tracehook.h>
+#include <linux/uaccess.h>
+
+#include <asm/abidefs.h>
+#include <asm/byteorder.h>
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+#include <asm/fpu.h>
+#include <asm/loongarch.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/syscall.h>
+#include <asm/reg.h>
+
+static void init_fp_ctx(struct task_struct *target)
+{
+ /* The target already has context */
+ if (tsk_used_math(target))
+ return;
+
+ /* Begin with data registers set to all 1s... */
+ memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
+ set_stopped_child_used_math(target);
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ *
+ * Make sure single step bits etc are not set.
+ */
+void ptrace_disable(struct task_struct *child)
+{
+ /* Don't load the watchpoint registers for the ex-child. */
+ clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
+}
+
+/* regset get/set implementations */
+
+static int gpr_get(struct task_struct *target,
+ const struct user_regset *regset,
+ struct membuf to)
+{
+ int r;
+ struct pt_regs *regs = task_pt_regs(target);
+
+ r = membuf_write(&to, ®s->regs, sizeof(u64) * GPR_NUM);
+ r = membuf_write(&to, ®s->orig_a0, sizeof(u64));
+ r = membuf_write(&to, ®s->csr_era, sizeof(u64));
+ r = membuf_write(&to, ®s->csr_badvaddr, sizeof(u64));
+
+ return r;
+}
+
+static int gpr_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ int err;
+ int a0_start = sizeof(u64) * GPR_NUM;
+ int era_start = a0_start + sizeof(u64);
+ int badvaddr_start = era_start + sizeof(u64);
+ struct pt_regs *regs = task_pt_regs(target);
+
+ err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+ ®s->regs,
+ 0, a0_start);
+ err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+ ®s->orig_a0,
+ a0_start, a0_start + sizeof(u64));
+ err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+ ®s->csr_era,
+ era_start, era_start + sizeof(u64));
+ err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+ ®s->csr_badvaddr,
+ badvaddr_start, badvaddr_start + sizeof(u64));
+
+ return err;
+}
+
+
+/*
+ * Get the general floating-point registers.
+ */
+static int gfpr_get(struct task_struct *target, struct membuf *to)
+{
+ return membuf_write(to, &target->thread.fpu.fpr,
+ sizeof(elf_fpreg_t) * NUM_FPU_REGS);
+}
+
+static int gfpr_get_simd(struct task_struct *target, struct membuf *to)
+{
+ int i, r;
+ u64 fpr_val;
+
+ BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
+ for (i = 0; i < NUM_FPU_REGS; i++) {
+ fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
+ r = membuf_write(to, &fpr_val, sizeof(elf_fpreg_t));
+ }
+
+ return r;
+}
+
+/*
+ * Choose the appropriate helper for general registers, and then copy
+ * the FCC and FCSR registers separately.
+ */
+static int fpr_get(struct task_struct *target,
+ const struct user_regset *regset,
+ struct membuf to)
+{
+ int r;
+
+ if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
+ r = gfpr_get(target, &to);
+ else
+ r = gfpr_get_simd(target, &to);
+
+ r = membuf_write(&to, &target->thread.fpu.fcc, sizeof(target->thread.fpu.fcc));
+ r = membuf_write(&to, &target->thread.fpu.fcsr, sizeof(target->thread.fpu.fcsr));
+
+ return r;
+}
+
+static int gfpr_set(struct task_struct *target,
+ unsigned int *pos, unsigned int *count,
+ const void **kbuf, const void __user **ubuf)
+{
+ return user_regset_copyin(pos, count, kbuf, ubuf,
+ &target->thread.fpu.fpr,
+ 0, NUM_FPU_REGS * sizeof(elf_fpreg_t));
+}
+
+static int gfpr_set_simd(struct task_struct *target,
+ unsigned int *pos, unsigned int *count,
+ const void **kbuf, const void __user **ubuf)
+{
+ int i, err;
+ u64 fpr_val;
+
+ BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
+ for (i = 0; i < NUM_FPU_REGS && *count > 0; i++) {
+ err = user_regset_copyin(pos, count, kbuf, ubuf,
+ &fpr_val, i * sizeof(elf_fpreg_t),
+ (i + 1) * sizeof(elf_fpreg_t));
+ if (err)
+ return err;
+ set_fpr64(&target->thread.fpu.fpr[i], 0, fpr_val);
+ }
+
+ return 0;
+}
+
+/*
+ * Choose the appropriate helper for general registers, and then copy
+ * the FCC register separately.
+ */
+static int fpr_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ const int fcc_start = NUM_FPU_REGS * sizeof(elf_fpreg_t);
+ const int fcc_end = fcc_start + sizeof(u64);
+ int err;
+
+ BUG_ON(count % sizeof(elf_fpreg_t));
+ if (pos + count > sizeof(elf_fpregset_t))
+ return -EIO;
+
+ init_fp_ctx(target);
+
+ if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
+ err = gfpr_set(target, &pos, &count, &kbuf, &ubuf);
+ else
+ err = gfpr_set_simd(target, &pos, &count, &kbuf, &ubuf);
+ if (err)
+ return err;
+
+ if (count > 0)
+ err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+ &target->thread.fpu.fcc,
+ fcc_start, fcc_end);
+
+ return err;
+}
+
+static int cfg_get(struct task_struct *target,
+ const struct user_regset *regset,
+ struct membuf to)
+{
+ int i, r;
+ u32 cfg_val;
+
+ i = 0;
+ while (to.left > 0) {
+ cfg_val = read_cpucfg(i++);
+ r = membuf_write(&to, &cfg_val, sizeof(u32));
+ }
+
+ return r;
+}
+
+/*
+ * CFG registers are read-only.
+ */
+static int cfg_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ return 0;
+}
+
+struct pt_regs_offset {
+ const char *name;
+ int offset;
+};
+
+#define REG_OFFSET_NAME(n, r) {.name = #n, .offset = offsetof(struct pt_regs, r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+static const struct pt_regs_offset regoffset_table[] = {
+ REG_OFFSET_NAME(r0, regs[0]),
+ REG_OFFSET_NAME(r1, regs[1]),
+ REG_OFFSET_NAME(r2, regs[2]),
+ REG_OFFSET_NAME(r3, regs[3]),
+ REG_OFFSET_NAME(r4, regs[4]),
+ REG_OFFSET_NAME(r5, regs[5]),
+ REG_OFFSET_NAME(r6, regs[6]),
+ REG_OFFSET_NAME(r7, regs[7]),
+ REG_OFFSET_NAME(r8, regs[8]),
+ REG_OFFSET_NAME(r9, regs[9]),
+ REG_OFFSET_NAME(r10, regs[10]),
+ REG_OFFSET_NAME(r11, regs[11]),
+ REG_OFFSET_NAME(r12, regs[12]),
+ REG_OFFSET_NAME(r13, regs[13]),
+ REG_OFFSET_NAME(r14, regs[14]),
+ REG_OFFSET_NAME(r15, regs[15]),
+ REG_OFFSET_NAME(r16, regs[16]),
+ REG_OFFSET_NAME(r17, regs[17]),
+ REG_OFFSET_NAME(r18, regs[18]),
+ REG_OFFSET_NAME(r19, regs[19]),
+ REG_OFFSET_NAME(r20, regs[20]),
+ REG_OFFSET_NAME(r21, regs[21]),
+ REG_OFFSET_NAME(r22, regs[22]),
+ REG_OFFSET_NAME(r23, regs[23]),
+ REG_OFFSET_NAME(r24, regs[24]),
+ REG_OFFSET_NAME(r25, regs[25]),
+ REG_OFFSET_NAME(r26, regs[26]),
+ REG_OFFSET_NAME(r27, regs[27]),
+ REG_OFFSET_NAME(r28, regs[28]),
+ REG_OFFSET_NAME(r29, regs[29]),
+ REG_OFFSET_NAME(r30, regs[30]),
+ REG_OFFSET_NAME(r31, regs[31]),
+ REG_OFFSET_NAME(csr_era, csr_era),
+ REG_OFFSET_NAME(csr_badvaddr, csr_badvaddr),
+ REG_OFFSET_NAME(csr_crmd, csr_crmd),
+ REG_OFFSET_NAME(csr_prmd, csr_prmd),
+ REG_OFFSET_NAME(csr_euen, csr_euen),
+ REG_OFFSET_NAME(csr_ecfg, csr_ecfg),
+ REG_OFFSET_NAME(csr_estat, csr_estat),
+ REG_OFFSET_END,
+};
+
+/**
+ * regs_query_register_offset() - query register offset from its name
+ * @name: the name of a register
+ *
+ * regs_query_register_offset() returns the offset of a register in struct
+ * pt_regs from its name. If the name is invalid, this returns -EINVAL;
+ */
+int regs_query_register_offset(const char *name)
+{
+ const struct pt_regs_offset *roff;
+
+ for (roff = regoffset_table; roff->name != NULL; roff++)
+ if (!strcmp(roff->name, name))
+ return roff->offset;
+ return -EINVAL;
+}
+
+enum loongarch_regset {
+ REGSET_GPR,
+ REGSET_FPR,
+ REGSET_CPUCFG,
+};
+
+static const struct user_regset loongarch64_regsets[] = {
+ [REGSET_GPR] = {
+ .core_note_type = NT_PRSTATUS,
+ .n = ELF_NGREG,
+ .size = sizeof(elf_greg_t),
+ .align = sizeof(elf_greg_t),
+ .regset_get = gpr_get,
+ .set = gpr_set,
+ },
+ [REGSET_FPR] = {
+ .core_note_type = NT_PRFPREG,
+ .n = ELF_NFPREG,
+ .size = sizeof(elf_fpreg_t),
+ .align = sizeof(elf_fpreg_t),
+ .regset_get = fpr_get,
+ .set = fpr_set,
+ },
+ [REGSET_CPUCFG] = {
+ .core_note_type = NT_LOONGARCH_CPUCFG,
+ .n = 64,
+ .size = sizeof(u32),
+ .align = sizeof(u32),
+ .regset_get = cfg_get,
+ .set = cfg_set,
+ },
+};
+
+static const struct user_regset_view user_loongarch64_view = {
+ .name = "loongarch64",
+ .e_machine = ELF_ARCH,
+ .regsets = loongarch64_regsets,
+ .n = ARRAY_SIZE(loongarch64_regsets),
+};
+
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+ return &user_loongarch64_view;
+}
+
+static inline int read_user(struct task_struct *target, unsigned long addr,
+ unsigned long __user *data)
+{
+ unsigned long tmp = 0;
+
+ switch (addr) {
+ case 0 ... 31:
+ tmp = task_pt_regs(target)->regs[addr];
+ break;
+ case ARG0:
+ tmp = task_pt_regs(target)->orig_a0;
+ break;
+ case PC:
+ tmp = task_pt_regs(target)->csr_era;
+ break;
+ case BADVADDR:
+ tmp = task_pt_regs(target)->csr_badvaddr;
+ break;
+ default:
+ return -EIO;
+ }
+
+ return put_user(tmp, data);
+}
+
+static inline int write_user(struct task_struct *target, unsigned long addr,
+ unsigned long data)
+{
+ switch (addr) {
+ case 0 ... 31:
+ task_pt_regs(target)->regs[addr] = data;
+ break;
+ case ARG0:
+ task_pt_regs(target)->orig_a0 = data;
+ break;
+ case PC:
+ task_pt_regs(target)->csr_era = data;
+ break;
+ case BADVADDR:
+ task_pt_regs(target)->csr_badvaddr = data;
+ break;
+ default:
+ return -EIO;
+ }
+
+ return 0;
+}
+
+long arch_ptrace(struct task_struct *child, long request,
+ unsigned long addr, unsigned long data)
+{
+ int ret;
+ unsigned long __user *datap = (void __user *) data;
+
+ switch (request) {
+ case PTRACE_PEEKUSR:
+ ret = read_user(child, addr, datap);
+ break;
+
+ case PTRACE_POKEUSR:
+ ret = write_user(child, addr, data);
+ break;
+
+ default:
+ ret = ptrace_request(child, request, addr, data);
+ break;
+ }
+
+ return ret;
+}
diff --git a/arch/loongarch/kernel/switch.S b/arch/loongarch/kernel/switch.S
new file mode 100644
index 000000000000..b864fde4a808
--- /dev/null
+++ b/arch/loongarch/kernel/switch.S
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/asm-offsets.h>
+#include <asm/loongarch.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/thread_info.h>
+
+/*
+ * task_struct *__switch_to(task_struct *prev, task_struct *next,
+ * struct thread_info *next_ti)
+ */
+ .align 5
+SYM_FUNC_START(__switch_to)
+ csrrd t1, LOONGARCH_CSR_PRMD
+ stptr.d t1, a0, THREAD_CSRPRMD
+
+ cpu_save_nonscratch a0
+ stptr.d ra, a0, THREAD_REG01
+ move tp, a2
+ cpu_restore_nonscratch a1
+
+ li.w t0, _THREAD_SIZE - 32
+ PTR_ADDU t0, t0, tp
+ set_saved_sp t0, t1, t2
+
+ ldptr.d t1, a1, THREAD_CSRPRMD
+ csrwr t1, LOONGARCH_CSR_PRMD
+
+ jr ra
+SYM_FUNC_END(__switch_to)
--
2.27.0
