[PATCH V4 13/22] LoongArch: Add system call support

From: Huacai Chen
Date: Mon Sep 27 2021 - 02:52:00 EST

This patch adds system call support and related code (uaccess and
seccomp) for LoongArch.

Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
arch/loongarch/include/asm/syscall.h | 74 +++++
arch/loongarch/include/asm/uaccess.h | 327 +++++++++++++++++++++++
arch/loongarch/include/asm/unistd.h | 11 +
arch/loongarch/include/uapi/asm/unistd.h | 6 +
arch/loongarch/kernel/entry.S | 88 ++++++
arch/loongarch/kernel/syscall.c | 59 ++++
6 files changed, 565 insertions(+)
create mode 100644 arch/loongarch/include/asm/syscall.h
create mode 100644 arch/loongarch/include/asm/uaccess.h
create mode 100644 arch/loongarch/include/asm/unistd.h
create mode 100644 arch/loongarch/include/uapi/asm/unistd.h
create mode 100644 arch/loongarch/kernel/entry.S
create mode 100644 arch/loongarch/kernel/syscall.c

diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
new file mode 100644
index 000000000000..da0cd5a02dad
--- /dev/null
+++ b/arch/loongarch/include/asm/syscall.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ */
+
+#ifndef __ASM_LOONGARCH_SYSCALL_H
+#define __ASM_LOONGARCH_SYSCALL_H
+
+#include <linux/compiler.h>
+#include <uapi/linux/audit.h>
+#include <linux/elf-em.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <asm/ptrace.h>
+#include <asm/unistd.h>
+
+extern void *sys_call_table[];
+
+static inline long syscall_get_nr(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs->regs[11];
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ regs->regs[4] = regs->orig_a0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ unsigned long error = regs->regs[4];
+
+ return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs->regs[4];
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+ struct pt_regs *regs,
+ int error, long val)
+{
+ regs->regs[4] = (long) error ? error : val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned long *args)
+{
+ args[0] = regs->orig_a0;
+ memcpy(&args[1], &regs->regs[5], 5 * sizeof(long));
+}
+
+static inline int syscall_get_arch(struct task_struct *task)
+{
+ return AUDIT_ARCH_LOONGARCH64;
+}
+
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
+{
+ return false;
+}
+
+#endif /* __ASM_LOONGARCH_SYSCALL_H */
diff --git a/arch/loongarch/include/asm/uaccess.h b/arch/loongarch/include/asm/uaccess.h
new file mode 100644
index 000000000000..3ffea5a81d1d
--- /dev/null
+++ b/arch/loongarch/include/asm/uaccess.h
@@ -0,0 +1,327 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ *
+ * Derived from MIPS:
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000, 03, 04 by Ralf Baechle
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2007 Maciej W. Rozycki
+ * Copyright (C) 2014, Imagination Technologies Ltd.
+ */
+#ifndef _ASM_UACCESS_H
+#define _ASM_UACCESS_H
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/extable.h>
+#include <asm-generic/extable.h>
+
+extern u64 __ua_limit;
+
+#define __UA_LIMIT __ua_limit
+
+#define __UA_ADDR ".dword"
+#define __UA_ADDU "add.d"
+#define __UA_LA "la.abs"
+
+/*
+ * Is a address valid? This does a straightforward calculation rather
+ * than tests.
+ *
+ * Address valid if:
+ * - "addr" doesn't have any high-bits set
+ * - AND "size" doesn't have any high-bits set
+ * - AND "addr+size" doesn't have any high-bits set
+ * - OR we are in kernel mode.
+ *
+ * __ua_size() is a trick to avoid runtime checking of positive constant
+ * sizes; for those we already know at compile time that the size is ok.
+ */
+#define __ua_size(size) \
+ ((__builtin_constant_p(size) && (signed long) (size) > 0) ? 0 : (size))
+
+/*
+ * access_ok: - Checks if a user space pointer is valid
+ * @addr: User space pointer to start of block to check
+ * @size: Size of block to check
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * Checks if a pointer to a block of memory in user space is valid.
+ *
+ * Returns true (nonzero) if the memory block may be valid, false (zero)
+ * if it is definitely invalid.
+ *
+ * Note that, depending on architecture, this function probably just
+ * checks that the pointer is in the user space range - after calling
+ * this function, memory access functions may still return -EFAULT.
+ */
+static inline int __access_ok(const void __user *p, unsigned long size)
+{
+ unsigned long addr = (unsigned long)p;
+ unsigned long end = addr + size - !!size;
+
+ return (__UA_LIMIT & (addr | end | __ua_size(size))) == 0;
+}
+
+#define access_ok(addr, size) \
+ likely(__access_ok((addr), (size)))
+
+/*
+ * get_user: - Get a simple variable from user space.
+ * @x: Variable to store result.
+ * @ptr: Source address, in user space.
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * This macro copies a single simple variable from user space to kernel
+ * space. It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and the result of
+ * dereferencing @ptr must be assignable to @x without a cast.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ * On error, the variable @x is set to zero.
+ */
+#define get_user(x, ptr) \
+({ \
+ int __gu_err = -EFAULT; \
+ const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
+ \
+ might_fault(); \
+ if (likely(access_ok(__gu_ptr, sizeof(*(ptr))))) { \
+ __get_user_common((x), sizeof(*(ptr)), __gu_ptr); \
+ } else \
+ (x) = 0; \
+ \
+ __gu_err; \
+})
+
+/*
+ * put_user: - Write a simple value into user space.
+ * @x: Value to copy to user space.
+ * @ptr: Destination address, in user space.
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * This macro copies a single simple value from kernel space to user
+ * space. It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and @x must be assignable
+ * to the result of dereferencing @ptr.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ */
+#define put_user(x, ptr) \
+({ \
+ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \
+ __typeof__(*(ptr)) __pu_val = (x); \
+ int __pu_err = -EFAULT; \
+ \
+ might_fault(); \
+ if (likely(access_ok(__pu_addr, sizeof(*(ptr))))) { \
+ __put_user_common(__pu_addr, sizeof(*(ptr))); \
+ } \
+ \
+ __pu_err; \
+})
+
+/*
+ * __get_user: - Get a simple variable from user space, with less checking.
+ * @x: Variable to store result.
+ * @ptr: Source address, in user space.
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * This macro copies a single simple variable from user space to kernel
+ * space. It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and the result of
+ * dereferencing @ptr must be assignable to @x without a cast.
+ *
+ * Caller must check the pointer with access_ok() before calling this
+ * function.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ * On error, the variable @x is set to zero.
+ */
+#define __get_user(x, ptr) \
+({ \
+ int __gu_err; \
+ \
+ __chk_user_ptr(ptr); \
+ __get_user_common((x), sizeof(*(ptr)), ptr); \
+ __gu_err; \
+})
+
+/*
+ * __put_user: - Write a simple value into user space, with less checking.
+ * @x: Value to copy to user space.
+ * @ptr: Destination address, in user space.
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * This macro copies a single simple value from kernel space to user
+ * space. It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and @x must be assignable
+ * to the result of dereferencing @ptr.
+ *
+ * Caller must check the pointer with access_ok() before calling this
+ * function.
+ *
+ * Returns zero on success, or -EFAULT on error.
+ */
+#define __put_user(x, ptr) \
+({ \
+ __typeof__(*(ptr)) __pu_val; \
+ int __pu_err = 0; \
+ \
+ __pu_val = (x); \
+ __chk_user_ptr(ptr); \
+ __put_user_common(ptr, sizeof(*(ptr))); \
+ __pu_err; \
+})
+
+struct __large_struct { unsigned long buf[100]; };
+#define __m(x) (*(struct __large_struct __user *)(x))
+
+#define __get_user_common(val, size, ptr) \
+do { \
+ switch (size) { \
+ case 1: __get_data_asm(val, "ld.b", ptr); break; \
+ case 2: __get_data_asm(val, "ld.h", ptr); break; \
+ case 4: __get_data_asm(val, "ld.w", ptr); break; \
+ case 8: __get_data_asm(val, "ld.d", ptr); break; \
+ default: BUILD_BUG(); break; \
+ } \
+} while (0)
+
+#define __get_kernel_common(val, size, ptr) __get_user_common(val, size, ptr)
+
+#define __get_data_asm(val, insn, addr) \
+{ \
+ long __gu_tmp; \
+ \
+ __asm__ __volatile__( \
+ "1: " insn " %1, %3 \n" \
+ "2: \n" \
+ " .section .fixup,\"ax\" \n" \
+ "3: li.w %0, %4 \n" \
+ " or %1, $r0, $r0 \n" \
+ " b 2b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " "__UA_ADDR "\t1b, 3b \n" \
+ " .previous \n" \
+ : "=r" (__gu_err), "=r" (__gu_tmp) \
+ : "0" (0), "o" (__m(addr)), "i" (-EFAULT)); \
+ \
+ (val) = (__typeof__(*(addr))) __gu_tmp; \
+}
+
+#define __put_user_common(ptr, size) \
+do { \
+ switch (size) { \
+ case 1: __put_data_asm("st.b", ptr); break; \
+ case 2: __put_data_asm("st.h", ptr); break; \
+ case 4: __put_data_asm("st.w", ptr); break; \
+ case 8: __put_data_asm("st.d", ptr); break; \
+ default: BUILD_BUG(); break; \
+ } \
+} while (0)
+
+#define __put_kernel_common(ptr, size) __put_user_common(ptr, size)
+
+#define __put_data_asm(insn, ptr) \
+{ \
+ __asm__ __volatile__( \
+ "1: " insn " %z2, %3 # __put_user_asm\n" \
+ "2: \n" \
+ " .section .fixup,\"ax\" \n" \
+ "3: li.w %0, %4 \n" \
+ " b 2b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " " __UA_ADDR " 1b, 3b \n" \
+ " .previous \n" \
+ : "=r" (__pu_err) \
+ : "0" (0), "Jr" (__pu_val), "o" (__m(ptr)), \
+ "i" (-EFAULT)); \
+}
+
+#define HAVE_GET_KERNEL_NOFAULT
+
+#define __get_kernel_nofault(dst, src, type, err_label) \
+do { \
+ int __gu_err; \
+ \
+ __get_kernel_common(*((type *)(dst)), sizeof(type), \
+ (__force type *)(src)); \
+ if (unlikely(__gu_err)) \
+ goto err_label; \
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label) \
+do { \
+ type __pu_val; \
+ int __pu_err = 0; \
+ \
+ __pu_val = *(__force type *)(src); \
+ __put_kernel_common(((type *)(dst)), sizeof(type)); \
+ if (unlikely(__pu_err)) \
+ goto err_label; \
+} while (0)
+
+extern unsigned long __copy_user(void *to, const void *from, __kernel_size_t n);
+
+static inline unsigned long __must_check
+raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ return __copy_user(to, from, n);
+}
+
+static inline unsigned long __must_check
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ return __copy_user(to, from, n);
+}
+
+#define INLINE_COPY_FROM_USER
+#define INLINE_COPY_TO_USER
+
+/*
+ * __clear_user: - Zero a block of memory in user space, with less checking.
+ * @addr: Destination address, in user space.
+ * @size: Number of bytes to zero.
+ *
+ * Zero a block of memory in user space. Caller must check
+ * the specified block with access_ok() before calling this function.
+ *
+ * Returns number of bytes that could not be cleared.
+ * On success, this will be zero.
+ */
+extern unsigned long __clear_user(void __user *addr, __kernel_size_t size);
+
+#define clear_user(addr, n) \
+({ \
+ void __user *__cl_addr = (addr); \
+ unsigned long __cl_size = (n); \
+ if (__cl_size && access_ok(__cl_addr, __cl_size)) \
+ __cl_size = __clear_user(__cl_addr, __cl_size); \
+ __cl_size; \
+})
+
+extern long strncpy_from_user(char *to, const char __user *from, long n);
+extern long strnlen_user(const char __user *str, long n);
+
+#endif /* _ASM_UACCESS_H */
diff --git a/arch/loongarch/include/asm/unistd.h b/arch/loongarch/include/asm/unistd.h
new file mode 100644
index 000000000000..25b6f2d0b4e5
--- /dev/null
+++ b/arch/loongarch/include/asm/unistd.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ */
+
+#include <uapi/asm/unistd.h>
+
+#define NR_syscalls (__NR_syscalls)
diff --git a/arch/loongarch/include/uapi/asm/unistd.h b/arch/loongarch/include/uapi/asm/unistd.h
new file mode 100644
index 000000000000..b344b1f91715
--- /dev/null
+++ b/arch/loongarch/include/uapi/asm/unistd.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#define __ARCH_WANT_NEW_STAT
+#define __ARCH_WANT_SYS_CLONE
+#define __ARCH_WANT_SYS_CLONE3
+
+#include <asm-generic/unistd.h>
diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
new file mode 100644
index 000000000000..59a1bd3800b7
--- /dev/null
+++ b/arch/loongarch/kernel/entry.S
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ *
+ * Derived from MIPS:
+ * Copyright (C) 1994 - 2000, 2001, 2003 Ralf Baechle
+ * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2001 MIPS Technologies, Inc.
+ */
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/loongarch.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/thread_info.h>
+
+ .text
+ .cfi_sections .debug_frame
+ .align 5
+SYM_FUNC_START(handle_syscall)
+ csrrd t0, PERCPU_BASE_KS
+ la.abs t1, kernelsp
+ add.d t1, t1, t0
+ move t2, sp
+ ld.d sp, t1, 0
+
+ addi.d sp, sp, -PT_SIZE
+ cfi_st t2, PT_R3
+ cfi_rel_offset sp, PT_R3
+ csrrd t2, LOONGARCH_CSR_PRMD
+ st.d t2, sp, PT_PRMD
+ csrrd t2, LOONGARCH_CSR_CRMD
+ st.d t2, sp, PT_CRMD
+ csrrd t2, LOONGARCH_CSR_EUEN
+ st.d t2, sp, PT_EUEN
+ csrrd t2, LOONGARCH_CSR_ECFG
+ st.d t2, sp, PT_ECFG
+ csrrd t2, LOONGARCH_CSR_ESTAT
+ st.d t2, sp, PT_ESTAT
+ cfi_st ra, PT_R1
+ cfi_st a0, PT_R4
+ cfi_st a1, PT_R5
+ cfi_st a2, PT_R6
+ cfi_st a3, PT_R7
+ cfi_st a4, PT_R8
+ cfi_st a5, PT_R9
+ cfi_st a6, PT_R10
+ cfi_st a7, PT_R11
+ csrrd ra, LOONGARCH_CSR_EPC
+ st.d ra, sp, PT_EPC
+ cfi_rel_offset ra, PT_EPC
+
+ cfi_st tp, PT_R2
+ cfi_st x0, PT_R21
+ cfi_st fp, PT_R22
+
+ SAVE_STATIC
+
+ move x0, t0
+ li.d tp, ~_THREAD_MASK
+ and tp, tp, sp
+
+ move a0, sp
+ bl do_syscall
+
+ RESTORE_ALL_AND_RET
+SYM_FUNC_END(handle_syscall)
+
+SYM_CODE_START(ret_from_fork)
+ bl schedule_tail # a0 = struct task_struct *prev
+ move a0, sp
+ bl syscall_exit_to_user_mode
+ RESTORE_STATIC
+ RESTORE_SOME
+ RESTORE_SP_AND_RET
+SYM_CODE_END(ret_from_fork)
+
+SYM_CODE_START(ret_from_kernel_thread)
+ bl schedule_tail # a0 = struct task_struct *prev
+ move a0, s1
+ jirl ra, s0, 0
+ move a0, sp
+ bl syscall_exit_to_user_mode
+ RESTORE_STATIC
+ RESTORE_SOME
+ RESTORE_SP_AND_RET
+SYM_CODE_END(ret_from_kernel_thread)
diff --git a/arch/loongarch/kernel/syscall.c b/arch/loongarch/kernel/syscall.c
new file mode 100644
index 000000000000..ed99010cc47c
--- /dev/null
+++ b/arch/loongarch/kernel/syscall.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
+ * Huacai Chen <chenhuacai@xxxxxxxxxxx>
+ *
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ */
+#include <linux/capability.h>
+#include <linux/entry-common.h>
+#include <linux/errno.h>
+#include <linux/linkage.h>
+#include <linux/syscalls.h>
+#include <linux/unistd.h>
+
+#include <asm/asm.h>
+#include <asm/signal.h>
+#include <asm/switch_to.h>
+#include <asm-generic/syscalls.h>
+
+#undef __SYSCALL
+#define __SYSCALL(nr, call) [nr] = (call),
+
+SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, unsigned long,
+ prot, unsigned long, flags, unsigned long, fd, off_t, offset)
+{
+ if (offset & ~PAGE_MASK)
+ return -EINVAL;
+
+ return ksys_mmap_pgoff(addr, len, prot, flags, fd, offset >> PAGE_SHIFT);
+}
+
+void *sys_call_table[__NR_syscalls] = {
+ [0 ... __NR_syscalls - 1] = sys_ni_syscall,
+#include <asm/unistd.h>
+};
+
+typedef long (*sys_call_fn)(unsigned long, unsigned long,
+ unsigned long, unsigned long, unsigned long, unsigned long);
+
+void noinstr do_syscall(struct pt_regs *regs)
+{
+ unsigned long nr;
+ sys_call_fn syscall_fn;
+
+ nr = regs->regs[11];
+ nr = syscall_enter_from_user_mode(regs, nr);
+
+ regs->csr_epc += 4;
+ regs->orig_a0 = regs->regs[4];
+ regs->regs[4] = -ENOSYS;
+ if (nr < NR_syscalls) {
+ regs->regs[0] = nr + 1;
+ syscall_fn = sys_call_table[nr];
+ regs->regs[4] = syscall_fn(regs->orig_a0, regs->regs[5], regs->regs[6],
+ regs->regs[7], regs->regs[8], regs->regs[9]);
+ }
+
+ syscall_exit_to_user_mode(regs);
+}
--
2.27.0