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    Subject[PATCH v7 19/37] nds32: System calls handling
    Date
    This patch adds support for system calls.

    Signed-off-by: Vincent Chen <vincentc@andestech.com>
    Signed-off-by: Greentime Hu <greentime@andestech.com>
    Reviewed-by: Arnd Bergmann <arnd@arndb.de>
    ---
    arch/nds32/include/asm/syscall.h | 188 +++++++++++++++++++++++++++++++++++
    arch/nds32/include/asm/syscalls.h | 13 +++
    arch/nds32/include/asm/unistd.h | 6 ++
    arch/nds32/include/uapi/asm/unistd.h | 11 ++
    arch/nds32/kernel/ex-scall.S | 98 ++++++++++++++++++
    arch/nds32/kernel/sys_nds32.c | 50 ++++++++++
    arch/nds32/kernel/syscall_table.c | 17 ++++
    7 files changed, 383 insertions(+)
    create mode 100644 arch/nds32/include/asm/syscall.h
    create mode 100644 arch/nds32/include/asm/syscalls.h
    create mode 100644 arch/nds32/include/asm/unistd.h
    create mode 100644 arch/nds32/include/uapi/asm/unistd.h
    create mode 100644 arch/nds32/kernel/ex-scall.S
    create mode 100644 arch/nds32/kernel/sys_nds32.c
    create mode 100644 arch/nds32/kernel/syscall_table.c

    diff --git a/arch/nds32/include/asm/syscall.h b/arch/nds32/include/asm/syscall.h
    new file mode 100644
    index 000000000000..f7e5e86765fe
    --- /dev/null
    +++ b/arch/nds32/include/asm/syscall.h
    @@ -0,0 +1,188 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#ifndef _ASM_NDS32_SYSCALL_H
    +#define _ASM_NDS32_SYSCALL_H 1
    +
    +#include <linux/err.h>
    +struct task_struct;
    +struct pt_regs;
    +
    +/**
    + * syscall_get_nr - find what system call a task is executing
    + * @task: task of interest, must be blocked
    + * @regs: task_pt_regs() of @task
    + *
    + * If @task is executing a system call or is at system call
    + * tracing about to attempt one, returns the system call number.
    + * If @task is not executing a system call, i.e. it's blocked
    + * inside the kernel for a fault or signal, returns -1.
    + *
    + * Note this returns int even on 64-bit machines. Only 32 bits of
    + * system call number can be meaningful. If the actual arch value
    + * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
    + *
    + * It's only valid to call this when @task is known to be blocked.
    + */
    +int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
    +{
    + return regs->syscallno;
    +}
    +
    +/**
    + * syscall_rollback - roll back registers after an aborted system call
    + * @task: task of interest, must be in system call exit tracing
    + * @regs: task_pt_regs() of @task
    + *
    + * It's only valid to call this when @task is stopped for system
    + * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
    + * after tracehook_report_syscall_entry() returned nonzero to prevent
    + * the system call from taking place.
    + *
    + * This rolls back the register state in @regs so it's as if the
    + * system call instruction was a no-op. The registers containing
    + * the system call number and arguments are as they were before the
    + * system call instruction. This may not be the same as what the
    + * register state looked like at system call entry tracing.
    + */
    +void syscall_rollback(struct task_struct *task, struct pt_regs *regs)
    +{
    + regs->uregs[0] = regs->orig_r0;
    +}
    +
    +/**
    + * syscall_get_error - check result of traced system call
    + * @task: task of interest, must be blocked
    + * @regs: task_pt_regs() of @task
    + *
    + * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
    + *
    + * It's only valid to call this when @task is stopped for tracing on exit
    + * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
    + */
    +long syscall_get_error(struct task_struct *task, struct pt_regs *regs)
    +{
    + unsigned long error = regs->uregs[0];
    + return IS_ERR_VALUE(error) ? error : 0;
    +}
    +
    +/**
    + * syscall_get_return_value - get the return value of a traced system call
    + * @task: task of interest, must be blocked
    + * @regs: task_pt_regs() of @task
    + *
    + * Returns the return value of the successful system call.
    + * This value is meaningless if syscall_get_error() returned nonzero.
    + *
    + * It's only valid to call this when @task is stopped for tracing on exit
    + * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
    + */
    +long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
    +{
    + return regs->uregs[0];
    +}
    +
    +/**
    + * syscall_set_return_value - change the return value of a traced system call
    + * @task: task of interest, must be blocked
    + * @regs: task_pt_regs() of @task
    + * @error: negative error code, or zero to indicate success
    + * @val: user return value if @error is zero
    + *
    + * This changes the results of the system call that user mode will see.
    + * If @error is zero, the user sees a successful system call with a
    + * return value of @val. If @error is nonzero, it's a negated errno
    + * code; the user sees a failed system call with this errno code.
    + *
    + * It's only valid to call this when @task is stopped for tracing on exit
    + * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
    + */
    +void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
    + int error, long val)
    +{
    + regs->uregs[0] = (long)error ? error : val;
    +}
    +
    +/**
    + * syscall_get_arguments - extract system call parameter values
    + * @task: task of interest, must be blocked
    + * @regs: task_pt_regs() of @task
    + * @i: argument index [0,5]
    + * @n: number of arguments; n+i must be [1,6].
    + * @args: array filled with argument values
    + *
    + * Fetches @n arguments to the system call starting with the @i'th argument
    + * (from 0 through 5). Argument @i is stored in @args[0], and so on.
    + * An arch inline version is probably optimal when @i and @n are constants.
    + *
    + * It's only valid to call this when @task is stopped for tracing on
    + * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
    + * It's invalid to call this with @i + @n > 6; we only support system calls
    + * taking up to 6 arguments.
    + */
    +#define SYSCALL_MAX_ARGS 6
    +void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
    + unsigned int i, unsigned int n, unsigned long *args)
    +{
    + if (n == 0)
    + return;
    + if (i + n > SYSCALL_MAX_ARGS) {
    + unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
    + unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
    + pr_warning("%s called with max args %d, handling only %d\n",
    + __func__, i + n, SYSCALL_MAX_ARGS);
    + memset(args_bad, 0, n_bad * sizeof(args[0]));
    + memset(args_bad, 0, n_bad * sizeof(args[0]));
    + }
    +
    + if (i == 0) {
    + args[0] = regs->orig_r0;
    + args++;
    + i++;
    + n--;
    + }
    +
    + memcpy(args, &regs->uregs[0] + i, n * sizeof(args[0]));
    +}
    +
    +/**
    + * syscall_set_arguments - change system call parameter value
    + * @task: task of interest, must be in system call entry tracing
    + * @regs: task_pt_regs() of @task
    + * @i: argument index [0,5]
    + * @n: number of arguments; n+i must be [1,6].
    + * @args: array of argument values to store
    + *
    + * Changes @n arguments to the system call starting with the @i'th argument.
    + * Argument @i gets value @args[0], and so on.
    + * An arch inline version is probably optimal when @i and @n are constants.
    + *
    + * It's only valid to call this when @task is stopped for tracing on
    + * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
    + * It's invalid to call this with @i + @n > 6; we only support system calls
    + * taking up to 6 arguments.
    + */
    +void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
    + unsigned int i, unsigned int n,
    + const unsigned long *args)
    +{
    + if (n == 0)
    + return;
    +
    + if (i + n > SYSCALL_MAX_ARGS) {
    + pr_warn("%s called with max args %d, handling only %d\n",
    + __func__, i + n, SYSCALL_MAX_ARGS);
    + n = SYSCALL_MAX_ARGS - i;
    + }
    +
    + if (i == 0) {
    + regs->orig_r0 = args[0];
    + args++;
    + i++;
    + n--;
    + }
    +
    + memcpy(&regs->uregs[0] + i, args, n * sizeof(args[0]));
    +}
    +#endif /* _ASM_NDS32_SYSCALL_H */
    diff --git a/arch/nds32/include/asm/syscalls.h b/arch/nds32/include/asm/syscalls.h
    new file mode 100644
    index 000000000000..78778ecff60c
    --- /dev/null
    +++ b/arch/nds32/include/asm/syscalls.h
    @@ -0,0 +1,13 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#ifndef __ASM_NDS32_SYSCALLS_H
    +#define __ASM_NDS32_SYSCALLS_H
    +
    +asmlinkage long sys_cacheflush(unsigned long addr, unsigned long len, unsigned int op);
    +asmlinkage long sys_fadvise64_64_wrapper(int fd, int advice, loff_t offset, loff_t len);
    +asmlinkage long sys_rt_sigreturn_wrapper(void);
    +
    +#include <asm-generic/syscalls.h>
    +
    +#endif /* __ASM_NDS32_SYSCALLS_H */
    diff --git a/arch/nds32/include/asm/unistd.h b/arch/nds32/include/asm/unistd.h
    new file mode 100644
    index 000000000000..b586a2862beb
    --- /dev/null
    +++ b/arch/nds32/include/asm/unistd.h
    @@ -0,0 +1,6 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#define __ARCH_WANT_SYS_CLONE
    +
    +#include <uapi/asm/unistd.h>
    diff --git a/arch/nds32/include/uapi/asm/unistd.h b/arch/nds32/include/uapi/asm/unistd.h
    new file mode 100644
    index 000000000000..6e95901cabe3
    --- /dev/null
    +++ b/arch/nds32/include/uapi/asm/unistd.h
    @@ -0,0 +1,11 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#define __ARCH_WANT_SYNC_FILE_RANGE2
    +
    +/* Use the standard ABI for syscalls */
    +#include <asm-generic/unistd.h>
    +
    +/* Additional NDS32 specific syscalls. */
    +#define __NR_cacheflush (__NR_arch_specific_syscall)
    +__SYSCALL(__NR_cacheflush, sys_cacheflush)
    diff --git a/arch/nds32/kernel/ex-scall.S b/arch/nds32/kernel/ex-scall.S
    new file mode 100644
    index 000000000000..36aa87ecdabd
    --- /dev/null
    +++ b/arch/nds32/kernel/ex-scall.S
    @@ -0,0 +1,98 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#include <linux/linkage.h>
    +#include <asm/unistd.h>
    +#include <asm/assembler.h>
    +#include <asm/nds32.h>
    +#include <asm/asm-offsets.h>
    +#include <asm/thread_info.h>
    +#include <asm/current.h>
    +
    +/*
    + * $r0 = previous task_struct,
    + * $r1 = next task_struct,
    + * previous and next are guaranteed not to be the same.
    + */
    +
    +ENTRY(__switch_to)
    +
    + la $p0, __entry_task
    + sw $r1, [$p0]
    + move $p1, $r0
    + addi $p1, $p1, #THREAD_CPU_CONTEXT
    + smw.bi $r6, [$p1], $r14, #0xb ! push r6~r14, fp, lp, sp
    + move $r25, $r1
    + addi $r1, $r1, #THREAD_CPU_CONTEXT
    + lmw.bi $r6, [$r1], $r14, #0xb ! pop r6~r14, fp, lp, sp
    + ret
    +
    +
    +#define tbl $r8
    +
    +/*
    + * $r7 will be writen as syscall nr
    + */
    + .macro get_scno
    + lwi $r7, [$sp + R15_OFFSET]
    + swi $r7, [$sp + SYSCALLNO_OFFSET]
    + .endm
    +
    + .macro updateipc
    + addi $r17, $r13, #4 ! $r13 is $IPC
    + swi $r17, [$sp + IPC_OFFSET]
    + .endm
    +
    +ENTRY(eh_syscall)
    + updateipc
    +
    + get_scno
    + gie_enable
    +
    + lwi $p0, [tsk+#TSK_TI_FLAGS] ! check for syscall tracing
    +
    + andi $p1, $p0, #_TIF_WORK_SYSCALL_ENTRY ! are we tracing syscalls?
    + bnez $p1, __sys_trace
    +
    + la $lp, ret_fast_syscall ! return address
    +jmp_systbl:
    + addi $p1, $r7, #-__NR_syscalls ! syscall number of syscall instruction is guarded by addembler
    + bgez $p1, _SCNO_EXCEED ! call sys_* routine
    + la tbl, sys_call_table ! load syscall table pointer
    + slli $p1, $r7, #2
    + add $p1, tbl, $p1
    + lwi $p1, [$p1]
    + jr $p1 ! no return
    +
    +_SCNO_EXCEED:
    + ori $r0, $r7, #0
    + ori $r1, $sp, #0
    + b bad_syscall
    +
    +/*
    + * This is the really slow path. We're going to be doing
    + * context switches, and waiting for our parent to respond.
    + */
    +__sys_trace:
    + move $r0, $sp
    + bal syscall_trace_enter
    + move $r7, $r0
    + la $lp, __sys_trace_return ! return address
    +
    + addi $p1, $r7, #1
    + beqz $p1, ret_slow_syscall ! fatal signal is pending
    +
    + addi $p1, $sp, #R0_OFFSET ! pointer to regs
    + lmw.bi $r0, [$p1], $r5 ! have to reload $r0 - $r5
    + b jmp_systbl
    +
    +__sys_trace_return:
    + swi $r0, [$sp+#R0_OFFSET] ! T: save returned $r0
    + move $r0, $sp ! set pt_regs for syscall_trace_leave
    + bal syscall_trace_leave
    + b ret_slow_syscall
    +
    +ENTRY(sys_rt_sigreturn_wrapper)
    + addi $r0, $sp, #0
    + b sys_rt_sigreturn
    +ENDPROC(sys_rt_sigreturn_wrapper)
    diff --git a/arch/nds32/kernel/sys_nds32.c b/arch/nds32/kernel/sys_nds32.c
    new file mode 100644
    index 000000000000..9de93ab4c52b
    --- /dev/null
    +++ b/arch/nds32/kernel/sys_nds32.c
    @@ -0,0 +1,50 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#include <linux/syscalls.h>
    +#include <linux/uaccess.h>
    +
    +#include <asm/cachectl.h>
    +#include <asm/proc-fns.h>
    +
    +SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
    + unsigned long, prot, unsigned long, flags,
    + unsigned long, fd, unsigned long, pgoff)
    +{
    + if (pgoff & (~PAGE_MASK >> 12))
    + return -EINVAL;
    +
    + return sys_mmap_pgoff(addr, len, prot, flags, fd,
    + pgoff >> (PAGE_SHIFT - 12));
    +}
    +
    +SYSCALL_DEFINE4(fadvise64_64_wrapper,int, fd, int, advice, loff_t, offset,
    + loff_t, len)
    +{
    + return sys_fadvise64_64(fd, offset, len, advice);
    +}
    +
    +SYSCALL_DEFINE3(cacheflush, unsigned int, start, unsigned int, end, int, cache)
    +{
    + struct vm_area_struct *vma;
    + bool flushi = true, wbd = true;
    +
    + vma = find_vma(current->mm, start);
    + if (!vma)
    + return -EFAULT;
    + switch (cache) {
    + case ICACHE:
    + wbd = false;
    + break;
    + case DCACHE:
    + flushi = false;
    + break;
    + case BCACHE:
    + break;
    + default:
    + return -EINVAL;
    + }
    + cpu_cache_wbinval_range_check(vma, start, end, flushi, wbd);
    +
    + return 0;
    +}
    diff --git a/arch/nds32/kernel/syscall_table.c b/arch/nds32/kernel/syscall_table.c
    new file mode 100644
    index 000000000000..7879c061b87f
    --- /dev/null
    +++ b/arch/nds32/kernel/syscall_table.c
    @@ -0,0 +1,17 @@
    +// SPDX-License-Identifier: GPL-2.0
    +// Copyright (C) 2005-2017 Andes Technology Corporation
    +
    +#include <linux/syscalls.h>
    +#include <linux/signal.h>
    +#include <linux/unistd.h>
    +#include <asm/syscalls.h>
    +
    +#undef __SYSCALL
    +#define __SYSCALL(nr, call) [nr] = (call),
    +
    +#define sys_rt_sigreturn sys_rt_sigreturn_wrapper
    +#define sys_fadvise64_64 sys_fadvise64_64_wrapper
    +void *sys_call_table[__NR_syscalls] __aligned(8192) = {
    + [0 ... __NR_syscalls - 1] = sys_ni_syscall,
    +#include <asm/unistd.h>
    +};
    --
    2.16.1
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