/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Access to user system call parameters and results
 *
 *  Copyright IBM Corp. 2008
 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#ifndef _ASM_SYSCALL_H
#define _ASM_SYSCALL_H  1

#include <uapi/linux/audit.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <asm/ptrace.h>

extern const sys_call_ptr_t sys_call_table[];

static inline long syscall_get_nr(struct task_struct *task,
                                  struct pt_regs *regs)
{
        return test_pt_regs_flag(regs, PIF_SYSCALL) ?
                (regs->int_code & 0xffff) : -1;
}

static inline void syscall_set_nr(struct task_struct *task,
                                  struct pt_regs *regs,
                                  int nr)
{
        /*
         * Unlike syscall_get_nr(), syscall_set_nr() can be called only when
         * the target task is stopped for tracing on entering syscall, so
         * there is no need to have the same check syscall_get_nr() has.
         */
        regs->int_code = (regs->int_code & ~0xffff) | (nr & 0xffff);
}

static inline void syscall_rollback(struct task_struct *task,
                                    struct pt_regs *regs)
{
        regs->gprs[2] = regs->orig_gpr2;
}

static inline long syscall_get_error(struct task_struct *task,
                                     struct pt_regs *regs)
{
        unsigned long error = regs->gprs[2];

        return IS_ERR_VALUE(error) ? error : 0;
}

static inline long syscall_get_return_value(struct task_struct *task,
                                            struct pt_regs *regs)
{
        return regs->gprs[2];
}

static inline void syscall_set_return_value(struct task_struct *task,
                                            struct pt_regs *regs,
                                            int error, long val)
{
        set_pt_regs_flag(regs, PIF_SYSCALL_RET_SET);
        regs->gprs[2] = error ? error : val;
}

static inline void syscall_get_arguments(struct task_struct *task,
                                         struct pt_regs *regs,
                                         unsigned long *args)
{
        unsigned long mask = -1UL;

        for (int i = 1; i < 6; i++)
                args[i] = regs->gprs[2 + i] & mask;

        args[0] = regs->orig_gpr2 & mask;
}

static inline void syscall_set_arguments(struct task_struct *task,
                                         struct pt_regs *regs,
                                         const unsigned long *args)
{
        regs->orig_gpr2 = args[0];
        for (int n = 1; n < 6; n++)
                regs->gprs[2 + n] = args[n];
}

static inline int syscall_get_arch(struct task_struct *task)
{
        return AUDIT_ARCH_S390X;
}

static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
{
        return false;
}

#define SYSCALL_FMT_0
#define SYSCALL_FMT_1 , "0" (r2)
#define SYSCALL_FMT_2 , "d" (r3) SYSCALL_FMT_1
#define SYSCALL_FMT_3 , "d" (r4) SYSCALL_FMT_2
#define SYSCALL_FMT_4 , "d" (r5) SYSCALL_FMT_3
#define SYSCALL_FMT_5 , "d" (r6) SYSCALL_FMT_4
#define SYSCALL_FMT_6 , "d" (r7) SYSCALL_FMT_5

#define SYSCALL_PARM_0
#define SYSCALL_PARM_1 , long arg1
#define SYSCALL_PARM_2 SYSCALL_PARM_1, long arg2
#define SYSCALL_PARM_3 SYSCALL_PARM_2, long arg3
#define SYSCALL_PARM_4 SYSCALL_PARM_3, long arg4
#define SYSCALL_PARM_5 SYSCALL_PARM_4, long arg5
#define SYSCALL_PARM_6 SYSCALL_PARM_5, long arg6

#define SYSCALL_REGS_0
#define SYSCALL_REGS_1                                                  \
        register long r2 asm("2") = arg1
#define SYSCALL_REGS_2                                                  \
        SYSCALL_REGS_1;                                                 \
        register long r3 asm("3") = arg2
#define SYSCALL_REGS_3                                                  \
        SYSCALL_REGS_2;                                                 \
        register long r4 asm("4") = arg3
#define SYSCALL_REGS_4                                                  \
        SYSCALL_REGS_3;                                                 \
        register long r5 asm("5") = arg4
#define SYSCALL_REGS_5                                                  \
        SYSCALL_REGS_4;                                                 \
        register long r6 asm("6") = arg5
#define SYSCALL_REGS_6                                                  \
        SYSCALL_REGS_5;                                                 \
        register long r7 asm("7") = arg6

#define GENERATE_SYSCALL_FUNC(nr)                                       \
static __always_inline                                                  \
long syscall##nr(unsigned long syscall SYSCALL_PARM_##nr)               \
{                                                                       \
        register unsigned long r1 asm ("1") = syscall;                  \
        register long rc asm ("2");                                     \
        SYSCALL_REGS_##nr;                                              \
                                                                        \
        asm volatile (                                                  \
                "       svc     0"                                      \
                : "=d" (rc)                                             \
                : "d" (r1) SYSCALL_FMT_##nr                             \
                : "memory");                                            \
        return rc;                                                      \
}

GENERATE_SYSCALL_FUNC(0)
GENERATE_SYSCALL_FUNC(1)
GENERATE_SYSCALL_FUNC(2)
GENERATE_SYSCALL_FUNC(3)
GENERATE_SYSCALL_FUNC(4)
GENERATE_SYSCALL_FUNC(5)
GENERATE_SYSCALL_FUNC(6)

#endif  /* _ASM_SYSCALL_H */