// 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, ®s->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(®s->uregs[0] + i, args, n * sizeof(args[0]));
}
#endif /* _ASM_NDS32_SYSCALL_H */