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Diffstat (limited to 'arch/nds32/include/asm/syscall.h')
| -rw-r--r-- | arch/nds32/include/asm/syscall.h | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/arch/nds32/include/asm/syscall.h b/arch/nds32/include/asm/syscall.h new file mode 100644 index 000000000..f7e5e8676 --- /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, ®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 */ |