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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889// SPDX-License-Identifier: GPL-2.0#include <linux/ptrace.h>#include <linux/sched.h>#include <linux/sched/task_stack.h>#include <linux/export.h>#include <asm/syscall.h>
static int collect_syscall(struct task_struct *target, struct syscall_info *info){ unsigned long args[6] = { }; struct pt_regs *regs;
if (!try_get_task_stack(target)) { /* Task has no stack, so the task isn't in a syscall. */ memset(info, 0, sizeof(*info)); info->data.nr = -1; return 0; }
regs = task_pt_regs(target); if (unlikely(!regs)) { put_task_stack(target); return -EAGAIN; }
info->sp = user_stack_pointer(regs); info->data.instruction_pointer = instruction_pointer(regs);
info->data.nr = syscall_get_nr(target, regs); if (info->data.nr != -1L) syscall_get_arguments(target, regs, args);
info->data.args[0] = args[0]; info->data.args[1] = args[1]; info->data.args[2] = args[2]; info->data.args[3] = args[3]; info->data.args[4] = args[4]; info->data.args[5] = args[5];
put_task_stack(target); return 0;}
/** * task_current_syscall - Discover what a blocked task is doing. * @target: thread to examine * @info: structure with the following fields: * .sp - filled with user stack pointer * .data.nr - filled with system call number or -1 * .data.args - filled with @maxargs system call arguments * .data.instruction_pointer - filled with user PC * * If @target is blocked in a system call, returns zero with @info.data.nr * set to the call's number and @info.data.args filled in with its * arguments. Registers not used for system call arguments may not be available * and it is not kosher to use &struct user_regset calls while the system * call is still in progress. Note we may get this result if @target * has finished its system call but not yet returned to user mode, such * as when it's stopped for signal handling or syscall exit tracing. * * If @target is blocked in the kernel during a fault or exception, * returns zero with *@info.data.nr set to -1 and does not fill in * @info.data.args. If so, it's now safe to examine @target using * &struct user_regset get() calls as long as we're sure @target won't return * to user mode. * * Returns -%EAGAIN if @target does not remain blocked. */int task_current_syscall(struct task_struct *target, struct syscall_info *info){ unsigned long ncsw; unsigned int state;
if (target == current) return collect_syscall(target, info);
state = READ_ONCE(target->__state); if (unlikely(!state)) return -EAGAIN;
ncsw = wait_task_inactive(target, state); if (unlikely(!ncsw) || unlikely(collect_syscall(target, info)) || unlikely(wait_task_inactive(target, state) != ncsw)) return -EAGAIN;
return 0;}