cregit-Linux how code gets into the kernel

Release 4.16 lib/syscall.c

Directory: lib
// 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, long *callno, unsigned long args[6], unsigned int maxargs, unsigned long *sp, unsigned long *pc) { struct pt_regs *regs; if (!try_get_task_stack(target)) { /* Task has no stack, so the task isn't in a syscall. */ *sp = *pc = 0; *callno = -1; return 0; } regs = task_pt_regs(target); if (unlikely(!regs)) { put_task_stack(target); return -EAGAIN; } *sp = user_stack_pointer(regs); *pc = instruction_pointer(regs); *callno = syscall_get_nr(target, regs); if (*callno != -1L && maxargs > 0) syscall_get_arguments(target, regs, 0, maxargs, args); put_task_stack(target); return 0; }


Roland McGrath11071.43%133.33%
Andrew Lutomirski3623.38%133.33%
Kees Cook85.19%133.33%

/** * task_current_syscall - Discover what a blocked task is doing. * @target: thread to examine * @callno: filled with system call number or -1 * @args: filled with @maxargs system call arguments * @maxargs: number of elements in @args to fill * @sp: filled with user stack pointer * @pc: filled with user PC * * If @target is blocked in a system call, returns zero with *@callno * set to the the call's number and @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 *@callno set to -1 and does not fill in @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. * * Returns -%EINVAL if @maxargs is too large (maximum is six). */
int task_current_syscall(struct task_struct *target, long *callno, unsigned long args[6], unsigned int maxargs, unsigned long *sp, unsigned long *pc) { long state; unsigned long ncsw; if (unlikely(maxargs > 6)) return -EINVAL; if (target == current) return collect_syscall(target, callno, args, maxargs, sp, pc); state = target->state; if (unlikely(!state)) return -EAGAIN; ncsw = wait_task_inactive(target, state); if (unlikely(!ncsw) || unlikely(collect_syscall(target, callno, args, maxargs, sp, pc)) || unlikely(wait_task_inactive(target, state) != ncsw)) return -EAGAIN; return 0; }


Roland McGrath149100.00%1100.00%

Overall Contributors

Roland McGrath27184.69%116.67%
Andrew Lutomirski3611.25%116.67%
Kees Cook82.50%116.67%
Ingo Molnar30.94%116.67%
Paul Gortmaker10.31%116.67%
Greg Kroah-Hartman10.31%116.67%
Directory: lib
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