arch/x86/um/syscalls_64.c

File Facts

System

Linux kernel

Corpus path

arch/x86/um/syscalls_64.c

Extension

.c

Size

1574 bytes

Lines

65

Domain

Architecture Layer

Bucket

arch/x86

Inferred role

Architecture Layer: syscall or user/kernel boundary

Status

core implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

• CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.
• Defines or participates in a user/kernel boundary; inspect argument validation, copy_from_user/copy_to_user, credentials, and dispatch target.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/sched.h
• linux/sched/mm.h
• linux/syscalls.h
• linux/uaccess.h
• asm/prctl.h
• registers.h
• os.h

Detected Declarations

• syscall arch_prctl
• syscall mmap
• function Copyright
• function arch_switch_to

Annotated Snippet

SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
{
	return arch_prctl(current, option, (unsigned long __user *) arg2);
}

void arch_switch_to(struct task_struct *to)
{
	/*
	 * Nothing needs to be done on x86_64.
	 * The FS_BASE/GS_BASE registers are saved in the ptrace register set.
	 */
}

SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, off)
{
	if (off & ~PAGE_MASK)
		return -EINVAL;

	return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
}

Annotation

• Immediate include surface: `linux/sched.h`, `linux/sched/mm.h`, `linux/syscalls.h`, `linux/uaccess.h`, `asm/prctl.h`, `registers.h`, `os.h`.
• Detected declarations: `syscall arch_prctl`, `syscall mmap`, `function Copyright`, `function arch_switch_to`.
• Atlas domain: Architecture Layer / arch/x86.
• Implementation status: core implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.