arch/csky/lib/usercopy.c

Source file repositories/reference/linux-study-clean/arch/csky/lib/usercopy.c

File Facts

System: Linux kernel
Corpus path: arch/csky/lib/usercopy.c
Extension: .c
Size: 7096 bytes
Lines: 215
Domain: Architecture Layer
Bucket: arch/csky
Inferred role: Architecture Layer: exported/initcall integration point
Status: integration 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.
Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.

Dependency Surface

linux/uaccess.h
linux/types.h

Detected Declarations

function raw_copy_from_user
function raw_copy_to_user
function access_ok
export raw_copy_from_user
export raw_copy_to_user
export __clear_user

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/uaccess.h>
#include <linux/types.h>

unsigned long raw_copy_from_user(void *to, const void *from,
			unsigned long n)
{
	int tmp, nsave;

	__asm__ __volatile__(
	"0:     cmpnei  %1, 0           \n"
	"       bf      7f              \n"
	"       mov     %3, %1          \n"
	"       or      %3, %2          \n"
	"       andi    %3, 3           \n"
	"       cmpnei  %3, 0           \n"
	"       bf      1f              \n"
	"       br      5f              \n"
	"1:     cmplti  %0, 16          \n"
	"       bt      3f              \n"
	"2:     ldw     %3, (%2, 0)     \n"
	"10:    ldw     %4, (%2, 4)     \n"
	"       stw     %3, (%1, 0)     \n"
	"       stw     %4, (%1, 4)     \n"
	"11:    ldw     %3, (%2, 8)     \n"
	"12:    ldw     %4, (%2, 12)    \n"
	"       stw     %3, (%1, 8)     \n"
	"       stw     %4, (%1, 12)    \n"
	"       addi    %2, 16          \n"
	"       addi    %1, 16          \n"
	"       subi    %0, 16          \n"
	"       br      1b              \n"
	"3:     cmplti  %0, 4           \n"
	"       bt      5f              \n"
	"4:     ldw     %3, (%2, 0)     \n"
	"       stw     %3, (%1, 0)     \n"
	"       addi    %2, 4           \n"
	"       addi    %1, 4           \n"
	"       subi    %0, 4           \n"
	"       br      3b              \n"
	"5:     cmpnei  %0, 0           \n"
	"       bf      7f              \n"
	"6:     ldb     %3, (%2, 0)     \n"
	"       stb     %3, (%1, 0)     \n"
	"       addi    %2,  1          \n"
	"       addi    %1,  1          \n"
	"       subi    %0,  1          \n"
	"       br      5b              \n"
	"8:     stw     %3, (%1, 0)     \n"
	"       subi    %0, 4           \n"
	"       bf      7f              \n"
	"9:     subi    %0, 8           \n"
	"       bf      7f              \n"
	"13:    stw     %3, (%1, 8)     \n"
	"       subi    %0, 12          \n"
	"       bf      7f              \n"
	".section __ex_table, \"a\"     \n"
	".align   2                     \n"
	".long    2b, 7f                \n"
	".long    4b, 7f                \n"
	".long    6b, 7f                \n"
	".long   10b, 8b                \n"
	".long   11b, 9b                \n"
	".long   12b,13b                \n"
	".previous                      \n"
	"7:                             \n"
	: "=r"(n), "=r"(to), "=r"(from), "=r"(nsave),
	  "=r"(tmp)
	: "0"(n), "1"(to), "2"(from)
	: "memory");

	return n;
}
EXPORT_SYMBOL(raw_copy_from_user);

unsigned long raw_copy_to_user(void *to, const void *from,
			unsigned long n)
{
	int w0, w1, w2, w3;

	__asm__ __volatile__(
	"0:     cmpnei  %1, 0           \n"
	"       bf      8f              \n"
	"       mov     %3, %1          \n"
	"       or      %3, %2          \n"
	"       andi    %3, 3           \n"
	"       cmpnei  %3, 0           \n"
	"       bf      1f              \n"

Annotation

Immediate include surface: `linux/uaccess.h`, `linux/types.h`.
Detected declarations: `function raw_copy_from_user`, `function raw_copy_to_user`, `function access_ok`, `export raw_copy_from_user`, `export raw_copy_to_user`, `export __clear_user`.
Atlas domain: Architecture Layer / arch/csky.
Implementation status: integration 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.