arch/arm/lib/csumpartialcopyuser.S

File Facts

System

Linux kernel

Corpus path

arch/arm/lib/csumpartialcopyuser.S

Extension

.S

Size

1908 bytes

Lines

102

Domain

Architecture Layer

Bucket

arch/arm

Inferred role

Architecture Layer: arch/arm

Status

atlas-only

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.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.

Dependency Surface

• linux/linkage.h
• asm/assembler.h
• asm/errno.h
• asm/asm-offsets.h
• csumpartialcopygeneric.S

Detected Declarations

• No top-level syscall, struct, function, initcall, or export declaration detected by the generator.

Annotated Snippet

#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>

		.text

#if defined(CONFIG_CPU_SW_DOMAIN_PAN)

		.macro	save_regs
		mrc	p15, 0, ip, c3, c0, 0
		stmfd	sp!, {r1, r2, r4 - r8, ip, lr}
		uaccess_enable ip
		.endm

		.macro	load_regs
		ldmfd	sp!, {r1, r2, r4 - r8, ip, lr}
		mcr	p15, 0, ip, c3, c0, 0
		ret	lr
		.endm

#elif defined(CONFIG_CPU_TTBR0_PAN)

		.macro	save_regs
		mrc	p15, 0, ip, c2, c0, 2		@ read TTBCR
		stmfd	sp!, {r1, r2, r4 - r8, ip, lr}
		uaccess_enable ip
		.endm

		.macro	load_regs
		ldmfd	sp!, {r1, r2, r4 - r8, ip, lr}
		mcr	p15, 0, ip, c2, c0, 2		@ restore TTBCR
		ret	lr
		.endm

#else

		.macro	save_regs
		stmfd	sp!, {r1, r2, r4 - r8, lr}
		.endm

		.macro	load_regs
		ldmfd	sp!, {r1, r2, r4 - r8, pc}
		.endm

#endif

		.macro	load1b,	reg1
		ldrusr	\reg1, r0, 1
		.endm

		.macro	load2b, reg1, reg2
		ldrusr	\reg1, r0, 1
		ldrusr	\reg2, r0, 1
		.endm

		.macro	load1l, reg1
		ldrusr	\reg1, r0, 4
		.endm

		.macro	load2l, reg1, reg2
		ldrusr	\reg1, r0, 4
		ldrusr	\reg2, r0, 4
		.endm

		.macro	load4l, reg1, reg2, reg3, reg4
		ldrusr	\reg1, r0, 4
		ldrusr	\reg2, r0, 4
		ldrusr	\reg3, r0, 4
		ldrusr	\reg4, r0, 4

Annotation

• Immediate include surface: `linux/linkage.h`, `asm/assembler.h`, `asm/errno.h`, `asm/asm-offsets.h`, `csumpartialcopygeneric.S`.
• Atlas domain: Architecture Layer / arch/arm.
• Implementation status: atlas-only.
• 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.