drivers/pci/syscall.c

File Facts

System

Linux kernel

Corpus path

drivers/pci/syscall.c

Extension

.c

Size

2688 bytes

Lines

138

Domain

Representative Device Path

Bucket

PCIe NVMe Storage Path

Inferred role

Representative Device Path: syscall or user/kernel boundary

Status

core implementation candidate

Why This File Exists

Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.

• Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.
• 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/errno.h
• linux/pci.h
• linux/security.h
• linux/syscalls.h
• linux/uaccess.h
• pci.h

Detected Declarations

• syscall pciconfig_read
• syscall pciconfig_write

Annotated Snippet

SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
		unsigned long, off, unsigned long, len, void __user *, buf)
{
	struct pci_dev *dev;
	u8 byte;
	u16 word;
	u32 dword;
	int err, cfg_ret;

	err = -EPERM;
	dev = NULL;
	if (!capable(CAP_SYS_ADMIN))
		goto error;

	err = -ENODEV;
	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
	if (!dev)
		goto error;

	switch (len) {
	case 1:
		cfg_ret = pci_user_read_config_byte(dev, off, &byte);
		break;
	case 2:
		cfg_ret = pci_user_read_config_word(dev, off, &word);
		break;
	case 4:
		cfg_ret = pci_user_read_config_dword(dev, off, &dword);
		break;
	default:
		err = -EINVAL;
		goto error;
	}

	err = -EIO;
	if (cfg_ret)
		goto error;

	switch (len) {
	case 1:
		err = put_user(byte, (u8 __user *)buf);
		break;
	case 2:
		err = put_user(word, (u16 __user *)buf);
		break;
	case 4:
		err = put_user(dword, (u32 __user *)buf);
		break;
	}
	pci_dev_put(dev);
	return err;

error:
	/* ??? XFree86 doesn't even check the return value.  They
	   just look for 0xffffffff in the output, since that's what
	   they get instead of a machine check on x86.  */
	switch (len) {
	case 1:
		put_user(-1, (u8 __user *)buf);
		break;
	case 2:
		put_user(-1, (u16 __user *)buf);
		break;
	case 4:
		put_user(-1, (u32 __user *)buf);
		break;
	}
	pci_dev_put(dev);
	return err;
}

SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
		unsigned long, off, unsigned long, len, void __user *, buf)
{
	struct pci_dev *dev;
	u8 byte;
	u16 word;
	u32 dword;
	int err = 0;

	if (!capable(CAP_SYS_ADMIN) ||
	    security_locked_down(LOCKDOWN_PCI_ACCESS))
		return -EPERM;

	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
	if (!dev)
		return -ENODEV;

	switch (len) {
	case 1:

Annotation

• Immediate include surface: `linux/errno.h`, `linux/pci.h`, `linux/security.h`, `linux/syscalls.h`, `linux/uaccess.h`, `pci.h`.
• Detected declarations: `syscall pciconfig_read`, `syscall pciconfig_write`.
• Atlas domain: Representative Device Path / PCIe NVMe Storage Path.
• 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.