arch/x86/entry/vdso/extable.c

Source file repositories/reference/linux-study-clean/arch/x86/entry/vdso/extable.c

File Facts

System
Linux kernel
Corpus path
arch/x86/entry/vdso/extable.c
Extension
.c
Size
1222 bytes
Lines
47
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source 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.

Dependency Surface

Detected Declarations

Annotated Snippet

struct vdso_exception_table_entry {
	int insn, fixup;
};

bool fixup_vdso_exception(struct pt_regs *regs, int trapnr,
			  unsigned long error_code, unsigned long fault_addr)
{
	const struct vdso_image *image = current->mm->context.vdso_image;
	const struct vdso_exception_table_entry *extable;
	unsigned int nr_entries, i;
	unsigned long base;

	/*
	 * Do not attempt to fixup #DB or #BP.  It's impossible to identify
	 * whether or not a #DB/#BP originated from within an SGX enclave and
	 * SGX enclaves are currently the only use case for vDSO fixup.
	 */
	if (trapnr == X86_TRAP_DB || trapnr == X86_TRAP_BP)
		return false;

	if (!current->mm->context.vdso)
		return false;

	base =  (unsigned long)current->mm->context.vdso + image->extable_base;
	nr_entries = image->extable_len / (sizeof(*extable));
	extable = image->extable;

	for (i = 0; i < nr_entries; i++) {
		if (regs->ip == base + extable[i].insn) {
			regs->ip = base + extable[i].fixup;
			regs->di = trapnr;
			regs->si = error_code;
			regs->dx = fault_addr;
			return true;
		}
	}

	return false;
}

Annotation

Implementation Notes