// SPDX-License-Identifier: GPL-2.0 #include <linux/err.h> #include <linux/mm.h> #include <asm/current.h> #include <asm/traps.h> #include <asm/vdso.h> 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; }