| 1 | // SPDX-License-Identifier: GPL-2.0 |
|---|---|
| 2 | #include <linux/err.h> |
| 3 | #include <linux/mm.h> |
| 4 | #include <asm/current.h> |
| 5 | #include <asm/traps.h> |
| 6 | #include <asm/vdso.h> |
| 7 | |
| 8 | struct vdso_exception_table_entry { |
| 9 | int insn, fixup; |
| 10 | }; |
| 11 | |
| 12 | bool fixup_vdso_exception(struct pt_regs *regs, int trapnr, |
| 13 | unsigned long error_code, unsigned long fault_addr) |
| 14 | { |
| 15 | const struct vdso_image *image = current->mm->context.vdso_image; |
| 16 | const struct vdso_exception_table_entry *extable; |
| 17 | unsigned int nr_entries, i; |
| 18 | unsigned long base; |
| 19 | |
| 20 | /* |
| 21 | * Do not attempt to fixup #DB or #BP. It's impossible to identify |
| 22 | * whether or not a #DB/#BP originated from within an SGX enclave and |
| 23 | * SGX enclaves are currently the only use case for vDSO fixup. |
| 24 | */ |
| 25 | if (trapnr == X86_TRAP_DB || trapnr == X86_TRAP_BP) |
| 26 | return false; |
| 27 | |
| 28 | if (!current->mm->context.vdso) |
| 29 | return false; |
| 30 | |
| 31 | base = (unsigned long)current->mm->context.vdso + image->extable_base; |
| 32 | nr_entries = image->extable_len / (sizeof(*extable)); |
| 33 | extable = image->extable; |
| 34 | |
| 35 | for (i = 0; i < nr_entries; i++) { |
| 36 | if (regs->ip == base + extable[i].insn) { |
| 37 | regs->ip = base + extable[i].fixup; |
| 38 | regs->di = trapnr; |
| 39 | regs->si = error_code; |
| 40 | regs->dx = fault_addr; |
| 41 | return true; |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | return false; |
| 46 | } |
| 47 |