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 |