diff options
| -rw-r--r-- | arch/x86/kernel/tls.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c index 7fc5e84..9692a5e 100644 --- a/arch/x86/kernel/tls.c +++ b/arch/x86/kernel/tls.c @@ -114,6 +114,7 @@ int do_set_thread_area(struct task_struct *p, int idx, int can_allocate) { struct user_desc info; + unsigned short __maybe_unused sel, modified_sel; if (copy_from_user(&info, u_info, sizeof(info))) return -EFAULT; @@ -141,6 +142,47 @@ int do_set_thread_area(struct task_struct *p, int idx, set_tls_desc(p, idx, &info, 1); + /* + * If DS, ES, FS, or GS points to the modified segment, forcibly + * refresh it. Only needed on x86_64 because x86_32 reloads them + * on return to user mode. + */ + modified_sel = (idx << 3) | 3; + + if (p == current) { +#ifdef CONFIG_X86_64 + savesegment(ds, sel); + if (sel == modified_sel) + loadsegment(ds, sel); + + savesegment(es, sel); + if (sel == modified_sel) + loadsegment(es, sel); + + savesegment(fs, sel); + if (sel == modified_sel) + loadsegment(fs, sel); + + savesegment(gs, sel); + if (sel == modified_sel) + load_gs_index(sel); +#endif + +#ifdef CONFIG_X86_32_LAZY_GS + savesegment(gs, sel); + if (sel == modified_sel) + loadsegment(gs, sel); +#endif + } else { +#ifdef CONFIG_X86_64 + if (p->thread.fsindex == modified_sel) + p->thread.fsbase = info.base_addr; + + if (p->thread.gsindex == modified_sel) + p->thread.gsbase = info.base_addr; +#endif + } + return 0; } |