diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 86 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 23 |
2 files changed, 50 insertions, 59 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 9ebaf63ba182..931f32f4578b 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1048,6 +1048,11 @@ ENTRY(\sym) CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 .if \paranoid + .if \paranoid == 1 + CFI_REMEMBER_STATE + testl $3, CS(%rsp) /* If coming from userspace, switch */ + jnz 1f /* stacks. */ + .endif call save_paranoid .else call error_entry @@ -1088,6 +1093,36 @@ ENTRY(\sym) jmp error_exit /* %ebx: no swapgs flag */ .endif + .if \paranoid == 1 + CFI_RESTORE_STATE + /* + * Paranoid entry from userspace. Switch stacks and treat it + * as a normal entry. This means that paranoid handlers + * run in real process context if user_mode(regs). + */ +1: + call error_entry + + DEFAULT_FRAME 0 + + movq %rsp,%rdi /* pt_regs pointer */ + call sync_regs + movq %rax,%rsp /* switch stack */ + + movq %rsp,%rdi /* pt_regs pointer */ + + .if \has_error_code + movq ORIG_RAX(%rsp),%rsi /* get error code */ + movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */ + .else + xorl %esi,%esi /* no error code */ + .endif + + call \do_sym + + jmp error_exit /* %ebx: no swapgs flag */ + .endif + CFI_ENDPROC END(\sym) .endm @@ -1108,7 +1143,7 @@ idtentry overflow do_overflow has_error_code=0 idtentry bounds do_bounds has_error_code=0 idtentry invalid_op do_invalid_op has_error_code=0 idtentry device_not_available do_device_not_available has_error_code=0 -idtentry double_fault do_double_fault has_error_code=1 paranoid=1 +idtentry double_fault do_double_fault has_error_code=1 paranoid=2 idtentry coprocessor_segment_overrun do_coprocessor_segment_overrun has_error_code=0 idtentry invalid_TSS do_invalid_TSS has_error_code=1 idtentry segment_not_present do_segment_not_present has_error_code=1 @@ -1289,16 +1324,14 @@ idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector( #endif /* - * "Paranoid" exit path from exception stack. - * Paranoid because this is used by NMIs and cannot take - * any kernel state for granted. - * We don't do kernel preemption checks here, because only - * NMI should be common and it does not enable IRQs and - * cannot get reschedule ticks. + * "Paranoid" exit path from exception stack. This is invoked + * only on return from non-NMI IST interrupts that came + * from kernel space. * - * "trace" is 0 for the NMI handler only, because irq-tracing - * is fundamentally NMI-unsafe. (we cannot change the soft and - * hard flags at once, atomically) + * We may be returning to very strange contexts (e.g. very early + * in syscall entry), so checking for preemption here would + * be complicated. Fortunately, we there's no good reason + * to try to handle preemption here. */ /* ebx: no swapgs flag */ @@ -1308,43 +1341,14 @@ ENTRY(paranoid_exit) TRACE_IRQS_OFF_DEBUG testl %ebx,%ebx /* swapgs needed? */ jnz paranoid_restore - testl $3,CS(%rsp) - jnz paranoid_userspace -paranoid_swapgs: TRACE_IRQS_IRETQ 0 SWAPGS_UNSAFE_STACK RESTORE_ALL 8 - jmp irq_return + INTERRUPT_RETURN paranoid_restore: TRACE_IRQS_IRETQ_DEBUG 0 RESTORE_ALL 8 - jmp irq_return -paranoid_userspace: - GET_THREAD_INFO(%rcx) - movl TI_flags(%rcx),%ebx - andl $_TIF_WORK_MASK,%ebx - jz paranoid_swapgs - movq %rsp,%rdi /* &pt_regs */ - call sync_regs - movq %rax,%rsp /* switch stack for scheduling */ - testl $_TIF_NEED_RESCHED,%ebx - jnz paranoid_schedule - movl %ebx,%edx /* arg3: thread flags */ - TRACE_IRQS_ON - ENABLE_INTERRUPTS(CLBR_NONE) - xorl %esi,%esi /* arg2: oldset */ - movq %rsp,%rdi /* arg1: &pt_regs */ - call do_notify_resume - DISABLE_INTERRUPTS(CLBR_NONE) - TRACE_IRQS_OFF - jmp paranoid_userspace -paranoid_schedule: - TRACE_IRQS_ON - ENABLE_INTERRUPTS(CLBR_ANY) - SCHEDULE_USER - DISABLE_INTERRUPTS(CLBR_ANY) - TRACE_IRQS_OFF - jmp paranoid_userspace + INTERRUPT_RETURN CFI_ENDPROC END(paranoid_exit) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 88900e288021..28f3e5ffc55d 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -466,27 +466,14 @@ NOKPROBE_SYMBOL(do_int3); #ifdef CONFIG_X86_64 /* - * Help handler running on IST stack to switch back to user stack - * for scheduling or signal handling. The actual stack switch is done in - * entry.S + * Help handler running on IST stack to switch off the IST stack if the + * interrupted code was in user mode. The actual stack switch is done in + * entry_64.S */ asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs) { - struct pt_regs *regs = eregs; - /* Did already sync */ - if (eregs == (struct pt_regs *)eregs->sp) - ; - /* Exception from user space */ - else if (user_mode(eregs)) - regs = task_pt_regs(current); - /* - * Exception from kernel and interrupts are enabled. Move to - * kernel process stack. - */ - else if (eregs->flags & X86_EFLAGS_IF) - regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs)); - if (eregs != regs) - *regs = *eregs; + struct pt_regs *regs = task_pt_regs(current); + *regs = *eregs; return regs; } NOKPROBE_SYMBOL(sync_regs); |