diff options
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 179 |
1 files changed, 142 insertions, 37 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index ce8dc33dd640..ca0b250eefc4 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -36,6 +36,7 @@ #include <asm/smap.h> #include <asm/pgtable_types.h> #include <asm/export.h> +#include <asm/frame.h> #include <linux/err.h> .code64 @@ -43,9 +44,10 @@ #ifdef CONFIG_PARAVIRT ENTRY(native_usergs_sysret64) + UNWIND_HINT_EMPTY swapgs sysretq -ENDPROC(native_usergs_sysret64) +END(native_usergs_sysret64) #endif /* CONFIG_PARAVIRT */ .macro TRACE_IRQS_IRETQ @@ -134,19 +136,14 @@ ENDPROC(native_usergs_sysret64) */ ENTRY(entry_SYSCALL_64) + UNWIND_HINT_EMPTY /* * Interrupts are off on entry. * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON, * it is too small to ever cause noticeable irq latency. */ - SWAPGS_UNSAFE_STACK - /* - * A hypervisor implementation might want to use a label - * after the swapgs, so that it can do the swapgs - * for the guest and jump here on syscall. - */ -GLOBAL(entry_SYSCALL_64_after_swapgs) + swapgs movq %rsp, PER_CPU_VAR(rsp_scratch) movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp @@ -158,6 +155,7 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) pushq %r11 /* pt_regs->flags */ pushq $__USER_CS /* pt_regs->cs */ pushq %rcx /* pt_regs->ip */ +GLOBAL(entry_SYSCALL_64_after_hwframe) pushq %rax /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ @@ -169,6 +167,7 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) pushq %r10 /* pt_regs->r10 */ pushq %r11 /* pt_regs->r11 */ sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ + UNWIND_HINT_REGS extra=0 /* * If we need to do entry work or if we guess we'll need to do @@ -223,6 +222,7 @@ entry_SYSCALL_64_fastpath: movq EFLAGS(%rsp), %r11 RESTORE_C_REGS_EXCEPT_RCX_R11 movq RSP(%rsp), %rsp + UNWIND_HINT_EMPTY USERGS_SYSRET64 1: @@ -316,6 +316,7 @@ syscall_return_via_sysret: /* rcx and r11 are already restored (see code above) */ RESTORE_C_REGS_EXCEPT_RCX_R11 movq RSP(%rsp), %rsp + UNWIND_HINT_EMPTY USERGS_SYSRET64 opportunistic_sysret_failed: @@ -343,6 +344,7 @@ ENTRY(stub_ptregs_64) DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF popq %rax + UNWIND_HINT_REGS extra=0 jmp entry_SYSCALL64_slow_path 1: @@ -351,6 +353,7 @@ END(stub_ptregs_64) .macro ptregs_stub func ENTRY(ptregs_\func) + UNWIND_HINT_FUNC leaq \func(%rip), %rax jmp stub_ptregs_64 END(ptregs_\func) @@ -367,6 +370,7 @@ END(ptregs_\func) * %rsi: next task */ ENTRY(__switch_to_asm) + UNWIND_HINT_FUNC /* * Save callee-saved registers * This must match the order in inactive_task_frame @@ -406,6 +410,7 @@ END(__switch_to_asm) * r12: kernel thread arg */ ENTRY(ret_from_fork) + UNWIND_HINT_EMPTY movq %rax, %rdi call schedule_tail /* rdi: 'prev' task parameter */ @@ -413,6 +418,7 @@ ENTRY(ret_from_fork) jnz 1f /* kernel threads are uncommon */ 2: + UNWIND_HINT_REGS movq %rsp, %rdi call syscall_return_slowpath /* returns with IRQs disabled */ TRACE_IRQS_ON /* user mode is traced as IRQS on */ @@ -440,13 +446,102 @@ END(ret_from_fork) ENTRY(irq_entries_start) vector=FIRST_EXTERNAL_VECTOR .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) + UNWIND_HINT_IRET_REGS pushq $(~vector+0x80) /* Note: always in signed byte range */ - vector=vector+1 jmp common_interrupt .align 8 + vector=vector+1 .endr END(irq_entries_start) +.macro DEBUG_ENTRY_ASSERT_IRQS_OFF +#ifdef CONFIG_DEBUG_ENTRY + pushfq + testl $X86_EFLAGS_IF, (%rsp) + jz .Lokay_\@ + ud2 +.Lokay_\@: + addq $8, %rsp +#endif +.endm + +/* + * Enters the IRQ stack if we're not already using it. NMI-safe. Clobbers + * flags and puts old RSP into old_rsp, and leaves all other GPRs alone. + * Requires kernel GSBASE. + * + * The invariant is that, if irq_count != -1, then the IRQ stack is in use. + */ +.macro ENTER_IRQ_STACK regs=1 old_rsp + DEBUG_ENTRY_ASSERT_IRQS_OFF + movq %rsp, \old_rsp + + .if \regs + UNWIND_HINT_REGS base=\old_rsp + .endif + + incl PER_CPU_VAR(irq_count) + jnz .Lirq_stack_push_old_rsp_\@ + + /* + * Right now, if we just incremented irq_count to zero, we've + * claimed the IRQ stack but we haven't switched to it yet. + * + * If anything is added that can interrupt us here without using IST, + * it must be *extremely* careful to limit its stack usage. This + * could include kprobes and a hypothetical future IST-less #DB + * handler. + * + * The OOPS unwinder relies on the word at the top of the IRQ + * stack linking back to the previous RSP for the entire time we're + * on the IRQ stack. For this to work reliably, we need to write + * it before we actually move ourselves to the IRQ stack. + */ + + movq \old_rsp, PER_CPU_VAR(irq_stack_union + IRQ_STACK_SIZE - 8) + movq PER_CPU_VAR(irq_stack_ptr), %rsp + +#ifdef CONFIG_DEBUG_ENTRY + /* + * If the first movq above becomes wrong due to IRQ stack layout + * changes, the only way we'll notice is if we try to unwind right + * here. Assert that we set up the stack right to catch this type + * of bug quickly. + */ + cmpq -8(%rsp), \old_rsp + je .Lirq_stack_okay\@ + ud2 + .Lirq_stack_okay\@: +#endif + +.Lirq_stack_push_old_rsp_\@: + pushq \old_rsp + + .if \regs + UNWIND_HINT_REGS indirect=1 + .endif +.endm + +/* + * Undoes ENTER_IRQ_STACK. + */ +.macro LEAVE_IRQ_STACK regs=1 + DEBUG_ENTRY_ASSERT_IRQS_OFF + /* We need to be off the IRQ stack before decrementing irq_count. */ + popq %rsp + + .if \regs + UNWIND_HINT_REGS + .endif + + /* + * As in ENTER_IRQ_STACK, irq_count == 0, we are still claiming + * the irq stack but we're not on it. + */ + + decl PER_CPU_VAR(irq_count) +.endm + /* * Interrupt entry/exit. * @@ -485,17 +580,7 @@ END(irq_entries_start) CALL_enter_from_user_mode 1: - /* - * Save previous stack pointer, optionally switch to interrupt stack. - * irq_count is used to check if a CPU is already on an interrupt stack - * or not. While this is essentially redundant with preempt_count it is - * a little cheaper to use a separate counter in the PDA (short of - * moving irq_enter into assembly, which would be too much work) - */ - movq %rsp, %rdi - incl PER_CPU_VAR(irq_count) - cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp - pushq %rdi + ENTER_IRQ_STACK old_rsp=%rdi /* We entered an interrupt context - irqs are off: */ TRACE_IRQS_OFF @@ -515,10 +600,8 @@ common_interrupt: ret_from_intr: DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF - decl PER_CPU_VAR(irq_count) - /* Restore saved previous stack */ - popq %rsp + LEAVE_IRQ_STACK testb $3, CS(%rsp) jz retint_kernel @@ -561,6 +644,7 @@ restore_c_regs_and_iret: INTERRUPT_RETURN ENTRY(native_iret) + UNWIND_HINT_IRET_REGS /* * Are we returning to a stack segment from the LDT? Note: in * 64-bit mode SS:RSP on the exception stack is always valid. @@ -633,6 +717,7 @@ native_irq_return_ldt: orq PER_CPU_VAR(espfix_stack), %rax SWAPGS movq %rax, %rsp + UNWIND_HINT_IRET_REGS offset=8 /* * At this point, we cannot write to the stack any more, but we can @@ -654,6 +739,7 @@ END(common_interrupt) */ .macro apicinterrupt3 num sym do_sym ENTRY(\sym) + UNWIND_HINT_IRET_REGS ASM_CLAC pushq $~(\num) .Lcommon_\sym: @@ -735,6 +821,8 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ENTRY(\sym) + UNWIND_HINT_IRET_REGS offset=8 + /* Sanity check */ .if \shift_ist != -1 && \paranoid == 0 .error "using shift_ist requires paranoid=1" @@ -758,6 +846,7 @@ ENTRY(\sym) .else call error_entry .endif + UNWIND_HINT_REGS /* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */ .if \paranoid @@ -855,6 +944,7 @@ idtentry simd_coprocessor_error do_simd_coprocessor_error has_error_code=0 * edi: new selector */ ENTRY(native_load_gs_index) + FRAME_BEGIN pushfq DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI) SWAPGS @@ -863,8 +953,9 @@ ENTRY(native_load_gs_index) 2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE SWAPGS popfq + FRAME_END ret -END(native_load_gs_index) +ENDPROC(native_load_gs_index) EXPORT_SYMBOL(native_load_gs_index) _ASM_EXTABLE(.Lgs_change, bad_gs) @@ -887,14 +978,12 @@ bad_gs: ENTRY(do_softirq_own_stack) pushq %rbp mov %rsp, %rbp - incl PER_CPU_VAR(irq_count) - cmove PER_CPU_VAR(irq_stack_ptr), %rsp - push %rbp /* frame pointer backlink */ + ENTER_IRQ_STACK regs=0 old_rsp=%r11 call __do_softirq + LEAVE_IRQ_STACK regs=0 leaveq - decl PER_CPU_VAR(irq_count) ret -END(do_softirq_own_stack) +ENDPROC(do_softirq_own_stack) #ifdef CONFIG_XEN idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0 @@ -918,14 +1007,14 @@ ENTRY(xen_do_hypervisor_callback) /* do_hypervisor_callback(struct *pt_regs) */ * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will * see the correct pointer to the pt_regs */ + UNWIND_HINT_FUNC movq %rdi, %rsp /* we don't return, adjust the stack frame */ -11: incl PER_CPU_VAR(irq_count) - movq %rsp, %rbp - cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp - pushq %rbp /* frame pointer backlink */ + UNWIND_HINT_REGS + + ENTER_IRQ_STACK old_rsp=%r10 call xen_evtchn_do_upcall - popq %rsp - decl PER_CPU_VAR(irq_count) + LEAVE_IRQ_STACK + #ifndef CONFIG_PREEMPT call xen_maybe_preempt_hcall #endif @@ -946,6 +1035,7 @@ END(xen_do_hypervisor_callback) * with its current contents: any discrepancy means we in category 1. */ ENTRY(xen_failsafe_callback) + UNWIND_HINT_EMPTY movl %ds, %ecx cmpw %cx, 0x10(%rsp) jne 1f @@ -965,11 +1055,13 @@ ENTRY(xen_failsafe_callback) pushq $0 /* RIP */ pushq %r11 pushq %rcx + UNWIND_HINT_IRET_REGS offset=8 jmp general_protection 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */ movq (%rsp), %rcx movq 8(%rsp), %r11 addq $0x30, %rsp + UNWIND_HINT_IRET_REGS pushq $-1 /* orig_ax = -1 => not a system call */ ALLOC_PT_GPREGS_ON_STACK SAVE_C_REGS @@ -1015,6 +1107,7 @@ idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vec * Return: ebx=0: need swapgs on exit, ebx=1: otherwise */ ENTRY(paranoid_entry) + UNWIND_HINT_FUNC cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 @@ -1042,6 +1135,7 @@ END(paranoid_entry) * On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it) */ ENTRY(paranoid_exit) + UNWIND_HINT_REGS DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF_DEBUG testl %ebx, %ebx /* swapgs needed? */ @@ -1063,6 +1157,7 @@ END(paranoid_exit) * Return: EBX=0: came from user mode; EBX=1: otherwise */ ENTRY(error_entry) + UNWIND_HINT_FUNC cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 @@ -1147,6 +1242,7 @@ END(error_entry) * 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode */ ENTRY(error_exit) + UNWIND_HINT_REGS DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF testl %ebx, %ebx @@ -1156,6 +1252,7 @@ END(error_exit) /* Runs on exception stack */ ENTRY(nmi) + UNWIND_HINT_IRET_REGS /* * Fix up the exception frame if we're on Xen. * PARAVIRT_ADJUST_EXCEPTION_FRAME is guaranteed to push at most @@ -1229,11 +1326,13 @@ ENTRY(nmi) cld movq %rsp, %rdx movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp + UNWIND_HINT_IRET_REGS base=%rdx offset=8 pushq 5*8(%rdx) /* pt_regs->ss */ pushq 4*8(%rdx) /* pt_regs->rsp */ pushq 3*8(%rdx) /* pt_regs->flags */ pushq 2*8(%rdx) /* pt_regs->cs */ pushq 1*8(%rdx) /* pt_regs->rip */ + UNWIND_HINT_IRET_REGS pushq $-1 /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ @@ -1250,6 +1349,7 @@ ENTRY(nmi) pushq %r13 /* pt_regs->r13 */ pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ + UNWIND_HINT_REGS ENCODE_FRAME_POINTER /* @@ -1404,6 +1504,7 @@ first_nmi: .rept 5 pushq 11*8(%rsp) .endr + UNWIND_HINT_IRET_REGS /* Everything up to here is safe from nested NMIs */ @@ -1419,6 +1520,7 @@ first_nmi: pushq $__KERNEL_CS /* CS */ pushq $1f /* RIP */ INTERRUPT_RETURN /* continues at repeat_nmi below */ + UNWIND_HINT_IRET_REGS 1: #endif @@ -1468,6 +1570,7 @@ end_repeat_nmi: * exceptions might do. */ call paranoid_entry + UNWIND_HINT_REGS /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ movq %rsp, %rdi @@ -1505,17 +1608,19 @@ nmi_restore: END(nmi) ENTRY(ignore_sysret) + UNWIND_HINT_EMPTY mov $-ENOSYS, %eax sysret END(ignore_sysret) ENTRY(rewind_stack_do_exit) + UNWIND_HINT_FUNC /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp movq PER_CPU_VAR(cpu_current_top_of_stack), %rax - leaq -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%rax), %rsp + leaq -PTREGS_SIZE(%rax), %rsp + UNWIND_HINT_FUNC sp_offset=PTREGS_SIZE call do_exit -1: jmp 1b END(rewind_stack_do_exit) |