diff options
| -rw-r--r-- | sys/amd64/amd64/db_trace.c | 3 | ||||
| -rw-r--r-- | sys/amd64/amd64/exception.S | 78 | ||||
| -rw-r--r-- | sys/amd64/amd64/genassym.c | 2 | ||||
| -rw-r--r-- | sys/amd64/amd64/trap.c | 3 |
4 files changed, 82 insertions, 4 deletions
diff --git a/sys/amd64/amd64/db_trace.c b/sys/amd64/amd64/db_trace.c index 264daaa..afffe2d 100644 --- a/sys/amd64/amd64/db_trace.c +++ b/sys/amd64/amd64/db_trace.c @@ -317,7 +317,8 @@ db_nextframe(struct amd64_frame **fp, db_addr_t *ip, struct thread *td) db_symbol_values(sym, &name, NULL); if (name != NULL) { if (strcmp(name, "calltrap") == 0 || - strcmp(name, "fork_trampoline") == 0) + strcmp(name, "fork_trampoline") == 0 || + strcmp(name, "nmi_calltrap") == 0) frame_type = TRAP; else if (strncmp(name, "Xatpic_intr", 11) == 0 || strncmp(name, "Xatpic_fastintr", 15) == 0 || diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S index 9161044..9b87cee 100644 --- a/sys/amd64/amd64/exception.S +++ b/sys/amd64/amd64/exception.S @@ -93,8 +93,6 @@ IDTVEC(bpt) jmp alltraps IDTVEC(div) TRAP(T_DIVIDE) -IDTVEC(nmi) - TRAP_NOEN(T_NMI) IDTVEC(ofl) TRAP(T_OFLOW) IDTVEC(bnd) @@ -313,6 +311,82 @@ IDTVEC(fast_syscall) IDTVEC(fast_syscall32) sysret +/* + * NMI handling is special. + * + * First, NMIs do not respect the state of the processor's RFLAGS.IF + * bit and the NMI handler may be invoked at any time, including when + * the processor is in a critical section with RFLAGS.IF == 0. In + * particular, this means that the processor's GS.base values could be + * inconsistent on entry to the handler, and so we need to read + * MSR_GSBASE to determine if a 'swapgs' is needed. We use '%ebx', a + * C-preserved register, to remember whether to swap GS back on the + * exit path. + * + * Second, the processor treats NMIs specially, blocking further NMIs + * until an 'iretq' instruction is executed. We therefore need to + * execute the NMI handler with interrupts disabled to prevent a + * nested interrupt from executing an 'iretq' instruction and + * inadvertently taking the processor out of NMI mode. + */ + +IDTVEC(nmi) + subq $TF_RIP,%rsp + movq $(T_NMI),TF_TRAPNO(%rsp) + movq $0,TF_ADDR(%rsp) + movq $0,TF_ERR(%rsp) + movq %rdi,TF_RDI(%rsp) + movq %rsi,TF_RSI(%rsp) + movq %rdx,TF_RDX(%rsp) + movq %rcx,TF_RCX(%rsp) + movq %r8,TF_R8(%rsp) + movq %r9,TF_R9(%rsp) + movq %rax,TF_RAX(%rsp) + movq %rbx,TF_RBX(%rsp) + movq %rbp,TF_RBP(%rsp) + movq %r10,TF_R10(%rsp) + movq %r11,TF_R11(%rsp) + movq %r12,TF_R12(%rsp) + movq %r13,TF_R13(%rsp) + movq %r14,TF_R14(%rsp) + movq %r15,TF_R15(%rsp) + xorl %ebx,%ebx + testb $SEL_RPL_MASK,TF_CS(%rsp) + jnz nmi_needswapgs /* we came from userland */ + movl $MSR_GSBASE,%ecx + rdmsr + cmpl $VM_MAXUSER_ADDRESS >> 32,%edx + jae nmi_calltrap /* GS.base holds a kernel VA */ +nmi_needswapgs: + incl %ebx + swapgs +/* Note: this label is also used by ddb and gdb: */ +nmi_calltrap: + FAKE_MCOUNT(TF_RIP(%rsp)) + call trap + MEXITCOUNT + testl %ebx,%ebx + jz nmi_restoreregs + swapgs +nmi_restoreregs: + movq TF_RDI(%rsp),%rdi + movq TF_RSI(%rsp),%rsi + movq TF_RDX(%rsp),%rdx + movq TF_RCX(%rsp),%rcx + movq TF_R8(%rsp),%r8 + movq TF_R9(%rsp),%r9 + movq TF_RAX(%rsp),%rax + movq TF_RBX(%rsp),%rbx + movq TF_RBP(%rsp),%rbp + movq TF_R10(%rsp),%r10 + movq TF_R11(%rsp),%r11 + movq TF_R12(%rsp),%r12 + movq TF_R13(%rsp),%r13 + movq TF_R14(%rsp),%r14 + movq TF_R15(%rsp),%r15 + addq $TF_RIP,%rsp + iretq + ENTRY(fork_trampoline) movq %r12, %rdi /* function */ movq %rbx, %rsi /* arg1 */ diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c index 3a51e6f..6157348 100644 --- a/sys/amd64/amd64/genassym.c +++ b/sys/amd64/amd64/genassym.c @@ -209,3 +209,5 @@ ASSYM(SEL_RPL_MASK, SEL_RPL_MASK); ASSYM(MTX_LOCK, offsetof(struct mtx, mtx_lock)); ASSYM(MTX_RECURSECNT, offsetof(struct mtx, mtx_recurse)); + +ASSYM(MSR_GSBASE, MSR_GSBASE); diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c index cb79c58..c70dc0b 100644 --- a/sys/amd64/amd64/trap.c +++ b/sys/amd64/amd64/trap.c @@ -210,7 +210,8 @@ trap(frame) printf( "pid %ld (%s): trap %d with interrupts disabled\n", (long)curproc->p_pid, curproc->p_comm, type); - else if (type != T_BPTFLT && type != T_TRCTRAP) { + else if (type != T_NMI && type != T_BPTFLT && + type != T_TRCTRAP) { /* * XXX not quite right, since this may be for a * multiple fault in user mode. |
