/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved. */ /* Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */ /* Copyright (c) 1984, 1986, 1987, 1988, 1989, 1990 AT&T */ /* All Rights Reserved */ /* */ /* Copyright (c) 1987, 1988 Microsoft Corporation */ /* All Rights Reserved */ /* */ /* * Copyright 2018 Joyent, Inc. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(__xpv) #include #endif #include #define USER 0x10000 /* user-mode flag added to trap type */ static const char *trap_type_mnemonic[] = { "de", "db", "2", "bp", "of", "br", "ud", "nm", "df", "9", "ts", "np", "ss", "gp", "pf", "15", "mf", "ac", "mc", "xf" }; static const char *trap_type[] = { "Divide error", /* trap id 0 */ "Debug", /* trap id 1 */ "NMI interrupt", /* trap id 2 */ "Breakpoint", /* trap id 3 */ "Overflow", /* trap id 4 */ "BOUND range exceeded", /* trap id 5 */ "Invalid opcode", /* trap id 6 */ "Device not available", /* trap id 7 */ "Double fault", /* trap id 8 */ "Coprocessor segment overrun", /* trap id 9 */ "Invalid TSS", /* trap id 10 */ "Segment not present", /* trap id 11 */ "Stack segment fault", /* trap id 12 */ "General protection", /* trap id 13 */ "Page fault", /* trap id 14 */ "Reserved", /* trap id 15 */ "x87 floating point error", /* trap id 16 */ "Alignment check", /* trap id 17 */ "Machine check", /* trap id 18 */ "SIMD floating point exception", /* trap id 19 */ }; #define TRAP_TYPES (sizeof (trap_type) / sizeof (trap_type[0])) #define SLOW_SCALL_SIZE 2 #define FAST_SCALL_SIZE 2 int tudebug = 0; int tudebugbpt = 0; int tudebugfpe = 0; int tudebugsse = 0; #if defined(TRAPDEBUG) || defined(lint) int tdebug = 0; int lodebug = 0; int faultdebug = 0; #else #define tdebug 0 #define lodebug 0 #define faultdebug 0 #endif /* defined(TRAPDEBUG) || defined(lint) */ #if defined(TRAPTRACE) /* * trap trace record for cpu0 is allocated here. * trap trace records for non-boot cpus are allocated in mp_startup_init(). */ static trap_trace_rec_t trap_tr0[TRAPTR_NENT]; trap_trace_ctl_t trap_trace_ctl[NCPU] = { { (uintptr_t)trap_tr0, /* next record */ (uintptr_t)trap_tr0, /* first record */ (uintptr_t)(trap_tr0 + TRAPTR_NENT), /* limit */ (uintptr_t)0 /* current */ }, }; /* * default trap buffer size */ size_t trap_trace_bufsize = TRAPTR_NENT * sizeof (trap_trace_rec_t); int trap_trace_freeze = 0; int trap_trace_off = 0; /* * A dummy TRAPTRACE entry to use after death. */ trap_trace_rec_t trap_trace_postmort; static void dump_ttrace(void); #endif /* TRAPTRACE */ static void dumpregs(struct regs *); static void showregs(uint_t, struct regs *, caddr_t); static int kern_gpfault(struct regs *); /*ARGSUSED*/ static int die(uint_t type, struct regs *rp, caddr_t addr, processorid_t cpuid) { struct panic_trap_info ti; const char *trap_name, *trap_mnemonic; if (type < TRAP_TYPES) { trap_name = trap_type[type]; trap_mnemonic = trap_type_mnemonic[type]; } else { trap_name = "trap"; trap_mnemonic = "-"; } #ifdef TRAPTRACE TRAPTRACE_FREEZE; #endif ti.trap_regs = rp; ti.trap_type = type & ~USER; ti.trap_addr = addr; curthread->t_panic_trap = &ti; if (type == T_PGFLT && addr < (caddr_t)kernelbase) { panic("BAD TRAP: type=%x (#%s %s) rp=%p addr=%p " "occurred in module \"%s\" due to %s", type, trap_mnemonic, trap_name, (void *)rp, (void *)addr, mod_containing_pc((caddr_t)rp->r_pc), addr < (caddr_t)PAGESIZE ? "a NULL pointer dereference" : "an illegal access to a user address"); } else panic("BAD TRAP: type=%x (#%s %s) rp=%p addr=%p", type, trap_mnemonic, trap_name, (void *)rp, (void *)addr); return (0); } /* * Rewrite the instruction at pc to be an int $T_SYSCALLINT instruction. * * int is two bytes: 0xCD */ static int rewrite_syscall(caddr_t pc) { uchar_t instr[SLOW_SCALL_SIZE] = { 0xCD, T_SYSCALLINT }; if (uwrite(curthread->t_procp, instr, SLOW_SCALL_SIZE, (uintptr_t)pc) != 0) return (1); return (0); } /* * Test to see if the instruction at pc is sysenter or syscall. The second * argument should be the x86 feature flag corresponding to the expected * instruction. * * sysenter is two bytes: 0x0F 0x34 * syscall is two bytes: 0x0F 0x05 * int $T_SYSCALLINT is two bytes: 0xCD 0x91 */ static int instr_is_other_syscall(caddr_t pc, int which) { uchar_t instr[FAST_SCALL_SIZE]; ASSERT(which == X86FSET_SEP || which == X86FSET_ASYSC || which == 0xCD); if (copyin_nowatch(pc, (caddr_t)instr, FAST_SCALL_SIZE) != 0) return (0); switch (which) { case X86FSET_SEP: if (instr[0] == 0x0F && instr[1] == 0x34) return (1); break; case X86FSET_ASYSC: if (instr[0] == 0x0F && instr[1] == 0x05) return (1); break; case 0xCD: if (instr[0] == 0xCD && instr[1] == T_SYSCALLINT) return (1); break; } return (0); } static const char * syscall_insn_string(int syscall_insn) { switch (syscall_insn) { case X86FSET_SEP: return ("sysenter"); case X86FSET_ASYSC: return ("syscall"); case 0xCD: return ("int"); default: return ("Unknown"); } } static int ldt_rewrite_syscall(struct regs *rp, proc_t *p, int syscall_insn) { caddr_t linearpc; int return_code = 0; mutex_enter(&p->p_ldtlock); /* Must be held across linear_pc() */ if (linear_pc(rp, p, &linearpc) == 0) { /* * If another thread beat us here, it already changed * this site to the slower (int) syscall instruction. */ if (instr_is_other_syscall(linearpc, 0xCD)) { return_code = 1; } else if (instr_is_other_syscall(linearpc, syscall_insn)) { if (rewrite_syscall(linearpc) == 0) { return_code = 1; } #ifdef DEBUG else cmn_err(CE_WARN, "failed to rewrite %s " "instruction in process %d", syscall_insn_string(syscall_insn), p->p_pid); #endif /* DEBUG */ } } mutex_exit(&p->p_ldtlock); /* Must be held across linear_pc() */ return (return_code); } /* * Test to see if the instruction at pc is a system call instruction. * * The bytes of an lcall instruction used for the syscall trap. * static uchar_t lcall[7] = { 0x9a, 0, 0, 0, 0, 0x7, 0 }; * static uchar_t lcallalt[7] = { 0x9a, 0, 0, 0, 0, 0x27, 0 }; */ #define LCALLSIZE 7 static int instr_is_lcall_syscall(caddr_t pc) { uchar_t instr[LCALLSIZE]; if (copyin_nowatch(pc, (caddr_t)instr, LCALLSIZE) == 0 && instr[0] == 0x9a && instr[1] == 0 && instr[2] == 0 && instr[3] == 0 && instr[4] == 0 && (instr[5] == 0x7 || instr[5] == 0x27) && instr[6] == 0) return (1); return (0); } /* * In the first revisions of amd64 CPUs produced by AMD, the LAHF and * SAHF instructions were not implemented in 64-bit mode. Later revisions * did implement these instructions. An extension to the cpuid instruction * was added to check for the capability of executing these instructions * in 64-bit mode. * * Intel originally did not implement these instructions in EM64T either, * but added them in later revisions. * * So, there are different chip revisions by both vendors out there that * may or may not implement these instructions. The easy solution is to * just always emulate these instructions on demand. * * SAHF == store %ah in the lower 8 bits of %rflags (opcode 0x9e) * LAHF == load the lower 8 bits of %rflags into %ah (opcode 0x9f) */ #define LSAHFSIZE 1 static int instr_is_lsahf(caddr_t pc, uchar_t *instr) { if (copyin_nowatch(pc, (caddr_t)instr, LSAHFSIZE) == 0 && (*instr == 0x9e || *instr == 0x9f)) return (1); return (0); } /* * Emulate the LAHF and SAHF instructions. The reference manuals define * these instructions to always load/store bit 1 as a 1, and bits 3 and 5 * as a 0. The other, defined, bits are copied (the PS_ICC bits and PS_P). * * Note that %ah is bits 8-15 of %rax. */ static void emulate_lsahf(struct regs *rp, uchar_t instr) { if (instr == 0x9e) { /* sahf. Copy bits from %ah to flags. */ rp->r_ps = (rp->r_ps & ~0xff) | ((rp->r_rax >> 8) & PSL_LSAHFMASK) | PS_MB1; } else { /* lahf. Copy bits from flags to %ah. */ rp->r_rax = (rp->r_rax & ~0xff00) | (((rp->r_ps & PSL_LSAHFMASK) | PS_MB1) << 8); } rp->r_pc += LSAHFSIZE; } #ifdef OPTERON_ERRATUM_91 /* * Test to see if the instruction at pc is a prefetch instruction. * * The first byte of prefetch instructions is always 0x0F. * The second byte is 0x18 for regular prefetch or 0x0D for AMD 3dnow prefetch. * The third byte (ModRM) contains the register field bits (bits 3-5). * These bits must be between 0 and 3 inclusive for regular prefetch and * 0 and 1 inclusive for AMD 3dnow prefetch. * * In 64-bit mode, there may be a one-byte REX prefex (0x40-0x4F). */ static int cmp_to_prefetch(uchar_t *p) { #ifdef _LP64 if ((p[0] & 0xF0) == 0x40) /* 64-bit REX prefix */ p++; #endif return ((p[0] == 0x0F && p[1] == 0x18 && ((p[2] >> 3) & 7) <= 3) || (p[0] == 0x0F && p[1] == 0x0D && ((p[2] >> 3) & 7) <= 1)); } static int instr_is_prefetch(caddr_t pc) { uchar_t instr[4]; /* optional REX prefix plus 3-byte opcode */ return (copyin_nowatch(pc, instr, sizeof (instr)) == 0 && cmp_to_prefetch(instr)); } #endif /* OPTERON_ERRATUM_91 */ /* * Called from the trap handler when a processor trap occurs. * * Note: All user-level traps that might call stop() must exit * trap() by 'goto out' or by falling through. * Note Also: trap() is usually called with interrupts enabled, (PS_IE == 1) * however, there are paths that arrive here with PS_IE == 0 so special care * must be taken in those cases. */ void trap(struct regs *rp, caddr_t addr, processorid_t cpuid) { kthread_t *ct = curthread; enum seg_rw rw; unsigned type; proc_t *p = ttoproc(ct); klwp_t *lwp = ttolwp(ct); uintptr_t lofault; label_t *onfault; faultcode_t pagefault(), res, errcode; enum fault_type fault_type; k_siginfo_t siginfo; uint_t fault = 0; int mstate; int sicode = 0; int watchcode; int watchpage; caddr_t vaddr; size_t sz; int ta; uchar_t instr; ASSERT_STACK_ALIGNED(); errcode = 0; mstate = 0; rw = S_OTHER; type = rp->r_trapno; CPU_STATS_ADDQ(CPU, sys, trap, 1); ASSERT(ct->t_schedflag & TS_DONT_SWAP); if (type == T_PGFLT) { errcode = rp->r_err; if (errcode & PF_ERR_WRITE) { rw = S_WRITE; } else if ((caddr_t)rp->r_pc == addr || (mmu.pt_nx != 0 && (errcode & PF_ERR_EXEC))) { rw = S_EXEC; } else { rw = S_READ; } } else if (type == T_SGLSTP && lwp != NULL) { lwp->lwp_pcb.pcb_drstat = (uintptr_t)addr; } if (tdebug) showregs(type, rp, addr); if (USERMODE(rp->r_cs)) { /* * Set up the current cred to use during this trap. u_cred * no longer exists. t_cred is used instead. * The current process credential applies to the thread for * the entire trap. If trapping from the kernel, this * should already be set up. */ if (ct->t_cred != p->p_cred) { cred_t *oldcred = ct->t_cred; /* * DTrace accesses t_cred in probe context. t_cred * must always be either NULL, or point to a valid, * allocated cred structure. */ ct->t_cred = crgetcred(); crfree(oldcred); } ASSERT(lwp != NULL); type |= USER; ASSERT(lwptoregs(lwp) == rp); lwp->lwp_state = LWP_SYS; switch (type) { case T_PGFLT + USER: if ((caddr_t)rp->r_pc == addr) mstate = LMS_TFAULT; else mstate = LMS_DFAULT; break; default: mstate = LMS_TRAP; break; } /* Kernel probe */ TNF_PROBE_1(thread_state, "thread", /* CSTYLED */, tnf_microstate, state, mstate); mstate = new_mstate(ct, mstate); bzero(&siginfo, sizeof (siginfo)); } switch (type) { case T_PGFLT + USER: case T_SGLSTP: case T_SGLSTP + USER: case T_BPTFLT + USER: break; default: FTRACE_2("trap(): type=0x%lx, regs=0x%lx", (ulong_t)type, (ulong_t)rp); break; } switch (type) { case T_SIMDFPE: /* Make sure we enable interrupts before die()ing */ sti(); /* The SIMD exception comes in via cmninttrap */ /*FALLTHROUGH*/ default: if (type & USER) { if (tudebug) showregs(type, rp, (caddr_t)0); printf("trap: Unknown trap type %d in user mode\n", type & ~USER); siginfo.si_signo = SIGILL; siginfo.si_code = ILL_ILLTRP; siginfo.si_addr = (caddr_t)rp->r_pc; siginfo.si_trapno = type & ~USER; fault = FLTILL; } else { (void) die(type, rp, addr, cpuid); /*NOTREACHED*/ } break; case T_PGFLT: /* system page fault */ /* * If we're under on_trap() protection (see ), * set ot_trap and bounce back to the on_trap() call site * via the installed trampoline. */ if ((ct->t_ontrap != NULL) && (ct->t_ontrap->ot_prot & OT_DATA_ACCESS)) { ct->t_ontrap->ot_trap |= OT_DATA_ACCESS; rp->r_pc = ct->t_ontrap->ot_trampoline; goto cleanup; } /* * If we have an Instruction fault in kernel mode, then that * means we've tried to execute a user page (SMEP) or both of * PAE and NXE are enabled. In either case, given that it's a * kernel fault, we should panic immediately and not try to make * any more forward progress. This indicates a bug in the * kernel, which if execution continued, could be exploited to * wreak havoc on the system. */ if (errcode & PF_ERR_EXEC) { (void) die(type, rp, addr, cpuid); } /* * We need to check if SMAP is in play. If SMAP is in play, then * any access to a user page will show up as a protection * violation. To see if SMAP is enabled we first check if it's a * user address and whether we have the feature flag set. If we * do and the interrupted registers do not allow for user * accesses (PS_ACHK is not enabled), then we need to die * immediately. */ if (addr < (caddr_t)kernelbase && is_x86_feature(x86_featureset, X86FSET_SMAP) == B_TRUE && (rp->r_ps & PS_ACHK) == 0) { (void) die(type, rp, addr, cpuid); } /* * See if we can handle as pagefault. Save lofault and onfault * across this. Here we assume that an address less than * KERNELBASE is a user fault. We can do this as copy.s * routines verify that the starting address is less than * KERNELBASE before starting and because we know that we * always have KERNELBASE mapped as invalid to serve as a * "barrier". */ lofault = ct->t_lofault; onfault = ct->t_onfault; ct->t_lofault = 0; mstate = new_mstate(ct, LMS_KFAULT); if (addr < (caddr_t)kernelbase) { res = pagefault(addr, (errcode & PF_ERR_PROT)? F_PROT: F_INVAL, rw, 0); if (res == FC_NOMAP && addr < p->p_usrstack && grow(addr)) res = 0; } else { res = pagefault(addr, (errcode & PF_ERR_PROT)? F_PROT: F_INVAL, rw, 1); } (void) new_mstate(ct, mstate); /* * Restore lofault and onfault. If we resolved the fault, exit. * If we didn't and lofault wasn't set, die. */ ct->t_lofault = lofault; ct->t_onfault = onfault; if (res == 0) goto cleanup; #if defined(OPTERON_ERRATUM_93) && defined(_LP64) if (lofault == 0 && opteron_erratum_93) { /* * Workaround for Opteron Erratum 93. On return from * a System Managment Interrupt at a HLT instruction * the %rip might be truncated to a 32 bit value. * BIOS is supposed to fix this, but some don't. * If this occurs we simply restore the high order bits. * The HLT instruction is 1 byte of 0xf4. */ uintptr_t rip = rp->r_pc; if ((rip & 0xfffffffful) == rip) { rip |= 0xfffffffful << 32; if (hat_getpfnum(kas.a_hat, (caddr_t)rip) != PFN_INVALID && (*(uchar_t *)rip == 0xf4 || *(uchar_t *)(rip - 1) == 0xf4)) { rp->r_pc = rip; goto cleanup; } } } #endif /* OPTERON_ERRATUM_93 && _LP64 */ #ifdef OPTERON_ERRATUM_91 if (lofault == 0 && opteron_erratum_91) { /* * Workaround for Opteron Erratum 91. Prefetches may * generate a page fault (they're not supposed to do * that!). If this occurs we simply return back to the * instruction. */ caddr_t pc = (caddr_t)rp->r_pc; /* * If the faulting PC is not mapped, this is a * legitimate kernel page fault that must result in a * panic. If the faulting PC is mapped, it could contain * a prefetch instruction. Check for that here. */ if (hat_getpfnum(kas.a_hat, pc) != PFN_INVALID) { if (cmp_to_prefetch((uchar_t *)pc)) { #ifdef DEBUG cmn_err(CE_WARN, "Opteron erratum 91 " "occurred: kernel prefetch" " at %p generated a page fault!", (void *)rp->r_pc); #endif /* DEBUG */ goto cleanup; } } (void) die(type, rp, addr, cpuid); } #endif /* OPTERON_ERRATUM_91 */ if (lofault == 0) (void) die(type, rp, addr, cpuid); /* * Cannot resolve fault. Return to lofault. */ if (lodebug) { showregs(type, rp, addr); traceregs(rp); } if (FC_CODE(res) == FC_OBJERR) res = FC_ERRNO(res); else res = EFAULT; rp->r_r0 = res; rp->r_pc = ct->t_lofault; goto cleanup; case T_PGFLT + USER: /* user page fault */ if (faultdebug) { char *fault_str; switch (rw) { case S_READ: fault_str = "read"; break; case S_WRITE: fault_str = "write"; break; case S_EXEC: fault_str = "exec"; break; default: fault_str = ""; break; } printf("user %s fault: addr=0x%lx errcode=0x%x\n", fault_str, (uintptr_t)addr, errcode); } #if defined(OPTERON_ERRATUM_100) && defined(_LP64) /* * Workaround for AMD erratum 100 * * A 32-bit process may receive a page fault on a non * 32-bit address by mistake. The range of the faulting * address will be * * 0xffffffff80000000 .. 0xffffffffffffffff or * 0x0000000100000000 .. 0x000000017fffffff * * The fault is always due to an instruction fetch, however * the value of r_pc should be correct (in 32 bit range), * so we ignore the page fault on the bogus address. */ if (p->p_model == DATAMODEL_ILP32 && (0xffffffff80000000 <= (uintptr_t)addr || (0x100000000 <= (uintptr_t)addr && (uintptr_t)addr <= 0x17fffffff))) { if (!opteron_erratum_100) panic("unexpected erratum #100"); if (rp->r_pc <= 0xffffffff) goto out; } #endif /* OPTERON_ERRATUM_100 && _LP64 */ ASSERT(!(curthread->t_flag & T_WATCHPT)); watchpage = (pr_watch_active(p) && pr_is_watchpage(addr, rw)); vaddr = addr; if (!watchpage || (sz = instr_size(rp, &vaddr, rw)) <= 0) fault_type = (errcode & PF_ERR_PROT)? F_PROT: F_INVAL; else if ((watchcode = pr_is_watchpoint(&vaddr, &ta, sz, NULL, rw)) != 0) { if (ta) { do_watch_step(vaddr, sz, rw, watchcode, rp->r_pc); fault_type = F_INVAL; } else { bzero(&siginfo, sizeof (siginfo)); siginfo.si_signo = SIGTRAP; siginfo.si_code = watchcode; siginfo.si_addr = vaddr; siginfo.si_trapafter = 0; siginfo.si_pc = (caddr_t)rp->r_pc; fault = FLTWATCH; break; } } else { /* XXX pr_watch_emul() never succeeds (for now) */ if (rw != S_EXEC && pr_watch_emul(rp, vaddr, rw)) goto out; do_watch_step(vaddr, sz, rw, 0, 0); fault_type = F_INVAL; } res = pagefault(addr, fault_type, rw, 0); /* * If pagefault() succeeded, ok. * Otherwise attempt to grow the stack. */ if (res == 0 || (res == FC_NOMAP && addr < p->p_usrstack && grow(addr))) { lwp->lwp_lastfault = FLTPAGE; lwp->lwp_lastfaddr = addr; if (prismember(&p->p_fltmask, FLTPAGE)) { bzero(&siginfo, sizeof (siginfo)); siginfo.si_addr = addr; (void) stop_on_fault(FLTPAGE, &siginfo); } goto out; } else if (res == FC_PROT && addr < p->p_usrstack && (mmu.pt_nx != 0 && (errcode & PF_ERR_EXEC))) { report_stack_exec(p, addr); } #ifdef OPTERON_ERRATUM_91 /* * Workaround for Opteron Erratum 91. Prefetches may generate a * page fault (they're not supposed to do that!). If this * occurs we simply return back to the instruction. * * We rely on copyin to properly fault in the page with r_pc. */ if (opteron_erratum_91 && addr != (caddr_t)rp->r_pc && instr_is_prefetch((caddr_t)rp->r_pc)) { #ifdef DEBUG cmn_err(CE_WARN, "Opteron erratum 91 occurred: " "prefetch at %p in pid %d generated a trap!", (void *)rp->r_pc, p->p_pid); #endif /* DEBUG */ goto out; } #endif /* OPTERON_ERRATUM_91 */ if (tudebug) showregs(type, rp, addr); /* * In the case where both pagefault and grow fail, * set the code to the value provided by pagefault. * We map all errors returned from pagefault() to SIGSEGV. */ bzero(&siginfo, sizeof (siginfo)); siginfo.si_addr = addr; switch (FC_CODE(res)) { case FC_HWERR: case FC_NOSUPPORT: siginfo.si_signo = SIGBUS; siginfo.si_code = BUS_ADRERR; fault = FLTACCESS; break; case FC_ALIGN: siginfo.si_signo = SIGBUS; siginfo.si_code = BUS_ADRALN; fault = FLTACCESS; break; case FC_OBJERR: if ((siginfo.si_errno = FC_ERRNO(res)) != EINTR) { siginfo.si_signo = SIGBUS; siginfo.si_code = BUS_OBJERR; fault = FLTACCESS; } break; default: /* FC_NOMAP or FC_PROT */ siginfo.si_signo = SIGSEGV; siginfo.si_code = (res == FC_NOMAP)? SEGV_MAPERR : SEGV_ACCERR; fault = FLTBOUNDS; break; } break; case T_ILLINST + USER: /* invalid opcode fault */ /* * If the syscall instruction is disabled due to LDT usage, a * user program that attempts to execute it will trigger a #ud * trap. Check for that case here. If this occurs on a CPU which * doesn't even support syscall, the result of all of this will * be to emulate that particular instruction. */ if (p->p_ldt != NULL && ldt_rewrite_syscall(rp, p, X86FSET_ASYSC)) goto out; /* * Emulate the LAHF and SAHF instructions if needed. * See the instr_is_lsahf function for details. */ if (p->p_model == DATAMODEL_LP64 && instr_is_lsahf((caddr_t)rp->r_pc, &instr)) { emulate_lsahf(rp, instr); goto out; } /*FALLTHROUGH*/ if (tudebug) showregs(type, rp, (caddr_t)0); siginfo.si_signo = SIGILL; siginfo.si_code = ILL_ILLOPC; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTILL; break; case T_ZERODIV + USER: /* integer divide by zero */ if (tudebug && tudebugfpe) showregs(type, rp, (caddr_t)0); siginfo.si_signo = SIGFPE; siginfo.si_code = FPE_INTDIV; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTIZDIV; break; case T_OVFLW + USER: /* integer overflow */ if (tudebug && tudebugfpe) showregs(type, rp, (caddr_t)0); siginfo.si_signo = SIGFPE; siginfo.si_code = FPE_INTOVF; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTIOVF; break; /* * When using an eager FPU on x86, the #NM trap is no longer meaningful. * Userland should not be able to trigger it. Anything that does * represents a fatal error in the kernel and likely in the register * state of the system. User FPU state should always be valid. */ case T_NOEXTFLT + USER: /* math coprocessor not available */ case T_NOEXTFLT: (void) die(type, rp, addr, cpuid); break; /* * Kernel threads leveraging floating point need to mask the exceptions * or ensure that they cannot happen. There is no recovery from this. */ case T_EXTERRFLT: /* x87 floating point exception pending */ sti(); /* T_EXTERRFLT comes in via cmninttrap */ (void) die(type, rp, addr, cpuid); break; case T_EXTERRFLT + USER: /* x87 floating point exception pending */ if (tudebug && tudebugfpe) showregs(type, rp, addr); if ((sicode = fpexterrflt(rp)) != 0) { siginfo.si_signo = SIGFPE; siginfo.si_code = sicode; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTFPE; } break; case T_SIMDFPE + USER: /* SSE and SSE2 exceptions */ if (tudebug && tudebugsse) showregs(type, rp, addr); if (!is_x86_feature(x86_featureset, X86FSET_SSE) && !is_x86_feature(x86_featureset, X86FSET_SSE2)) { /* * There are rumours that some user instructions * on older CPUs can cause this trap to occur; in * which case send a SIGILL instead of a SIGFPE. */ siginfo.si_signo = SIGILL; siginfo.si_code = ILL_ILLTRP; siginfo.si_addr = (caddr_t)rp->r_pc; siginfo.si_trapno = type & ~USER; fault = FLTILL; } else if ((sicode = fpsimderrflt(rp)) != 0) { siginfo.si_signo = SIGFPE; siginfo.si_code = sicode; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTFPE; } sti(); /* The SIMD exception comes in via cmninttrap */ break; case T_BPTFLT: /* breakpoint trap */ /* * Kernel breakpoint traps should only happen when kmdb is * active, and even then, it'll have interposed on the IDT, so * control won't get here. If it does, we've hit a breakpoint * without the debugger, which is very strange, and very * fatal. */ if (tudebug && tudebugbpt) showregs(type, rp, (caddr_t)0); (void) die(type, rp, addr, cpuid); break; case T_SGLSTP: /* single step/hw breakpoint exception */ #if !defined(__xpv) /* * We'd never normally get here, as kmdb handles its own single * step traps. There is one nasty exception though, as * described in more detail in sys_sysenter(). Note that * checking for all four locations covers both the KPTI and the * non-KPTI cases correctly: the former will never be found at * (brand_)sys_sysenter, and vice versa. */ if (lwp != NULL && (lwp->lwp_pcb.pcb_drstat & DR_SINGLESTEP)) { if (rp->r_pc == (greg_t)brand_sys_sysenter || rp->r_pc == (greg_t)sys_sysenter || rp->r_pc == (greg_t)tr_brand_sys_sysenter || rp->r_pc == (greg_t)tr_sys_sysenter) { rp->r_pc += 0x3; /* sizeof (swapgs) */ rp->r_ps &= ~PS_T; /* turn off trace */ lwp->lwp_pcb.pcb_flags |= DEBUG_PENDING; ct->t_post_sys = 1; aston(curthread); goto cleanup; } else { if (tudebug && tudebugbpt) showregs(type, rp, (caddr_t)0); } } #endif /* !__xpv */ if (boothowto & RB_DEBUG) debug_enter((char *)NULL); else (void) die(type, rp, addr, cpuid); break; case T_NMIFLT: /* NMI interrupt */ printf("Unexpected NMI in system mode\n"); goto cleanup; case T_NMIFLT + USER: /* NMI interrupt */ printf("Unexpected NMI in user mode\n"); break; case T_GPFLT: /* general protection violation */ /* * Any #GP that occurs during an on_trap .. no_trap bracket * with OT_DATA_ACCESS or OT_SEGMENT_ACCESS protection, * or in a on_fault .. no_fault bracket, is forgiven * and we trampoline. This protection is given regardless * of whether we are 32/64 bit etc - if a distinction is * required then define new on_trap protection types. * * On amd64, we can get a #gp from referencing addresses * in the virtual address hole e.g. from a copyin or in * update_sregs while updating user segment registers. * * On the 32-bit hypervisor we could also generate one in * mfn_to_pfn by reaching around or into where the hypervisor * lives which is protected by segmentation. */ /* * If we're under on_trap() protection (see ), * set ot_trap and trampoline back to the on_trap() call site * for OT_DATA_ACCESS or OT_SEGMENT_ACCESS. */ if (ct->t_ontrap != NULL) { int ttype = ct->t_ontrap->ot_prot & (OT_DATA_ACCESS | OT_SEGMENT_ACCESS); if (ttype != 0) { ct->t_ontrap->ot_trap |= ttype; if (tudebug) showregs(type, rp, (caddr_t)0); rp->r_pc = ct->t_ontrap->ot_trampoline; goto cleanup; } } /* * If we're under lofault protection (copyin etc.), * longjmp back to lofault with an EFAULT. */ if (ct->t_lofault) { /* * Fault is not resolvable, so just return to lofault */ if (lodebug) { showregs(type, rp, addr); traceregs(rp); } rp->r_r0 = EFAULT; rp->r_pc = ct->t_lofault; goto cleanup; } /* * We fall through to the next case, which repeats * the OT_SEGMENT_ACCESS check which we've already * done, so we'll always fall through to the * T_STKFLT case. */ /*FALLTHROUGH*/ case T_SEGFLT: /* segment not present fault */ /* * One example of this is #NP in update_sregs while * attempting to update a user segment register * that points to a descriptor that is marked not * present. */ if (ct->t_ontrap != NULL && ct->t_ontrap->ot_prot & OT_SEGMENT_ACCESS) { ct->t_ontrap->ot_trap |= OT_SEGMENT_ACCESS; if (tudebug) showregs(type, rp, (caddr_t)0); rp->r_pc = ct->t_ontrap->ot_trampoline; goto cleanup; } /*FALLTHROUGH*/ case T_STKFLT: /* stack fault */ case T_TSSFLT: /* invalid TSS fault */ if (tudebug) showregs(type, rp, (caddr_t)0); if (kern_gpfault(rp)) (void) die(type, rp, addr, cpuid); goto cleanup; /* * ONLY 32-bit PROCESSES can USE a PRIVATE LDT! 64-bit apps * should have no need for them, so we put a stop to it here. * * So: not-present fault is ONLY valid for 32-bit processes with * a private LDT trying to do a system call. Emulate it. * * #gp fault is ONLY valid for 32-bit processes also, which DO NOT * have a private LDT, and are trying to do a system call. Emulate it. */ case T_SEGFLT + USER: /* segment not present fault */ case T_GPFLT + USER: /* general protection violation */ #ifdef _SYSCALL32_IMPL if (p->p_model != DATAMODEL_NATIVE) { #endif /* _SYSCALL32_IMPL */ if (instr_is_lcall_syscall((caddr_t)rp->r_pc)) { if (type == T_SEGFLT + USER) ASSERT(p->p_ldt != NULL); if ((p->p_ldt == NULL && type == T_GPFLT + USER) || type == T_SEGFLT + USER) { /* * The user attempted a system call via the obsolete * call gate mechanism. Because the process doesn't have * an LDT (i.e. the ldtr contains 0), a #gp results. * Emulate the syscall here, just as we do above for a * #np trap. */ /* * Since this is a not-present trap, rp->r_pc points to * the trapping lcall instruction. We need to bump it * to the next insn so the app can continue on. */ rp->r_pc += LCALLSIZE; lwp->lwp_regs = rp; /* * Normally the microstate of the LWP is forced back to * LMS_USER by the syscall handlers. Emulate that * behavior here. */ mstate = LMS_USER; dosyscall(); goto out; } } #ifdef _SYSCALL32_IMPL } #endif /* _SYSCALL32_IMPL */ /* * If the current process is using a private LDT and the * trapping instruction is sysenter, the sysenter instruction * has been disabled on the CPU because it destroys segment * registers. If this is the case, rewrite the instruction to * be a safe system call and retry it. If this occurs on a CPU * which doesn't even support sysenter, the result of all of * this will be to emulate that particular instruction. */ if (p->p_ldt != NULL && ldt_rewrite_syscall(rp, p, X86FSET_SEP)) goto out; /*FALLTHROUGH*/ case T_BOUNDFLT + USER: /* bound fault */ case T_STKFLT + USER: /* stack fault */ case T_TSSFLT + USER: /* invalid TSS fault */ if (tudebug) showregs(type, rp, (caddr_t)0); siginfo.si_signo = SIGSEGV; siginfo.si_code = SEGV_MAPERR; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTBOUNDS; break; case T_ALIGNMENT + USER: /* user alignment error (486) */ if (tudebug) showregs(type, rp, (caddr_t)0); bzero(&siginfo, sizeof (siginfo)); siginfo.si_signo = SIGBUS; siginfo.si_code = BUS_ADRALN; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTACCESS; break; case T_SGLSTP + USER: /* single step/hw breakpoint exception */ if (tudebug && tudebugbpt) showregs(type, rp, (caddr_t)0); /* Was it single-stepping? */ if (lwp->lwp_pcb.pcb_drstat & DR_SINGLESTEP) { pcb_t *pcb = &lwp->lwp_pcb; rp->r_ps &= ~PS_T; /* * If both NORMAL_STEP and WATCH_STEP are in effect, * give precedence to WATCH_STEP. If neither is set, * user must have set the PS_T bit in %efl; treat this * as NORMAL_STEP. */ if ((fault = undo_watch_step(&siginfo)) == 0 && ((pcb->pcb_flags & NORMAL_STEP) || !(pcb->pcb_flags & WATCH_STEP))) { siginfo.si_signo = SIGTRAP; siginfo.si_code = TRAP_TRACE; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTTRACE; } pcb->pcb_flags &= ~(NORMAL_STEP|WATCH_STEP); } break; case T_BPTFLT + USER: /* breakpoint trap */ if (tudebug && tudebugbpt) showregs(type, rp, (caddr_t)0); /* * int 3 (the breakpoint instruction) leaves the pc referring * to the address one byte after the breakpointed address. * If the P_PR_BPTADJ flag has been set via /proc, We adjust * it back so it refers to the breakpointed address. */ if (p->p_proc_flag & P_PR_BPTADJ) rp->r_pc--; siginfo.si_signo = SIGTRAP; siginfo.si_code = TRAP_BRKPT; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTBPT; break; case T_AST: /* * This occurs only after the cs register has been made to * look like a kernel selector, either through debugging or * possibly by functions like setcontext(). The thread is * about to cause a general protection fault at common_iret() * in locore. We let that happen immediately instead of * doing the T_AST processing. */ goto cleanup; case T_AST + USER: /* profiling, resched, h/w error pseudo trap */ if (lwp->lwp_pcb.pcb_flags & ASYNC_HWERR) { proc_t *p = ttoproc(curthread); extern void print_msg_hwerr(ctid_t ct_id, proc_t *p); lwp->lwp_pcb.pcb_flags &= ~ASYNC_HWERR; print_msg_hwerr(p->p_ct_process->conp_contract.ct_id, p); contract_process_hwerr(p->p_ct_process, p); siginfo.si_signo = SIGKILL; siginfo.si_code = SI_NOINFO; } else if (lwp->lwp_pcb.pcb_flags & CPC_OVERFLOW) { lwp->lwp_pcb.pcb_flags &= ~CPC_OVERFLOW; if (kcpc_overflow_ast()) { /* * Signal performance counter overflow */ if (tudebug) showregs(type, rp, (caddr_t)0); bzero(&siginfo, sizeof (siginfo)); siginfo.si_signo = SIGEMT; siginfo.si_code = EMT_CPCOVF; siginfo.si_addr = (caddr_t)rp->r_pc; fault = FLTCPCOVF; } } break; } /* * We can't get here from a system trap */ ASSERT(type & USER); if (fault) { /* We took a fault so abort single step. */ lwp->lwp_pcb.pcb_flags &= ~(NORMAL_STEP|WATCH_STEP); /* * Remember the fault and fault adddress * for real-time (SIGPROF) profiling. */ lwp->lwp_lastfault = fault; lwp->lwp_lastfaddr = siginfo.si_addr; DTRACE_PROC2(fault, int, fault, ksiginfo_t *, &siginfo); /* * If a debugger has declared this fault to be an * event of interest, stop the lwp. Otherwise just * deliver the associated signal. */ if (siginfo.si_signo != SIGKILL && prismember(&p->p_fltmask, fault) && stop_on_fault(fault, &siginfo) == 0) siginfo.si_signo = 0; } if (siginfo.si_signo) trapsig(&siginfo, (fault != FLTFPE && fault != FLTCPCOVF)); if (lwp->lwp_oweupc) profil_tick(rp->r_pc); if (ct->t_astflag | ct->t_sig_check) { /* * Turn off the AST flag before checking all the conditions that * may have caused an AST. This flag is on whenever a signal or * unusual condition should be handled after the next trap or * syscall. */ astoff(ct); /* * If a single-step trap occurred on a syscall (see above) * recognize it now. Do this before checking for signals * because deferred_singlestep_trap() may generate a SIGTRAP to * the LWP or may otherwise mark the LWP to call issig(FORREAL). */ if (lwp->lwp_pcb.pcb_flags & DEBUG_PENDING) deferred_singlestep_trap((caddr_t)rp->r_pc); ct->t_sig_check = 0; /* * As in other code paths that check against TP_CHANGEBIND, * we perform the check first without p_lock held -- only * acquiring p_lock in the unlikely event that it is indeed * set. This is safe because we are doing this after the * astoff(); if we are racing another thread setting * TP_CHANGEBIND on us, we will pick it up on a subsequent * lap through. */ if (curthread->t_proc_flag & TP_CHANGEBIND) { mutex_enter(&p->p_lock); if (curthread->t_proc_flag & TP_CHANGEBIND) { timer_lwpbind(); curthread->t_proc_flag &= ~TP_CHANGEBIND; } mutex_exit(&p->p_lock); } /* * for kaio requests that are on the per-process poll queue, * aiop->aio_pollq, they're AIO_POLL bit is set, the kernel * should copyout their result_t to user memory. by copying * out the result_t, the user can poll on memory waiting * for the kaio request to complete. */ if (p->p_aio) aio_cleanup(0); /* * If this LWP was asked to hold, call holdlwp(), which will * stop. holdlwps() sets this up and calls pokelwps() which * sets the AST flag. * * Also check TP_EXITLWP, since this is used by fresh new LWPs * through lwp_rtt(). That flag is set if the lwp_create(2) * syscall failed after creating the LWP. */ if (ISHOLD(p)) holdlwp(); /* * All code that sets signals and makes ISSIG evaluate true must * set t_astflag afterwards. */ if (ISSIG_PENDING(ct, lwp, p)) { if (issig(FORREAL)) psig(); ct->t_sig_check = 1; } if (ct->t_rprof != NULL) { realsigprof(0, 0, 0); ct->t_sig_check = 1; } /* * /proc can't enable/disable the trace bit itself * because that could race with the call gate used by * system calls via "lcall". If that happened, an * invalid EFLAGS would result. prstep()/prnostep() * therefore schedule an AST for the purpose. */ if (lwp->lwp_pcb.pcb_flags & REQUEST_STEP) { lwp->lwp_pcb.pcb_flags &= ~REQUEST_STEP; rp->r_ps |= PS_T; } if (lwp->lwp_pcb.pcb_flags & REQUEST_NOSTEP) { lwp->lwp_pcb.pcb_flags &= ~REQUEST_NOSTEP; rp->r_ps &= ~PS_T; } } out: /* We can't get here from a system trap */ ASSERT(type & USER); if (ISHOLD(p)) holdlwp(); /* * Set state to LWP_USER here so preempt won't give us a kernel * priority if it occurs after this point. Call CL_TRAPRET() to * restore the user-level priority. * * It is important that no locks (other than spinlocks) be entered * after this point before returning to user mode (unless lwp_state * is set back to LWP_SYS). */ lwp->lwp_state = LWP_USER; if (ct->t_trapret) { ct->t_trapret = 0; thread_lock(ct); CL_TRAPRET(ct); thread_unlock(ct); } if (CPU->cpu_runrun || curthread->t_schedflag & TS_ANYWAITQ) preempt(); prunstop(); (void) new_mstate(ct, mstate); /* Kernel probe */ TNF_PROBE_1(thread_state, "thread", /* CSTYLED */, tnf_microstate, state, LMS_USER); return; cleanup: /* system traps end up here */ ASSERT(!(type & USER)); } /* * Patch non-zero to disable preemption of threads in the kernel. */ int IGNORE_KERNEL_PREEMPTION = 0; /* XXX - delete this someday */ struct kpreempt_cnts { /* kernel preemption statistics */ int kpc_idle; /* executing idle thread */ int kpc_intr; /* executing interrupt thread */ int kpc_clock; /* executing clock thread */ int kpc_blocked; /* thread has blocked preemption (t_preempt) */ int kpc_notonproc; /* thread is surrendering processor */ int kpc_inswtch; /* thread has ratified scheduling decision */ int kpc_prilevel; /* processor interrupt level is too high */ int kpc_apreempt; /* asynchronous preemption */ int kpc_spreempt; /* synchronous preemption */ } kpreempt_cnts; /* * kernel preemption: forced rescheduling, preempt the running kernel thread. * the argument is old PIL for an interrupt, * or the distingished value KPREEMPT_SYNC. */ void kpreempt(int asyncspl) { kthread_t *ct = curthread; if (IGNORE_KERNEL_PREEMPTION) { aston(CPU->cpu_dispthread); return; } /* * Check that conditions are right for kernel preemption */ do { if (ct->t_preempt) { /* * either a privileged thread (idle, panic, interrupt) * or will check when t_preempt is lowered * We need to specifically handle the case where * the thread is in the middle of swtch (resume has * been called) and has its t_preempt set * [idle thread and a thread which is in kpreempt * already] and then a high priority thread is * available in the local dispatch queue. * In this case the resumed thread needs to take a * trap so that it can call kpreempt. We achieve * this by using siron(). * How do we detect this condition: * idle thread is running and is in the midst of * resume: curthread->t_pri == -1 && CPU->dispthread * != CPU->thread * Need to ensure that this happens only at high pil * resume is called at high pil * Only in resume_from_idle is the pil changed. */ if (ct->t_pri < 0) { kpreempt_cnts.kpc_idle++; if (CPU->cpu_dispthread != CPU->cpu_thread) siron(); } else if (ct->t_flag & T_INTR_THREAD) { kpreempt_cnts.kpc_intr++; if (ct->t_pil == CLOCK_LEVEL) kpreempt_cnts.kpc_clock++; } else { kpreempt_cnts.kpc_blocked++; if (CPU->cpu_dispthread != CPU->cpu_thread) siron(); } aston(CPU->cpu_dispthread); return; } if (ct->t_state != TS_ONPROC || ct->t_disp_queue != CPU->cpu_disp) { /* this thread will be calling swtch() shortly */ kpreempt_cnts.kpc_notonproc++; if (CPU->cpu_thread != CPU->cpu_dispthread) { /* already in swtch(), force another */ kpreempt_cnts.kpc_inswtch++; siron(); } return; } if (getpil() >= DISP_LEVEL) { /* * We can't preempt this thread if it is at * a PIL >= DISP_LEVEL since it may be holding * a spin lock (like sched_lock). */ siron(); /* check back later */ kpreempt_cnts.kpc_prilevel++; return; } if (!interrupts_enabled()) { /* * Can't preempt while running with ints disabled */ kpreempt_cnts.kpc_prilevel++; return; } if (asyncspl != KPREEMPT_SYNC) kpreempt_cnts.kpc_apreempt++; else kpreempt_cnts.kpc_spreempt++; ct->t_preempt++; preempt(); ct->t_preempt--; } while (CPU->cpu_kprunrun); } /* * Print out debugging info. */ static void showregs(uint_t type, struct regs *rp, caddr_t addr) { int s; s = spl7(); type &= ~USER; if (PTOU(curproc)->u_comm[0]) printf("%s: ", PTOU(curproc)->u_comm); if (type < TRAP_TYPES) printf("#%s %s\n", trap_type_mnemonic[type], trap_type[type]); else switch (type) { case T_SYSCALL: printf("Syscall Trap:\n"); break; case T_AST: printf("AST\n"); break; default: printf("Bad Trap = %d\n", type); break; } if (type == T_PGFLT) { printf("Bad %s fault at addr=0x%lx\n", USERMODE(rp->r_cs) ? "user": "kernel", (uintptr_t)addr); } else if (addr) { printf("addr=0x%lx\n", (uintptr_t)addr); } printf("pid=%d, pc=0x%lx, sp=0x%lx, eflags=0x%lx\n", (ttoproc(curthread) && ttoproc(curthread)->p_pidp) ? ttoproc(curthread)->p_pid : 0, rp->r_pc, rp->r_sp, rp->r_ps); #if defined(__lint) /* * this clause can be deleted when lint bug 4870403 is fixed * (lint thinks that bit 32 is illegal in a %b format string) */ printf("cr0: %x cr4: %b\n", (uint_t)getcr0(), (uint_t)getcr4(), FMT_CR4); #else printf("cr0: %b cr4: %b\n", (uint_t)getcr0(), FMT_CR0, (uint_t)getcr4(), FMT_CR4); #endif /* __lint */ printf("cr2: %lx ", getcr2()); #if !defined(__xpv) printf("cr3: %lx ", getcr3()); printf("cr8: %lx\n", getcr8()); #endif printf("\n"); dumpregs(rp); splx(s); } static void dumpregs(struct regs *rp) { const char fmt[] = "\t%3s: %16lx %3s: %16lx %3s: %16lx\n"; printf(fmt, "rdi", rp->r_rdi, "rsi", rp->r_rsi, "rdx", rp->r_rdx); printf(fmt, "rcx", rp->r_rcx, " r8", rp->r_r8, " r9", rp->r_r9); printf(fmt, "rax", rp->r_rax, "rbx", rp->r_rbx, "rbp", rp->r_rbp); printf(fmt, "r10", rp->r_r10, "r11", rp->r_r11, "r12", rp->r_r12); printf(fmt, "r13", rp->r_r13, "r14", rp->r_r14, "r15", rp->r_r15); printf(fmt, "fsb", rdmsr(MSR_AMD_FSBASE), "gsb", rdmsr(MSR_AMD_GSBASE), " ds", rp->r_ds); printf(fmt, " es", rp->r_es, " fs", rp->r_fs, " gs", rp->r_gs); printf(fmt, "trp", rp->r_trapno, "err", rp->r_err, "rip", rp->r_rip); printf(fmt, " cs", rp->r_cs, "rfl", rp->r_rfl, "rsp", rp->r_rsp); printf("\t%3s: %16lx\n", " ss", rp->r_ss); } /* * Test to see if the instruction is iret on i386 or iretq on amd64. * * On the hypervisor we can only test for nopop_sys_rtt_syscall. If true * then we are in the context of hypervisor's failsafe handler because it * tried to iret and failed due to a bad selector. See xen_failsafe_callback. */ static int instr_is_iret(caddr_t pc) { #if defined(__xpv) extern void nopop_sys_rtt_syscall(void); return ((pc == (caddr_t)nopop_sys_rtt_syscall) ? 1 : 0); #else static const uint8_t iret_insn[2] = { 0x48, 0xcf }; /* iretq */ return (bcmp(pc, iret_insn, sizeof (iret_insn)) == 0); #endif /* __xpv */ } /* * Test to see if the instruction is part of _sys_rtt (or the KPTI trampolines * which are used by _sys_rtt). * * Again on the hypervisor if we try to IRET to user land with a bad code * or stack selector we will get vectored through xen_failsafe_callback. * In which case we assume we got here via _sys_rtt since we only allow * IRET to user land to take place in _sys_rtt. */ static int instr_is_sys_rtt(caddr_t pc) { extern void _sys_rtt(), _sys_rtt_end(); #if !defined(__xpv) extern void tr_sysc_ret_start(), tr_sysc_ret_end(); extern void tr_intr_ret_start(), tr_intr_ret_end(); if ((uintptr_t)pc >= (uintptr_t)tr_sysc_ret_start && (uintptr_t)pc <= (uintptr_t)tr_sysc_ret_end) return (1); if ((uintptr_t)pc >= (uintptr_t)tr_intr_ret_start && (uintptr_t)pc <= (uintptr_t)tr_intr_ret_end) return (1); #endif if ((uintptr_t)pc < (uintptr_t)_sys_rtt || (uintptr_t)pc > (uintptr_t)_sys_rtt_end) return (0); return (1); } /* * Handle #gp faults in kernel mode. * * One legitimate way this can happen is if we attempt to update segment * registers to naughty values on the way out of the kernel. * * This can happen in a couple of ways: someone - either accidentally or * on purpose - creates (setcontext(2), lwp_create(2)) or modifies * (signal(2)) a ucontext that contains silly segment register values. * Or someone - either accidentally or on purpose - modifies the prgregset_t * of a subject process via /proc to contain silly segment register values. * * (The unfortunate part is that we can end up discovering the bad segment * register value in the middle of an 'iret' after we've popped most of the * stack. So it becomes quite difficult to associate an accurate ucontext * with the lwp, because the act of taking the #gp trap overwrites most of * what we were going to send the lwp.) * * OTOH if it turns out that's -not- the problem, and we're -not- an lwp * trying to return to user mode and we get a #gp fault, then we need * to die() -- which will happen if we return non-zero from this routine. */ static int kern_gpfault(struct regs *rp) { kthread_t *t = curthread; proc_t *p = ttoproc(t); klwp_t *lwp = ttolwp(t); struct regs tmpregs, *trp = NULL; caddr_t pc = (caddr_t)rp->r_pc; int v; uint32_t auditing = AU_AUDITING(); /* * if we're not an lwp, or in the case of running native the * pc range is outside _sys_rtt, then we should immediately * be die()ing horribly. */ if (lwp == NULL || !instr_is_sys_rtt(pc)) return (1); /* * So at least we're in the right part of the kernel. * * Disassemble the instruction at the faulting pc. * Once we know what it is, we carefully reconstruct the stack * based on the order in which the stack is deconstructed in * _sys_rtt. Ew. */ if (instr_is_iret(pc)) { /* * We took the #gp while trying to perform the IRET. * This means that either %cs or %ss are bad. * All we know for sure is that most of the general * registers have been restored, including the * segment registers, and all we have left on the * topmost part of the lwp's stack are the * registers that the iretq was unable to consume. * * All the rest of the state was crushed by the #gp * which pushed -its- registers atop our old save area * (because we had to decrement the stack pointer, sigh) so * all that we can try and do is to reconstruct the * crushed frame from the #gp trap frame itself. */ trp = &tmpregs; trp->r_ss = lwptoregs(lwp)->r_ss; trp->r_sp = lwptoregs(lwp)->r_sp; trp->r_ps = lwptoregs(lwp)->r_ps; trp->r_cs = lwptoregs(lwp)->r_cs; trp->r_pc = lwptoregs(lwp)->r_pc; bcopy(rp, trp, offsetof(struct regs, r_pc)); /* * Validate simple math */ ASSERT(trp->r_pc == lwptoregs(lwp)->r_pc); ASSERT(trp->r_err == rp->r_err); } if (trp == NULL && PCB_NEED_UPDATE_SEGS(&lwp->lwp_pcb)) { /* * This is the common case -- we're trying to load * a bad segment register value in the only section * of kernel code that ever loads segment registers. * * We don't need to do anything at this point because * the pcb contains all the pending segment register * state, and the regs are still intact because we * didn't adjust the stack pointer yet. Given the fidelity * of all this, we could conceivably send a signal * to the lwp, rather than core-ing. */ trp = lwptoregs(lwp); ASSERT((caddr_t)trp == (caddr_t)rp->r_sp); } if (trp == NULL) return (1); /* * If we get to here, we're reasonably confident that we've * correctly decoded what happened on the way out of the kernel. * Rewrite the lwp's registers so that we can create a core dump * the (at least vaguely) represents the mcontext we were * being asked to restore when things went so terribly wrong. */ /* * Make sure that we have a meaningful %trapno and %err. */ trp->r_trapno = rp->r_trapno; trp->r_err = rp->r_err; if ((caddr_t)trp != (caddr_t)lwptoregs(lwp)) bcopy(trp, lwptoregs(lwp), sizeof (*trp)); mutex_enter(&p->p_lock); lwp->lwp_cursig = SIGSEGV; mutex_exit(&p->p_lock); /* * Terminate all LWPs but don't discard them. If another lwp beat * us to the punch by calling exit(), evaporate now. */ proc_is_exiting(p); if (exitlwps(1) != 0) { mutex_enter(&p->p_lock); lwp_exit(); } if (auditing) /* audit core dump */ audit_core_start(SIGSEGV); v = core(SIGSEGV, B_FALSE); if (auditing) /* audit core dump */ audit_core_finish(v ? CLD_KILLED : CLD_DUMPED); exit(v ? CLD_KILLED : CLD_DUMPED, SIGSEGV); return (0); } /* * dump_tss() - Display the TSS structure */ #if !defined(__xpv) static void dump_tss(void) { const char tss_fmt[] = "tss.%s:\t0x%p\n"; /* Format string */ tss_t *tss = CPU->cpu_tss; printf(tss_fmt, "tss_rsp0", (void *)tss->tss_rsp0); printf(tss_fmt, "tss_rsp1", (void *)tss->tss_rsp1); printf(tss_fmt, "tss_rsp2", (void *)tss->tss_rsp2); printf(tss_fmt, "tss_ist1", (void *)tss->tss_ist1); printf(tss_fmt, "tss_ist2", (void *)tss->tss_ist2); printf(tss_fmt, "tss_ist3", (void *)tss->tss_ist3); printf(tss_fmt, "tss_ist4", (void *)tss->tss_ist4); printf(tss_fmt, "tss_ist5", (void *)tss->tss_ist5); printf(tss_fmt, "tss_ist6", (void *)tss->tss_ist6); printf(tss_fmt, "tss_ist7", (void *)tss->tss_ist7); } #endif /* !__xpv */ #if defined(TRAPTRACE) int ttrace_nrec = 10; /* number of records to dump out */ int ttrace_dump_nregs = 0; /* dump out this many records with regs too */ /* * Dump out the last ttrace_nrec traptrace records on each CPU */ static void dump_ttrace(void) { trap_trace_ctl_t *ttc; trap_trace_rec_t *rec; uintptr_t current; int i, j; int n = NCPU; const char banner[] = "CPU ADDRESS TIMESTAMP TYPE VC HANDLER PC\n"; /* Define format for the CPU, ADDRESS, and TIMESTAMP fields */ const char fmt1[] = "%3d %016lx %12llx"; char data1[34]; /* length of string formatted by fmt1 + 1 */ /* Define format for the TYPE and VC fields */ const char fmt2[] = "%4s %3x"; const char fmt2s[] = "%4s %3s"; char data2[9]; /* length of string formatted by fmt2 + 1 */ /* * Define format for the HANDLER field. Width is arbitrary, but should * be enough for common handler's names, and leave enough space for * the PC field, especially when we are in kmdb. */ const char fmt3h[] = "#%-15s"; const char fmt3p[] = "%-16p"; const char fmt3s[] = "%-16s"; char data3[17]; /* length of string formatted by fmt3* + 1 */ if (ttrace_nrec == 0) return; printf("\n"); printf(banner); for (i = 0; i < n; i++) { ttc = &trap_trace_ctl[i]; if (ttc->ttc_first == (uintptr_t)NULL) continue; current = ttc->ttc_next - sizeof (trap_trace_rec_t); for (j = 0; j < ttrace_nrec; j++) { struct sysent *sys; struct autovec *vec; extern struct av_head autovect[]; int type; ulong_t off; char *sym, *stype; if (current < ttc->ttc_first) current = ttc->ttc_limit - sizeof (trap_trace_rec_t); if (current == (uintptr_t)NULL) continue; rec = (trap_trace_rec_t *)current; if (rec->ttr_stamp == 0) break; (void) snprintf(data1, sizeof (data1), fmt1, i, (uintptr_t)rec, rec->ttr_stamp); switch (rec->ttr_marker) { case TT_SYSCALL: case TT_SYSENTER: case TT_SYSC: case TT_SYSC64: sys = &sysent32[rec->ttr_sysnum]; switch (rec->ttr_marker) { case TT_SYSC64: sys = &sysent[rec->ttr_sysnum]; /* FALLTHROUGH */ case TT_SYSC: stype = "sysc"; /* syscall */ break; case TT_SYSCALL: stype = "lcal"; /* lcall */ break; case TT_SYSENTER: stype = "syse"; /* sysenter */ break; default: stype = ""; break; } (void) snprintf(data2, sizeof (data2), fmt2, stype, rec->ttr_sysnum); if (sys != NULL) { sym = kobj_getsymname( (uintptr_t)sys->sy_callc, &off); if (sym != NULL) { (void) snprintf(data3, sizeof (data3), fmt3s, sym); } else { (void) snprintf(data3, sizeof (data3), fmt3p, sys->sy_callc); } } else { (void) snprintf(data3, sizeof (data3), fmt3s, "unknown"); } break; case TT_INTERRUPT: if (rec->ttr_regs.r_trapno == T_SOFTINT) { (void) snprintf(data2, sizeof (data2), fmt2s, "intr", "-"); (void) snprintf(data3, sizeof (data3), fmt3s, "(fakesoftint)"); break; } (void) snprintf(data2, sizeof (data2), fmt2, "intr", rec->ttr_vector); if (get_intr_handler != NULL) vec = (struct autovec *) (*get_intr_handler) (rec->ttr_cpuid, rec->ttr_vector); else vec = autovect[rec->ttr_vector].avh_link; if (vec != NULL) { sym = kobj_getsymname( (uintptr_t)vec->av_vector, &off); if (sym != NULL) { (void) snprintf(data3, sizeof (data3), fmt3s, sym); } else { (void) snprintf(data3, sizeof (data3), fmt3p, vec->av_vector); } } else { (void) snprintf(data3, sizeof (data3), fmt3s, "unknown"); } break; case TT_TRAP: case TT_EVENT: type = rec->ttr_regs.r_trapno; (void) snprintf(data2, sizeof (data2), fmt2, "trap", type); if (type < TRAP_TYPES) { (void) snprintf(data3, sizeof (data3), fmt3h, trap_type_mnemonic[type]); } else { switch (type) { case T_AST: (void) snprintf(data3, sizeof (data3), fmt3s, "ast"); break; default: (void) snprintf(data3, sizeof (data3), fmt3s, ""); break; } } break; default: break; } sym = kobj_getsymname(rec->ttr_regs.r_pc, &off); if (sym != NULL) { printf("%s %s %s %s+%lx\n", data1, data2, data3, sym, off); } else { printf("%s %s %s %lx\n", data1, data2, data3, rec->ttr_regs.r_pc); } if (ttrace_dump_nregs-- > 0) { int s; if (rec->ttr_marker == TT_INTERRUPT) printf( "\t\tipl %x spl %x pri %x\n", rec->ttr_ipl, rec->ttr_spl, rec->ttr_pri); dumpregs(&rec->ttr_regs); printf("\t%3s: %p\n\n", " ct", (void *)rec->ttr_curthread); /* * print out the pc stack that we recorded * at trap time (if any) */ for (s = 0; s < rec->ttr_sdepth; s++) { uintptr_t fullpc; if (s >= TTR_STACK_DEPTH) { printf("ttr_sdepth corrupt\n"); break; } fullpc = (uintptr_t)rec->ttr_stack[s]; sym = kobj_getsymname(fullpc, &off); if (sym != NULL) printf("-> %s+0x%lx()\n", sym, off); else printf("-> 0x%lx()\n", fullpc); } printf("\n"); } current -= sizeof (trap_trace_rec_t); } } } #endif /* TRAPTRACE */ void panic_showtrap(struct panic_trap_info *tip) { showregs(tip->trap_type, tip->trap_regs, tip->trap_addr); #if defined(TRAPTRACE) dump_ttrace(); #endif #if !defined(__xpv) if (tip->trap_type == T_DBLFLT) dump_tss(); #endif } void panic_savetrap(panic_data_t *pdp, struct panic_trap_info *tip) { panic_saveregs(pdp, tip->trap_regs); }