2 * Copyright (c) 1989, 1990 William F. Jolitz.
3 * Copyright (c) 1990 The Regents of the University of California.
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36 #include <machine/asmacros.h>
37 #include <machine/psl.h>
38 #include <machine/trap.h>
42 #define SEL_RPL_MASK 0x0003
46 /*****************************************************************************/
48 /*****************************************************************************/
50 * Trap and fault vector routines.
52 * Most traps are 'trap gates', SDT_SYS386TGT. A trap gate pushes state on
53 * the stack that mostly looks like an interrupt, but does not disable
54 * interrupts. A few of the traps we are use are interrupt gates,
55 * SDT_SYS386IGT, which are nearly the same thing except interrupts are
58 * The cpu will push a certain amount of state onto the kernel stack for
59 * the current process. The amount of state depends on the type of trap
60 * and whether the trap crossed rings or not. See i386/include/frame.h.
61 * At the very least the current EFLAGS (status register, which includes
62 * the interrupt disable state prior to the trap), the code segment register,
63 * and the return instruction pointer are pushed by the cpu. The cpu
64 * will also push an 'error' code for certain traps. We push a dummy
65 * error code for those traps where the cpu doesn't in order to maintain
66 * a consistent frame. We also push a contrived 'trap number'.
68 * The cpu does not push the general registers, we must do that, and we
69 * must restore them prior to calling 'iret'. The cpu adjusts the %cs and
70 * %ss segment registers, but does not mess with %ds, %es, or %fs. Thus we
71 * must load them with appropriate values for supervisor mode operation.
77 #define TRAP(a) pushl $(a) ; jmp alltraps
80 pushl $0; TRAP(T_DIVIDE)
82 pushl $0; TRAP(T_TRCTRAP)
86 pushl $0; TRAP(T_BPTFLT)
88 pushl $0; TRAP(T_OFLOW)
90 pushl $0; TRAP(T_BOUND)
92 pushl $0; TRAP(T_PRIVINFLT)
96 pushl $0; TRAP(T_FPOPFLT)
108 pushl $0; TRAP(T_MCHK)
110 pushl $0; TRAP(T_RESERVED)
112 pushl $0; TRAP(T_ARITHTRAP)
116 pushl $0; TRAP(T_XMMFLT)
119 * alltraps entry point. Interrupts are enabled if this was a trap
120 * gate (TGT), else disabled if this was an interrupt gate (IGT).
121 * Note that int0x80_syscall is a trap gate. Interrupt gates are
122 * used by page faults, non-maskable interrupts, debug and breakpoint
128 .type alltraps,@function
134 alltraps_with_regs_pushed:
136 FAKE_MCOUNT(TF_EIP(%esp))
143 * Return via doreti to handle ASTs.
149 * SYSCALL CALL GATE (old entry point for a.out binaries)
151 * The intersegment call has been set up to specify one dummy parameter.
153 * This leaves a place to put eflags so that the call frame can be
154 * converted to a trap frame. Note that the eflags is (semi-)bogusly
155 * pushed into (what will be) tf_err and then copied later into the
156 * final spot. It has to be done this way because esp can't be just
157 * temporarily altered for the pushfl - an interrupt might come in
158 * and clobber the saved cs/eip.
161 IDTVEC(lcall_syscall)
162 pushfl /* save eflags */
163 popl 8(%esp) /* shuffle into tf_eflags */
164 pushl $7 /* sizeof "lcall 7,0" */
165 subl $4,%esp /* skip over tf_trapno */
171 FAKE_MCOUNT(TF_EIP(%esp))
179 * Call gate entry for FreeBSD ELF and Linux/NetBSD syscall (int 0x80)
181 * Even though the name says 'int0x80', this is actually a TGT (trap gate)
182 * rather then an IGT (interrupt gate). Thus interrupts are enabled on
183 * entry just as they are for a normal syscall.
186 IDTVEC(int0x80_syscall)
187 pushl $2 /* sizeof "int 0x80" */
188 subl $4,%esp /* skip over tf_trapno */
194 FAKE_MCOUNT(TF_EIP(%esp))
201 ENTRY(fork_trampoline)
202 pushl %esp /* trapframe pointer */
203 pushl %ebx /* arg1 */
204 pushl %esi /* function */
207 /* cut from syscall */
210 * Return via doreti to handle ASTs.
217 * To efficiently implement classification of trap and interrupt handlers
218 * for profiling, there must be only trap handlers between the labels btrap
219 * and bintr, and only interrupt handlers between the labels bintr and
220 * eintr. This is implemented (partly) by including files that contain
221 * some of the handlers. Before including the files, set up a normal asm
222 * environment so that the included files doen't need to know that they are
232 #include <i386/isa/atpic_vector.s>
240 #include <i386/i386/apic_vector.s>
247 #include <i386/i386/vm86bios.s>
253 * void doreti(struct trapframe)
255 * Handle return from interrupts, traps and syscalls.
259 .type doreti,@function
261 FAKE_MCOUNT($bintr) /* init "from" bintr -> doreti */
264 * Check if ASTs can be handled now. PSL_VM must be checked first
265 * since segment registers only have an RPL in non-VM86 mode.
267 testl $PSL_VM,TF_EFLAGS(%esp) /* are we in vm86 mode? */
269 movl PCPU(CURPCB),%ecx
270 testl $PCB_VM86CALL,PCB_FLAGS(%ecx) /* are we in a vm86 call? */
271 jz doreti_ast /* can handle ASTS now if not */
275 testb $SEL_RPL_MASK,TF_CS(%esp) /* are we returning to user mode? */
276 jz doreti_exit /* can't handle ASTs now if not */
280 * Check for ASTs atomically with returning. Disabling CPU
281 * interrupts provides sufficient locking even in the SMP case,
282 * since we will be informed of any new ASTs by an IPI.
285 movl PCPU(CURTHREAD),%eax
286 testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%eax)
289 pushl %esp /* pass a pointer to the trapframe */
295 * doreti_exit: pop registers, iret.
297 * The segment register pop is a special case, since it may
298 * fault if (for example) a sigreturn specifies bad segment
299 * registers. The fault is handled in trap.c.
304 .globl doreti_popl_fs
307 .globl doreti_popl_es
310 .globl doreti_popl_ds
320 * doreti_iret_fault and friends. Alternative return code for
321 * the case where we get a fault in the doreti_exit code
322 * above. trap() (i386/i386/trap.c) catches this specific
323 * case, sends the process a signal and continues in the
324 * corresponding place in the code below.
327 .globl doreti_iret_fault
332 .globl doreti_popl_ds_fault
333 doreti_popl_ds_fault:
335 .globl doreti_popl_es_fault
336 doreti_popl_es_fault:
338 .globl doreti_popl_fs_fault
339 doreti_popl_fs_fault:
340 movl $0,TF_ERR(%esp) /* XXX should be the error code */
341 movl $T_PROTFLT,TF_TRAPNO(%esp)
342 jmp alltraps_with_regs_pushed