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Fix single-stepping of instructions emulated by vm86.

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In vm86.c, fix 2 (rarely used) cases where the return code lost the
single-step indicator.  While here, fix 2 misspellings of PSL_T as
PSL_TF (TF is the CPU manufacturer's spelling, but we use T).

In trap.c, turn T_PROTFLT and T_STKFLT into T_TRCTRAP if
vm86_emulate() asked for this (it does this when the instruction is
being traced and was successully emulated).  In the kernel case, we
used to deliver the trap as SIGTRAP to the process, where it always
terminated the process; now we deliver the trap as T_TRCTRAP to kdb,
where it normally gives single-stepping.  In the user case, the only
difference is that we now clear PSL_T and initialize ucode properly.

Reviewed by:	kib
This commit is contained in:
Bruce Evans 2016-09-08 14:43:39 +00:00
parent e62264e2dd
commit 8b530941f4
2 changed files with 14 additions and 4 deletions
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10
sys/i386/i386/trap.c
View File

@ -335,6 +335,7 @@ trap(struct trapframe *frame)
goto out;
}
#endif
user_trctrap_out:
frame->tf_eflags &= ~PSL_T;
i = SIGTRAP;
ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
@ -360,6 +361,10 @@ trap(struct trapframe *frame)
case T_STKFLT: /* stack fault */
if (frame->tf_eflags & PSL_VM) {
i = vm86_emulate((struct vm86frame *)frame);
if (i == SIGTRAP) {
type = T_TRCTRAP;
goto user_trctrap_out;
}
if (i == 0)
goto user;
break;
@ -566,6 +571,10 @@ trap(struct trapframe *frame)
case T_STKFLT: /* stack fault */
if (frame->tf_eflags & PSL_VM) {
i = vm86_emulate((struct vm86frame *)frame);
if (i == SIGTRAP) {
type = T_TRCTRAP;
goto kernel_trctrap;
}
if (i != 0)
/*
* returns to original process
@ -654,6 +663,7 @@ trap(struct trapframe *frame)
break;
case T_TRCTRAP: /* trace trap */
kernel_trctrap:
if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) {
/*
* We've just entered system mode via the

8
sys/i386/i386/vm86.c
View File

@ -171,7 +171,7 @@ vm86_emulate(vmf)
PUSHL((vmf->vmf_eflags & PUSH_MASK)
| PSL_IOPL, vmf);
vmf->vmf_ip += inc_ip;
return (0);
return (retcode);
case POPF:
temp_flags = POPL(vmf) & POP_MASK;
@ -185,7 +185,7 @@ vm86_emulate(vmf)
} else {
vmf->vmf_eflags &= ~PSL_VIF;
}
return (0);
return (retcode);
}
break;
@ -203,7 +203,7 @@ vm86_emulate(vmf)
case INTn:
break;
/* VME if trying to set PSL_TF, or PSL_I when VIP is set */
/* VME if trying to set PSL_T, or PSL_I when VIP is set */
case POPF:
temp_flags = POP(vmf) & POP_MASK;
vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
@ -218,7 +218,7 @@ vm86_emulate(vmf)
}
return (retcode);
/* VME if trying to set PSL_TF, or PSL_I when VIP is set */
/* VME if trying to set PSL_T, or PSL_I when VIP is set */
case IRET:
vmf->vmf_ip = POP(vmf);
vmf->vmf_cs = POP(vmf);