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Clear the single-step flag for signal handlers. This fixes bogus trace

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traps on the first instruction of signal handlers.

In trap.c:syscall(), fake a trace trap if the single-step flag was set
on entry to the kernel, not if it will be set on exit from the kernel.
This fixes bogus trace traps after the last instruction of signal handlers.

gdb-4.18 (the version in FreeBSD) still has problems with the program in
the PR.  These seem to be due to bugs in gdb and not in FreeBSD, and are
fixed in gdb-5.1 (the distribution version).

PR:		33262
Tested by:	k Macy <kip_macy@yahoo.com>
MFC after:	1 day
This commit is contained in:
Bruce Evans 2002-01-10 11:49:55 +00:00
parent 52f1d68ff8
commit 846ac2266b
8 changed files with 25 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
sys/amd64/amd64/machdep.c
View File

@ -401,7 +401,7 @@ osendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/* See sendsig() for comments. */
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -417,6 +417,7 @@ osendsig(catcher, sig, mask, code)
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - szosigcode;
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
@ -546,17 +547,13 @@ sendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/*
* We should never have PSL_T set when returning from vm86
* mode. It may be set here if we deliver a signal before
* getting to vm86 mode, so turn it off.
*
* Clear PSL_NT to inhibit T_TSSFLT faults on return from
* syscalls made by the signal handler. This just avoids
* wasting time for our lazy fixup of such faults. PSL_NT
* does nothing in vm86 mode, but vm86 programs can set it
* almost legitimately in probes for old cpu types.
*/
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -572,6 +569,7 @@ sendsig(catcher, sig, mask, code)
regs->tf_esp = (int)sfp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;

4
sys/amd64/amd64/trap.c
View File

@ -933,6 +933,7 @@ syscall(frame)
struct sysent *callp;
struct thread *td = curthread;
struct proc *p = td->td_proc;
register_t orig_tf_eflags;
u_int sticks;
int error;
int narg;
@ -958,6 +959,7 @@ syscall(frame)
PROC_UNLOCK(p);
params = (caddr_t)frame.tf_esp + sizeof(int);
code = frame.tf_eax;
orig_tf_eflags = frame.tf_eflags;
if (p->p_sysent->sv_prepsyscall) {
/*
@ -1065,7 +1067,7 @@ syscall(frame)
/*
* Traced syscall.
*/
if ((frame.tf_eflags & PSL_T) && !(frame.tf_eflags & PSL_VM)) {
if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) {
frame.tf_eflags &= ~PSL_T;
trapsignal(p, SIGTRAP, 0);
}

10
sys/i386/i386/machdep.c
View File

@ -401,7 +401,7 @@ osendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/* See sendsig() for comments. */
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -417,6 +417,7 @@ osendsig(catcher, sig, mask, code)
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - szosigcode;
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
@ -546,17 +547,13 @@ sendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/*
* We should never have PSL_T set when returning from vm86
* mode. It may be set here if we deliver a signal before
* getting to vm86 mode, so turn it off.
*
* Clear PSL_NT to inhibit T_TSSFLT faults on return from
* syscalls made by the signal handler. This just avoids
* wasting time for our lazy fixup of such faults. PSL_NT
* does nothing in vm86 mode, but vm86 programs can set it
* almost legitimately in probes for old cpu types.
*/
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -572,6 +569,7 @@ sendsig(catcher, sig, mask, code)
regs->tf_esp = (int)sfp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;

4
sys/i386/i386/trap.c
View File

@ -933,6 +933,7 @@ syscall(frame)
struct sysent *callp;
struct thread *td = curthread;
struct proc *p = td->td_proc;
register_t orig_tf_eflags;
u_int sticks;
int error;
int narg;
@ -958,6 +959,7 @@ syscall(frame)
PROC_UNLOCK(p);
params = (caddr_t)frame.tf_esp + sizeof(int);
code = frame.tf_eax;
orig_tf_eflags = frame.tf_eflags;
if (p->p_sysent->sv_prepsyscall) {
/*
@ -1065,7 +1067,7 @@ syscall(frame)
/*
* Traced syscall.
*/
if ((frame.tf_eflags & PSL_T) && !(frame.tf_eflags & PSL_VM)) {
if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) {
frame.tf_eflags &= ~PSL_T;
trapsignal(p, SIGTRAP, 0);
}

4
sys/i386/linux/linux_sysvec.c
View File

@ -385,7 +385,7 @@ linux_rt_sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode) +
linux_sznonrtsigcode;
regs->tf_eflags &= ~PSL_VM;
regs->tf_eflags &= ~(PSL_T | PSL_VM);
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
@ -519,7 +519,7 @@ linux_sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
*/
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_eflags &= ~PSL_VM;
regs->tf_eflags &= ~(PSL_T | PSL_VM);
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;

1
sys/i386/svr4/svr4_machdep.c
View File

@ -492,6 +492,7 @@ svr4_sendsig(catcher, sig, mask, code)
#else
tf->tf_esp = (int)fp;
tf->tf_eip = (int)(((char *)PS_STRINGS) - *(p->p_sysent->sv_szsigcode));
tf->tf_eflags &= ~PSL_T;
tf->tf_cs = _ucodesel;
tf->tf_ds = _udatasel;
tf->tf_es = _udatasel;

10
sys/pc98/i386/machdep.c
View File

@ -414,7 +414,7 @@ osendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/* See sendsig() for comments. */
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -430,6 +430,7 @@ osendsig(catcher, sig, mask, code)
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - szosigcode;
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
@ -558,17 +559,13 @@ sendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/*
* We should never have PSL_T set when returning from vm86
* mode. It may be set here if we deliver a signal before
* getting to vm86 mode, so turn it off.
*
* Clear PSL_NT to inhibit T_TSSFLT faults on return from
* syscalls made by the signal handler. This just avoids
* wasting time for our lazy fixup of such faults. PSL_NT
* does nothing in vm86 mode, but vm86 programs can set it
* almost legitimately in probes for old cpu types.
*/
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -584,6 +581,7 @@ sendsig(catcher, sig, mask, code)
regs->tf_esp = (int)sfp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;

10
sys/pc98/pc98/machdep.c
View File

@ -414,7 +414,7 @@ osendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/* See sendsig() for comments. */
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -430,6 +430,7 @@ osendsig(catcher, sig, mask, code)
regs->tf_esp = (int)fp;
regs->tf_eip = PS_STRINGS - szosigcode;
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
@ -558,17 +559,13 @@ sendsig(catcher, sig, mask, code)
(vm86->vm86_eflags & (PSL_VIF | PSL_VIP));
/*
* We should never have PSL_T set when returning from vm86
* mode. It may be set here if we deliver a signal before
* getting to vm86 mode, so turn it off.
*
* Clear PSL_NT to inhibit T_TSSFLT faults on return from
* syscalls made by the signal handler. This just avoids
* wasting time for our lazy fixup of such faults. PSL_NT
* does nothing in vm86 mode, but vm86 programs can set it
* almost legitimately in probes for old cpu types.
*/
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_T | PSL_VIF | PSL_VIP);
tf->tf_eflags &= ~(PSL_VM | PSL_NT | PSL_VIF | PSL_VIP);
}
/* Copy the sigframe out to the user's stack. */
@ -584,6 +581,7 @@ sendsig(catcher, sig, mask, code)
regs->tf_esp = (int)sfp;
regs->tf_eip = PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_eflags &= ~PSL_T;
regs->tf_cs = _ucodesel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;