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Add thread-private flag to indicate that error value is already placed

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in td_errno. Flag is supposed to be used by syscalls returning
EJUSTRETURN because errno was already placed into the usermode frame
by a call to set_syscall_retval(9). Both ktrace and dtrace get errno
value from td_errno if the flag is set.

Use the flag to fix sigsuspend(2) error return ktrace records.

Requested by:	bde
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2012-04-12 10:48:43 +00:00
parent d5d42003f4
commit 2dd9ea6f70
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=234172
3 changed files with 10 additions and 3 deletions
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2
sys/kern/kern_sig.c
View File

@ -1465,6 +1465,8 @@ kern_sigsuspend(struct thread *td, sigset_t mask)
mtx_unlock(&p->p_sigacts->ps_mtx);
}
PROC_UNLOCK(p);
td->td_errno = EINTR;
td->td_pflags |= TDP_NERRNO;
return (EJUSTRETURN);
}

10
sys/kern/subr_syscall.c
View File

@ -136,7 +136,8 @@ syscallenter(struct thread *td, struct syscall_args *sa)
AUDIT_SYSCALL_EXIT(error, td);
/* Save the latest error return value. */
td->td_errno = error;
if ((td->td_pflags & TDP_NERRNO) == 0)
td->td_errno = error;
#ifdef KDTRACE_HOOKS
/*
@ -191,9 +192,12 @@ syscallret(struct thread *td, int error, struct syscall_args *sa __unused)
syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name);
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSRET))
ktrsysret(sa->code, error, td->td_retval[0]);
if (KTRPOINT(td, KTR_SYSRET)) {
ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
error : td->td_errno, td->td_retval[0]);
}
#endif
td->td_pflags &= ~TDP_NERRNO;
if (p->p_flag & P_TRACED) {
traced = 1;

1
sys/sys/proc.h
View File

@ -418,6 +418,7 @@ do { \
#define TDP_AUDITREC 0x01000000 /* Audit record pending on thread */
#define TDP_RFPPWAIT 0x02000000 /* Handle RFPPWAIT on syscall exit */
#define TDP_RESETSPUR 0x04000000 /* Reset spurious page fault history. */
#define TDP_NERRNO 0x08000000 /* Last errno is already in td_errno */
/*
* Reasons that the current thread can not be run yet.