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Add some DIAGNOSTIC code.

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While in userland, keep the thread's ucred reference in a shadow
field so that the usual place to store it is NULL.
If DIAGNOSTIC is not set, the thread ucred is kept valid until the next
kernel entry, at which time it is checked against the process cred
and possibly corrected. Produces a BIG speedup in
kernels with INVARIANTS set. (A previous commit corrected it
for the non INVARIANTS case already)

Reviewed by:	dillon@freebsd.org
This commit is contained in:
julian 2002-02-22 23:58:22 +00:00
parent 5b69d7da62
commit 53eb1d9219
10 changed files with 190 additions and 94 deletions
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34
sys/alpha/alpha/trap.c
View File

@ -297,7 +297,12 @@ trap(a0, a1, a2, entry, framep)
if (user) {
sticks = td->td_kse->ke_sticks;
td->td_frame = framep;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap: thread got a cred while in userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
} else {
@ -625,12 +630,12 @@ out:
framep->tf_regs[FRAME_SP] = alpha_pal_rdusp();
userret(td, framep, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap: thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif
#endif /* DIAGNOSTIC */
}
return;
@ -699,7 +704,12 @@ syscall(code, framep)
td->td_frame = framep;
opc = framep->tf_regs[FRAME_PC] - 4;
sticks = td->td_kse->ke_sticks;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("syscall:thread got a cred while in userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -822,12 +832,12 @@ syscall(code, framep)
*/
STOPEVENT(p, S_SCX, code);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("syscall:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif
#endif /* DIAGNOSTIC */
#ifdef WITNESS
if (witness_list(td)) {
panic("system call %s returning with mutex(s) held\n",

39
sys/amd64/amd64/trap.c
View File

@ -255,7 +255,12 @@ trap(frame)
sticks = td->td_kse->ke_sticks;
td->td_frame = &frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -643,12 +648,12 @@ user:
userret(td, &frame, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
userout:
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
out:
return;
}
@ -954,7 +959,12 @@ syscall(frame)
sticks = td->td_kse->ke_sticks;
td->td_frame = &frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
params = (caddr_t)frame.tf_esp + sizeof(int);
@ -1099,12 +1109,13 @@ bad:
*/
STOPEVENT(p, S_SCX, code);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("syscall:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
#ifdef WITNESS
if (witness_list(td)) {
panic("system call %s returning with mutex(s) held\n",

39
sys/i386/i386/trap.c
View File

@ -255,7 +255,12 @@ trap(frame)
sticks = td->td_kse->ke_sticks;
td->td_frame = &frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -643,12 +648,12 @@ user:
userret(td, &frame, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
userout:
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
out:
return;
}
@ -954,7 +959,12 @@ syscall(frame)
sticks = td->td_kse->ke_sticks;
td->td_frame = &frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
params = (caddr_t)frame.tf_esp + sizeof(int);
@ -1099,12 +1109,13 @@ bad:
*/
STOPEVENT(p, S_SCX, code);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("syscall:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
#ifdef WITNESS
if (witness_list(td)) {
panic("system call %s returning with mutex(s) held\n",

38
sys/ia64/ia64/trap.c
View File

@ -323,7 +323,12 @@ trap(int vector, int imm, struct trapframe *framep)
if (user) {
sticks = td->td_kse->ke_sticks;
td->td_frame = framep;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
} else {
@ -708,12 +713,12 @@ out:
if (user) {
userret(td, framep, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
}
return;
@ -758,7 +763,12 @@ syscall(int code, u_int64_t *args, struct trapframe *framep)
td->td_frame = framep;
sticks = td->td_kse->ke_sticks;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -865,12 +875,12 @@ syscall(int code, u_int64_t *args, struct trapframe *framep)
*/
STOPEVENT(p, S_SCX, code);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
#ifdef WITNESS
if (witness_list(td)) {
panic("system call %s returning with mutex(s) held\n",

15
sys/kern/kern_fork.c
View File

@ -477,6 +477,9 @@ again:
PROC_LOCK(p1);
p2->p_ucred = crhold(p1->p_ucred);
td2->td_ucred = crhold(p2->p_ucred); /* XXXKSE */
#ifdef DIAGNOSTIC /* see the comment in ast() */
td2->td_ucred_cache = NULL;
#endif
if (p2->p_args)
p2->p_args->ar_ref++;
@ -802,12 +805,12 @@ fork_exit(callout, arg, frame)
kthread_exit(0);
}
PROC_UNLOCK(p);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("fork_exit:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
mtx_assert(&Giant, MA_NOTOWNED);
}

36
sys/kern/subr_trap.c
View File

@ -131,7 +131,6 @@ ast(framep)
#endif
KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
KASSERT(td->td_ucred == NULL, ("leaked ucred"));
#ifdef WITNESS
if (witness_list(td))
panic("Returning to user mode with mutex(s) held");
@ -161,6 +160,30 @@ ast(framep)
p->p_stats->p_prof.pr_ticks = 0;
}
mtx_unlock_spin(&sched_lock);
#ifdef DIAGNOSTIC
/*
* As a diagnostic tool we make sure that td->td_ucred
* is NULL while we are in user space. This is
* because theoreticaly this field is only defined
* while the thread is in the kernel. Making it NULL
* will immediatly trap invalid usage of this field.
* In practice however we keep the reference to the ucred
* because it's almost always going to be the same cred we will
* need at the next syscall, and it can be expensive
* to keep dropping and reacquiring the reference.
* We thus stash it away elsewhere until we return
* to the kernel, where we bring it back. If
* DIAGNOSTIC is not defined we don't bother with
* making it NULL, and just leave it in place.
* (don't remove this comment without removing the pointers
* to it in sys/proc.h, */*/trap.c, kern/kern_fork.c and here.)
*/
if (td->td_ucred)
panic("ast:thread got a cred before reaching AST");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (flags & KEF_OWEUPC && sflag & PS_PROFIL)
@ -187,12 +210,13 @@ ast(framep)
}
userret(td, framep, sticks);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
#ifdef DIAGNOSTIC /* see comment above */
if (td->td_ucred_cache)
panic("ast:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif
#endif /* DIAGNOSTIC */
s = cpu_critical_enter();
}
mtx_assert(&Giant, MA_NOTOWNED);

20
sys/powerpc/aim/trap.c
View File

@ -226,7 +226,12 @@ trap(struct trapframe *frame)
if (user) {
sticks = td->td_kse->ke_sticks;
td->td_frame = frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -288,6 +293,7 @@ trap(struct trapframe *frame)
default:
trap_fatal(frame);
}
/* NOTREACHED */
}
if (sig != 0) {
if (p->p_sysent->sv_transtrap != NULL)
@ -296,12 +302,12 @@ trap(struct trapframe *frame)
}
userret(td, frame, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
}
void

20
sys/powerpc/powerpc/trap.c
View File

@ -226,7 +226,12 @@ trap(struct trapframe *frame)
if (user) {
sticks = td->td_kse->ke_sticks;
td->td_frame = frame;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
@ -288,6 +293,7 @@ trap(struct trapframe *frame)
default:
trap_fatal(frame);
}
/* NOTREACHED */
}
if (sig != 0) {
if (p->p_sysent->sv_transtrap != NULL)
@ -296,12 +302,12 @@ trap(struct trapframe *frame)
}
userret(td, frame, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
}
void

38
sys/sparc64/sparc64/trap.c
View File

@ -175,7 +175,12 @@ trap(struct trapframe *tf)
if ((type & T_KERNEL) == 0) {
sticks = td->td_kse->ke_sticks;
td->td_frame = tf;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("trap:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
} else {
@ -379,12 +384,12 @@ trapsig:
user:
userret(td, tf, sticks);
mtx_assert(&Giant, MA_NOTOWNED);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("trap:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
out:
CTR1(KTR_TRAP, "trap: td=%p return", td);
return;
@ -540,7 +545,12 @@ syscall(struct trapframe *tf)
sticks = td->td_kse->ke_sticks;
td->td_frame = tf;
KASSERT(td->td_ucred == NULL, ("already have a ucred"));
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred)
panic("syscall:thread got a cred while userspace");
td->td_ucred = td->td_ucred_cache;
td->td_ucred_cache = NULL;
#endif /* DIAGNOSTIC */
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
code = tf->tf_global[1];
@ -677,12 +687,12 @@ bad:
*/
STOPEVENT(p, S_SCX, code);
#ifdef INVARIANTS
mtx_lock(&Giant);
crfree(td->td_ucred);
mtx_unlock(&Giant);
td->td_ucred = NULL;
#endif
#ifdef DIAGNOSTIC /* see the comment in ast() */
if (td->td_ucred_cache)
panic("syscall:thread already has cached ucred");
td->td_ucred_cache = td->td_ucred;
td->td_ucred = NULL;
#endif /* DIAGNOSTIC */
#ifdef WITNESS
if (witness_list(td)) {
panic("system call %s returning with mutex(s) held\n",

5
sys/sys/proc.h
View File

@ -272,6 +272,11 @@ struct thread {
#define td_endcopy td_pcb
struct ucred *td_ucred; /* (k) Reference to credentials. */
#ifdef DIAGNOSTIC /* see the comment in ast() */
struct ucred *td_ucred_cache; /* (k) hide cred here for DIAGNOSTIC */
#else
void *td_dontuse; /* keep the size the same if not DIAG */
#endif
struct pcb *td_pcb; /* (k) Kernel VA of pcb and kstack. */
struct callout td_slpcallout; /* (h) Callout for sleep. */
struct trapframe *td_frame; /* (k) */