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Generalised support for copy-on-write structures shared by threads.

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Thread credentials are maintained as follows: each thread has a pointer to
creds and a reference on them. The pointer is compared with proc's creds on
userspace<->kernel boundary and updated if needed.

This patch introduces a counter which can be compared instead, so that more
structures can use this scheme without adding more comparisons on the boundary.
This commit is contained in:
Mateusz Guzik 2015-06-10 10:43:59 +00:00
parent 8bd0e17595
commit 4ea6a9a28f
16 changed files with 85 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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

@ -257,8 +257,8 @@ trap(struct trapframe *frame)
td->td_pticks = 0;
td->td_frame = frame;
addr = frame->tf_rip;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
switch (type) {
case T_PRIVINFLT: /* privileged instruction fault */

4
sys/arm/arm/trap-v6.c
View File

@ -395,8 +395,8 @@ abort_handler(struct trapframe *tf, int prefetch)
p = td->td_proc;
if (usermode) {
td->td_pticks = 0;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
}
/* Invoke the appropriate handler, if necessary. */

8
sys/arm/arm/trap.c
View File

@ -214,8 +214,8 @@ abort_handler(struct trapframe *tf, int type)
if (user) {
td->td_pticks = 0;
td->td_frame = tf;
if (td->td_ucred != td->td_proc->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != td->td_proc->p_cowgen)
thread_cow_update(td);
}
/* Grab the current pcb */
@ -644,8 +644,8 @@ prefetch_abort_handler(struct trapframe *tf)
if (TRAP_USERMODE(tf)) {
td->td_frame = tf;
if (td->td_ucred != td->td_proc->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != td->td_proc->p_cowgen)
thread_cow_update(td);
}
fault_pc = tf->tf_pc;
if (td->td_md.md_spinlock_count == 0) {

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

@ -306,8 +306,8 @@ trap(struct trapframe *frame)
td->td_pticks = 0;
td->td_frame = frame;
addr = frame->tf_eip;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
switch (type) {
case T_PRIVINFLT: /* privileged instruction fault */

8
sys/kern/init_main.c
View File

@ -523,8 +523,6 @@ proc0_init(void *dummy __unused)
#ifdef MAC
mac_cred_create_swapper(newcred);
#endif
td->td_ucred = crhold(newcred);
/* Create sigacts. */
p->p_sigacts = sigacts_alloc();
@ -556,6 +554,10 @@ proc0_init(void *dummy __unused)
p->p_limit->pl_rlimit[RLIMIT_MEMLOCK].rlim_max = pageablemem;
p->p_cpulimit = RLIM_INFINITY;
PROC_LOCK(p);
thread_cow_get_proc(td, p);
PROC_UNLOCK(p);
/* Initialize resource accounting structures. */
racct_create(&p->p_racct);
@ -843,10 +845,10 @@ create_init(const void *udata __unused)
audit_cred_proc1(newcred);
#endif
proc_set_cred(initproc, newcred);
cred_update_thread(FIRST_THREAD_IN_PROC(initproc));
PROC_UNLOCK(initproc);
sx_xunlock(&proctree_lock);
crfree(oldcred);
cred_update_thread(FIRST_THREAD_IN_PROC(initproc));
cpu_set_fork_handler(FIRST_THREAD_IN_PROC(initproc), start_init, NULL);
}
SYSINIT(init, SI_SUB_CREATE_INIT, SI_ORDER_FIRST, create_init, NULL);

3
sys/kern/kern_fork.c
View File

@ -496,7 +496,6 @@ do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
p2->p_swtick = ticks;
if (p1->p_flag & P_PROFIL)
startprofclock(p2);
td2->td_ucred = crhold(p2->p_ucred);
if (flags & RFSIGSHARE) {
p2->p_sigacts = sigacts_hold(p1->p_sigacts);
@ -526,6 +525,8 @@ do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
*/
lim_fork(p1, p2);
thread_cow_get_proc(td2, p2);
pstats_fork(p1->p_stats, p2->p_stats);
PROC_UNLOCK(p1);

2
sys/kern/kern_kthread.c
View File

@ -289,7 +289,7 @@ kthread_add(void (*func)(void *), void *arg, struct proc *p,
cpu_set_fork_handler(newtd, func, arg);
newtd->td_pflags |= TDP_KTHREAD;
newtd->td_ucred = crhold(p->p_ucred);
thread_cow_get_proc(newtd, p);
/* this code almost the same as create_thread() in kern_thr.c */
p->p_flag |= P_HADTHREADS;

5
sys/kern/kern_prot.c
View File

@ -1946,9 +1946,8 @@ cred_update_thread(struct thread *td)
p = td->td_proc;
cred = td->td_ucred;
PROC_LOCK(p);
PROC_LOCK_ASSERT(p, MA_OWNED);
td->td_ucred = crhold(p->p_ucred);
PROC_UNLOCK(p);
if (cred != NULL)
crfree(cred);
}
@ -1987,6 +1986,8 @@ proc_set_cred(struct proc *p, struct ucred *newcred)
oldcred = p->p_ucred;
p->p_ucred = newcred;
if (newcred != NULL)
PROC_UPDATE_COW(p);
return (oldcred);
}

2
sys/kern/kern_syscalls.c
View File

@ -31,6 +31,8 @@ __FBSDID("$FreeBSD$");
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sx.h>
#include <sys/syscall.h>
#include <sys/sysent.h>

6
sys/kern/kern_thr.c
View File

@ -220,13 +220,13 @@ create_thread(struct thread *td, mcontext_t *ctx,
bcopy(&td->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
newtd->td_proc = td->td_proc;
newtd->td_ucred = crhold(td->td_ucred);
thread_cow_get(newtd, td);
if (ctx != NULL) { /* old way to set user context */
error = set_mcontext(newtd, ctx);
if (error != 0) {
thread_cow_free(newtd);
thread_free(newtd);
crfree(td->td_ucred);
goto fail;
}
} else {
@ -238,8 +238,8 @@ create_thread(struct thread *td, mcontext_t *ctx,
/* Setup user TLS address and TLS pointer register. */
error = cpu_set_user_tls(newtd, tls_base);
if (error != 0) {
thread_cow_free(newtd);
thread_free(newtd);
crfree(td->td_ucred);
goto fail;
}
}

43
sys/kern/kern_thread.c
View File

@ -327,8 +327,7 @@ thread_reap(void)
mtx_unlock_spin(&zombie_lock);
while (td_first) {
td_next = TAILQ_NEXT(td_first, td_slpq);
if (td_first->td_ucred)
crfree(td_first->td_ucred);
thread_cow_free(td_first);
thread_free(td_first);
td_first = td_next;
}
@ -384,6 +383,44 @@ thread_free(struct thread *td)
uma_zfree(thread_zone, td);
}
void
thread_cow_get_proc(struct thread *newtd, struct proc *p)
{
PROC_LOCK_ASSERT(p, MA_OWNED);
newtd->td_ucred = crhold(p->p_ucred);
newtd->td_cowgen = p->p_cowgen;
}
void
thread_cow_get(struct thread *newtd, struct thread *td)
{
newtd->td_ucred = crhold(td->td_ucred);
newtd->td_cowgen = td->td_cowgen;
}
void
thread_cow_free(struct thread *td)
{
if (td->td_ucred)
crfree(td->td_ucred);
}
void
thread_cow_update(struct thread *td)
{
struct proc *p;
p = td->td_proc;
PROC_LOCK(p);
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
td->td_cowgen = p->p_cowgen;
PROC_UNLOCK(p);
}
/*
* Discard the current thread and exit from its context.
* Always called with scheduler locked.
@ -521,7 +558,7 @@ thread_wait(struct proc *p)
cpuset_rel(td->td_cpuset);
td->td_cpuset = NULL;
cpu_thread_clean(td);
crfree(td->td_ucred);
thread_cow_free(td);
thread_reap(); /* check for zombie threads etc. */
}

4
sys/kern/subr_syscall.c
View File

@ -61,8 +61,8 @@ syscallenter(struct thread *td, struct syscall_args *sa)
p = td->td_proc;
td->td_pticks = 0;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
if (p->p_flag & P_TRACED) {
traced = 1;
PROC_LOCK(p);

4
sys/kern/subr_trap.c
View File

@ -220,8 +220,8 @@ ast(struct trapframe *framep)
thread_unlock(td);
PCPU_INC(cnt.v_trap);
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
td->td_profil_ticks = 0;

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

@ -196,8 +196,8 @@ trap(struct trapframe *frame)
if (user) {
td->td_pticks = 0;
td->td_frame = frame;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
/* User Mode Traps */
switch (type) {

4
sys/sparc64/sparc64/trap.c
View File

@ -277,8 +277,8 @@ trap(struct trapframe *tf)
td->td_pticks = 0;
td->td_frame = tf;
addr = tf->tf_tpc;
if (td->td_ucred != p->p_ucred)
cred_update_thread(td);
if (td->td_cowgen != p->p_cowgen)
thread_cow_update(td);
switch (tf->tf_type) {
case T_DATA_MISS:

11
sys/sys/proc.h
View File

@ -308,6 +308,7 @@ struct thread {
off_t tdu_off;
} td_uretoff; /* (k) Syscall aux returns. */
#define td_retval td_uretoff.tdu_retval
u_int td_cowgen; /* (k) Generation of COW pointers. */
struct callout td_slpcallout; /* (h) Callout for sleep. */
struct trapframe *td_frame; /* (k) */
struct vm_object *td_kstack_obj;/* (a) Kstack object. */
@ -533,6 +534,7 @@ struct proc {
pid_t p_oppid; /* (c + e) Save ppid in ptrace. XXX */
struct vmspace *p_vmspace; /* (b) Address space. */
u_int p_swtick; /* (c) Tick when swapped in or out. */
u_int p_cowgen; /* (c) Generation of COW pointers. */
struct itimerval p_realtimer; /* (c) Alarm timer. */
struct rusage p_ru; /* (a) Exit information. */
struct rusage_ext p_rux; /* (cu) Internal resource usage. */
@ -833,6 +835,11 @@ extern pid_t pid_max;
KASSERT((p)->p_lock == 0, ("process held")); \
} while (0)
#define PROC_UPDATE_COW(p) do { \
PROC_LOCK_ASSERT((p), MA_OWNED); \
(p)->p_cowgen++; \
} while (0)
/* Check whether a thread is safe to be swapped out. */
#define thread_safetoswapout(td) ((td)->td_flags & TDF_CANSWAP)
@ -977,6 +984,10 @@ void cpu_thread_swapin(struct thread *);
void cpu_thread_swapout(struct thread *);
struct thread *thread_alloc(int pages);
int thread_alloc_stack(struct thread *, int pages);
void thread_cow_get_proc(struct thread *newtd, struct proc *p);
void thread_cow_get(struct thread *newtd, struct thread *td);
void thread_cow_free(struct thread *td);
void thread_cow_update(struct thread *td);
void thread_exit(void) __dead2;
void thread_free(struct thread *td);
void thread_link(struct thread *td, struct proc *p);