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Add an API for easily creating userspace threads in kernelspace.

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This change refactors the existing create_thread() function to be more
generic. It replaces almost all of its arguments by a callback that can
be used to extract the thread ID and copy it out to the right place, but
also to perform additional initialization steps, such as setting the
trapframe. This also makes the difference between thr_new() and
thr_create() more clear in my opinion.

This function is going to be used by the CloudABI compatibility layer.

Reviewed by:	kib
MFC after:	1 month
This commit is contained in:
Ed Schouten 2015-07-17 16:34:01 +00:00
parent b8bbefed30
commit 82a3d2cbfc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=285656
2 changed files with 63 additions and 64 deletions
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125
sys/kern/kern_thr.c
View File

@ -89,29 +89,39 @@ suword_lwpid(void *addr, lwpid_t lwpid)
#define suword_lwpid suword
#endif
static int create_thread(struct thread *td, mcontext_t *ctx,
void (*start_func)(void *), void *arg,
char *stack_base, size_t stack_size,
char *tls_base,
long *child_tid, long *parent_tid,
int flags, struct rtprio *rtp);
/*
* System call interface.
*/
struct thr_create_initthr_args {
ucontext_t ctx;
long *tid;
};
static int
thr_create_initthr(struct thread *td, void *thunk)
{
struct thr_create_initthr_args *args;
/* Copy out the child tid. */
args = thunk;
if (args->tid != NULL && suword_lwpid(args->tid, td->td_tid))
return (EFAULT);
return (set_mcontext(td, &args->ctx.uc_mcontext));
}
int
sys_thr_create(struct thread *td, struct thr_create_args *uap)
/* ucontext_t *ctx, long *id, int flags */
{
ucontext_t ctx;
struct thr_create_initthr_args args;
int error;
if ((error = copyin(uap->ctx, &ctx, sizeof(ctx))))
if ((error = copyin(uap->ctx, &args.ctx, sizeof(args.ctx))))
return (error);
error = create_thread(td, &ctx.uc_mcontext, NULL, NULL,
NULL, 0, NULL, uap->id, NULL, uap->flags, NULL);
return (error);
args.tid = uap->id;
return (thread_create(td, NULL, thr_create_initthr, &args));
}
int
@ -129,6 +139,35 @@ sys_thr_new(struct thread *td, struct thr_new_args *uap)
return (kern_thr_new(td, &param));
}
static int
thr_new_initthr(struct thread *td, void *thunk)
{
stack_t stack;
struct thr_param *param;
/*
* Here we copy out tid to two places, one for child and one
* for parent, because pthread can create a detached thread,
* if parent wants to safely access child tid, it has to provide
* its storage, because child thread may exit quickly and
* memory is freed before parent thread can access it.
*/
param = thunk;
if ((param->child_tid != NULL &&
suword_lwpid(param->child_tid, td->td_tid)) ||
(param->parent_tid != NULL &&
suword_lwpid(param->parent_tid, td->td_tid)))
return (EFAULT);
/* Set up our machine context. */
stack.ss_sp = param->stack_base;
stack.ss_size = param->stack_size;
/* Set upcall address to user thread entry function. */
cpu_set_upcall_kse(td, param->start_func, param->arg, &stack);
/* Setup user TLS address and TLS pointer register. */
return (cpu_set_user_tls(td, param->tls_base));
}
int
kern_thr_new(struct thread *td, struct thr_param *param)
{
@ -142,22 +181,13 @@ kern_thr_new(struct thread *td, struct thr_param *param)
return (error);
rtpp = &rtp;
}
error = create_thread(td, NULL, param->start_func, param->arg,
param->stack_base, param->stack_size, param->tls_base,
param->child_tid, param->parent_tid, param->flags,
rtpp);
return (error);
return (thread_create(td, rtpp, thr_new_initthr, param));
}
static int
create_thread(struct thread *td, mcontext_t *ctx,
void (*start_func)(void *), void *arg,
char *stack_base, size_t stack_size,
char *tls_base,
long *child_tid, long *parent_tid,
int flags, struct rtprio *rtp)
int
thread_create(struct thread *td, struct rtprio *rtp,
int (*initialize_thread)(struct thread *, void *), void *thunk)
{
stack_t stack;
struct thread *newtd;
struct proc *p;
int error;
@ -199,24 +229,6 @@ create_thread(struct thread *td, mcontext_t *ctx,
cpu_set_upcall(newtd, td);
/*
* Try the copyout as soon as we allocate the td so we don't
* have to tear things down in a failure case below.
* Here we copy out tid to two places, one for child and one
* for parent, because pthread can create a detached thread,
* if parent wants to safely access child tid, it has to provide
* its storage, because child thread may exit quickly and
* memory is freed before parent thread can access it.
*/
if ((child_tid != NULL &&
suword_lwpid(child_tid, newtd->td_tid)) ||
(parent_tid != NULL &&
suword_lwpid(parent_tid, newtd->td_tid))) {
thread_free(newtd);
error = EFAULT;
goto fail;
}
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
bcopy(&td->td_startcopy, &newtd->td_startcopy,
@ -224,26 +236,11 @@ create_thread(struct thread *td, mcontext_t *ctx,
newtd->td_proc = td->td_proc;
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);
goto fail;
}
} else {
/* Set up our machine context. */
stack.ss_sp = stack_base;
stack.ss_size = stack_size;
/* Set upcall address to user thread entry function. */
cpu_set_upcall_kse(newtd, start_func, arg, &stack);
/* 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);
goto fail;
}
error = initialize_thread(newtd, thunk);
if (error != 0) {
thread_cow_free(newtd);
thread_free(newtd);
goto fail;
}
PROC_LOCK(p);

2
sys/sys/proc.h
View File

@ -992,6 +992,8 @@ 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);
int thread_create(struct thread *td, struct rtprio *rtp,
int (*initialize_thread)(struct thread *, void *), void *thunk);
void thread_exit(void) __dead2;
void thread_free(struct thread *td);
void thread_link(struct thread *td, struct proc *p);