From 9787b8afc5f471e5bc889a0624cd18c397ae5611 Mon Sep 17 00:00:00 2001 From: marius Date: Sat, 19 Nov 2011 12:55:34 +0000 Subject: [PATCH] MFC: r227537 As it turns out, r186347 actually is insufficient to avoid the use of the curthread-accessing part of mtx_{,un}lock(9) when using a r210623-style curthread implementation on sparc64, crashing the kernel in its early cycles as PCPU isn't set up, yet (and can't be set up as OFW is one of the things we need for that, which leads to a chicken-and-egg problem). What happens is that due to the fact that the idea of r210623 actually is to allow the compiler to cache invocations of curthread, it factors out obtaining curthread needed for both mtx_lock(9) and mtx_unlock(9) to before the branch based on kobj_mutex_inited when compiling the kernel without the debugging options. So change kobj_class_compile_static(9) to just never acquire kobj_mtx, effectively restricting it to its documented use, and add a kobj_init_static(9) for initializing objects using a class compiled with the former and that also avoids using mutex(9) (and malloc(9)). Also assert in both of these functions that they are used in their intended way only. While at it, inline kobj_register_method() and kobj_unregister_method() as there wasn't much point for factoring them out in the first place and so that a reader of the code has to figure out the locking for fewer functions missing a KOBJ_ASSERT. Tested on powerpc{,64} by andreast. Reviewed by: nwhitehorn (earlier version), jhb Approved by: re (kib) git-svn-id: svn://svn.freebsd.org/base/releng/9.0@227712 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- share/man/man9/Makefile | 3 +- share/man/man9/kobj.9 | 16 +++++- sys/dev/ofw/openfirm.c | 2 +- sys/kern/subr_kobj.c | 75 ++++++++++++----------------- sys/powerpc/powerpc/platform.c | 4 +- sys/powerpc/powerpc/pmap_dispatch.c | 2 +- sys/sys/kobj.h | 1 + 7 files changed, 52 insertions(+), 51 deletions(-) diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile index 7d34c318..d392a5a0 100644 --- a/share/man/man9/Makefile +++ b/share/man/man9/Makefile @@ -724,7 +724,8 @@ MLINKS+=kobj.9 DEFINE_CLASS.9 \ kobj.9 kobj_class_free.9 \ kobj.9 kobj_create.9 \ kobj.9 kobj_delete.9 \ - kobj.9 kobj_init.9 + kobj.9 kobj_init.9 \ + kobj.9 kobj_init_static.9 MLINKS+=kproc.9 kproc_create.9 \ kproc.9 kproc_exit.9 \ kproc.9 kproc_resume.9 \ diff --git a/share/man/man9/kobj.9 b/share/man/man9/kobj.9 index aed12442..0e1745e6 100644 --- a/share/man/man9/kobj.9 +++ b/share/man/man9/kobj.9 @@ -28,7 +28,7 @@ .\" .\" $FreeBSD$ .\" -.Dd April 4, 2000 +.Dd November 14, 2011 .Dt KOBJ 9 .Os .Sh NAME @@ -48,6 +48,8 @@ .Ft void .Fn kobj_init "kobj_t obj" "kobj_class_t cls" .Ft void +.Fn kobj_init_static "kobj_t obj" "kobj_class_t cls" +.Ft void .Fn kobj_delete "kobj_t obj" "struct malloc_type *mtype" .Fn DEFINE_CLASS name "kobj_method_t *methods" "size_t size" .Sh DESCRIPTION @@ -88,10 +90,14 @@ Objects created in this way should be freed by calling Clients which would like to manage the allocation of memory themselves should call .Fn kobj_init +or +.Fn kobj_init_static with a pointer to the memory for the object and the class which implements it. It is also possible to use .Fn kobj_init +and +.Fn kobj_init_static to change the class for an object. This should be done with care as the classes must agree on the layout of the object. @@ -109,13 +115,19 @@ A client should not normally need to call these since a class will automatically be compiled the first time it is used. If a class is to be used before .Xr malloc 9 -is initialised, +and +.Xr mutex 9 +are initialised, then .Fn kobj_class_compile_static should be called with the class and a pointer to a statically allocated .Vt kobj_ops structure before the class is used to initialise any objects. +In that case, also +.Fn kobj_init_static +should be used instead of +.Fn kobj_init . .Pp To define a class, first define a simple array of .Vt kobj_method_t . diff --git a/sys/dev/ofw/openfirm.c b/sys/dev/ofw/openfirm.c index a8cb8f7c..9ff72dfc 100644 --- a/sys/dev/ofw/openfirm.c +++ b/sys/dev/ofw/openfirm.c @@ -127,7 +127,7 @@ OF_init(void *cookie) * then statically initialize the OFW object. */ kobj_class_compile_static(ofw_def_impl, &ofw_kernel_kops); - kobj_init((kobj_t)ofw_obj, ofw_def_impl); + kobj_init_static((kobj_t)ofw_obj, ofw_def_impl); rv = OFW_INIT(ofw_obj, cookie); diff --git a/sys/kern/subr_kobj.c b/sys/kern/subr_kobj.c index 4ee71824..2c814fb5 100644 --- a/sys/kern/subr_kobj.c +++ b/sys/kern/subr_kobj.c @@ -60,18 +60,9 @@ static struct mtx kobj_mtx; static int kobj_mutex_inited; static int kobj_next_id = 1; -/* - * In the event that kobj_mtx has not been initialized yet, - * we will ignore it, and run without locks in order to support - * use of KOBJ before mutexes are available. This early in the boot - * process, everything is single threaded and so races should not - * happen. This is used to provide the PMAP layer on PowerPC, as well - * as board support. - */ - -#define KOBJ_LOCK() if (kobj_mutex_inited) mtx_lock(&kobj_mtx); -#define KOBJ_UNLOCK() if (kobj_mutex_inited) mtx_unlock(&kobj_mtx); -#define KOBJ_ASSERT(what) if (kobj_mutex_inited) mtx_assert(&kobj_mtx,what); +#define KOBJ_LOCK() mtx_lock(&kobj_mtx) +#define KOBJ_UNLOCK() mtx_unlock(&kobj_mtx) +#define KOBJ_ASSERT(what) mtx_assert(&kobj_mtx, what); SYSCTL_INT(_kern, OID_AUTO, kobj_methodcount, CTLFLAG_RD, &kobj_next_id, 0, ""); @@ -103,29 +94,12 @@ kobj_error_method(void) return ENXIO; } -static void -kobj_register_method(struct kobjop_desc *desc) -{ - KOBJ_ASSERT(MA_OWNED); - - if (desc->id == 0) { - desc->id = kobj_next_id++; - } -} - -static void -kobj_unregister_method(struct kobjop_desc *desc) -{ -} - static void kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops) { kobj_method_t *m; int i; - KOBJ_ASSERT(MA_OWNED); - /* * Don't do anything if we are already compiled. */ @@ -135,8 +109,10 @@ kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops) /* * First register any methods which need it. */ - for (i = 0, m = cls->methods; m->desc; i++, m++) - kobj_register_method(m->desc); + for (i = 0, m = cls->methods; m->desc; i++, m++) { + if (m->desc->id == 0) + m->desc->id = kobj_next_id++; + } /* * Then initialise the ops table. @@ -159,7 +135,7 @@ kobj_class_compile(kobj_class_t cls) */ ops = malloc(sizeof(struct kobj_ops), M_KOBJ, M_NOWAIT); if (!ops) - panic("kobj_compile_methods: out of memory"); + panic("%s: out of memory", __func__); KOBJ_LOCK(); @@ -182,17 +158,14 @@ void kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops) { - KOBJ_ASSERT(MA_NOTOWNED); + KASSERT(kobj_mutex_inited == 0, + ("%s: only supported during early cycles", __func__)); /* * Increment refs to make sure that the ops table is not freed. */ - KOBJ_LOCK(); - cls->refs++; kobj_class_compile_common(cls, ops); - - KOBJ_UNLOCK(); } static kobj_method_t* @@ -259,8 +232,6 @@ kobj_lookup_method(kobj_class_t cls, void kobj_class_free(kobj_class_t cls) { - int i; - kobj_method_t *m; void* ops = NULL; KOBJ_ASSERT(MA_NOTOWNED); @@ -272,10 +243,9 @@ kobj_class_free(kobj_class_t cls) */ if (cls->refs == 0) { /* - * Unregister any methods which are no longer used. + * For now we don't do anything to unregister any methods + * which are no longer used. */ - for (i = 0, m = cls->methods; m->desc; i++, m++) - kobj_unregister_method(m->desc); /* * Free memory and clean up. @@ -308,6 +278,14 @@ kobj_create(kobj_class_t cls, return obj; } +static void +kobj_init_common(kobj_t obj, kobj_class_t cls) +{ + + obj->ops = cls->ops; + cls->refs++; +} + void kobj_init(kobj_t obj, kobj_class_t cls) { @@ -329,12 +307,21 @@ kobj_init(kobj_t obj, kobj_class_t cls) goto retry; } - obj->ops = cls->ops; - cls->refs++; + kobj_init_common(obj, cls); KOBJ_UNLOCK(); } +void +kobj_init_static(kobj_t obj, kobj_class_t cls) +{ + + KASSERT(kobj_mutex_inited == 0, + ("%s: only supported during early cycles", __func__)); + + kobj_init_common(obj, cls); +} + void kobj_delete(kobj_t obj, struct malloc_type *mtype) { diff --git a/sys/powerpc/powerpc/platform.c b/sys/powerpc/powerpc/platform.c index 9eb8f30e..28771343 100644 --- a/sys/powerpc/powerpc/platform.c +++ b/sys/powerpc/powerpc/platform.c @@ -184,7 +184,7 @@ platform_probe_and_attach() * then statically initialise the MMU object */ kobj_class_compile_static(platp, &plat_kernel_kops); - kobj_init((kobj_t)plat_obj, platp); + kobj_init_static((kobj_t)plat_obj, platp); prio = PLATFORM_PROBE(plat_obj); @@ -223,7 +223,7 @@ platform_probe_and_attach() */ kobj_class_compile_static(plat_def_impl, &plat_kernel_kops); - kobj_init((kobj_t)plat_obj, plat_def_impl); + kobj_init_static((kobj_t)plat_obj, plat_def_impl); strlcpy(plat_name,plat_def_impl->name,sizeof(plat_name)); diff --git a/sys/powerpc/powerpc/pmap_dispatch.c b/sys/powerpc/powerpc/pmap_dispatch.c index fe104293..4715a93b 100644 --- a/sys/powerpc/powerpc/pmap_dispatch.c +++ b/sys/powerpc/powerpc/pmap_dispatch.c @@ -410,7 +410,7 @@ pmap_bootstrap(vm_offset_t start, vm_offset_t end) * then statically initialise the MMU object */ kobj_class_compile_static(mmu_def_impl, &mmu_kernel_kops); - kobj_init((kobj_t)mmu_obj, mmu_def_impl); + kobj_init_static((kobj_t)mmu_obj, mmu_def_impl); MMU_BOOTSTRAP(mmu_obj, start, end); } diff --git a/sys/sys/kobj.h b/sys/sys/kobj.h index 3143bea4..5df5dccc 100644 --- a/sys/sys/kobj.h +++ b/sys/sys/kobj.h @@ -201,6 +201,7 @@ kobj_t kobj_create(kobj_class_t cls, * Initialise a pre-allocated object. */ void kobj_init(kobj_t obj, kobj_class_t cls); +void kobj_init_static(kobj_t obj, kobj_class_t cls); /* * Delete an object. If mtype is non-zero, free the memory. -- 2.42.0