Date: Sat, 4 Oct 2014 18:38:14 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r272536 - in head/sys: conf kern sys vm Message-ID: <201410041838.s94IcEYm004488@svn.freebsd.org>
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Author: kib Date: Sat Oct 4 18:38:14 2014 New Revision: 272536 URL: https://svnweb.freebsd.org/changeset/base/272536 Log: Add kernel option KSTACK_USAGE_PROF to sample the stack depth on interrupts and report the largest value seen as sysctl debug.max_kstack_used. Useful to estimate how close the kernel stack size is to overflow. In collaboration with: Larry Baird <lab@gta.com> Sponsored by: The FreeBSD Foundation (kib) MFC after: 1 week Modified: head/sys/conf/NOTES head/sys/conf/options head/sys/kern/kern_intr.c head/sys/sys/systm.h head/sys/vm/vm_glue.c Modified: head/sys/conf/NOTES ============================================================================== --- head/sys/conf/NOTES Sat Oct 4 18:35:00 2014 (r272535) +++ head/sys/conf/NOTES Sat Oct 4 18:38:14 2014 (r272536) @@ -2958,6 +2958,7 @@ options SC_RENDER_DEBUG # syscons rende options VFS_BIO_DEBUG # VFS buffer I/O debugging options KSTACK_MAX_PAGES=32 # Maximum pages to give the kernel stack +options KSTACK_USAGE_PROF # Adaptec Array Controller driver options options AAC_DEBUG # Debugging levels: Modified: head/sys/conf/options ============================================================================== --- head/sys/conf/options Sat Oct 4 18:35:00 2014 (r272535) +++ head/sys/conf/options Sat Oct 4 18:38:14 2014 (r272536) @@ -136,6 +136,7 @@ KDTRACE_FRAME opt_kdtrace.h KN_HASHSIZE opt_kqueue.h KSTACK_MAX_PAGES KSTACK_PAGES +KSTACK_USAGE_PROF KTRACE KTRACE_REQUEST_POOL opt_ktrace.h LIBICONV Modified: head/sys/kern/kern_intr.c ============================================================================== --- head/sys/kern/kern_intr.c Sat Oct 4 18:35:00 2014 (r272535) +++ head/sys/kern/kern_intr.c Sat Oct 4 18:38:14 2014 (r272536) @@ -28,6 +28,7 @@ __FBSDID("$FreeBSD$"); #include "opt_ddb.h" +#include "opt_kstack_usage_prof.h" #include <sys/param.h> #include <sys/bus.h> @@ -1396,6 +1397,10 @@ intr_event_handle(struct intr_event *ie, td = curthread; +#ifdef KSTACK_USAGE_PROF + intr_prof_stack_use(td, frame); +#endif + /* An interrupt with no event or handlers is a stray interrupt. */ if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers)) return (EINVAL); Modified: head/sys/sys/systm.h ============================================================================== --- head/sys/sys/systm.h Sat Oct 4 18:35:00 2014 (r272535) +++ head/sys/sys/systm.h Sat Oct 4 18:38:14 2014 (r272536) @@ -443,4 +443,6 @@ bitcount16(uint32_t x) return (x); } +void intr_prof_stack_use(struct thread *td, struct trapframe *frame); + #endif /* !_SYS_SYSTM_H_ */ Modified: head/sys/vm/vm_glue.c ============================================================================== --- head/sys/vm/vm_glue.c Sat Oct 4 18:35:00 2014 (r272535) +++ head/sys/vm/vm_glue.c Sat Oct 4 18:38:14 2014 (r272536) @@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$"); #include "opt_vm.h" #include "opt_kstack_pages.h" #include "opt_kstack_max_pages.h" +#include "opt_kstack_usage_prof.h" #include <sys/param.h> #include <sys/systm.h> @@ -98,6 +99,8 @@ __FBSDID("$FreeBSD$"); #include <vm/vm_pager.h> #include <vm/swap_pager.h> +#include <machine/cpu.h> + #ifndef NO_SWAPPING static int swapout(struct proc *); static void swapclear(struct proc *); @@ -486,6 +489,52 @@ kstack_cache_init(void *nulll) SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); +#ifdef KSTACK_USAGE_PROF +/* + * Track maximum stack used by a thread in kernel. + */ +static int max_kstack_used; + +SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD, + &max_kstack_used, 0, + "Maxiumum stack depth used by a thread in kernel"); + +void +intr_prof_stack_use(struct thread *td, struct trapframe *frame) +{ + vm_offset_t stack_top; + vm_offset_t current; + int used, prev_used; + + /* + * Testing for interrupted kernel mode isn't strictly + * needed. It optimizes the execution, since interrupts from + * usermode will have only the trap frame on the stack. + */ + if (TRAPF_USERMODE(frame)) + return; + + stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE; + current = (vm_offset_t)(uintptr_t)&stack_top; + + /* + * Try to detect if interrupt is using kernel thread stack. + * Hardware could use a dedicated stack for interrupt handling. + */ + if (stack_top <= current || current < td->td_kstack) + return; + + used = stack_top - current; + for (;;) { + prev_used = max_kstack_used; + if (prev_used >= used) + break; + if (atomic_cmpset_int(&max_kstack_used, prev_used, used)) + break; + } +} +#endif /* KSTACK_USAGE_PROF */ + #ifndef NO_SWAPPING /* * Allow a thread's kernel stack to be paged out.
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