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
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=272536
@ -2958,6 +2958,7 @@ options SC_RENDER_DEBUG # syscons rendering debugging
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options VFS_BIO_DEBUG # VFS buffer I/O debugging
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options KSTACK_MAX_PAGES=32 # Maximum pages to give the kernel stack
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options KSTACK_USAGE_PROF
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# Adaptec Array Controller driver options
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options AAC_DEBUG # Debugging levels:
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@ -136,6 +136,7 @@ KDTRACE_FRAME opt_kdtrace.h
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KN_HASHSIZE opt_kqueue.h
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KSTACK_MAX_PAGES
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KSTACK_PAGES
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KSTACK_USAGE_PROF
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KTRACE
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KTRACE_REQUEST_POOL opt_ktrace.h
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LIBICONV
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@ -28,6 +28,7 @@
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__FBSDID("$FreeBSD$");
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#include "opt_ddb.h"
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#include "opt_kstack_usage_prof.h"
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#include <sys/param.h>
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#include <sys/bus.h>
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@ -1396,6 +1397,10 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame)
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td = curthread;
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#ifdef KSTACK_USAGE_PROF
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intr_prof_stack_use(td, frame);
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#endif
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/* An interrupt with no event or handlers is a stray interrupt. */
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if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers))
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return (EINVAL);
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@ -443,4 +443,6 @@ bitcount16(uint32_t x)
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return (x);
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}
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void intr_prof_stack_use(struct thread *td, struct trapframe *frame);
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#endif /* !_SYS_SYSTM_H_ */
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@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$");
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#include "opt_vm.h"
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#include "opt_kstack_pages.h"
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#include "opt_kstack_max_pages.h"
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#include "opt_kstack_usage_prof.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -98,6 +99,8 @@ __FBSDID("$FreeBSD$");
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#include <vm/vm_pager.h>
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#include <vm/swap_pager.h>
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#include <machine/cpu.h>
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#ifndef NO_SWAPPING
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static int swapout(struct proc *);
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static void swapclear(struct proc *);
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@ -486,6 +489,52 @@ kstack_cache_init(void *nulll)
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SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
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#ifdef KSTACK_USAGE_PROF
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/*
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* Track maximum stack used by a thread in kernel.
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*/
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static int max_kstack_used;
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SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
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&max_kstack_used, 0,
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"Maxiumum stack depth used by a thread in kernel");
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void
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intr_prof_stack_use(struct thread *td, struct trapframe *frame)
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{
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vm_offset_t stack_top;
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vm_offset_t current;
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int used, prev_used;
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/*
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* Testing for interrupted kernel mode isn't strictly
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* needed. It optimizes the execution, since interrupts from
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* usermode will have only the trap frame on the stack.
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*/
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if (TRAPF_USERMODE(frame))
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return;
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stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
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current = (vm_offset_t)(uintptr_t)&stack_top;
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/*
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* Try to detect if interrupt is using kernel thread stack.
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* Hardware could use a dedicated stack for interrupt handling.
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*/
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if (stack_top <= current || current < td->td_kstack)
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return;
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used = stack_top - current;
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for (;;) {
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prev_used = max_kstack_used;
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if (prev_used >= used)
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break;
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if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
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break;
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}
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}
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#endif /* KSTACK_USAGE_PROF */
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#ifndef NO_SWAPPING
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/*
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* Allow a thread's kernel stack to be paged out.
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