> Date: Fri, 11 Sep 2020 10:23:34 +0200
> From: Martin Pieuchot <[email protected]>
>
> To investigate the race exposed by the last locking change in
> uvm_map_inentry() [0], I'd like to add the following tracepoints.
>
> The idea is to compare page fault addresses and permissions with
> the insertion/removal of entries in a given map. Diff below is
> the first part of the puzzle, ok?
>
> [0] https://marc.info/?l=openbsd-tech&m=157293690312531&w=2
>
> An example of bt(5) script using those tracepoints look like this:
>
> tracepoint:uvm:fault {
> printf("%s:%d(%s) fault 0x%x type=0x%x, prot=0x%x\n",
> nsecs, tid, comm, arg0, arg1, arg2);
> }
> tracepoint:uvm:map_insert {
> printf("%s:%d(%s) insert [0x%x, 0x%x), prot=0x%x\n",
> nsecs, tid, comm, arg0, arg1, arg2);
> }
> tracepoint:uvm:map_remove {
> printf("%s:%d(%s) remove [0x%x, 0x%x) prot=0x%x\n",
> nsecs, tid, comm, arg0, arg1, arg2);
> }
Having more examples will help people to make use of this functionality.
ok kettenis@
> Index: uvm/uvm_fault.c
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm_fault.c,v
> retrieving revision 1.97
> diff -u -p -r1.97 uvm_fault.c
> --- uvm/uvm_fault.c 8 Dec 2019 12:37:45 -0000 1.97
> +++ uvm/uvm_fault.c 11 Sep 2020 07:16:01 -0000
> @@ -38,6 +38,7 @@
> #include <sys/proc.h>
> #include <sys/malloc.h>
> #include <sys/mman.h>
> +#include <sys/tracepoint.h>
>
> #include <uvm/uvm.h>
>
> @@ -507,6 +508,7 @@ uvm_fault(vm_map_t orig_map, vaddr_t vad
> pg = NULL;
>
> uvmexp.faults++; /* XXX: locking? */
> + TRACEPOINT(uvm, fault, vaddr, fault_type, access_type, NULL);
>
> /* init the IN parameters in the ufi */
> ufi.orig_map = orig_map;
> Index: uvm/uvm_map.c
> ===================================================================
> RCS file: /cvs/src/sys/uvm/uvm_map.c,v
> retrieving revision 1.265
> diff -u -p -r1.265 uvm_map.c
> --- uvm/uvm_map.c 6 Jul 2020 19:22:40 -0000 1.265
> +++ uvm/uvm_map.c 11 Sep 2020 07:41:53 -0000
> @@ -95,6 +95,7 @@
> #include <sys/signalvar.h>
> #include <sys/syslog.h>
> #include <sys/user.h>
> +#include <sys/tracepoint.h>
>
> #ifdef SYSVSHM
> #include <sys/shm.h>
> @@ -455,6 +456,9 @@ uvm_mapent_addr_insert(struct vm_map *ma
> KDASSERT((entry->start & (vaddr_t)PAGE_MASK) == 0 &&
> (entry->end & (vaddr_t)PAGE_MASK) == 0);
>
> + TRACEPOINT(uvm, map_insert,
> + entry->start, entry->end, entry->protection, NULL);
> +
> UVM_MAP_REQ_WRITE(map);
> res = RBT_INSERT(uvm_map_addr, &map->addr, entry);
> if (res != NULL) {
> @@ -474,6 +478,9 @@ void
> uvm_mapent_addr_remove(struct vm_map *map, struct vm_map_entry *entry)
> {
> struct vm_map_entry *res;
> +
> + TRACEPOINT(uvm, map_remove,
> + entry->start, entry->end, entry->protection, NULL);
>
> UVM_MAP_REQ_WRITE(map);
> res = RBT_REMOVE(uvm_map_addr, &map->addr, entry);
> Index: dev/dt/dt_prov_static.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/dt/dt_prov_static.c,v
> retrieving revision 1.2
> diff -u -p -r1.2 dt_prov_static.c
> --- dev/dt/dt_prov_static.c 25 Mar 2020 14:59:23 -0000 1.2
> +++ dev/dt/dt_prov_static.c 11 Sep 2020 07:43:58 -0000
> @@ -34,7 +34,7 @@ struct dt_provider dt_prov_static = {
> };
>
> /*
> - * Scheduler provider
> + * Scheduler
> */
> DT_STATIC_PROBE2(sched, dequeue, "pid_t", "pid_t");
> DT_STATIC_PROBE2(sched, enqueue, "pid_t", "pid_t");
> @@ -51,6 +51,13 @@ DT_STATIC_PROBE1(raw_syscalls, sys_enter
> DT_STATIC_PROBE1(raw_syscalls, sys_exit, "register_t");
>
> /*
> + * UVM
> + */
> +DT_STATIC_PROBE3(uvm, fault, "vaddr_t", "vm_fault_t", "vm_prot_t");
> +DT_STATIC_PROBE3(uvm, map_insert, "vaddr_t", "vaddr_t", "vm_prot_t");
> +DT_STATIC_PROBE3(uvm, map_remove, "vaddr_t", "vaddr_t", "vm_prot_t");
> +
> +/*
> * List of all static probes
> */
> struct dt_probe *dtps_static[] = {
> @@ -65,6 +72,10 @@ struct dt_probe *dtps_static[] = {
> /* Raw syscalls */
> &_DT_STATIC_P(raw_syscalls, sys_enter),
> &_DT_STATIC_P(raw_syscalls, sys_exit),
> + /* UVM */
> + &_DT_STATIC_P(uvm, fault),
> + &_DT_STATIC_P(uvm, map_insert),
> + &_DT_STATIC_P(uvm, map_remove),
> };
>
> int
>
>
