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Stop updating the struct vdso_timehands from even handler executed in

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the scheduled task from tc_windup(). Do it directly from tc_windup in
interrupt context [1].

Establish the permanent mapping of the shared page into the kernel
address space, avoiding the potential need to sleep waiting for
allocation of sf buffer during vdso_timehands update. As a
consequence, shared_page_write_start() and shared_page_write_end()
functions are not needed anymore.

Guess and memorize the pointers to native host and compat32 sysentvec
during initialization, to avoid the need to get shared_page_alloc_sx
lock during the update.

In tc_fill_vdso_timehands(), do not loop waiting for timehands
generation to stabilize, since vdso_timehands is written in the same
interrupt context which wrote timehands.

Requested by:	  mav [1]
MFC after:	  29 days
This commit is contained in:
kib 2012-06-23 09:33:06 +00:00
parent e19c8fe0ff
commit 497817697c
4 changed files with 66 additions and 101 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

97
sys/kern/kern_exec.c
View File

@ -1517,42 +1517,13 @@ exec_unregister(execsw_arg)
static struct sx shared_page_alloc_sx;
static vm_object_t shared_page_obj;
static int shared_page_free;
struct sf_buf *
shared_page_write_start(int base)
{
vm_page_t m;
struct sf_buf *s;
VM_OBJECT_LOCK(shared_page_obj);
m = vm_page_grab(shared_page_obj, OFF_TO_IDX(base), VM_ALLOC_RETRY);
VM_OBJECT_UNLOCK(shared_page_obj);
s = sf_buf_alloc(m, SFB_DEFAULT);
return (s);
}
void
shared_page_write_end(struct sf_buf *sf)
{
vm_page_t m;
m = sf_buf_page(sf);
sf_buf_free(sf);
VM_OBJECT_LOCK(shared_page_obj);
vm_page_wakeup(m);
VM_OBJECT_UNLOCK(shared_page_obj);
}
char *shared_page_mapping;
void
shared_page_write(int base, int size, const void *data)
{
struct sf_buf *sf;
vm_offset_t sk;
sf = shared_page_write_start(base);
sk = sf_buf_kva(sf);
bcopy(data, (void *)(sk + (base & PAGE_MASK)), size);
shared_page_write_end(sf);
bcopy(data, shared_page_mapping + base, size);
}
static int
@ -1596,6 +1567,7 @@ static void
shared_page_init(void *dummy __unused)
{
vm_page_t m;
vm_offset_t addr;
sx_init(&shared_page_alloc_sx, "shpsx");
shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
@ -1605,25 +1577,24 @@ shared_page_init(void *dummy __unused)
VM_ALLOC_ZERO);
m->valid = VM_PAGE_BITS_ALL;
VM_OBJECT_UNLOCK(shared_page_obj);
addr = kmem_alloc_nofault(kernel_map, PAGE_SIZE);
pmap_qenter(addr, &m, 1);
shared_page_mapping = (char *)addr;
}
SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
NULL);
static void
timehands_update(void *arg)
timehands_update(struct sysentvec *sv)
{
struct sysentvec *sv;
struct sf_buf *sf;
struct vdso_timehands th;
struct vdso_timekeep *tk;
uint32_t enabled, idx;
sv = arg;
sx_xlock(&shared_page_alloc_sx);
enabled = tc_fill_vdso_timehands(&th);
sf = shared_page_write_start(sv->sv_timekeep_off);
tk = (void *)(sf_buf_kva(sf) + (sv->sv_timekeep_off & PAGE_MASK));
tk = (struct vdso_timekeep *)(shared_page_mapping +
sv->sv_timekeep_off);
idx = sv->sv_timekeep_curr;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
if (++idx >= VDSO_TH_NUM)
@ -1637,25 +1608,19 @@ timehands_update(void *arg)
tk->tk_enabled = enabled;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
tk->tk_current = idx;
shared_page_write_end(sf);
sx_xunlock(&shared_page_alloc_sx);
}
#ifdef COMPAT_FREEBSD32
static void
timehands_update32(void *arg)
timehands_update32(struct sysentvec *sv)
{
struct sysentvec *sv;
struct sf_buf *sf;
struct vdso_timekeep32 *tk;
struct vdso_timehands32 th;
uint32_t enabled, idx;
sv = arg;
sx_xlock(&shared_page_alloc_sx);
enabled = tc_fill_vdso_timehands32(&th);
sf = shared_page_write_start(sv->sv_timekeep_off);
tk = (void *)(sf_buf_kva(sf) + (sv->sv_timekeep_off & PAGE_MASK));
tk = (struct vdso_timekeep32 *)(shared_page_mapping +
sv->sv_timekeep_off);
idx = sv->sv_timekeep_curr;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
if (++idx >= VDSO_TH_NUM)
@ -1669,11 +1634,32 @@ timehands_update32(void *arg)
tk->tk_enabled = enabled;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
tk->tk_current = idx;
shared_page_write_end(sf);
sx_xunlock(&shared_page_alloc_sx);
}
#endif
/*
* This is hackish, but easiest way to avoid creating list structures
* that needs to be iterated over from the hardclock interrupt
* context.
*/
static struct sysentvec *host_sysentvec;
#ifdef COMPAT_FREEBSD32
static struct sysentvec *compat32_sysentvec;
#endif
void
timekeep_push_vdso(void)
{
if (host_sysentvec != NULL && host_sysentvec->sv_timekeep_base != 0)
timehands_update(host_sysentvec);
#ifdef COMPAT_FREEBSD32
if (compat32_sysentvec != NULL &&
compat32_sysentvec->sv_timekeep_base != 0)
timehands_update32(compat32_sysentvec);
#endif
}
void
exec_sysvec_init(void *param)
{
@ -1688,29 +1674,32 @@ exec_sysvec_init(void *param)
sv->sv_shared_page_obj = shared_page_obj;
sv->sv_sigcode_base = sv->sv_shared_page_base +
shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
return;
tk_ver = VDSO_TK_VER_CURR;
#ifdef COMPAT_FREEBSD32
if ((sv->sv_flags & SV_ILP32) != 0) {
tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
EVENTHANDLER_REGISTER(tc_windup, timehands_update32, sv,
EVENTHANDLER_PRI_ANY);
shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
tk_ver), sizeof(uint32_t), &tk_ver);
KASSERT(compat32_sysentvec == 0,
("Native compat32 already registered"));
compat32_sysentvec = sv;
} else {
#endif
tk_base = shared_page_alloc(sizeof(struct vdso_timekeep) +
sizeof(struct vdso_timehands) * VDSO_TH_NUM, 16);
KASSERT(tk_base != -1, ("tk_base -1 for native"));
EVENTHANDLER_REGISTER(tc_windup, timehands_update, sv,
EVENTHANDLER_PRI_ANY);
shared_page_write(tk_base + offsetof(struct vdso_timekeep,
tk_ver), sizeof(uint32_t), &tk_ver);
KASSERT(host_sysentvec == 0, ("Native already registered"));
host_sysentvec = sv;
#ifdef COMPAT_FREEBSD32
}
#endif
sv->sv_timekeep_base = sv->sv_shared_page_base + tk_base;
sv->sv_timekeep_off = tk_base;
EVENTHANDLER_INVOKE(tc_windup);
timekeep_push_vdso();
}

62
sys/kern/kern_tc.c
View File

@ -31,7 +31,6 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/timeffc.h>
#include <sys/timepps.h>
#include <sys/taskqueue.h>
#include <sys/timetc.h>
#include <sys/timex.h>
#include <sys/vdso.h>
@ -121,12 +120,8 @@ SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
&timestepwarnings, 0, "Log time steps");
static void tc_windup(void);
static void tc_windup_push_vdso(void *ctx, int pending);
static void cpu_tick_calibrate(int);
static struct task tc_windup_push_vdso_task = TASK_INITIALIZER(0,
tc_windup_push_vdso, 0);
static int
sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
{
@ -1367,7 +1362,7 @@ tc_windup(void)
#endif
timehands = th;
taskqueue_enqueue_fast(taskqueue_fast, &tc_windup_push_vdso_task);
timekeep_push_vdso();
}
/* Report or change the active timecounter hardware. */
@ -1394,7 +1389,7 @@ sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
(void)newtc->tc_get_timecount(newtc);
timecounter = newtc;
EVENTHANDLER_INVOKE(tc_windup);
timekeep_push_vdso();
return (0);
}
return (EINVAL);
@ -1865,7 +1860,7 @@ sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
if (error != 0)
return (error);
vdso_th_enable = old_vdso_th_enable;
EVENTHANDLER_INVOKE(tc_windup);
timekeep_push_vdso();
return (0);
}
SYSCTL_PROC(_kern_timecounter, OID_AUTO, fast_gettime,
@ -1877,19 +1872,15 @@ tc_fill_vdso_timehands(struct vdso_timehands *vdso_th)
{
struct timehands *th;
uint32_t enabled;
int gen;
do {
th = timehands;
gen = th->th_generation;
vdso_th->th_algo = VDSO_TH_ALGO_1;
vdso_th->th_scale = th->th_scale;
vdso_th->th_offset_count = th->th_offset_count;
vdso_th->th_counter_mask = th->th_counter->tc_counter_mask;
vdso_th->th_offset = th->th_offset;
vdso_th->th_boottime = boottimebin;
enabled = cpu_fill_vdso_timehands(vdso_th);
} while (gen == 0 || timehands->th_generation != gen);
th = timehands;
vdso_th->th_algo = VDSO_TH_ALGO_1;
vdso_th->th_scale = th->th_scale;
vdso_th->th_offset_count = th->th_offset_count;
vdso_th->th_counter_mask = th->th_counter->tc_counter_mask;
vdso_th->th_offset = th->th_offset;
vdso_th->th_boottime = boottimebin;
enabled = cpu_fill_vdso_timehands(vdso_th);
if (!vdso_th_enable)
enabled = 0;
return (enabled);
@ -1901,30 +1892,19 @@ tc_fill_vdso_timehands32(struct vdso_timehands32 *vdso_th32)
{
struct timehands *th;
uint32_t enabled;
int gen;
do {
th = timehands;
gen = th->th_generation;
vdso_th32->th_algo = VDSO_TH_ALGO_1;
*(uint64_t *)&vdso_th32->th_scale[0] = th->th_scale;
vdso_th32->th_offset_count = th->th_offset_count;
vdso_th32->th_counter_mask = th->th_counter->tc_counter_mask;
vdso_th32->th_offset.sec = th->th_offset.sec;
*(uint64_t *)&vdso_th32->th_offset.frac[0] = th->th_offset.frac;
vdso_th32->th_boottime.sec = boottimebin.sec;
*(uint64_t *)&vdso_th32->th_boottime.frac[0] = boottimebin.frac;
enabled = cpu_fill_vdso_timehands32(vdso_th32);
} while (gen == 0 || timehands->th_generation != gen);
th = timehands;
vdso_th32->th_algo = VDSO_TH_ALGO_1;
*(uint64_t *)&vdso_th32->th_scale[0] = th->th_scale;
vdso_th32->th_offset_count = th->th_offset_count;
vdso_th32->th_counter_mask = th->th_counter->tc_counter_mask;
vdso_th32->th_offset.sec = th->th_offset.sec;
*(uint64_t *)&vdso_th32->th_offset.frac[0] = th->th_offset.frac;
vdso_th32->th_boottime.sec = boottimebin.sec;
*(uint64_t *)&vdso_th32->th_boottime.frac[0] = boottimebin.frac;
enabled = cpu_fill_vdso_timehands32(vdso_th32);
if (!vdso_th_enable)
enabled = 0;
return (enabled);
}
#endif
static void
tc_windup_push_vdso(void *ctx, int pending)
{
EVENTHANDLER_INVOKE(tc_windup);
}

2
sys/sys/sysent.h
View File

@ -265,8 +265,6 @@ int shared_page_alloc(int size, int align);
int shared_page_fill(int size, int align, const void *data);
void shared_page_write(int base, int size, const void *data);
void exec_sysvec_init(void *param);
struct sf_buf *shared_page_write_start(int base);
void shared_page_write_end(struct sf_buf *sf);
#define INIT_SYSENTVEC(name, sv) \
SYSINIT(name, SI_SUB_EXEC, SI_ORDER_ANY, \

6
sys/sys/vdso.h
View File

@ -29,7 +29,6 @@
#define _SYS_VDSO_H
#include <sys/types.h>
#include <sys/eventhandler.h>
#include <machine/vdso.h>
struct vdso_timehands {
@ -74,6 +73,8 @@ u_int __vdso_gettc(const struct vdso_timehands *vdso_th);
#ifdef _KERNEL
void timekeep_push_vdso(void);
uint32_t tc_fill_vdso_timehands(struct vdso_timehands *vdso_th);
/*
@ -86,9 +87,6 @@ uint32_t tc_fill_vdso_timehands(struct vdso_timehands *vdso_th);
*/
uint32_t cpu_fill_vdso_timehands(struct vdso_timehands *vdso_th);
typedef void (*tc_windup_fn)(void *);
EVENTHANDLER_DECLARE(tc_windup, tc_windup_fn);
#define VDSO_TH_NUM 4
#ifdef COMPAT_FREEBSD32