freebsd-nq/sys/cddl/dev/dtrace/arm/dtrace_subr.c
Robert Watson 30b68ecda8 Changes that improve DTrace FBT reliability on freebsd/arm64:
- Implement a dtrace_getnanouptime(), matching the existing
  dtrace_getnanotime(), to avoid DTrace calling out to a potentially
  instrumentable function.

  (These should probably both be under KDTRACE_HOOKS.  Also, it's not clear
  to me that they are correct implementations for the DTrace thread time
  functions they are used in .. fixes for another commit.)

- Don't allow FBT to instrument functions involved in EL1 exception handling
  that are involved in FBT trap processing: handle_el1h_sync() and
  do_el1h_sync().

- Don't allow FBT to instrument DDB and KDB functions, as that makes it
  rather harder to debug FBT problems.

Prior to these changes, use of FBT on FreeBSD/arm64 rapidly led to kernel
panics due to recursion in DTrace.

Reliable FBT on FreeBSD/arm64 is reliant on another change from @andrew to
have the aarch64 instrumentor more carefully check that instructions it
replaces are against the stack pointer, which can otherwise lead to memory
corruption.  That change remains under review.

MFC after:	2 weeks
Reviewed by:	andrew, kp, markj (earlier version), jrtc27 (earlier version)
Differential revision:	https://reviews.freebsd.org/D27766
2021-01-11 15:42:22 +00:00

358 lines
8.3 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* $FreeBSD$
*
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/kmem.h>
#include <sys/smp.h>
#include <sys/dtrace_impl.h>
#include <sys/dtrace_bsd.h>
#include <machine/armreg.h>
#include <machine/clock.h>
#include <machine/frame.h>
#include <machine/trap.h>
#include <vm/pmap.h>
#define DELAYBRANCH(x) ((int)(x) < 0)
#define BIT_PC 15
#define BIT_LR 14
#define BIT_SP 13
extern dtrace_id_t dtrace_probeid_error;
extern int (*dtrace_invop_jump_addr)(struct trapframe *);
extern void dtrace_getnanotime(struct timespec *tsp);
extern void dtrace_getnanouptime(struct timespec *tsp);
int dtrace_invop(uintptr_t, struct trapframe *, uintptr_t);
void dtrace_invop_init(void);
void dtrace_invop_uninit(void);
typedef struct dtrace_invop_hdlr {
int (*dtih_func)(uintptr_t, struct trapframe *, uintptr_t);
struct dtrace_invop_hdlr *dtih_next;
} dtrace_invop_hdlr_t;
dtrace_invop_hdlr_t *dtrace_invop_hdlr;
int
dtrace_invop(uintptr_t addr, struct trapframe *frame, uintptr_t eax)
{
dtrace_invop_hdlr_t *hdlr;
int rval;
for (hdlr = dtrace_invop_hdlr; hdlr != NULL; hdlr = hdlr->dtih_next)
if ((rval = hdlr->dtih_func(addr, frame, eax)) != 0)
return (rval);
return (0);
}
void
dtrace_invop_add(int (*func)(uintptr_t, struct trapframe *, uintptr_t))
{
dtrace_invop_hdlr_t *hdlr;
hdlr = kmem_alloc(sizeof (dtrace_invop_hdlr_t), KM_SLEEP);
hdlr->dtih_func = func;
hdlr->dtih_next = dtrace_invop_hdlr;
dtrace_invop_hdlr = hdlr;
}
void
dtrace_invop_remove(int (*func)(uintptr_t, struct trapframe *, uintptr_t))
{
dtrace_invop_hdlr_t *hdlr = dtrace_invop_hdlr, *prev = NULL;
for (;;) {
if (hdlr == NULL)
panic("attempt to remove non-existent invop handler");
if (hdlr->dtih_func == func)
break;
prev = hdlr;
hdlr = hdlr->dtih_next;
}
if (prev == NULL) {
ASSERT(dtrace_invop_hdlr == hdlr);
dtrace_invop_hdlr = hdlr->dtih_next;
} else {
ASSERT(dtrace_invop_hdlr != hdlr);
prev->dtih_next = hdlr->dtih_next;
}
kmem_free(hdlr, 0);
}
/*ARGSUSED*/
void
dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit))
{
/*
* There are no ranges to exclude that are common to all 32-bit arm
* platforms. This function only needs to exclude ranges "... in
* which it is impossible to recover from such a load after it has been
* attempted." -- i.e., accessing within the range causes some sort
* fault in the system which is not handled by the normal arm
* exception-handling mechanisms. If systems exist where that is the
* case, a method to handle this functionality would have to be added to
* the platform_if interface so that those systems could provide their
* specific toxic range(s).
*/
}
void
dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg)
{
cpuset_t cpus;
if (cpu == DTRACE_CPUALL)
cpus = all_cpus;
else
CPU_SETOF(cpu, &cpus);
smp_rendezvous_cpus(cpus, smp_no_rendezvous_barrier, func,
smp_no_rendezvous_barrier, arg);
}
static void
dtrace_sync_func(void)
{
}
void
dtrace_sync(void)
{
dtrace_xcall(DTRACE_CPUALL, (dtrace_xcall_t)dtrace_sync_func, NULL);
}
/*
* DTrace needs a high resolution time function which can
* be called from a probe context and guaranteed not to have
* instrumented with probes itself.
*
* Returns nanoseconds since boot.
*/
uint64_t
dtrace_gethrtime()
{
struct timespec curtime;
dtrace_getnanouptime(&curtime);
return (curtime.tv_sec * 1000000000UL + curtime.tv_nsec);
}
uint64_t
dtrace_gethrestime(void)
{
struct timespec current_time;
dtrace_getnanotime(&current_time);
return (current_time.tv_sec * 1000000000UL + current_time.tv_nsec);
}
/* Function to handle DTrace traps during probes. See amd64/amd64/trap.c */
int
dtrace_trap(struct trapframe *frame, u_int type)
{
/*
* A trap can occur while DTrace executes a probe. Before
* executing the probe, DTrace blocks re-scheduling and sets
* a flag in its per-cpu flags to indicate that it doesn't
* want to fault. On returning from the probe, the no-fault
* flag is cleared and finally re-scheduling is enabled.
*
* Check if DTrace has enabled 'no-fault' mode:
*
*/
if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) != 0) {
/*
* There are only a couple of trap types that are expected.
* All the rest will be handled in the usual way.
*/
switch (type) {
/* Page fault. */
case FAULT_ALIGN:
/* Flag a bad address. */
cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_BADADDR;
cpu_core[curcpu].cpuc_dtrace_illval = 0;
/*
* Offset the instruction pointer to the instruction
* following the one causing the fault.
*/
frame->tf_pc += sizeof(int);
return (1);
default:
/* Handle all other traps in the usual way. */
break;
}
}
/* Handle the trap in the usual way. */
return (0);
}
void
dtrace_probe_error(dtrace_state_t *state, dtrace_epid_t epid, int which,
int fault, int fltoffs, uintptr_t illval)
{
dtrace_probe(dtrace_probeid_error, (uint64_t)(uintptr_t)state,
(uintptr_t)epid,
(uintptr_t)which, (uintptr_t)fault, (uintptr_t)fltoffs);
}
static int
dtrace_invop_start(struct trapframe *frame)
{
register_t *r0, *sp;
int data, invop, reg, update_sp;
invop = dtrace_invop(frame->tf_pc, frame, frame->tf_r0);
switch (invop & DTRACE_INVOP_MASK) {
case DTRACE_INVOP_PUSHM:
sp = (register_t *)frame->tf_svc_sp;
r0 = &frame->tf_r0;
data = DTRACE_INVOP_DATA(invop);
/*
* Store the pc, lr, and sp. These have their own
* entries in the struct.
*/
if (data & (1 << BIT_PC)) {
sp--;
*sp = frame->tf_pc;
}
if (data & (1 << BIT_LR)) {
sp--;
*sp = frame->tf_svc_lr;
}
if (data & (1 << BIT_SP)) {
sp--;
*sp = frame->tf_svc_sp;
}
/* Store the general registers */
for (reg = 12; reg >= 0; reg--) {
if (data & (1 << reg)) {
sp--;
*sp = r0[reg];
}
}
/* Update the stack pointer and program counter to continue */
frame->tf_svc_sp = (register_t)sp;
frame->tf_pc += 4;
break;
case DTRACE_INVOP_POPM:
sp = (register_t *)frame->tf_svc_sp;
r0 = &frame->tf_r0;
data = DTRACE_INVOP_DATA(invop);
/* Read the general registers */
for (reg = 0; reg <= 12; reg++) {
if (data & (1 << reg)) {
r0[reg] = *sp;
sp++;
}
}
/*
* Set the stack pointer. If we don't update it here we will
* need to update it at the end as the instruction would do
*/
update_sp = 1;
if (data & (1 << BIT_SP)) {
frame->tf_svc_sp = *sp;
*sp++;
update_sp = 0;
}
/* Update the link register, we need to use the correct copy */
if (data & (1 << BIT_LR)) {
frame->tf_svc_lr = *sp;
*sp++;
}
/*
* And the program counter. If it's not in the list skip over
* it when we return so to not hit this again.
*/
if (data & (1 << BIT_PC)) {
frame->tf_pc = *sp;
*sp++;
} else
frame->tf_pc += 4;
/* Update the stack pointer if we haven't already done so */
if (update_sp)
frame->tf_svc_sp = (register_t)sp;
break;
case DTRACE_INVOP_B:
data = DTRACE_INVOP_DATA(invop) & 0x00ffffff;
/* Sign extend the data */
if ((data & (1 << 23)) != 0)
data |= 0xff000000;
/* The data is the number of 4-byte words to change the pc */
data *= 4;
data += 8;
frame->tf_pc += data;
break;
default:
return (-1);
break;
}
return (0);
}
void dtrace_invop_init(void)
{
dtrace_invop_jump_addr = dtrace_invop_start;
}
void dtrace_invop_uninit(void)
{
dtrace_invop_jump_addr = 0;
}