swh:1:snp:49cd9498d6cccc5e78252c27dcb645bcf7bf0c91
Tip revision: 69973b830859bc6529a7a0468ba0d80ee5117826 authored by Linus Torvalds on 11 December 2016, 19:17:54 UTC
Linux 4.9
Linux 4.9
Tip revision: 69973b8
hw_breakpoint.c
/*
* Xtensa hardware breakpoints/watchpoints handling functions
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2016 Cadence Design Systems Inc.
*/
#include <linux/hw_breakpoint.h>
#include <linux/log2.h>
#include <linux/percpu.h>
#include <linux/perf_event.h>
#include <variant/core.h>
/* Breakpoint currently in use for each IBREAKA. */
static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[XCHAL_NUM_IBREAK]);
/* Watchpoint currently in use for each DBREAKA. */
static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[XCHAL_NUM_DBREAK]);
int hw_breakpoint_slots(int type)
{
switch (type) {
case TYPE_INST:
return XCHAL_NUM_IBREAK;
case TYPE_DATA:
return XCHAL_NUM_DBREAK;
default:
pr_warn("unknown slot type: %d\n", type);
return 0;
}
}
int arch_check_bp_in_kernelspace(struct perf_event *bp)
{
unsigned int len;
unsigned long va;
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
va = info->address;
len = bp->attr.bp_len;
return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
/*
* Construct an arch_hw_breakpoint from a perf_event.
*/
static int arch_build_bp_info(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
/* Type */
switch (bp->attr.bp_type) {
case HW_BREAKPOINT_X:
info->type = XTENSA_BREAKPOINT_EXECUTE;
break;
case HW_BREAKPOINT_R:
info->type = XTENSA_BREAKPOINT_LOAD;
break;
case HW_BREAKPOINT_W:
info->type = XTENSA_BREAKPOINT_STORE;
break;
case HW_BREAKPOINT_RW:
info->type = XTENSA_BREAKPOINT_LOAD | XTENSA_BREAKPOINT_STORE;
break;
default:
return -EINVAL;
}
/* Len */
info->len = bp->attr.bp_len;
if (info->len < 1 || info->len > 64 || !is_power_of_2(info->len))
return -EINVAL;
/* Address */
info->address = bp->attr.bp_addr;
if (info->address & (info->len - 1))
return -EINVAL;
return 0;
}
int arch_validate_hwbkpt_settings(struct perf_event *bp)
{
int ret;
/* Build the arch_hw_breakpoint. */
ret = arch_build_bp_info(bp);
return ret;
}
int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
unsigned long val, void *data)
{
return NOTIFY_DONE;
}
static void xtensa_wsr(unsigned long v, u8 sr)
{
/* We don't have indexed wsr and creating instruction dynamically
* doesn't seem worth it given how small XCHAL_NUM_IBREAK and
* XCHAL_NUM_DBREAK are. Thus the switch. In case build breaks here
* the switch below needs to be extended.
*/
BUILD_BUG_ON(XCHAL_NUM_IBREAK > 2);
BUILD_BUG_ON(XCHAL_NUM_DBREAK > 2);
switch (sr) {
#if XCHAL_NUM_IBREAK > 0
case SREG_IBREAKA + 0:
WSR(v, SREG_IBREAKA + 0);
break;
#endif
#if XCHAL_NUM_IBREAK > 1
case SREG_IBREAKA + 1:
WSR(v, SREG_IBREAKA + 1);
break;
#endif
#if XCHAL_NUM_DBREAK > 0
case SREG_DBREAKA + 0:
WSR(v, SREG_DBREAKA + 0);
break;
case SREG_DBREAKC + 0:
WSR(v, SREG_DBREAKC + 0);
break;
#endif
#if XCHAL_NUM_DBREAK > 1
case SREG_DBREAKA + 1:
WSR(v, SREG_DBREAKA + 1);
break;
case SREG_DBREAKC + 1:
WSR(v, SREG_DBREAKC + 1);
break;
#endif
}
}
static int alloc_slot(struct perf_event **slot, size_t n,
struct perf_event *bp)
{
size_t i;
for (i = 0; i < n; ++i) {
if (!slot[i]) {
slot[i] = bp;
return i;
}
}
return -EBUSY;
}
static void set_ibreak_regs(int reg, struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
unsigned long ibreakenable;
xtensa_wsr(info->address, SREG_IBREAKA + reg);
RSR(ibreakenable, SREG_IBREAKENABLE);
WSR(ibreakenable | (1 << reg), SREG_IBREAKENABLE);
}
static void set_dbreak_regs(int reg, struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
unsigned long dbreakc = DBREAKC_MASK_MASK & -info->len;
if (info->type & XTENSA_BREAKPOINT_LOAD)
dbreakc |= DBREAKC_LOAD_MASK;
if (info->type & XTENSA_BREAKPOINT_STORE)
dbreakc |= DBREAKC_STOR_MASK;
xtensa_wsr(info->address, SREG_DBREAKA + reg);
xtensa_wsr(dbreakc, SREG_DBREAKC + reg);
}
int arch_install_hw_breakpoint(struct perf_event *bp)
{
int i;
if (counter_arch_bp(bp)->type == XTENSA_BREAKPOINT_EXECUTE) {
/* Breakpoint */
i = alloc_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp);
if (i < 0)
return i;
set_ibreak_regs(i, bp);
} else {
/* Watchpoint */
i = alloc_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp);
if (i < 0)
return i;
set_dbreak_regs(i, bp);
}
return 0;
}
static int free_slot(struct perf_event **slot, size_t n,
struct perf_event *bp)
{
size_t i;
for (i = 0; i < n; ++i) {
if (slot[i] == bp) {
slot[i] = NULL;
return i;
}
}
return -EBUSY;
}
void arch_uninstall_hw_breakpoint(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
int i;
if (info->type == XTENSA_BREAKPOINT_EXECUTE) {
unsigned long ibreakenable;
/* Breakpoint */
i = free_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp);
if (i >= 0) {
RSR(ibreakenable, SREG_IBREAKENABLE);
WSR(ibreakenable & ~(1 << i), SREG_IBREAKENABLE);
}
} else {
/* Watchpoint */
i = free_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp);
if (i >= 0)
xtensa_wsr(0, SREG_DBREAKC + i);
}
}
void hw_breakpoint_pmu_read(struct perf_event *bp)
{
}
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
int i;
struct thread_struct *t = &tsk->thread;
for (i = 0; i < XCHAL_NUM_IBREAK; ++i) {
if (t->ptrace_bp[i]) {
unregister_hw_breakpoint(t->ptrace_bp[i]);
t->ptrace_bp[i] = NULL;
}
}
for (i = 0; i < XCHAL_NUM_DBREAK; ++i) {
if (t->ptrace_wp[i]) {
unregister_hw_breakpoint(t->ptrace_wp[i]);
t->ptrace_wp[i] = NULL;
}
}
}
/*
* Set ptrace breakpoint pointers to zero for this task.
* This is required in order to prevent child processes from unregistering
* breakpoints held by their parent.
*/
void clear_ptrace_hw_breakpoint(struct task_struct *tsk)
{
memset(tsk->thread.ptrace_bp, 0, sizeof(tsk->thread.ptrace_bp));
memset(tsk->thread.ptrace_wp, 0, sizeof(tsk->thread.ptrace_wp));
}
void restore_dbreak(void)
{
int i;
for (i = 0; i < XCHAL_NUM_DBREAK; ++i) {
struct perf_event *bp = this_cpu_ptr(wp_on_reg)[i];
if (bp)
set_dbreak_regs(i, bp);
}
clear_thread_flag(TIF_DB_DISABLED);
}
int check_hw_breakpoint(struct pt_regs *regs)
{
if (regs->debugcause & BIT(DEBUGCAUSE_IBREAK_BIT)) {
int i;
struct perf_event **bp = this_cpu_ptr(bp_on_reg);
for (i = 0; i < XCHAL_NUM_IBREAK; ++i) {
if (bp[i] && !bp[i]->attr.disabled &&
regs->pc == bp[i]->attr.bp_addr)
perf_bp_event(bp[i], regs);
}
return 0;
} else if (regs->debugcause & BIT(DEBUGCAUSE_DBREAK_BIT)) {
struct perf_event **bp = this_cpu_ptr(wp_on_reg);
int dbnum = (regs->debugcause & DEBUGCAUSE_DBNUM_MASK) >>
DEBUGCAUSE_DBNUM_SHIFT;
if (dbnum < XCHAL_NUM_DBREAK && bp[dbnum]) {
if (user_mode(regs)) {
perf_bp_event(bp[dbnum], regs);
} else {
set_thread_flag(TIF_DB_DISABLED);
xtensa_wsr(0, SREG_DBREAKC + dbnum);
}
} else {
WARN_ONCE(1,
"Wrong/unconfigured DBNUM reported in DEBUGCAUSE: %d\n",
dbnum);
}
return 0;
}
return -ENOENT;
}