/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) 2009, 2010 ARM Limited
*
* Author: Will Deacon <will.deacon@arm.com>
*/
/*
* HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
* using the CPU's debug registers.
*/
#define pr_fmt(fmt) "hw-breakpoint: " fmt
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/current.h>
#include <asm/hw_breakpoint.h>
#include <asm/kdebug.h>
#include <asm/system.h>
#include <asm/traps.h>
/* Breakpoint currently in use for each BRP. */
static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
/* Watchpoint currently in use for each WRP. */
static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
/* Number of BRP/WRP registers on this CPU. */
static int core_num_brps;
static int core_num_reserved_brps;
static int core_num_wrps;
/* Debug architecture version. */
static u8 debug_arch;
/* Maximum supported watchpoint length. */
static u8 max_watchpoint_len;
#define READ_WB_REG_CASE(OP2, M, VAL) \
case ((OP2 << 4) + M): \
ARM_DBG_READ(c ## M, OP2, VAL); \
break
#define WRITE_WB_REG_CASE(OP2, M, VAL) \
case ((OP2 << 4) + M): \
ARM_DBG_WRITE(c ## M, OP2, VAL);\
break
#define GEN_READ_WB_REG_CASES(OP2, VAL) \
READ_WB_REG_CASE(OP2, 0, VAL); \
READ_WB_REG_CASE(OP2, 1, VAL); \
READ_WB_REG_CASE(OP2, 2, VAL); \
READ_WB_REG_CASE(OP2, 3, VAL); \
READ_WB_REG_CASE(OP2, 4, VAL); \
READ_WB_REG_CASE(OP2, 5, VAL); \
READ_WB_REG_CASE(OP2, 6, VAL); \
READ_WB_REG_CASE(OP2, 7, VAL); \
READ_WB_REG_CASE(OP2, 8, VAL); \
READ_WB_REG_CASE(OP2, 9, VAL); \
READ_WB_REG_CASE(OP2, 10, VAL); \
READ_WB_REG_CASE(OP2, 11, VAL); \
READ_WB_REG_CASE(OP2, 12, VAL); \
READ_WB_REG_CASE(OP2, 13, VAL); \
READ_WB_REG_CASE(OP2, 14, VAL); \
READ_WB_REG_CASE(OP2, 15, VAL)
#define GEN_WRITE_WB_REG_CASES(OP2, VAL) \
WRITE_WB_REG_CASE(OP2, 0, VAL); \
WRITE_WB_REG_CASE(OP2, 1, VAL); \
WRITE_WB_REG_CASE(OP2, 2, VAL); \
WRITE_WB_REG_CASE(OP2, 3, VAL); \
WRITE_WB_REG_CASE(OP2, 4, VAL); \
WRITE_WB_REG_CASE(OP2, 5, VAL); \
WRITE_WB_REG_CASE(OP2, 6, VAL); \
WRITE_WB_REG_CASE(OP2, 7, VAL); \
WRITE_WB_REG_CASE(OP2, 8, VAL); \
WRITE_WB_REG_CASE(OP2, 9, VAL); \
WRITE_WB_REG_CASE(OP2, 10, VAL); \
WRITE_WB_REG_CASE(OP2, 11, VAL); \
WRITE_WB_REG_CASE(OP2, 12, VAL); \
WRITE_WB_REG_CASE(OP2, 13, VAL); \
WRITE_WB_REG_CASE(OP2, 14, VAL); \
WRITE_WB_REG_CASE(OP2, 15, VAL)
static u32 read_wb_reg(int n)
{
u32 val = 0;
switch (n) {
GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val);
GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val);
GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val);
GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val);
default:
pr_warning("attempt to read from unknown breakpoint "
"register %d\n", n);
}
return val;
}
static void write_wb_reg(int n, u32 val)
{
switch (n) {
GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val);
GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val);
GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val);
GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val);
default:
pr_warning("attempt to write to unknown breakpoint "
"register %d\n", n);
}
isb();
}
/* Determine debug architecture. */
static u8 get_debug_arch(void)
{
u32 didr;
/* Do we implement the extended CPUID interface? */
if (WARN_ONCE((((read_cpuid_id() >> 16) & 0xf) != 0xf),
"CPUID feature registers not supported. "
"Assuming v6 debug is present.\n"))
return ARM_DEBUG_ARCH_V6;
ARM_DBG_READ(c0, 0, didr);
return (didr >> 16) & 0xf;
}
u8 arch_get_debug_arch(void)
{
return debug_arch;
}
static int debug_arch_supported(void)
{
u8 arch = get_debug_arch();
return arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14;
}
/* Determine number of BRP register available. */
static int get_num_brp_resources(void)
{
u32 didr;
ARM_DBG_READ(c0, 0, didr);
return ((didr >> 24) & 0xf) + 1;
}
/* Does this core support mismatch breakpoints? */
static int core_has_mismatch_brps(void)
{
return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 &&
get_num_brp_resources() > 1);
}
/* Determine number of usable WRPs available. */
static int get_num_wrps(void)
{
/*
* FIXME: When a watchpoint fires, the only way to work out which
* watchpoint it was is by disassembling the faulting instruction
* and working out the address of the memory access.
*
* Furthermore, we can only do this if the watchpoint was precise
* since imprecise watchpoints prevent us from calculating register
* based addresses.
*
* Providing we have more than 1 breakpoint register, we only report
* a single watchpoint register for the time being. This way, we always
* know which watchpoint fired. In the future we can either add a
* disassembler and address generation emulator, or we can insert a
* check to see if the DFAR is set on watchpoint exception entry
* [the ARM ARM states that the DFAR is UNKNOWN, but experience shows
* that it is set on some implementations].
*/
#if 0
int wrps;
u32 didr;
ARM_DBG_READ(c0, 0, didr);
wrps = ((didr >> 28) & 0xf) + 1;
#endif
int wrps = 1;
if (core_has_mismatch_brps() && wrps >= get_num_brp_resources())
wrps = get_num_brp_resources() - 1;
return wrps;
}
/* We reserve one breakpoint for each watchpoint. */
static int get_num_reserved_brps(void)
{
if (core_has_mismatch_brps())
return get_num_wrps();
return 0;
}
/* Determine number of usable BRPs available. */
static int get_num_brps(void)
{
int brps = get_num_brp_resources();
if (core_has_mismatch_brps())
brps -= get_num_reserved_brps();
return brps;
}
/*
* In order to access the breakpoint/watchpoint control registers,
* we must be running in debug monitor mode. Unfortunately, we can
* be put into halting debug mode at any time by an external debugger
* but there is nothing we can do to prevent that.
*/
static int enable_monitor_mode(void)
{
u32 dscr;
int ret = 0;
ARM_DBG_READ(c1, 0, dscr);
/* Ensure that halting mode is disabled. */
if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN, "halting debug mode enabled."
"Unable to access hardware resources.")) {
ret = -EPERM;
goto out;
}
/* If monitor mode is already enabled, just return. */
if (dscr & ARM_DSCR_MDBGEN)
goto out;
/* Write to the corresponding DSCR. */
switch (get_debug_arch()) {
case ARM_DEBUG_ARCH_V6:
case ARM_DEBUG_ARCH_V6_1:
ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
break;
case ARM_DEBUG_ARCH_V7_ECP14:
ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
break;
default:
ret = -ENODEV;
goto out;
}
/* Check that the write made it through. */
ARM_DBG_READ(c1, 0, dscr);
if (!(dscr & ARM_DSCR_MDBGEN))
ret = -EPERM;
out:
return ret;
}
int hw_breakpoint_slots(int type)
{
if (!debug_arch_supported())
return 0;
/*
* We can be called early, so don't rely on
* our static variables being initialised.
*/
switch (type) {
case TYPE_INST:
return get_num_brps();
case TYPE_DATA:
return get_num_wrps();
default:
pr_warning("unknown slot type: %d\n", type);
return 0;
}
}
/*
* Check if 8-bit byte-address select is available.
* This clobbers WRP 0.
*/
static u8 get_max_wp_len(void)
{
u32 ctrl_reg;
struct arch_hw_breakpoint_ctrl ctrl;
u8 size = 4;
if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14)
goto out;
memset(&ctrl, 0, sizeof(ctrl));
ctrl.len = ARM_BREAKPOINT_LEN_8;
ctrl_reg = encode_ctrl_reg(ctrl);
write_wb_reg(ARM_BASE_WVR, 0);
write_wb_reg(ARM_BASE_WCR, ctrl_reg);
if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg)
size = 8;
out:
return size;
}
u8 arch_get_max_wp_len(void)
{
return max_watchpoint_len;
}
/*
* Install a perf counter breakpoint.
*/
int arch_install_hw_breakpoint(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
struct perf_event **slot, **slots;
int i, max_slots, ctrl_base, val_base, ret = 0;
u32 addr, ctrl;
/* Ensure that we are in monitor mode and halting mode is disabled. */
ret = enable_monitor_mode();
if (ret)
goto out;
addr = info->address;
ctrl = encode_ctrl_reg(info->ctrl) | 0x1;
if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
/* Breakpoint */
ctrl_base = ARM_BASE_BCR;
val_base = ARM_BASE_BVR;
slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
max_slots = core_num_brps;
if (info->step_ctrl.enabled) {
/* Override the breakpoint data with the step data. */
addr = info->trigger & ~0x3;
ctrl = encode_ctrl_reg(info->step_ctrl);
}
} else {
/* Watchpoint */
if (info->step_ctrl.enabled) {
/* Install into the reserved breakpoint region. */
ctrl_base = ARM_BASE_BCR + core_num_brps;
val_base = ARM_BASE_BVR + core_num_brps;
/* Override the watchpoint data with the step data. */
addr = info->trigger & ~0x3;
ctrl = encode_ctrl_reg(info->step_ctrl);
} else {
ctrl_base = ARM_BASE_WCR;
val_base = ARM_BASE_WVR;
}
slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
max_slots = core_num_wrps;
}
for (i = 0; i < max_slots; ++i) {
slot = &slots[i];
if (!*slot) {
*slot = bp;
break;
}
}
if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot")) {
ret = -EBUSY;
goto out;
}
/* Setup the address register. */
write_wb_reg(val_base + i, addr);
/* Setup the control register. */
write_wb_reg(ctrl_base + i, ctrl);
out:
return ret;
}
void arch_uninstall_hw_breakpoint(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
struct perf_event **slot, **slots;
int i, max_slots, base;
if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
/* Breakpoint */
base = ARM_BASE_BCR;
slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
max_slots = core_num_brps;
} else {
/* Watchpoint */
if (info->step_ctrl.enabled)
base = ARM_BASE_BCR + core_num_brps;
else
base = ARM_BASE_WCR;
slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
max_slots = core_num_wrps;
}
/* Remove the breakpoint. */
for (i = 0; i < max_slots; ++i) {
slot = &slots[i];
if (*slot == bp) {
*slot = NULL;
break;
}
}
if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
return;
/* Reset the control register. */
write_wb_reg(base + i, 0);
}
static int get_hbp_len(u8 hbp_len)
{
unsigned int len_in_bytes = 0;
switch (hbp_len) {
case ARM_BREAKPOINT_LEN_1:
len_in_bytes = 1;
break;
case ARM_BREAKPOINT_LEN_2:
len_in_bytes = 2;
break;
case ARM_BREAKPOINT_LEN_4:
len_in_bytes = 4;
break;
case ARM_BREAKPOINT_LEN_8:
len_in_bytes = 8;
break;
}
return len_in_bytes;
}
/*
* Check whether bp virtual address is in kernel space.
*/
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 = get_hbp_len(info->ctrl.len);
return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
/*
* Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
* Hopefully this will disappear when ptrace can bypass the conversion
* to generic breakpoint descriptions.
*/
int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
int *gen_len, int *gen_type)
{
/* Type */
switch (ctrl.type) {
case ARM_BREAKPOINT_EXECUTE:
*gen_type = HW_BREAKPOINT_X;
break;
case ARM_BREAKPOINT_LOAD:
*gen_type = HW_BREAKPOINT_R;
break;
case ARM_BREAKPOINT_STORE:
*gen_type = HW_BREAKPOINT_W;
break;
case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
*gen_type = HW_BREAKPOINT_RW;
break;
default:
return -EINVAL;
}
/* Len */
switch (ctrl.len) {
case ARM_BREAKPOINT_LEN_1:
*gen_len = HW_BREAKPOINT_LEN_1;
break;
case ARM_BREAKPOINT_LEN_2:
*gen_len = HW_BREAKPOINT_LEN_2;
break;
case ARM_BREAKPOINT_LEN_4:
*gen_len = HW_BREAKPOINT_LEN_4;
break;
case ARM_BREAKPOINT_LEN_8:
*gen_len = HW_BREAKPOINT_LEN_8;
break;
default:
return -EINVAL;
}
return 0;
}
/*
* 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->ctrl.type = ARM_BREAKPOINT_EXECUTE;
break;
case HW_BREAKPOINT_R:
info->ctrl.type = ARM_BREAKPOINT_LOAD;
break;
case HW_BREAKPOINT_W:
info->ctrl.type = ARM_BREAKPOINT_STORE;
break;
case HW_BREAKPOINT_RW:
info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
break;
default:
return -EINVAL;
}
/* Len */
switch (bp->attr.bp_len) {
case HW_BREAKPOINT_LEN_1:
info->ctrl.len = ARM_BREAKPOINT_LEN_1;
break;
case HW_BREAKPOINT_LEN_2:
info->ctrl.len = ARM_BREAKPOINT_LEN_2;
break;
case HW_BREAKPOINT_LEN_4:
info->ctrl.len = ARM_BREAKPOINT_LEN_4;
break;
case HW_BREAKPOINT_LEN_8:
info->ctrl.len = ARM_BREAKPOINT_LEN_8;
if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE)
&& max_watchpoint_len >= 8)
break;
default:
return -EINVAL;
}
/*
* Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
* Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
* by the hardware and must be aligned to the appropriate number of
* bytes.
*/
if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
info->ctrl.len != ARM_BREAKPOINT_LEN_4)
return -EINVAL;
/* Address */
info->address = bp->attr.bp_addr;
/* Privilege */
info->ctrl.privilege = ARM_BREAKPOINT_USER;
if (arch_check_bp_in_kernelspace(bp))
info->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
/* Enabled? */
info->ctrl.enabled = !bp->attr.disabled;
/* Mismatch */
info->ctrl.mismatch = 0;
return 0;
}
/*
* Validate the arch-specific HW Breakpoint register settings.
*/
int arch_validate_hwbkpt_settings(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
int ret = 0;
u32 offset, alignment_mask = 0x3;
/* Build the arch_hw_breakpoint. */
ret = arch_build_bp_info(bp);
if (ret)
goto out;
/* Check address alignment. */
if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
alignment_mask = 0x7;
offset = info->address & alignment_mask;
switch (offset) {
case 0:
/* Aligned */
break;
case 1:
/* Allow single byte watchpoint. */
if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
break;
case 2:
/* Allow halfword watchpoints and breakpoints. */
if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
break;
default:
ret = -EINVAL;
goto out;
}
info->address &= ~alignment_mask;
info->ctrl.len <<= offset;
/*
* Currently we rely on an overflow handler to take
* care of single-stepping the breakpoint when it fires.
* In the case of userspace breakpoints on a core with V7 debug,
* we can use the mismatch feature as a poor-man's hardware
* single-step, but this only works for per-task breakpoints.
*/
if (WARN_ONCE(!bp->overflow_handler &&
(arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()
|| !bp->hw.bp_target),
"overflow handler required but none found")) {
ret = -EINVAL;
}
out:
return ret;
}
/*
* Enable/disable single-stepping over the breakpoint bp at address addr.
*/
static void enable_single_step(struct perf_event *bp, u32 addr)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
arch_uninstall_hw_breakpoint(bp);
info->step_ctrl.mismatch = 1;
info->step_ctrl.len = ARM_BREAKPOINT_LEN_4;
info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE;
info->step_ctrl.privilege = info->ctrl.privilege;
info->step_ctrl.enabled = 1;
info->trigger = addr;
arch_install_hw_breakpoint(bp);
}
static void disable_single_step(struct perf_event *bp)
{
arch_uninstall_hw_breakpoint(bp);
counter_arch_bp(bp)->step_ctrl.enabled = 0;
arch_install_hw_breakpoint(bp);
}
static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs)
{
int i;
struct perf_event *wp, **slots;
struct arch_hw_breakpoint *info;
slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
/* Without a disassembler, we can only handle 1 watchpoint. */
BUG_ON(core_num_wrps > 1);
for (i = 0; i < core_num_wrps; ++i) {
rcu_read_lock();
wp = slots[i];
if (wp == NULL) {
rcu_read_unlock();
continue;
}
/*
* The DFAR is an unknown value. Since we only allow a
* single watchpoint, we can set the trigger to the lowest
* possible faulting address.
*/
info = counter_arch_bp(wp);
info->trigger = wp->attr.bp_addr;
pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
perf_bp_event(wp, regs);
/*
* If no overflow handler is present, insert a temporary
* mismatch breakpoint so we can single-step over the
* watchpoint trigger.
*/
if (!wp->overflow_handler)
enable_single_step(wp, instruction_pointer(regs));
rcu_read_unlock();
}
}
static void watchpoint_single_step_handler(unsigned long pc)
{
int i;
struct perf_event *wp, **slots;
struct arch_hw_breakpoint *info;
slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
for (i = 0; i < core_num_reserved_brps; ++i) {
rcu_read_lock();
wp = slots[i];
if (wp == NULL)
goto unlock;
info = counter_arch_bp(wp);
if (!info->step_ctrl.enabled)
goto unlock;
/*
* Restore the original watchpoint if we've completed the
* single-step.
*/
if (info->trigger != pc)
disable_single_step(wp);
unlock:
rcu_read_unlock();
}
}
static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
{
int i;
u32 ctrl_reg, val, addr;
struct perf_event *bp, **slots;
struct arch_hw_breakpoint *info;
struct arch_hw_breakpoint_ctrl ctrl;
slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
/* The exception entry code places the amended lr in the PC. */
addr = regs->ARM_pc;
/* Check the currently installed breakpoints first. */
for (i = 0; i < core_num_brps; ++i) {
rcu_read_lock();
bp = slots[i];
if (bp == NULL)
goto unlock;
info = counter_arch_bp(bp);
/* Check if the breakpoint value matches. */
val = read_wb_reg(ARM_BASE_BVR + i);
if (val != (addr & ~0x3))
goto mismatch;
/* Possible match, check the byte address select to confirm. */
ctrl_reg = read_wb_reg(ARM_BASE_BCR + i);
decode_ctrl_reg(ctrl_reg, &ctrl);
if ((1 << (addr & 0x3)) & ctrl.len) {
info->trigger = addr;
pr_debug("breakpoint fired: address = 0x%x\n", addr);
perf_bp_event(bp, regs);
if (!bp->overflow_handler)
enable_single_step(bp, addr);
goto unlock;
}
mismatch:
/* If we're stepping a breakpoint, it can now be restored. */
if (info->step_ctrl.enabled)
disable_single_step(bp);
unlock:
rcu_read_unlock();
}
/* Handle any pending watchpoint single-step breakpoints. */
watchpoint_single_step_handler(addr);
}
/*
* Called from either the Data Abort Handler [watchpoint] or the
* Prefetch Abort Handler [breakpoint] with preemption disabled.
*/
static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
{
int ret = 0;
u32 dscr;
/* We must be called with preemption disabled. */
WARN_ON(preemptible());
/* We only handle watchpoints and hardware breakpoints. */
ARM_DBG_READ(c1, 0, dscr);
/* Perform perf callbacks. */
switch (ARM_DSCR_MOE(dscr)) {
case ARM_ENTRY_BREAKPOINT:
breakpoint_handler(addr, regs);
break;
case ARM_ENTRY_ASYNC_WATCHPOINT:
WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
case ARM_ENTRY_SYNC_WATCHPOINT:
watchpoint_handler(addr, regs);
break;
default:
ret = 1; /* Unhandled fault. */
}
/*
* Re-enable preemption after it was disabled in the
* low-level exception handling code.
*/
preempt_enable();
return ret;
}
/*
* One-time initialisation.
*/
static void reset_ctrl_regs(void *unused)
{
int i;
/*
* v7 debug contains save and restore registers so that debug state
* can be maintained across low-power modes without leaving the debug
* logic powered up. It is IMPLEMENTATION DEFINED whether we can access
* the debug registers out of reset, so we must unlock the OS Lock
* Access Register to avoid taking undefined instruction exceptions
* later on.
*/
if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) {
/*
* Unconditionally clear the lock by writing a value
* other than 0xC5ACCE55 to the access register.
*/
asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
isb();
}
if (enable_monitor_mode())
return;
/* We must also reset any reserved registers. */
for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) {
write_wb_reg(ARM_BASE_BCR + i, 0UL);
write_wb_reg(ARM_BASE_BVR + i, 0UL);
}
for (i = 0; i < core_num_wrps; ++i) {
write_wb_reg(ARM_BASE_WCR + i, 0UL);
write_wb_reg(ARM_BASE_WVR + i, 0UL);
}
}
static int __cpuinit dbg_reset_notify(struct notifier_block *self,
unsigned long action, void *cpu)
{
if (action == CPU_ONLINE)
smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata dbg_reset_nb = {
.notifier_call = dbg_reset_notify,
};
static int __init arch_hw_breakpoint_init(void)
{
u32 dscr;
debug_arch = get_debug_arch();
if (!debug_arch_supported()) {
pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
return 0;
}
/* Determine how many BRPs/WRPs are available. */
core_num_brps = get_num_brps();
core_num_reserved_brps = get_num_reserved_brps();
core_num_wrps = get_num_wrps();
pr_info("found %d breakpoint and %d watchpoint registers.\n",
core_num_brps + core_num_reserved_brps, core_num_wrps);
if (core_num_reserved_brps)
pr_info("%d breakpoint(s) reserved for watchpoint "
"single-step.\n", core_num_reserved_brps);
/*
* Reset the breakpoint resources. We assume that a halting
* debugger will leave the world in a nice state for us.
*/
on_each_cpu(reset_ctrl_regs, NULL, 1);
ARM_DBG_READ(c1, 0, dscr);
if (dscr & ARM_DSCR_HDBGEN) {
max_watchpoint_len = 4;
pr_warning("halting debug mode enabled. Assuming maximum "
"watchpoint size of %u bytes.", max_watchpoint_len);
} else {
/* Work out the maximum supported watchpoint length. */
max_watchpoint_len = get_max_wp_len();
pr_info("maximum watchpoint size is %u bytes.\n",
max_watchpoint_len);
}
/* Register debug fault handler. */
hook_fault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
"watchpoint debug exception");
hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
"breakpoint debug exception");
/* Register hotplug notifier. */
register_cpu_notifier(&dbg_reset_nb);
return 0;
}
arch_initcall(arch_hw_breakpoint_init);
void hw_breakpoint_pmu_read(struct perf_event *bp)
{
}
/*
* Dummy function to register with die_notifier.
*/
int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
unsigned long val, void *data)
{
return NOTIFY_DONE;
}
