aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/hw_breakpoint.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/kernel/hw_breakpoint.c')
-rw-r--r--arch/arm/kernel/hw_breakpoint.c216
1 files changed, 129 insertions, 87 deletions
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index ba386bd9410..5ff2e77782b 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -52,14 +52,14 @@ 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); \
+#define READ_WB_REG_CASE(OP2, M, VAL) \
+ case ((OP2 << 4) + M): \
+ ARM_DBG_READ(c0, c ## M, OP2, VAL); \
break
-#define WRITE_WB_REG_CASE(OP2, M, VAL) \
- case ((OP2 << 4) + M): \
- ARM_DBG_WRITE(c ## M, OP2, VAL);\
+#define WRITE_WB_REG_CASE(OP2, M, VAL) \
+ case ((OP2 << 4) + M): \
+ ARM_DBG_WRITE(c0, c ## M, OP2, VAL); \
break
#define GEN_READ_WB_REG_CASES(OP2, VAL) \
@@ -136,12 +136,12 @@ static u8 get_debug_arch(void)
/* Do we implement the extended CPUID interface? */
if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
- pr_warning("CPUID feature registers not supported. "
- "Assuming v6 debug is present.\n");
+ pr_warn_once("CPUID feature registers not supported. "
+ "Assuming v6 debug is present.\n");
return ARM_DEBUG_ARCH_V6;
}
- ARM_DBG_READ(c0, 0, didr);
+ ARM_DBG_READ(c0, c0, 0, didr);
return (didr >> 16) & 0xf;
}
@@ -159,11 +159,17 @@ static int debug_arch_supported(void)
arch >= ARM_DEBUG_ARCH_V7_1;
}
+/* Can we determine the watchpoint access type from the fsr? */
+static int debug_exception_updates_fsr(void)
+{
+ return 0;
+}
+
/* Determine number of WRP registers available. */
static int get_num_wrp_resources(void)
{
u32 didr;
- ARM_DBG_READ(c0, 0, didr);
+ ARM_DBG_READ(c0, c0, 0, didr);
return ((didr >> 28) & 0xf) + 1;
}
@@ -171,7 +177,7 @@ static int get_num_wrp_resources(void)
static int get_num_brp_resources(void)
{
u32 didr;
- ARM_DBG_READ(c0, 0, didr);
+ ARM_DBG_READ(c0, c0, 0, didr);
return ((didr >> 24) & 0xf) + 1;
}
@@ -222,19 +228,17 @@ static int get_num_brps(void)
* 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)
+static int monitor_mode_enabled(void)
{
u32 dscr;
- int ret = 0;
-
- ARM_DBG_READ(c1, 0, dscr);
+ ARM_DBG_READ(c0, c1, 0, dscr);
+ return !!(dscr & ARM_DSCR_MDBGEN);
+}
- /* Ensure that halting mode is disabled. */
- if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN,
- "halting debug mode enabled. Unable to access hardware resources.\n")) {
- ret = -EPERM;
- goto out;
- }
+static int enable_monitor_mode(void)
+{
+ u32 dscr;
+ ARM_DBG_READ(c0, c1, 0, dscr);
/* If monitor mode is already enabled, just return. */
if (dscr & ARM_DSCR_MDBGEN)
@@ -244,24 +248,27 @@ static int enable_monitor_mode(void)
switch (get_debug_arch()) {
case ARM_DEBUG_ARCH_V6:
case ARM_DEBUG_ARCH_V6_1:
- ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN));
+ ARM_DBG_WRITE(c0, c1, 0, (dscr | ARM_DSCR_MDBGEN));
break;
case ARM_DEBUG_ARCH_V7_ECP14:
case ARM_DEBUG_ARCH_V7_1:
- ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN));
+ ARM_DBG_WRITE(c0, c2, 2, (dscr | ARM_DSCR_MDBGEN));
+ isb();
break;
default:
- ret = -ENODEV;
- goto out;
+ return -ENODEV;
}
/* Check that the write made it through. */
- ARM_DBG_READ(c1, 0, dscr);
- if (!(dscr & ARM_DSCR_MDBGEN))
- ret = -EPERM;
+ ARM_DBG_READ(c0, c1, 0, dscr);
+ if (!(dscr & ARM_DSCR_MDBGEN)) {
+ pr_warn_once("Failed to enable monitor mode on CPU %d.\n",
+ smp_processor_id());
+ return -EPERM;
+ }
out:
- return ret;
+ return 0;
}
int hw_breakpoint_slots(int type)
@@ -322,14 +329,9 @@ 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;
+ int i, max_slots, ctrl_base, val_base;
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;
@@ -356,9 +358,9 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
}
}
- if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n")) {
- ret = -EBUSY;
- goto out;
+ if (i == max_slots) {
+ pr_warning("Can't find any breakpoint slot\n");
+ return -EBUSY;
}
/* Override the breakpoint data with the step data. */
@@ -377,9 +379,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
/* Setup the control register. */
write_wb_reg(ctrl_base + i, ctrl);
-
-out:
- return ret;
+ return 0;
}
void arch_uninstall_hw_breakpoint(struct perf_event *bp)
@@ -410,8 +410,10 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
}
}
- if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n"))
+ if (i == max_slots) {
+ pr_warning("Can't find any breakpoint slot\n");
return;
+ }
/* Ensure that we disable the mismatch breakpoint. */
if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE &&
@@ -590,6 +592,10 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
int ret = 0;
u32 offset, alignment_mask = 0x3;
+ /* Ensure that we are in monitor debug mode. */
+ if (!monitor_mode_enabled())
+ return -ENODEV;
+
/* Build the arch_hw_breakpoint. */
ret = arch_build_bp_info(bp);
if (ret)
@@ -604,13 +610,14 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
/* 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;
+ case 3:
+ /* Allow single byte watchpoint. */
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
+ break;
default:
ret = -EINVAL;
goto out;
@@ -619,18 +626,35 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
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 (!bp->overflow_handler && (arch_check_bp_in_kernelspace(bp) ||
- !core_has_mismatch_brps() || !bp->hw.bp_target)) {
- pr_warning("overflow handler required but none found\n");
- ret = -EINVAL;
+ if (!bp->overflow_handler) {
+ /*
+ * Mismatch breakpoints are required for single-stepping
+ * breakpoints.
+ */
+ if (!core_has_mismatch_brps())
+ return -EINVAL;
+
+ /* We don't allow mismatch breakpoints in kernel space. */
+ if (arch_check_bp_in_kernelspace(bp))
+ return -EPERM;
+
+ /*
+ * Per-cpu breakpoints are not supported by our stepping
+ * mechanism.
+ */
+ if (!bp->hw.bp_target)
+ return -EINVAL;
+
+ /*
+ * We only support specific access types if the fsr
+ * reports them.
+ */
+ if (!debug_exception_updates_fsr() &&
+ (info->ctrl.type == ARM_BREAKPOINT_LOAD ||
+ info->ctrl.type == ARM_BREAKPOINT_STORE))
+ return -EINVAL;
}
+
out:
return ret;
}
@@ -706,10 +730,12 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
goto unlock;
/* Check that the access type matches. */
- access = (fsr & ARM_FSR_ACCESS_MASK) ? HW_BREAKPOINT_W :
- HW_BREAKPOINT_R;
- if (!(access & hw_breakpoint_type(wp)))
- goto unlock;
+ if (debug_exception_updates_fsr()) {
+ access = (fsr & ARM_FSR_ACCESS_MASK) ?
+ HW_BREAKPOINT_W : HW_BREAKPOINT_R;
+ if (!(access & hw_breakpoint_type(wp)))
+ goto unlock;
+ }
/* We have a winner. */
info->trigger = addr;
@@ -832,7 +858,7 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
local_irq_enable();
/* We only handle watchpoints and hardware breakpoints. */
- ARM_DBG_READ(c1, 0, dscr);
+ ARM_DBG_READ(c0, c1, 0, dscr);
/* Perform perf callbacks. */
switch (ARM_DSCR_MOE(dscr)) {
@@ -880,7 +906,7 @@ static struct undef_hook debug_reg_hook = {
static void reset_ctrl_regs(void *unused)
{
int i, raw_num_brps, err = 0, cpu = smp_processor_id();
- u32 dbg_power;
+ u32 val;
/*
* v7 debug contains save and restore registers so that debug state
@@ -893,23 +919,30 @@ static void reset_ctrl_regs(void *unused)
switch (debug_arch) {
case ARM_DEBUG_ARCH_V6:
case ARM_DEBUG_ARCH_V6_1:
- /* ARMv6 cores just need to reset the registers. */
- goto reset_regs;
+ /* ARMv6 cores clear the registers out of reset. */
+ goto out_mdbgen;
case ARM_DEBUG_ARCH_V7_ECP14:
/*
* Ensure sticky power-down is clear (i.e. debug logic is
* powered up).
*/
- asm volatile("mrc p14, 0, %0, c1, c5, 4" : "=r" (dbg_power));
- if ((dbg_power & 0x1) == 0)
+ ARM_DBG_READ(c1, c5, 4, val);
+ if ((val & 0x1) == 0)
err = -EPERM;
+
+ /*
+ * Check whether we implement OS save and restore.
+ */
+ ARM_DBG_READ(c1, c1, 4, val);
+ if ((val & 0x9) == 0)
+ goto clear_vcr;
break;
case ARM_DEBUG_ARCH_V7_1:
/*
* Ensure the OS double lock is clear.
*/
- asm volatile("mrc p14, 0, %0, c1, c3, 4" : "=r" (dbg_power));
- if ((dbg_power & 0x1) == 1)
+ ARM_DBG_READ(c1, c3, 4, val);
+ if ((val & 0x1) == 1)
err = -EPERM;
break;
}
@@ -921,24 +954,29 @@ static void reset_ctrl_regs(void *unused)
}
/*
- * Unconditionally clear the lock by writing a value
+ * Unconditionally clear the OS lock by writing a value
* other than 0xC5ACCE55 to the access register.
*/
- asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
+ ARM_DBG_WRITE(c1, c0, 4, 0);
isb();
/*
* Clear any configured vector-catch events before
* enabling monitor mode.
*/
- asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
+clear_vcr:
+ ARM_DBG_WRITE(c0, c7, 0, 0);
isb();
-reset_regs:
- if (enable_monitor_mode())
+ if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
+ pr_warning("CPU %d failed to disable vector catch\n", cpu);
return;
+ }
- /* We must also reset any reserved registers. */
+ /*
+ * The control/value register pairs are UNKNOWN out of reset so
+ * clear them to avoid spurious debug events.
+ */
raw_num_brps = get_num_brp_resources();
for (i = 0; i < raw_num_brps; ++i) {
write_wb_reg(ARM_BASE_BCR + i, 0UL);
@@ -949,6 +987,19 @@ reset_regs:
write_wb_reg(ARM_BASE_WCR + i, 0UL);
write_wb_reg(ARM_BASE_WVR + i, 0UL);
}
+
+ if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
+ pr_warning("CPU %d failed to clear debug register pairs\n", cpu);
+ return;
+ }
+
+ /*
+ * Have a crack at enabling monitor mode. We don't actually need
+ * it yet, but reporting an error early is useful if it fails.
+ */
+out_mdbgen:
+ if (enable_monitor_mode())
+ cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
}
static int __cpuinit dbg_reset_notify(struct notifier_block *self,
@@ -966,8 +1017,6 @@ static struct notifier_block __cpuinitdata dbg_reset_nb = {
static int __init arch_hw_breakpoint_init(void)
{
- u32 dscr;
-
debug_arch = get_debug_arch();
if (!debug_arch_supported()) {
@@ -1002,17 +1051,10 @@ static int __init arch_hw_breakpoint_init(void)
core_num_brps, core_has_mismatch_brps() ? "(+1 reserved) " :
"", core_num_wrps);
- 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.\n",
- 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);
- }
+ /* 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(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,