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authorWill Deacon <will.deacon@arm.com>2010-12-01 14:12:13 +0000
committerWill Deacon <will.deacon@arm.com>2010-12-06 11:55:57 +0000
commit9ebb3cbcc39d4e61ae6751167086acfb5c201e6f (patch)
tree4e88970d75cb2e7b3a5a2f1b50c58ab358d30339 /arch/arm/kernel/hw_breakpoint.c
parent93a04a3416da12647c47840ebe2bb812fcb801d0 (diff)
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ARM: hw_breakpoint: unify single-stepping code for watchpoints and breakpoints
The single-stepping code is currently different depending on whether we are stepping over a breakpoint or a watchpoint. There is no good reason for this, so let's sort it out. This patch adds functions for enabling/disabling single-step for a particular hw_breakpoint and integrates this with the exception handling code. Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm/kernel/hw_breakpoint.c')
-rw-r--r--arch/arm/kernel/hw_breakpoint.c81
1 files changed, 40 insertions, 41 deletions
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 81b63e94dfe0..36cd7680d3d2 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -339,6 +339,11 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
val_base = ARM_BASE_BVR;
slots = __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) {
@@ -628,21 +633,28 @@ out:
return ret;
}
-static void update_mismatch_flag(int idx, int flag)
+/*
+ * Enable/disable single-stepping over the breakpoint bp at address addr.
+ */
+static void enable_single_step(struct perf_event *bp, u32 addr)
{
- struct perf_event *bp = __get_cpu_var(bp_on_reg[idx]);
- struct arch_hw_breakpoint *info;
-
- if (bp == NULL)
- return;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- 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);
+}
- /* Update the mismatch field to enter/exit `single-step' mode */
- if (!bp->overflow_handler && info->ctrl.mismatch != flag) {
- info->ctrl.mismatch = flag;
- write_wb_reg(ARM_BASE_BCR + idx, encode_ctrl_reg(info->ctrl) | 0x1);
- }
+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)
@@ -679,16 +691,8 @@ static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs)
* mismatch breakpoint so we can single-step over the
* watchpoint trigger.
*/
- if (!wp->overflow_handler) {
- arch_uninstall_hw_breakpoint(wp);
- 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 = regs->ARM_pc;
- arch_install_hw_breakpoint(wp);
- }
+ if (!wp->overflow_handler)
+ enable_single_step(wp, instruction_pointer(regs));
rcu_read_unlock();
}
@@ -716,11 +720,8 @@ static void watchpoint_single_step_handler(unsigned long pc)
* Restore the original watchpoint if we've completed the
* single-step.
*/
- if (info->trigger != pc) {
- arch_uninstall_hw_breakpoint(wp);
- info->step_ctrl.enabled = 0;
- arch_install_hw_breakpoint(wp);
- }
+ if (info->trigger != pc)
+ disable_single_step(wp);
unlock:
rcu_read_unlock();
@@ -730,7 +731,6 @@ unlock:
static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
{
int i;
- int mismatch;
u32 ctrl_reg, val, addr;
struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg);
struct arch_hw_breakpoint *info;
@@ -745,34 +745,33 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
bp = slots[i];
- if (bp == NULL) {
- rcu_read_unlock();
- continue;
- }
+ if (bp == NULL)
+ goto unlock;
- mismatch = 0;
+ info = counter_arch_bp(bp);
/* Check if the breakpoint value matches. */
val = read_wb_reg(ARM_BASE_BVR + i);
if (val != (addr & ~0x3))
- goto unlock;
+ 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) {
- mismatch = 1;
- info = counter_arch_bp(bp);
info->trigger = addr;
- }
-
-unlock:
- if (mismatch && !info->ctrl.mismatch) {
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;
}
- update_mismatch_flag(i, mismatch);
+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();
}