[PATCH] ppc64: Add ptrace data breakpoint support

Add hardware data breakpoint support.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

6 files changed, 77 insertions, 2 deletions

diff --git a/arch/ppc64/kernel/process.c b/arch/ppc64/kernel/process.c
index 7a7e027653a..887005358eb 100644
--- a/arch/ppc64/kernel/process.c
+++ b/arch/ppc64/kernel/process.c
@@ -54,6 +54,7 @@
 #include <asm/sections.h>
 #include <asm/tlbflush.h>
 #include <asm/time.h>
+#include <asm/plpar_wrappers.h>
 
 #ifndef CONFIG_SMP
 struct task_struct *last_task_used_math = NULL;
@@ -163,7 +164,30 @@ int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 
 #endif /* CONFIG_ALTIVEC */
 
+static void set_dabr_spr(unsigned long val)
+{
+	mtspr(SPRN_DABR, val);
+}
+
+int set_dabr(unsigned long dabr)
+{
+	int ret = 0;
+
+	if (firmware_has_feature(FW_FEATURE_XDABR)) {
+		/* We want to catch accesses from kernel and userspace */
+		unsigned long flags = H_DABRX_KERNEL|H_DABRX_USER;
+		ret = plpar_set_xdabr(dabr, flags);
+	} else if (firmware_has_feature(FW_FEATURE_DABR)) {
+		ret = plpar_set_dabr(dabr);
+	} else {
+		set_dabr_spr(dabr);
+	}
+
+	return ret;
+}
+
 DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
+static DEFINE_PER_CPU(unsigned long, current_dabr);
 
 struct task_struct *__switch_to(struct task_struct *prev,
 				struct task_struct *new)
@@ -198,6 +222,11 @@ struct task_struct *__switch_to(struct task_struct *prev,
 		new->thread.regs->msr |= MSR_VEC;
 #endif /* CONFIG_ALTIVEC */
 
+	if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
+		set_dabr(new->thread.dabr);
+		__get_cpu_var(current_dabr) = new->thread.dabr;
+	}
+
 	flush_tlb_pending();
 
 	new_thread = &new->thread;
@@ -334,6 +363,11 @@ void flush_thread(void)
 		last_task_used_altivec = NULL;
 #endif /* CONFIG_ALTIVEC */
 #endif /* CONFIG_SMP */
+
+	if (current->thread.dabr) {
+		current->thread.dabr = 0;
+		set_dabr(0);
+	}
 }
 
 void
diff --git a/arch/ppc64/kernel/ptrace.c b/arch/ppc64/kernel/ptrace.c
index bf7116d4c4c..85ed3188a91 100644
--- a/arch/ppc64/kernel/ptrace.c
+++ b/arch/ppc64/kernel/ptrace.c
@@ -207,6 +207,19 @@ int sys_ptrace(long request, long pid, long addr, long data)
 		break;
 	}
 
+	case PTRACE_GET_DEBUGREG: {
+		ret = -EINVAL;
+		/* We only support one DABR and no IABRS at the moment */
+		if (addr > 0)
+			break;
+		ret = put_user(child->thread.dabr,
+			       (unsigned long __user *)data);
+		break;
+	}
+
+	case PTRACE_SET_DEBUGREG:
+		ret = ptrace_set_debugreg(child, addr, data);
+
 	case PTRACE_DETACH:
 		ret = ptrace_detach(child, data);
 		break;
diff --git a/arch/ppc64/kernel/ptrace32.c b/arch/ppc64/kernel/ptrace32.c
index cbb1e0fb881..fb8c22d6084 100644
--- a/arch/ppc64/kernel/ptrace32.c
+++ b/arch/ppc64/kernel/ptrace32.c
@@ -338,6 +338,19 @@ int sys32_ptrace(long request, long pid, unsigned long addr, unsigned long data)
 		break;
 	}
 
+	case PTRACE_GET_DEBUGREG: {
+		ret = -EINVAL;
+		/* We only support one DABR and no IABRS at the moment */
+		if (addr > 0)
+			break;
+		ret = put_user(child->thread.dabr, (u32 __user *)data);
+		break;
+	}
+
+	case PTRACE_SET_DEBUGREG:
+		ret = ptrace_set_debugreg(child, addr, data);
+		break;
+
 	case PTRACE_DETACH:
 		ret = ptrace_detach(child, data);
 		break;
diff --git a/arch/ppc64/kernel/ras.c b/arch/ppc64/kernel/ras.c
index 3c00f7bfc1b..41b97dc9cc0 100644
--- a/arch/ppc64/kernel/ras.c
+++ b/arch/ppc64/kernel/ras.c
@@ -59,8 +59,6 @@ char mce_data_buf[RTAS_ERROR_LOG_MAX]
 /* This is true if we are using the firmware NMI handler (typically LPAR) */
 extern int fwnmi_active;
 
-extern void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr);
-
 static int ras_get_sensor_state_token;
 static int ras_check_exception_token;
 
diff --git a/arch/ppc64/kernel/signal.c b/arch/ppc64/kernel/signal.c
index 49a79a55c32..347112cca3c 100644
--- a/arch/ppc64/kernel/signal.c
+++ b/arch/ppc64/kernel/signal.c
@@ -550,6 +550,15 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 		/* Whee!  Actually deliver the signal.  */
 		if (TRAP(regs) == 0x0C00)
 			syscall_restart(regs, &ka);
+
+		/*
+		 * Reenable the DABR before delivering the signal to
+		 * user space. The DABR will have been cleared if it
+		 * triggered inside the kernel.
+		 */
+		if (current->thread.dabr)
+			set_dabr(current->thread.dabr);
+
 		return handle_signal(signr, &ka, &info, oldset, regs);
 	}
 
diff --git a/arch/ppc64/kernel/signal32.c b/arch/ppc64/kernel/signal32.c
index 46f4d6cc7fc..a8b7a5a56bb 100644
--- a/arch/ppc64/kernel/signal32.c
+++ b/arch/ppc64/kernel/signal32.c
@@ -970,6 +970,14 @@ int do_signal32(sigset_t *oldset, struct pt_regs *regs)
 		newsp = regs->gpr[1];
 	newsp &= ~0xfUL;
 
+	/*
+	 * Reenable the DABR before delivering the signal to
+	 * user space. The DABR will have been cleared if it
+	 * triggered inside the kernel.
+	 */
+	if (current->thread.dabr)
+		set_dabr(current->thread.dabr);
+
 	/* Whee!  Actually deliver the signal.  */
 	if (ka.sa.sa_flags & SA_SIGINFO)
 		ret = handle_rt_signal32(signr, &ka, &info, oldset, regs, newsp);