ps3-debugging: Setup DABR register

For debugging only.

Helper routine to setup DABR (Data Address Breakpoint) register
for kernel use.

4 files changed, 55 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/ps3.h b/arch/powerpc/include/asm/ps3.h
index a5f36546a05240..733b9a24a04041 100644
--- a/arch/powerpc/include/asm/ps3.h
+++ b/arch/powerpc/include/asm/ps3.h
@@ -514,4 +514,13 @@ u64 ps3_get_spe_id(void *arg);
 
 void ps3_early_mm_init(void);
 
+/* kernel debug routines */
+
+#define   DABR_TRANSLATION	(1UL << 2)
+#define   DABR_DATA_WRITE	(1UL << 1)
+#define   DABR_DATA_READ	(1UL << 0)
+
+int ps3_debug_setup_dabr(u64 address, unsigned int dabr_flags,
+	unsigned int dabrx);
+
 #endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1fefafb2b29be5..f0b4675f575fe9 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -610,6 +610,9 @@ EXPORT_SYMBOL(flush_all_to_thread);
 void do_send_trap(struct pt_regs *regs, unsigned long address,
 		  unsigned long error_code, int breakpt)
 {
+	printk("%s:%d: address %016lxh, code %08lxh\n",
+		__func__, __LINE__, address, error_code);
+
 	current->thread.trap_nr = TRAP_HWBKPT;
 	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
 			11, SIGSEGV) == NOTIFY_STOP)
@@ -618,6 +621,15 @@ void do_send_trap(struct pt_regs *regs, unsigned long address,
 	/* Deliver the signal to userspace */
 	force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */
 				    (void __user *)address);
+	/* Clear the breakpoint */
+	hw_breakpoint_disable();
+
+	if (!user_mode(regs)) {
+		show_regs(regs);
+		printk("%s:%d: done: address %016lxh\n", __func__, __LINE__,
+		address);
+		return;
+	}
 }
 #else	/* !CONFIG_PPC_ADV_DEBUG_REGS */
 
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 531177a4ee0881..ad91fb0d0c7531 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -438,10 +438,10 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
 	 * take a page fault to a kernel address or a page fault to a user
 	 * address outside of dedicated places
 	 */
-	if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write))) {
+	if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write)
+		&& !(error_code & DSISR_DABRMATCH))) {
 		if (kfence_handle_page_fault(address, is_write, regs))
 			return 0;
-
 		return SIGSEGV;
 	}
 
diff --git a/arch/powerpc/platforms/ps3/setup.c b/arch/powerpc/platforms/ps3/setup.c
index 5144f11359f798..dccc4f56c7a2ee 100644
--- a/arch/powerpc/platforms/ps3/setup.c
+++ b/arch/powerpc/platforms/ps3/setup.c
@@ -183,6 +183,38 @@ static int ps3_set_dabr(unsigned long dabr, unsigned long dabrx)
 	return lv1_set_dabr(dabr, dabrx) ? -1 : 0;
 }
 
+/**
+ * ps3_debug_setup_dabr - Setup the DABR for kernel use.
+ * @dabr_flags: DABR_DATA_WRITE, DABR_DATA_READ, DABR_TRANSLATION
+ * @dabrx: DABRX_BTI, DABRX_KERNEL, DABRX_USER
+ */
+
+int ps3_debug_setup_dabr(u64 address, unsigned int dabr_flags,
+	unsigned int dabrx)
+{
+	int result;
+	u64 reg;
+
+	BUG_ON(dabr_flags
+		& ~(DABR_DATA_WRITE | DABR_DATA_READ | DABR_TRANSLATION));
+
+	/* PS3 seems to need DABR_TRANSLATION set to work */
+
+	reg = (address & -8L) | dabr_flags | DABR_TRANSLATION;
+
+	printk("%s: address %016llxh, flags %xh = %016llxh\n", __func__,
+		address, dabr_flags, reg);
+
+	result = ps3_set_dabr(reg, dabrx);
+
+	if (result)
+		printk("%s: failed: %d %s\n", __func__, result,
+			ps3_result(result));
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(ps3_debug_setup_dabr);
+
 static ssize_t ps3_fw_version_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf)
 {