powerpc/booke: Add support for advanced debug registers

powerpc/booke: Add support for advanced debug registers

From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

Based on patches originally written by Torez Smith.

This patch defines context switch and trap related functionality
for BookE specific Debug Registers. It adds support to ptrace()
for setting and getting BookE related Debug Registers

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <dwg@au1.ibm.com>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Sergio Durigan Junior <sergiodj@br.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@br.ibm.com>
Cc: linuxppc-dev list <Linuxppc-dev@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 72 insertions, 19 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 4e293b7..987437e 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1034,9 +1034,68 @@ void SoftwareEmulation(struct pt_regs *regs)
 #endif /* CONFIG_8xx */
 
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
+static void handle_debug(struct pt_regs *regs, unsigned long debug_status)
+{
+	int changed = 0;
+	/*
+	 * Determine the cause of the debug event, clear the
+	 * event flags and send a trap to the handler. Torez
+	 */
+	if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {
+		dbcr_dac(current) &= ~(DBCR_DAC1R | DBCR_DAC1W);
+#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
+		current->thread.dbcr2 &= ~DBCR2_DAC12MODE;
+#endif
+		do_send_trap(regs, mfspr(SPRN_DAC1), debug_status, TRAP_HWBKPT,
+			     5);
+		changed |= 0x01;
+	}  else if (debug_status & (DBSR_DAC2R | DBSR_DAC2W)) {
+		dbcr_dac(current) &= ~(DBCR_DAC2R | DBCR_DAC2W);
+		do_send_trap(regs, mfspr(SPRN_DAC2), debug_status, TRAP_HWBKPT,
+			     6);
+		changed |= 0x01;
+	}  else if (debug_status & DBSR_IAC1) {
+		current->thread.dbcr0 &= ~DBCR0_IAC1;
+		dbcr_iac_range(current) &= ~DBCR_IAC12MODE;
+		do_send_trap(regs, mfspr(SPRN_IAC1), debug_status, TRAP_HWBKPT,
+			     1);
+		changed |= 0x01;
+	}  else if (debug_status & DBSR_IAC2) {
+		current->thread.dbcr0 &= ~DBCR0_IAC2;
+		do_send_trap(regs, mfspr(SPRN_IAC2), debug_status, TRAP_HWBKPT,
+			     2);
+		changed |= 0x01;
+	}  else if (debug_status & DBSR_IAC3) {
+		current->thread.dbcr0 &= ~DBCR0_IAC3;
+		dbcr_iac_range(current) &= ~DBCR_IAC34MODE;
+		do_send_trap(regs, mfspr(SPRN_IAC3), debug_status, TRAP_HWBKPT,
+			     3);
+		changed |= 0x01;
+	}  else if (debug_status & DBSR_IAC4) {
+		current->thread.dbcr0 &= ~DBCR0_IAC4;
+		do_send_trap(regs, mfspr(SPRN_IAC4), debug_status, TRAP_HWBKPT,
+			     4);
+		changed |= 0x01;
+	}
+	/*
+	 * At the point this routine was called, the MSR(DE) was turned off.
+	 * Check all other debug flags and see if that bit needs to be turned
+	 * back on or not.
+	 */
+	if (DBCR_ACTIVE_EVENTS(current->thread.dbcr0, current->thread.dbcr1))
+		regs->msr |= MSR_DE;
+	else
+		/* Make sure the IDM flag is off */
+		current->thread.dbcr0 &= ~DBCR0_IDM;
+
+	if (changed & 0x01)
+		mtspr(SPRN_DBCR0, current->thread.dbcr0);
+}
 
 void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
 {
+	current->thread.dbsr = debug_status;
+
 	/* Hack alert: On BookE, Branch Taken stops on the branch itself, while
 	 * on server, it stops on the target of the branch. In order to simulate
 	 * the server behaviour, we thus restart right away with a single step
@@ -1080,27 +1139,21 @@ void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
 		if (debugger_sstep(regs))
 			return;
 
-		if (user_mode(regs))
-			current->thread.dbcr0 &= ~(DBCR0_IC);
-
-		_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
-	} else if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {
-		regs->msr &= ~MSR_DE;
-
 		if (user_mode(regs)) {
-			current->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W |
-								DBCR0_IDM);
-		} else {
-			/* Disable DAC interupts */
-			mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~(DBSR_DAC1R |
-						DBSR_DAC1W | DBCR0_IDM));
-
-			/* Clear the DAC event */
-			mtspr(SPRN_DBSR, (DBSR_DAC1R | DBSR_DAC1W));
+			current->thread.dbcr0 &= ~DBCR0_IC;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+			if (DBCR_ACTIVE_EVENTS(current->thread.dbcr0,
+					       current->thread.dbcr1))
+				regs->msr |= MSR_DE;
+			else
+				/* Make sure the IDM bit is off */
+				current->thread.dbcr0 &= ~DBCR0_IDM;
+#endif
 		}
-		/* Setup and send the trap to the handler */
-		do_dabr(regs, mfspr(SPRN_DAC1), debug_status);
-	}
+
+		_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
+	} else
+		handle_debug(regs, debug_status);
 }
 #endif /* CONFIG_PPC_ADV_DEBUG_REGS */