commit d6a61bfc06d6f2248f3e75f208d64e794082013c
author Luis Machado <luisgpm@linux.vnet.ibm.com> Thu Jul 24 02:10:41 2008 +1000
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> Fri Jul 25 15:44:39 2008 +1000
tree d46aec6b68e30f9d7d9198bd9102fcf1c054ab7e
parent 00bf6e906156b07cd641fe154ad0efe78f989692

powerpc: BookE hardware watchpoint support

This patch implements support for HW based watchpoint via the
DBSR_DAC (Data Address Compare) facility of the BookE processors.

It does so by interfacing with the existing DABR breakpoint code
and adding the necessary bits and pieces for the new bits to
be properly set or cleared

Signed-off-by: Luis Machado <luisgpm@br.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/process.c

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 219f363..db2497c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -47,6 +47,8 @@
 #ifdef CONFIG_PPC64
 #include <asm/firmware.h>
 #endif
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
 
 extern unsigned long _get_SP(void);
 
@@ -239,6 +241,35 @@
 }
 #endif /* CONFIG_SMP */
 
+void do_dabr(struct pt_regs *regs, unsigned long address,
+		    unsigned long error_code)
+{
+	siginfo_t info;
+
+	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
+			11, SIGSEGV) == NOTIFY_STOP)
+		return;
+
+	if (debugger_dabr_match(regs))
+		return;
+
+	/* Clear the DAC and struct entries.  One shot trigger */
+#if (defined(CONFIG_44x) || defined(CONFIG_BOOKE))
+	mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~(DBSR_DAC1R | DBSR_DAC1W
+							| DBCR0_IDM));
+#endif
+
+	/* Clear the DABR */
+	set_dabr(0);
+
+	/* Deliver the signal to userspace */
+	info.si_signo = SIGTRAP;
+	info.si_errno = 0;
+	info.si_code = TRAP_HWBKPT;
+	info.si_addr = (void __user *)address;
+	force_sig_info(SIGTRAP, &info, current);
+}
+
 static DEFINE_PER_CPU(unsigned long, current_dabr);
 
 int set_dabr(unsigned long dabr)
@@ -254,6 +285,11 @@
 #if defined(CONFIG_PPC64) || defined(CONFIG_6xx)
 	mtspr(SPRN_DABR, dabr);
 #endif
+
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+	mtspr(SPRN_DAC1, dabr);
+#endif
+
 	return 0;
 }
 
@@ -337,6 +373,12 @@
 	if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr))
 		set_dabr(new->thread.dabr);
 
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+	/* If new thread DAC (HW breakpoint) is the same then leave it */
+	if (new->thread.dabr)
+		set_dabr(new->thread.dabr);
+#endif
+
 	new_thread = &new->thread;
 	old_thread = &current->thread;
 
@@ -525,6 +567,10 @@
 	if (current->thread.dabr) {
 		current->thread.dabr = 0;
 		set_dabr(0);
+
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+		current->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W);
+#endif
 	}
 }