[GIT PULL] hw-breakpoints: Various fixes

[GIT PULL] hw-breakpoints: Various fixes

[Frederic Weisbecker]

Ingo,

Please pull the tracing/hw-breakpoints branch that can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/hw-breakpoints

Thanks,
	Frederic
---

Frederic Weisbecker (3):
      hw-breakpoints: Fix broken a.out format dump
      hw-breakpoints: Fix broken hw-breakpoint sample module
      hw-breakpoints: Wrap in the KVM breakpoint active state check

Paul Mundt (1):
      ksym_tracer: Support read accesses independent of read/write.


 arch/x86/include/asm/a.out-core.h       |   10 +------
 arch/x86/include/asm/debugreg.h         |    7 +++++
 arch/x86/kernel/hw_breakpoint.c         |   35 +++++++++++++++++++++++++
 arch/x86/kvm/x86.c                      |    2 +-
 kernel/hw_breakpoint.c                  |    3 +-
 kernel/kallsyms.c                       |    1 +
 kernel/trace/trace_ksym.c               |   11 +++++++-
 samples/hw_breakpoint/data_breakpoint.c |   43 +++++++++++++++++-------------
 8 files changed, 82 insertions(+), 30 deletions(-)

[PATCH 1/4] ksym_tracer: Support read accesses independent of read/write.

[Frederic Weisbecker]

From: Paul Mundt <lethal@linux-sh.org>

All of the infrastructure already exists to support read accesses
for platforms that support a read access independently of read/write
(such as in the case of the SuperH UBC). This just trivially hooks
up the read case by itself.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20091109083733.GA25848@linux-sh.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/trace_ksym.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index fea83ee..11935b5 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -136,6 +136,7 @@ static int ksym_trace_get_access_type(char *str)
 		access |= HW_BREAKPOINT_X;
 
 	switch (access) {
+	case HW_BREAKPOINT_R:
 	case HW_BREAKPOINT_W:
 	case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
 		return access;
@@ -239,7 +240,9 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
 
 	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
 		ret = trace_seq_printf(s, "%pS:", (void *)entry->ksym_addr);
-		if (entry->type == HW_BREAKPOINT_W)
+		if (entry->type == HW_BREAKPOINT_R)
+			ret = trace_seq_puts(s, "r--\n");
+		else if (entry->type == HW_BREAKPOINT_W)
 			ret = trace_seq_puts(s, "-w-\n");
 		else if (entry->type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R))
 			ret = trace_seq_puts(s, "rw-\n");
@@ -414,6 +417,9 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
 		return TRACE_TYPE_PARTIAL_LINE;
 
 	switch (field->type) {
+	case HW_BREAKPOINT_R:
+		ret = trace_seq_printf(s, " R  ");
+		break;
 	case HW_BREAKPOINT_W:
 		ret = trace_seq_printf(s, " W  ");
 		break;
@@ -488,6 +494,9 @@ static int ksym_tracer_stat_show(struct seq_file *m, void *v)
 	access_type = entry->type;
 
 	switch (access_type) {
+	case HW_BREAKPOINT_R:
+		seq_puts(m, "  R           ");
+		break;
 	case HW_BREAKPOINT_W:
 		seq_puts(m, "  W           ");
 		break;
-- 
1.6.2.3

[PATCH 2/4] hw-breakpoints: Fix broken a.out format dump

[Frederic Weisbecker]

Fix the broken a.out format dump. For now we only dump the ptrace
breakpoints.

TODO: Dump every perf breakpoints for the current thread, not only
ptrace based ones.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
---
 arch/x86/include/asm/a.out-core.h |   10 ++--------
 arch/x86/include/asm/debugreg.h   |    2 ++
 arch/x86/kernel/hw_breakpoint.c   |   35 +++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/a.out-core.h b/arch/x86/include/asm/a.out-core.h
index fc4685d..7a15588 100644
--- a/arch/x86/include/asm/a.out-core.h
+++ b/arch/x86/include/asm/a.out-core.h
@@ -17,6 +17,7 @@
 
 #include <linux/user.h>
 #include <linux/elfcore.h>
+#include <asm/debugreg.h>
 
 /*
  * fill in the user structure for an a.out core dump
@@ -32,14 +33,7 @@ static inline void aout_dump_thread(struct pt_regs *regs, struct user *dump)
 			>> PAGE_SHIFT;
 	dump->u_dsize -= dump->u_tsize;
 	dump->u_ssize = 0;
-	dump->u_debugreg[0] = current->thread.debugreg[0];
-	dump->u_debugreg[1] = current->thread.debugreg[1];
-	dump->u_debugreg[2] = current->thread.debugreg[2];
-	dump->u_debugreg[3] = current->thread.debugreg[3];
-	dump->u_debugreg[4] = 0;
-	dump->u_debugreg[5] = 0;
-	dump->u_debugreg[6] = current->thread.debugreg6;
-	dump->u_debugreg[7] = current->thread.debugreg7;
+	aout_dump_debugregs(dump);
 
 	if (dump->start_stack < TASK_SIZE)
 		dump->u_ssize = ((unsigned long)(TASK_SIZE - dump->start_stack))
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 9a3333c..f1b673f 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -89,6 +89,8 @@ static inline void hw_breakpoint_disable(void)
 	set_debugreg(0UL, 3);
 }
 
+extern void aout_dump_debugregs(struct user *dump);
+
 #ifdef CONFIG_KVM
 extern void hw_breakpoint_restore(void);
 #endif
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index e622620..57dcee5 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -376,6 +376,41 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
 }
 
 /*
+ * Dump the debug register contents to the user.
+ * We can't dump our per cpu values because it
+ * may contain cpu wide breakpoint, something that
+ * doesn't belong to the current task.
+ *
+ * TODO: include non-ptrace user breakpoints (perf)
+ */
+void aout_dump_debugregs(struct user *dump)
+{
+	int i;
+	int dr7 = 0;
+	struct perf_event *bp;
+	struct arch_hw_breakpoint *info;
+	struct thread_struct *thread = &current->thread;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		bp = thread->ptrace_bps[i];
+
+		if (bp && !bp->attr.disabled) {
+			dump->u_debugreg[i] = bp->attr.bp_addr;
+			info = counter_arch_bp(bp);
+			dr7 |= encode_dr7(i, info->len, info->type);
+		} else {
+			dump->u_debugreg[i] = 0;
+		}
+	}
+
+	dump->u_debugreg[4] = 0;
+	dump->u_debugreg[5] = 0;
+	dump->u_debugreg[6] = current->thread.debugreg6;
+
+	dump->u_debugreg[7] = dr7;
+}
+
+/*
  * Release the user breakpoints used by ptrace
  */
 void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
-- 
1.6.2.3

[PATCH 3/4] hw-breakpoints: Fix broken hw-breakpoint sample module

[Frederic Weisbecker]

The hw-breakpoint sample module has been broken during the
hw-breakpoint internals refactoring. Propagate the changes
to it.

Reported-by: "K. Prasad" <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/hw_breakpoint.c                  |    3 +-
 kernel/kallsyms.c                       |    1 +
 samples/hw_breakpoint/data_breakpoint.c |   43 +++++++++++++++++-------------
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index e662dc9..9ea9414 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -454,6 +454,7 @@ fail:
 	/* return the error if any */
 	return ERR_PTR(err);
 }
+EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
 
 /**
  * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
@@ -470,7 +471,7 @@ void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
 	}
 	free_percpu(cpu_events);
 }
-
+EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
 
 static struct notifier_block hw_breakpoint_exceptions_nb = {
 	.notifier_call = hw_breakpoint_exceptions_notify,
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 8b6b8b6..8e5288a 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -181,6 +181,7 @@ unsigned long kallsyms_lookup_name(const char *name)
 	}
 	return module_kallsyms_lookup_name(name);
 }
+EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
 
 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
 				      unsigned long),
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index 9cbdbb8..5bc9819 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -27,18 +27,19 @@
 #include <linux/module.h>	/* Needed by all modules */
 #include <linux/kernel.h>	/* Needed for KERN_INFO */
 #include <linux/init.h>		/* Needed for the macros */
+#include <linux/kallsyms.h>
 
-#include <asm/hw_breakpoint.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
 
-struct hw_breakpoint sample_hbp;
+struct perf_event **sample_hbp;
 
 static char ksym_name[KSYM_NAME_LEN] = "pid_max";
 module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
 MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
 			" write operations on the kernel symbol");
 
-void sample_hbp_handler(struct hw_breakpoint *temp, struct pt_regs
-								*temp_regs)
+static void sample_hbp_handler(struct perf_event *temp, void *data)
 {
 	printk(KERN_INFO "%s value is changed\n", ksym_name);
 	dump_stack();
@@ -48,30 +49,34 @@ void sample_hbp_handler(struct hw_breakpoint *temp, struct pt_regs
 static int __init hw_break_module_init(void)
 {
 	int ret;
+	unsigned long addr;
 
-#ifdef CONFIG_X86
-	sample_hbp.info.name = ksym_name;
-	sample_hbp.info.type = HW_BREAKPOINT_WRITE;
-	sample_hbp.info.len = HW_BREAKPOINT_LEN_4;
-#endif /* CONFIG_X86 */
+	addr = kallsyms_lookup_name(ksym_name);
 
-	sample_hbp.triggered = (void *)sample_hbp_handler;
+	sample_hbp = register_wide_hw_breakpoint(addr, HW_BREAKPOINT_LEN_4,
+						 HW_BREAKPOINT_W | HW_BREAKPOINT_R,
+						 sample_hbp_handler, true);
+	if (IS_ERR(sample_hbp)) {
+		ret = PTR_ERR(sample_hbp);
+		goto fail;
+	} else if (!sample_hbp) {
+		ret = -EINVAL;
+		goto fail;
+	}
 
-	ret = register_kernel_hw_breakpoint(&sample_hbp);
-
-	if (ret < 0) {
-		printk(KERN_INFO "Breakpoint registration failed\n");
-		return ret;
-	} else
-		printk(KERN_INFO "HW Breakpoint for %s write installed\n",
-								ksym_name);
+	printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name);
 
 	return 0;
+
+fail:
+	printk(KERN_INFO "Breakpoint registration failed\n");
+
+	return ret;
 }
 
 static void __exit hw_break_module_exit(void)
 {
-	unregister_kernel_hw_breakpoint(&sample_hbp);
+	unregister_wide_hw_breakpoint(sample_hbp);
 	printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
 }
 
-- 
1.6.2.3

[PATCH 4/4] hw-breakpoints: Wrap in the KVM breakpoint active state check

[Frederic Weisbecker]

Wrap in the cpu dr7 check that tells if we have active
breakpoints that need to be restored in the cpu.

This wrapper makes the check more self-explainable and also
reusable for any further other uses.

Reported-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
---
 arch/x86/include/asm/debugreg.h |    5 +++++
 arch/x86/kvm/x86.c              |    2 +-
 2 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index f1b673f..0f6e92a 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -89,6 +89,11 @@ static inline void hw_breakpoint_disable(void)
 	set_debugreg(0UL, 3);
 }
 
+static inline int hw_breakpoint_active(void)
+{
+	return __get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK;
+}
+
 extern void aout_dump_debugregs(struct user *dump);
 
 #ifdef CONFIG_KVM
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 22dee7a..3817220 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3651,7 +3651,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	 * care about the messed up debug address registers. But if
 	 * we have some of them active, restore the old state.
 	 */
-	if (__get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK)
+	if (hw_breakpoint_active())
 		hw_breakpoint_restore();
 
 	set_bit(KVM_REQ_KICK, &vcpu->requests);
-- 
1.6.2.3