hw-breakpoints: Tag ptrace breakpoint as exclude_kernel

Tag ptrace breakpoints with the exclude_kernel attribute set. This
will make it easier to set generic policies on breakpoints, when it
comes to ensure nobody unpriviliged try to breakpoint on the kernel.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: K. Prasad <prasad@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>

3 files changed, 8 insertions, 2 deletions

diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 7759a9a93211..d4104ce9fe53 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -85,7 +85,7 @@ static int set_single_step(struct task_struct *tsk, unsigned long addr)
 
         bp = thread->ptrace_bps[0];
         if (!bp) {
-                hw_breakpoint_init(&attr);
+                ptrace_breakpoint_init(&attr);
 
                 attr.bp_addr = addr;
                 attr.bp_len = HW_BREAKPOINT_LEN_2;
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 055be0afd330..70c4872cd8aa 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -688,7 +688,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
         struct perf_event_attr attr;
 
         if (!t->ptrace_bps[nr]) {
-                hw_breakpoint_init(&attr);
+                ptrace_breakpoint_init(&attr);
                 /*
                  * Put stub len and type to register (reserve) an inactive but
                  * correct bp
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index c70d27af03f9..a0aa5a9cfb0e 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -34,6 +34,12 @@ static inline void hw_breakpoint_init(struct perf_event_attr *attr)
         attr->sample_period = 1;
 }
 
+static inline void ptrace_breakpoint_init(struct perf_event_attr *attr)
+{
+        hw_breakpoint_init(attr);
+        attr->exclude_kernel = 1;
+}
+
 static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
 {
         return bp->attr.bp_addr;