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authorJiri Olsa <jolsa@kernel.org>2018-03-12 14:45:43 +0100
committerIngo Molnar <mingo@kernel.org>2018-03-13 06:56:07 +0100
commitea6a9d530c1779b9bd30944b803820c462f01eac (patch)
treeb03b353fcfe947349054084544fa17331300d2b0 /kernel/events
parent1ad9ff7dea4c42bee43f98b7d7ce8037ee22e133 (diff)
downloadlinux-ea6a9d530c1779b9bd30944b803820c462f01eac.tar.bz2
hw_breakpoint: Add modify_bp_slot() function
Add the modify_bp_slot() function to keep slot numbers correct when changing the breakpoint type. Using existing __release_bp_slot()/__reserve_bp_slot() call sequence to update the slot counts. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Hari Bathini <hbathini@linux.vnet.ibm.com> Cc: Jin Yao <yao.jin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Milind Chabbi <chabbi.milind@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Oleg Nesterov <onestero@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/20180312134548.31532-4-jolsa@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/hw_breakpoint.c46
1 files changed, 39 insertions, 7 deletions
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 9b31fbcc3305..776948beb4ac 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -44,6 +44,7 @@
#include <linux/list.h>
#include <linux/cpu.h>
#include <linux/smp.h>
+#include <linux/bug.h>
#include <linux/hw_breakpoint.h>
/*
@@ -344,6 +345,38 @@ void release_bp_slot(struct perf_event *bp)
mutex_unlock(&nr_bp_mutex);
}
+static int __modify_bp_slot(struct perf_event *bp, u64 old_type)
+{
+ int err;
+
+ __release_bp_slot(bp, old_type);
+
+ err = __reserve_bp_slot(bp, bp->attr.bp_type);
+ if (err) {
+ /*
+ * Reserve the old_type slot back in case
+ * there's no space for the new type.
+ *
+ * This must succeed, because we just released
+ * the old_type slot in the __release_bp_slot
+ * call above. If not, something is broken.
+ */
+ WARN_ON(__reserve_bp_slot(bp, old_type));
+ }
+
+ return err;
+}
+
+static int modify_bp_slot(struct perf_event *bp, u64 old_type)
+{
+ int ret;
+
+ mutex_lock(&nr_bp_mutex);
+ ret = __modify_bp_slot(bp, old_type);
+ mutex_unlock(&nr_bp_mutex);
+ return ret;
+}
+
/*
* Allow the kernel debugger to reserve breakpoint slots without
* taking a lock using the dbg_* variant of for the reserve and
@@ -435,6 +468,7 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
u64 old_addr = bp->attr.bp_addr;
u64 old_len = bp->attr.bp_len;
int old_type = bp->attr.bp_type;
+ bool modify = attr->bp_type != old_type;
int err = 0;
/*
@@ -452,12 +486,9 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
bp->attr.bp_type = attr->bp_type;
bp->attr.bp_len = attr->bp_len;
- if (attr->disabled)
- goto end;
-
err = validate_hw_breakpoint(bp);
- if (!err)
- perf_event_enable(bp);
+ if (!err && modify)
+ err = modify_bp_slot(bp, old_type);
if (err) {
bp->attr.bp_addr = old_addr;
@@ -469,9 +500,10 @@ int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *att
return err;
}
-end:
- bp->attr.disabled = attr->disabled;
+ if (!attr->disabled)
+ perf_event_enable(bp);
+ bp->attr.disabled = attr->disabled;
return 0;
}
EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);