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Subject[tip: locking/urgent] kcsan: Refactor passing watchpoint/other_info
The following commit has been merged into the locking/urgent branch of tip:

Commit-ID: 95f7524d7f0c6fddbc24fb623d61b7d508626f41
Gitweb: https://git.kernel.org/tip/95f7524d7f0c6fddbc24fb623d61b7d508626f41
Author: Mark Rutland <mark.rutland@arm.com>
AuthorDate: Wed, 14 Apr 2021 13:28:19 +02:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Tue, 18 May 2021 10:58:14 -07:00

kcsan: Refactor passing watchpoint/other_info

The `watchpoint_idx` argument to kcsan_report() isn't meaningful for
races which were not detected by a watchpoint, and it would be clearer
if callers passed the other_info directly so that a NULL value can be
passed in this case.

Given that callers manipulate their watchpoints before passing the index
into kcsan_report_*(), and given we index the `other_infos` array using
this before we sanity-check it, the subsequent sanity check isn't all
that useful.

Let's remove the `watchpoint_idx` sanity check, and move the job of
finding the `other_info` out of kcsan_report().

Other than the removal of the check, there should be no functional
change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/kcsan/report.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index 5232bf2..88225f6 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -600,7 +600,7 @@ static noinline bool prepare_report(unsigned long *flags,

static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
enum kcsan_value_change value_change,
- enum kcsan_report_type type, int watchpoint_idx)
+ enum kcsan_report_type type, struct other_info *other_info)
{
unsigned long flags = 0;
const struct access_info ai = {
@@ -610,12 +610,8 @@ static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
.task_pid = in_task() ? task_pid_nr(current) : -1,
.cpu_id = raw_smp_processor_id()
};
- struct other_info *other_info = type == KCSAN_REPORT_RACE_UNKNOWN_ORIGIN
- ? NULL : &other_infos[watchpoint_idx];

kcsan_disable_current();
- if (WARN_ON(watchpoint_idx < 0 || watchpoint_idx >= ARRAY_SIZE(other_infos)))
- goto out;

/*
* Because we may generate reports when we're in scheduler code, the use
@@ -642,7 +638,6 @@ static void kcsan_report(const volatile void *ptr, size_t size, int access_type,
}

lockdep_on();
-out:
kcsan_enable_current();
}

@@ -650,18 +645,18 @@ void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_typ
int watchpoint_idx)
{
kcsan_report(ptr, size, access_type, KCSAN_VALUE_CHANGE_MAYBE,
- KCSAN_REPORT_CONSUMED_WATCHPOINT, watchpoint_idx);
+ KCSAN_REPORT_CONSUMED_WATCHPOINT, &other_infos[watchpoint_idx]);
}

void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
enum kcsan_value_change value_change, int watchpoint_idx)
{
kcsan_report(ptr, size, access_type, value_change,
- KCSAN_REPORT_RACE_SIGNAL, watchpoint_idx);
+ KCSAN_REPORT_RACE_SIGNAL, &other_infos[watchpoint_idx]);
}

void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type)
{
kcsan_report(ptr, size, access_type, KCSAN_VALUE_CHANGE_TRUE,
- KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, 0);
+ KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, NULL);
}
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