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To improve the general usefulness of the IRQ state trace events with
KCSAN enabled, save and restore the trace information when entering and
exiting the KCSAN runtime as well as when generating a KCSAN report.
Without this, reporting the IRQ trace events (whether via a KCSAN report
or outside of KCSAN via a lockdep report) is rather useless due to
continuously being touched by KCSAN. This is because if KCSAN is
enabled, every instrumented memory access causes changes to IRQ trace
events (either by KCSAN disabling/enabling interrupts or taking
report_lock when generating a report).
Before "lockdep: Prepare for NMI IRQ state tracking", KCSAN avoided
touching the IRQ trace events via raw_local_irq_save/restore() and
lockdep_off/on().
Fixes: 248591f5d2 ("kcsan: Make KCSAN compatible with new IRQ state tracking")
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200729110916.3920464-2-elver@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
150 lines
3.4 KiB
C
150 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
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* see Documentation/dev-tools/kcsan.rst.
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*/
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#ifndef _KERNEL_KCSAN_KCSAN_H
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#define _KERNEL_KCSAN_KCSAN_H
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#include <linux/kcsan.h>
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#include <linux/sched.h>
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/* The number of adjacent watchpoints to check. */
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#define KCSAN_CHECK_ADJACENT 1
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#define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
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extern unsigned int kcsan_udelay_task;
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extern unsigned int kcsan_udelay_interrupt;
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/*
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* Globally enable and disable KCSAN.
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*/
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extern bool kcsan_enabled;
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/*
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* Save/restore IRQ flags state trace dirtied by KCSAN.
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*/
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void kcsan_save_irqtrace(struct task_struct *task);
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void kcsan_restore_irqtrace(struct task_struct *task);
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/*
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* Initialize debugfs file.
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*/
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void kcsan_debugfs_init(void);
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enum kcsan_counter_id {
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/*
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* Number of watchpoints currently in use.
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*/
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KCSAN_COUNTER_USED_WATCHPOINTS,
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/*
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* Total number of watchpoints set up.
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*/
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KCSAN_COUNTER_SETUP_WATCHPOINTS,
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/*
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* Total number of data races.
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*/
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KCSAN_COUNTER_DATA_RACES,
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/*
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* Total number of ASSERT failures due to races. If the observed race is
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* due to two conflicting ASSERT type accesses, then both will be
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* counted.
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*/
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KCSAN_COUNTER_ASSERT_FAILURES,
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/*
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* Number of times no watchpoints were available.
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*/
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KCSAN_COUNTER_NO_CAPACITY,
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/*
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* A thread checking a watchpoint raced with another checking thread;
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* only one will be reported.
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*/
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KCSAN_COUNTER_REPORT_RACES,
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/*
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* Observed data value change, but writer thread unknown.
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*/
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KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
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/*
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* The access cannot be encoded to a valid watchpoint.
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*/
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KCSAN_COUNTER_UNENCODABLE_ACCESSES,
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/*
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* Watchpoint encoding caused a watchpoint to fire on mismatching
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* accesses.
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*/
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KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
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KCSAN_COUNTER_COUNT, /* number of counters */
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};
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/*
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* Increment/decrement counter with given id; avoid calling these in fast-path.
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*/
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extern void kcsan_counter_inc(enum kcsan_counter_id id);
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extern void kcsan_counter_dec(enum kcsan_counter_id id);
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/*
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* Returns true if data races in the function symbol that maps to func_addr
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* (offsets are ignored) should *not* be reported.
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*/
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extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
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/*
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* Value-change states.
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*/
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enum kcsan_value_change {
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/*
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* Did not observe a value-change, however, it is valid to report the
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* race, depending on preferences.
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*/
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KCSAN_VALUE_CHANGE_MAYBE,
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/*
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* Did not observe a value-change, and it is invalid to report the race.
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*/
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KCSAN_VALUE_CHANGE_FALSE,
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/*
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* The value was observed to change, and the race should be reported.
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*/
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KCSAN_VALUE_CHANGE_TRUE,
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};
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enum kcsan_report_type {
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/*
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* The thread that set up the watchpoint and briefly stalled was
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* signalled that another thread triggered the watchpoint.
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*/
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KCSAN_REPORT_RACE_SIGNAL,
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/*
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* A thread found and consumed a matching watchpoint.
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*/
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KCSAN_REPORT_CONSUMED_WATCHPOINT,
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/*
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* No other thread was observed to race with the access, but the data
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* value before and after the stall differs.
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*/
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KCSAN_REPORT_RACE_UNKNOWN_ORIGIN,
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};
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/*
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* Print a race report from thread that encountered the race.
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*/
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extern void kcsan_report(const volatile void *ptr, size_t size, int access_type,
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enum kcsan_value_change value_change,
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enum kcsan_report_type type, int watchpoint_idx);
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#endif /* _KERNEL_KCSAN_KCSAN_H */
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