linux.git/kernel/kcsan/debugfs.c, branch v6.18.21 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git kcsan: Remove redundant call of kallsyms_lookup_name() 2024-10-14T14:44:56+00:00 Ran Xiaokai ran.xiaokai@zte.com.cn 2024-09-25T14:31:51+00:00 b86f7c9fad06b960f3ac5594cb3838a7eaeb1892 There is no need to repeatedly call kallsyms_lookup_name, we can reuse the return value of this function. Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Signed-off-by: Marco Elver <elver@google.com> 
There is no need to repeatedly call kallsyms_lookup_name, we can reuse
the return value of this function.

Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Signed-off-by: Marco Elver <elver@google.com>
kcsan: Turn report_filterlist_lock into a raw_spinlock 2024-10-14T14:44:48+00:00 Marco Elver elver@google.com 2024-10-01T14:00:45+00:00 59458fa4ddb47e7891c61b4a928d13d5f5b00aa0 Ran Xiaokai reports that with a KCSAN-enabled PREEMPT_RT kernel, we can see splats like: | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 10002, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 156674 | hardirqs last enabled at (156673): [<ffffffff81130bd9>] do_idle+0x1f9/0x240 | hardirqs last disabled at (156674): [<ffffffff82254f84>] sysvec_apic_timer_interrupt+0x14/0xc0 | softirqs last enabled at (0): [<ffffffff81099f47>] copy_process+0xfc7/0x4b60 | softirqs last disabled at (0): [<0000000000000000>] 0x0 | Preemption disabled at: | [<ffffffff814a3e2a>] paint_ptr+0x2a/0x90 | CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.11.0+ #3 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 | Call Trace: | <IRQ> | dump_stack_lvl+0x7e/0xc0 | dump_stack+0x1d/0x30 | __might_resched+0x1a2/0x270 | rt_spin_lock+0x68/0x170 | kcsan_skip_report_debugfs+0x43/0xe0 | print_report+0xb5/0x590 | kcsan_report_known_origin+0x1b1/0x1d0 | kcsan_setup_watchpoint+0x348/0x650 | __tsan_unaligned_write1+0x16d/0x1d0 | hrtimer_interrupt+0x3d6/0x430 | __sysvec_apic_timer_interrupt+0xe8/0x3a0 | sysvec_apic_timer_interrupt+0x97/0xc0 | </IRQ> On a detected data race, KCSAN's reporting logic checks if it should filter the report. That list is protected by the report_filterlist_lock *non-raw* spinlock which may sleep on RT kernels. Since KCSAN may report data races in any context, convert it to a raw_spinlock. This requires being careful about when to allocate memory for the filter list itself which can be done via KCSAN's debugfs interface. Concurrent modification of the filter list via debugfs should be rare: the chosen strategy is to optimistically pre-allocate memory before the critical section and discard if unused. Link: https://lore.kernel.org/all/20240925143154.2322926-1-ranxiaokai627@163.com/ Reported-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Tested-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Signed-off-by: Marco Elver <elver@google.com> 
Ran Xiaokai reports that with a KCSAN-enabled PREEMPT_RT kernel, we can see
splats like:

| BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
| in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1
| preempt_count: 10002, expected: 0
| RCU nest depth: 0, expected: 0
| no locks held by swapper/1/0.
| irq event stamp: 156674
| hardirqs last  enabled at (156673): [<ffffffff81130bd9>] do_idle+0x1f9/0x240
| hardirqs last disabled at (156674): [<ffffffff82254f84>] sysvec_apic_timer_interrupt+0x14/0xc0
| softirqs last  enabled at (0): [<ffffffff81099f47>] copy_process+0xfc7/0x4b60
| softirqs last disabled at (0): [<0000000000000000>] 0x0
| Preemption disabled at:
| [<ffffffff814a3e2a>] paint_ptr+0x2a/0x90
| CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.11.0+ #3
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
| Call Trace:
|  <IRQ>
|  dump_stack_lvl+0x7e/0xc0
|  dump_stack+0x1d/0x30
|  __might_resched+0x1a2/0x270
|  rt_spin_lock+0x68/0x170
|  kcsan_skip_report_debugfs+0x43/0xe0
|  print_report+0xb5/0x590
|  kcsan_report_known_origin+0x1b1/0x1d0
|  kcsan_setup_watchpoint+0x348/0x650
|  __tsan_unaligned_write1+0x16d/0x1d0
|  hrtimer_interrupt+0x3d6/0x430
|  __sysvec_apic_timer_interrupt+0xe8/0x3a0
|  sysvec_apic_timer_interrupt+0x97/0xc0
|  </IRQ>

On a detected data race, KCSAN's reporting logic checks if it should
filter the report. That list is protected by the report_filterlist_lock
*non-raw* spinlock which may sleep on RT kernels.

Since KCSAN may report data races in any context, convert it to a
raw_spinlock.

This requires being careful about when to allocate memory for the filter
list itself which can be done via KCSAN's debugfs interface. Concurrent
modification of the filter list via debugfs should be rare: the chosen
strategy is to optimistically pre-allocate memory before the critical
section and discard if unused.

Link: https://lore.kernel.org/all/20240925143154.2322926-1-ranxiaokai627@163.com/
Reported-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Tested-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Signed-off-by: Marco Elver <elver@google.com>
kcsan: Use min() to fix Coccinelle warning 2024-08-01T23:40:44+00:00 Thorsten Blum thorsten.blum@toblux.com 2024-06-24T17:57:28+00:00 43d631bf06ec961bbe4c824b931fe03be44c419c Fixes the following Coccinelle/coccicheck warning reported by minmax.cocci: WARNING opportunity for min() Use const size_t instead of int for the result of min(). Compile-tested with CONFIG_KCSAN=y. Reviewed-by: Marco Elver <elver@google.com> Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Fixes the following Coccinelle/coccicheck warning reported by
minmax.cocci:

	WARNING opportunity for min()

Use const size_t instead of int for the result of min().

Compile-tested with CONFIG_KCSAN=y.

Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan: use u64 instead of cycles_t 2021-07-30T15:09:02+00:00 Heiko Carstens hca@linux.ibm.com 2021-07-29T14:28:11+00:00 09b1b13461e12e6962baf0c5bb9f65bedf284d90 cycles_t has a different type across architectures: unsigned int, unsinged long, or unsigned long long. Depending on architecture this will generate this warning: kernel/kcsan/debugfs.c: In function ‘microbenchmark’: ./include/linux/kern_levels.h:5:25: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘cycles_t’ {aka ‘long unsigned int’} [-Wformat=] To avoid this simply change the type of cycle to u64 in microbenchmark(), since u64 is of type unsigned long long for all architectures. Acked-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20210729142811.1309391-1-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com> 
cycles_t has a different type across architectures: unsigned int,
unsinged long, or unsigned long long. Depending on architecture this
will generate this warning:

kernel/kcsan/debugfs.c: In function ‘microbenchmark’:
./include/linux/kern_levels.h:5:25: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘cycles_t’ {aka ‘long unsigned int’} [-Wformat=]

To avoid this simply change the type of cycle to u64 in microbenchmark(),
since u64 is of type unsigned long long for all architectures.

Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210729142811.1309391-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
kcsan: Fix debugfs initcall return type 2021-05-18T17:58:02+00:00 Arnd Bergmann arnd@arndb.de 2021-05-14T14:00:08+00:00 976aac5f882989e4f6c1b3a7224819bf0e801c6a clang with CONFIG_LTO_CLANG points out that an initcall function should return an 'int' due to the changes made to the initcall macros in commit 3578ad11f3fb ("init: lto: fix PREL32 relocations"): kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int' late_initcall(kcsan_debugfs_init); ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ include/linux/init.h:292:46: note: expanded from macro 'late_initcall' #define late_initcall(fn) __define_initcall(fn, 7) Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init") Cc: stable <stable@vger.kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
clang with CONFIG_LTO_CLANG points out that an initcall function should
return an 'int' due to the changes made to the initcall macros in commit
3578ad11f3fb ("init: lto: fix PREL32 relocations"):

kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int'
late_initcall(kcsan_debugfs_init);
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
include/linux/init.h:292:46: note: expanded from macro 'late_initcall'
 #define late_initcall(fn)               __define_initcall(fn, 7)

Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan: Add missing license and copyright headers 2021-03-08T22:27:43+00:00 Marco Elver elver@google.com 2021-01-15T17:09:53+00:00 bd0ccc4afca2d6ae0029cae35c4f1d2e2ade7579 Adds missing license and/or copyright headers for KCSAN source files. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Adds missing license and/or copyright headers for KCSAN source files.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan, debugfs: Move debugfs file creation out of early init 2021-03-08T22:27:43+00:00 Marco Elver elver@google.com 2021-03-03T09:38:45+00:00 e36299efe7d749976fbdaaf756dee6ef32543c2c Commit 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") forbids creating new debugfs files until debugfs is fully initialized. This means that KCSAN's debugfs file creation, which happened at the end of __init(), no longer works. And was apparently never supposed to work! However, there is no reason to create KCSAN's debugfs file so early. This commit therefore moves its creation to a late_initcall() callback. Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: stable <stable@vger.kernel.org> Fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Commit 56348560d495 ("debugfs: do not attempt to create a new file
before the filesystem is initalized") forbids creating new debugfs files
until debugfs is fully initialized.  This means that KCSAN's debugfs
file creation, which happened at the end of __init(), no longer works.
And was apparently never supposed to work!

However, there is no reason to create KCSAN's debugfs file so early.
This commit therefore moves its creation to a late_initcall() callback.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable <stable@vger.kernel.org>
Fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan: Optimize debugfs stats counters 2020-08-24T22:10:23+00:00 Marco Elver elver@google.com 2020-08-10T08:06:25+00:00 2e986b81f698e73c95e6456183f27b861f47bb87 Remove kcsan_counter_inc/dec() functions, as they perform no other logic, and are no longer needed. This avoids several calls in kcsan_setup_watchpoint() and kcsan_found_watchpoint(), as well as lets the compiler warn us about potential out-of-bounds accesses as the array's size is known at all usage sites at compile-time. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Remove kcsan_counter_inc/dec() functions, as they perform no other
logic, and are no longer needed.

This avoids several calls in kcsan_setup_watchpoint() and
kcsan_found_watchpoint(), as well as lets the compiler warn us about
potential out-of-bounds accesses as the array's size is known at all
usage sites at compile-time.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan: Use pr_fmt for consistency 2020-08-24T22:10:23+00:00 Marco Elver elver@google.com 2020-07-31T08:17:23+00:00 178a1877d782c034f466edd80e30a107af5469df Use the same pr_fmt throughout for consistency. [ The only exception is report.c, where the format must be kept precisely as-is. ] Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Use the same pr_fmt throughout for consistency. [ The only exception is
report.c, where the format must be kept precisely as-is. ]

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
kcsan: Remove debugfs test command 2020-08-24T22:10:22+00:00 Marco Elver elver@google.com 2020-07-31T08:17:21+00:00 4700ccdf18fa3002d66769b69cf715cc58beea37 Remove the debugfs test command, as it is no longer needed now that we have the KUnit+Torture based kcsan-test module. This is to avoid confusion around how KCSAN should be tested, as only the kcsan-test module is maintained. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> 
Remove the debugfs test command, as it is no longer needed now that we
have the KUnit+Torture based kcsan-test module. This is to avoid
confusion around how KCSAN should be tested, as only the kcsan-test
module is maintained.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>