linux-toradex.git/kernel/trace, branch v5.7-rc5 Linux kernel for Apalis and Colibri modules Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-09T20:57:10+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-05-09T20:57:10+00:00 78a5255ffb6a1af189a83e493d916ba1c54d8c75 We have some rather random rules about when we accept the "maybe-initialized" warnings, and when we don't. For example, we consider it unreliable for gcc versions < 4.9, but also if -O3 is enabled, or if optimizing for size. And then various kernel config options disabled it, because they know that they trigger that warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES). And now gcc-10 seems to be introducing a lot of those warnings too, so it falls under the same heading as 4.9 did. At the same time, we have a very straightforward way to _enable_ that warning when wanted: use "W=2" to enable more warnings. So stop playing these ad-hoc games, and just disable that warning by default, with the known and straight-forward "if you want to work on the extra compiler warnings, use W=123". Would it be great to have code that is always so obvious that it never confuses the compiler whether a variable is used initialized or not? Yes, it would. In a perfect world, the compilers would be smarter, and our source code would be simpler. That's currently not the world we live in, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.

For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size.  And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).

And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.

At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.

So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".

Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would.  In a perfect world, the compilers would be smarter, and
our source code would be simpler.

That's currently not the world we live in, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
tracing: Make tracing_snapshot_instance_cond() static 2020-05-07T17:32:58+00:00 Zou Wei zou_wei@huawei.com 2020-04-23T04:08:25+00:00 192b7993b3ff92b62b687e940e5e88fa0218d764 Fix the following sparse warning: kernel/trace/trace.c:950:6: warning: symbol 'tracing_snapshot_instance_cond' was not declared. Should it be static? Link: http://lkml.kernel.org/r/1587614905-48692-1-git-send-email-zou_wei@huawei.com Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Fix the following sparse warning:

kernel/trace/trace.c:950:6: warning: symbol 'tracing_snapshot_instance_cond'
was not declared. Should it be static?

Link: http://lkml.kernel.org/r/1587614905-48692-1-git-send-email-zou_wei@huawei.com

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing: Add a vmalloc_sync_mappings() for safe measure 2020-05-07T17:32:57+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-05-06T14:36:18+00:00 11f5efc3ab66284f7aaacc926e9351d658e2577b x86_64 lazily maps in the vmalloc pages, and the way this works with per_cpu areas can be complex, to say the least. Mappings may happen at boot up, and if nothing synchronizes the page tables, those page mappings may not be synced till they are used. This causes issues for anything that might touch one of those mappings in the path of the page fault handler. When one of those unmapped mappings is touched in the page fault handler, it will cause another page fault, which in turn will cause a page fault, and leave us in a loop of page faults. Commit 763802b53a42 ("x86/mm: split vmalloc_sync_all()") split vmalloc_sync_all() into vmalloc_sync_unmappings() and vmalloc_sync_mappings(), as on system exit, it did not need to do a full sync on x86_64 (although it still needed to be done on x86_32). By chance, the vmalloc_sync_all() would synchronize the page mappings done at boot up and prevent the per cpu area from being a problem for tracing in the page fault handler. But when that synchronization in the exit of a task became a nop, it caused the problem to appear. Link: https://lore.kernel.org/r/20200429054857.66e8e333@oasis.local.home Cc: stable@vger.kernel.org Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code") Reported-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> Suggested-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
x86_64 lazily maps in the vmalloc pages, and the way this works with per_cpu
areas can be complex, to say the least. Mappings may happen at boot up, and
if nothing synchronizes the page tables, those page mappings may not be
synced till they are used. This causes issues for anything that might touch
one of those mappings in the path of the page fault handler. When one of
those unmapped mappings is touched in the page fault handler, it will cause
another page fault, which in turn will cause a page fault, and leave us in
a loop of page faults.

Commit 763802b53a42 ("x86/mm: split vmalloc_sync_all()") split
vmalloc_sync_all() into vmalloc_sync_unmappings() and
vmalloc_sync_mappings(), as on system exit, it did not need to do a full
sync on x86_64 (although it still needed to be done on x86_32). By chance,
the vmalloc_sync_all() would synchronize the page mappings done at boot up
and prevent the per cpu area from being a problem for tracing in the page
fault handler. But when that synchronization in the exit of a task became a
nop, it caused the problem to appear.

Link: https://lore.kernel.org/r/20200429054857.66e8e333@oasis.local.home

Cc: stable@vger.kernel.org
Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code")
Reported-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Suggested-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing: Wait for preempt irq delay thread to finish 2020-05-07T17:32:40+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-05-06T14:20:10+00:00 d16a8c31077e75ecb9427fbfea59b74eed00f698 Running on a slower machine, it is possible that the preempt delay kernel thread may still be executing if the module was immediately removed after added, and this can cause the kernel to crash as the kernel thread might be executing after its code has been removed. There's no reason that the caller of the code shouldn't just wait for the delay thread to finish, as the thread can also be created by a trigger in the sysfs code, which also has the same issues. Link: http://lore.kernel.org/r/5EA2B0C8.2080706@cn.fujitsu.com Cc: stable@vger.kernel.org Fixes: 793937236d1ee ("lib: Add module for testing preemptoff/irqsoff latency tracers") Reported-by: Xiao Yang <yangx.jy@cn.fujitsu.com> Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com> Reviewed-by: Joel Fernandes <joel@joelfernandes.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Running on a slower machine, it is possible that the preempt delay kernel
thread may still be executing if the module was immediately removed after
added, and this can cause the kernel to crash as the kernel thread might be
executing after its code has been removed.

There's no reason that the caller of the code shouldn't just wait for the
delay thread to finish, as the thread can also be created by a trigger in
the sysfs code, which also has the same issues.

Link: http://lore.kernel.org/r/5EA2B0C8.2080706@cn.fujitsu.com

Cc: stable@vger.kernel.org
Fixes: 793937236d1ee ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Reported-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing/kprobes: Reject new event if loc is NULL 2020-05-06T13:04:11+00:00 Masami Hiramatsu mhiramat@kernel.org 2020-04-25T05:49:26+00:00 5b4dcd2d201a395ad4054067bfae4a07554fbd65 Reject the new event which has NULL location for kprobes. For kprobes, user must specify at least the location. Link: http://lkml.kernel.org/r/158779376597.6082.1411212055469099461.stgit@devnote2 Cc: Tom Zanussi <zanussi@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: 2a588dd1d5d6 ("tracing: Add kprobe event command generation functions") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Reject the new event which has NULL location for kprobes.
For kprobes, user must specify at least the location.

Link: http://lkml.kernel.org/r/158779376597.6082.1411212055469099461.stgit@devnote2

Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 2a588dd1d5d6 ("tracing: Add kprobe event command generation functions")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing/boottime: Fix kprobe event API usage 2020-05-06T13:04:11+00:00 Masami Hiramatsu mhiramat@kernel.org 2020-04-25T05:49:17+00:00 da0f1f4167e3af69e1d8b32d6d65195ddd2bfb64 Fix boottime kprobe events to use API correctly for multiple events. For example, when we set a multiprobe kprobe events in bootconfig like below, ftrace.event.kprobes.myevent { probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2" } This cause an error; trace_boot: Failed to add probe: p:kprobes/myevent (null) vfs_read $arg1 $arg2 vfs_write $arg1 $arg2 This shows the 1st argument becomes NULL and multiprobes are merged to 1 probe. Link: http://lkml.kernel.org/r/158779375766.6082.201939936008972838.stgit@devnote2 Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: 29a154810546 ("tracing: Change trace_boot to use kprobe_event interface") Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Fix boottime kprobe events to use API correctly for
multiple events.

For example, when we set a multiprobe kprobe events in
bootconfig like below,

  ftrace.event.kprobes.myevent {
  	probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2"
  }

This cause an error;

  trace_boot: Failed to add probe: p:kprobes/myevent (null)  vfs_read $arg1 $arg2  vfs_write $arg1 $arg2

This shows the 1st argument becomes NULL and multiprobes
are merged to 1 probe.

Link: http://lkml.kernel.org/r/158779375766.6082.201939936008972838.stgit@devnote2

Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 29a154810546 ("tracing: Change trace_boot to use kprobe_event interface")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing/kprobes: Fix a double initialization typo 2020-05-06T13:04:11+00:00 Masami Hiramatsu mhiramat@kernel.org 2020-04-25T05:49:09+00:00 dcbd21c9fca5e954fd4e3d91884907eb6d47187e Fix a typo that resulted in an unnecessary double initialization to addr. Link: http://lkml.kernel.org/r/158779374968.6082.2337484008464939919.stgit@devnote2 Cc: Tom Zanussi <zanussi@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: c7411a1a126f ("tracing/kprobe: Check whether the non-suffixed symbol is notrace") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Fix a typo that resulted in an unnecessary double
initialization to addr.

Link: http://lkml.kernel.org/r/158779374968.6082.2337484008464939919.stgit@devnote2

Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c7411a1a126f ("tracing/kprobe: Check whether the non-suffixed symbol is notrace")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing: Convert local functions in tracing_map.c to static 2020-04-23T02:07:26+00:00 Jason Yan yanaijie@huawei.com 2020-04-10T07:33:12+00:00 d013496f99c5608e0f80afd67acb1ba93c4144ea Fix the following sparse warning: kernel/trace/tracing_map.c:286:6: warning: symbol 'tracing_map_array_clear' was not declared. Should it be static? kernel/trace/tracing_map.c:297:6: warning: symbol 'tracing_map_array_free' was not declared. Should it be static? kernel/trace/tracing_map.c:319:26: warning: symbol 'tracing_map_array_alloc' was not declared. Should it be static? Link: http://lkml.kernel.org/r/20200410073312.38855-1-yanaijie@huawei.com Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
Fix the following sparse warning:

kernel/trace/tracing_map.c:286:6: warning: symbol
'tracing_map_array_clear' was not declared. Should it be static?
kernel/trace/tracing_map.c:297:6: warning: symbol
'tracing_map_array_free' was not declared. Should it be static?
kernel/trace/tracing_map.c:319:26: warning: symbol
'tracing_map_array_alloc' was not declared. Should it be static?

Link: http://lkml.kernel.org/r/20200410073312.38855-1-yanaijie@huawei.com

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
ftrace: Fix memory leak caused by not freeing entry in unregister_ftrace_direct() 2020-04-23T02:04:27+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-04-23T01:38:45+00:00 353da87921a5ec654e7e9024e083f099f1b33c97 kmemleak reported the following: unreferenced object 0xffff90d47127a920 (size 32): comm "modprobe", pid 1766, jiffies 4294792031 (age 162.568s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 22 01 00 00 00 00 ad de ........"....... 00 78 12 a7 ff ff ff ff 00 00 b6 c0 ff ff ff ff .x.............. backtrace: [<00000000bb79e72e>] register_ftrace_direct+0xcb/0x3a0 [<00000000295e4f79>] do_one_initcall+0x72/0x340 [<00000000873ead18>] do_init_module+0x5a/0x220 [<00000000974d9de5>] load_module+0x2235/0x2550 [<0000000059c3d6ce>] __do_sys_finit_module+0xc0/0x120 [<000000005a8611b4>] do_syscall_64+0x60/0x230 [<00000000a0cdc49e>] entry_SYSCALL_64_after_hwframe+0x49/0xb3 The entry used to save the direct descriptor needs to be freed when unregistering. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
kmemleak reported the following:

unreferenced object 0xffff90d47127a920 (size 32):
  comm "modprobe", pid 1766, jiffies 4294792031 (age 162.568s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 22 01 00 00 00 00 ad de  ........".......
    00 78 12 a7 ff ff ff ff 00 00 b6 c0 ff ff ff ff  .x..............
  backtrace:
    [<00000000bb79e72e>] register_ftrace_direct+0xcb/0x3a0
    [<00000000295e4f79>] do_one_initcall+0x72/0x340
    [<00000000873ead18>] do_init_module+0x5a/0x220
    [<00000000974d9de5>] load_module+0x2235/0x2550
    [<0000000059c3d6ce>] __do_sys_finit_module+0xc0/0x120
    [<000000005a8611b4>] do_syscall_64+0x60/0x230
    [<00000000a0cdc49e>] entry_SYSCALL_64_after_hwframe+0x49/0xb3

The entry used to save the direct descriptor needs to be freed
when unregistering.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tracing: Fix memory leaks in trace_events_hist.c 2020-04-23T01:24:00+00:00 Vamshi K Sthambamkadi vamshi.k.sthambamkadi@gmail.com 2020-04-22T06:15:06+00:00 9da73974eb9c965dd9989befb593b8c8da9e4bdc kmemleak report 1: [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270 [<05a2c9ed>] create_field_var+0xcf/0x180 [<528a2d68>] action_create+0xe2/0xc80 [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920 [<28ea5d3d>] trigger_process_regex+0x7b/0xc0 [<3138e86f>] event_trigger_write+0x4d/0xb0 [<ffd66c19>] __vfs_write+0x30/0x200 [<4f424a0d>] vfs_write+0x96/0x1b0 [<da59a290>] ksys_write+0x53/0xc0 [<3717101a>] __ia32_sys_write+0x15/0x20 [<c5f23497>] do_fast_syscall_32+0x70/0x250 [<46e2629c>] entry_SYSENTER_32+0xaf/0x102 This is because save_vars[] of struct hist_trigger_data are not destroyed kmemleak report 2: [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270 [<6e5e97c5>] create_var+0x3c/0x110 [<de82f1b9>] create_field_var+0xaf/0x180 [<528a2d68>] action_create+0xe2/0xc80 [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920 [<28ea5d3d>] trigger_process_regex+0x7b/0xc0 [<3138e86f>] event_trigger_write+0x4d/0xb0 [<ffd66c19>] __vfs_write+0x30/0x200 [<4f424a0d>] vfs_write+0x96/0x1b0 [<da59a290>] ksys_write+0x53/0xc0 [<3717101a>] __ia32_sys_write+0x15/0x20 [<c5f23497>] do_fast_syscall_32+0x70/0x250 [<46e2629c>] entry_SYSENTER_32+0xaf/0x102 struct hist_field allocated through create_var() do not initialize "ref" field to 1. The code in __destroy_hist_field() does not destroy object if "ref" is initialized to zero, the condition if (--hist_field->ref > 1) always passes since unsigned int wraps. kmemleak report 3: [<f8666fcc>] __kmalloc_track_caller+0x139/0x2b0 [<bb7f80a5>] kstrdup+0x27/0x50 [<39d70006>] init_var_ref+0x58/0xd0 [<8ca76370>] create_var_ref+0x89/0xe0 [<f045fc39>] action_create+0x38f/0xc80 [<7c146821>] event_hist_trigger_func+0x15b5/0x1920 [<07de3f61>] trigger_process_regex+0x7b/0xc0 [<e87daf8f>] event_trigger_write+0x4d/0xb0 [<19bf1512>] __vfs_write+0x30/0x200 [<64ce4d27>] vfs_write+0x96/0x1b0 [<a6f34170>] ksys_write+0x53/0xc0 [<7d4230cd>] __ia32_sys_write+0x15/0x20 [<8eadca00>] do_fast_syscall_32+0x70/0x250 [<235cf985>] entry_SYSENTER_32+0xaf/0x102 hist_fields (system & event_name) are not freed Link: http://lkml.kernel.org/r/20200422061503.GA5151@cosmos Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> 
kmemleak report 1:
    [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270
    [<05a2c9ed>] create_field_var+0xcf/0x180
    [<528a2d68>] action_create+0xe2/0xc80
    [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920
    [<28ea5d3d>] trigger_process_regex+0x7b/0xc0
    [<3138e86f>] event_trigger_write+0x4d/0xb0
    [<ffd66c19>] __vfs_write+0x30/0x200
    [<4f424a0d>] vfs_write+0x96/0x1b0
    [<da59a290>] ksys_write+0x53/0xc0
    [<3717101a>] __ia32_sys_write+0x15/0x20
    [<c5f23497>] do_fast_syscall_32+0x70/0x250
    [<46e2629c>] entry_SYSENTER_32+0xaf/0x102

This is because save_vars[] of struct hist_trigger_data are
not destroyed

kmemleak report 2:
    [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270
    [<6e5e97c5>] create_var+0x3c/0x110
    [<de82f1b9>] create_field_var+0xaf/0x180
    [<528a2d68>] action_create+0xe2/0xc80
    [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920
    [<28ea5d3d>] trigger_process_regex+0x7b/0xc0
    [<3138e86f>] event_trigger_write+0x4d/0xb0
    [<ffd66c19>] __vfs_write+0x30/0x200
    [<4f424a0d>] vfs_write+0x96/0x1b0
    [<da59a290>] ksys_write+0x53/0xc0
    [<3717101a>] __ia32_sys_write+0x15/0x20
    [<c5f23497>] do_fast_syscall_32+0x70/0x250
    [<46e2629c>] entry_SYSENTER_32+0xaf/0x102

struct hist_field allocated through create_var() do not initialize
"ref" field to 1. The code in __destroy_hist_field() does not destroy
object if "ref" is initialized to zero, the condition
if (--hist_field->ref > 1) always passes since unsigned int wraps.

kmemleak report 3:
    [<f8666fcc>] __kmalloc_track_caller+0x139/0x2b0
    [<bb7f80a5>] kstrdup+0x27/0x50
    [<39d70006>] init_var_ref+0x58/0xd0
    [<8ca76370>] create_var_ref+0x89/0xe0
    [<f045fc39>] action_create+0x38f/0xc80
    [<7c146821>] event_hist_trigger_func+0x15b5/0x1920
    [<07de3f61>] trigger_process_regex+0x7b/0xc0
    [<e87daf8f>] event_trigger_write+0x4d/0xb0
    [<19bf1512>] __vfs_write+0x30/0x200
    [<64ce4d27>] vfs_write+0x96/0x1b0
    [<a6f34170>] ksys_write+0x53/0xc0
    [<7d4230cd>] __ia32_sys_write+0x15/0x20
    [<8eadca00>] do_fast_syscall_32+0x70/0x250
    [<235cf985>] entry_SYSENTER_32+0xaf/0x102

hist_fields (system & event_name) are not freed

Link: http://lkml.kernel.org/r/20200422061503.GA5151@cosmos

Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>