linux-stable.git/tools, branch linux-5.8.y Linux kernel stable tree bpf: Fix comment for helper bpf_current_task_under_cgroup() 2020-11-01T11:45:41+00:00 Song Liu songliubraving@fb.com 2020-09-10T20:33:14+00:00 a42b1273af7390001f843285004909527f5ab3f2 commit 1aef5b4391f0c75c0a1523706a7b0311846ee12f upstream. This should be "current" not "skb". Fixes: c6b5fb8690fa ("bpf: add documentation for eBPF helpers (42-50)") Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/bpf/20200910203314.70018-1-songliubraving@fb.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1aef5b4391f0c75c0a1523706a7b0311846ee12f upstream.

This should be "current" not "skb".

Fixes: c6b5fb8690fa ("bpf: add documentation for eBPF helpers (42-50)")
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/bpf/20200910203314.70018-1-songliubraving@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
x86/copy_mc: Introduce copy_mc_enhanced_fast_string() 2020-11-01T11:45:37+00:00 Dan Williams dan.j.williams@intel.com 2020-10-06T03:40:25+00:00 61ececc852746242042da22059e8720317ad1424 commit 5da8e4a658109e3b7e1f45ae672b7c06ac3e7158 upstream. The motivations to go rework memcpy_mcsafe() are that the benefit of doing slow and careful copies is obviated on newer CPUs, and that the current opt-in list of CPUs to instrument recovery is broken relative to those CPUs. There is no need to keep an opt-in list up to date on an ongoing basis if pmem/dax operations are instrumented for recovery by default. With recovery enabled by default the old "mcsafe_key" opt-in to careful copying can be made a "fragile" opt-out. Where the "fragile" list takes steps to not consume poison across cachelines. The discussion with Linus made clear that the current "_mcsafe" suffix was imprecise to a fault. The operations that are needed by pmem/dax are to copy from a source address that might throw #MC to a destination that may write-fault, if it is a user page. So copy_to_user_mcsafe() becomes copy_mc_to_user() to indicate the separate precautions taken on source and destination. copy_mc_to_kernel() is introduced as a non-SMAP version that does not expect write-faults on the destination, but is still prepared to abort with an error code upon taking #MC. The original copy_mc_fragile() implementation had negative performance implications since it did not use the fast-string instruction sequence to perform copies. For this reason copy_mc_to_kernel() fell back to plain memcpy() to preserve performance on platforms that did not indicate the capability to recover from machine check exceptions. However, that capability detection was not architectural and now that some platforms can recover from fast-string consumption of memory errors the memcpy() fallback now causes these more capable platforms to fail. Introduce copy_mc_enhanced_fast_string() as the fast default implementation of copy_mc_to_kernel() and finalize the transition of copy_mc_fragile() to be a platform quirk to indicate 'copy-carefully'. With this in place, copy_mc_to_kernel() is fast and recovery-ready by default regardless of hardware capability. Thanks to Vivek for identifying that copy_user_generic() is not suitable as the copy_mc_to_user() backend since the #MC handler explicitly checks ex_has_fault_handler(). Thanks to the 0day robot for catching a performance bug in the x86/copy_mc_to_user implementation. [ bp: Add the "why" for this change from the 0/2th message, massage. ] Fixes: 92b0729c34ca ("x86/mm, x86/mce: Add memcpy_mcsafe()") Reported-by: Erwin Tsaur <erwin.tsaur@intel.com> Reported-by: 0day robot <lkp@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Tested-by: Erwin Tsaur <erwin.tsaur@intel.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/160195562556.2163339.18063423034951948973.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5da8e4a658109e3b7e1f45ae672b7c06ac3e7158 upstream.

The motivations to go rework memcpy_mcsafe() are that the benefit of
doing slow and careful copies is obviated on newer CPUs, and that the
current opt-in list of CPUs to instrument recovery is broken relative to
those CPUs.  There is no need to keep an opt-in list up to date on an
ongoing basis if pmem/dax operations are instrumented for recovery by
default. With recovery enabled by default the old "mcsafe_key" opt-in to
careful copying can be made a "fragile" opt-out. Where the "fragile"
list takes steps to not consume poison across cachelines.

The discussion with Linus made clear that the current "_mcsafe" suffix
was imprecise to a fault. The operations that are needed by pmem/dax are
to copy from a source address that might throw #MC to a destination that
may write-fault, if it is a user page.

So copy_to_user_mcsafe() becomes copy_mc_to_user() to indicate
the separate precautions taken on source and destination.
copy_mc_to_kernel() is introduced as a non-SMAP version that does not
expect write-faults on the destination, but is still prepared to abort
with an error code upon taking #MC.

The original copy_mc_fragile() implementation had negative performance
implications since it did not use the fast-string instruction sequence
to perform copies. For this reason copy_mc_to_kernel() fell back to
plain memcpy() to preserve performance on platforms that did not indicate
the capability to recover from machine check exceptions. However, that
capability detection was not architectural and now that some platforms
can recover from fast-string consumption of memory errors the memcpy()
fallback now causes these more capable platforms to fail.

Introduce copy_mc_enhanced_fast_string() as the fast default
implementation of copy_mc_to_kernel() and finalize the transition of
copy_mc_fragile() to be a platform quirk to indicate 'copy-carefully'.
With this in place, copy_mc_to_kernel() is fast and recovery-ready by
default regardless of hardware capability.

Thanks to Vivek for identifying that copy_user_generic() is not suitable
as the copy_mc_to_user() backend since the #MC handler explicitly checks
ex_has_fault_handler(). Thanks to the 0day robot for catching a
performance bug in the x86/copy_mc_to_user implementation.

 [ bp: Add the "why" for this change from the 0/2th message, massage. ]

Fixes: 92b0729c34ca ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Reported-by: Erwin Tsaur <erwin.tsaur@intel.com>
Reported-by: 0day robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Erwin Tsaur <erwin.tsaur@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/160195562556.2163339.18063423034951948973.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() 2020-11-01T11:45:37+00:00 Dan Williams dan.j.williams@intel.com 2020-10-06T03:40:16+00:00 a092869e0351eae21cbe3f62a3cf254c6f9c000a commit ec6347bb43395cb92126788a1a5b25302543f815 upstream. In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: <stable@vger.kernel.org> Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ec6347bb43395cb92126788a1a5b25302543f815 upstream.

In reaction to a proposal to introduce a memcpy_mcsafe_fast()
implementation Linus points out that memcpy_mcsafe() is poorly named
relative to communicating the scope of the interface. Specifically what
addresses are valid to pass as source, destination, and what faults /
exceptions are handled.

Of particular concern is that even though x86 might be able to handle
the semantics of copy_mc_to_user() with its common copy_user_generic()
implementation other archs likely need / want an explicit path for this
case:

  On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote:
  >
  > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote:
  > >
  > > However now I see that copy_user_generic() works for the wrong reason.
  > > It works because the exception on the source address due to poison
  > > looks no different than a write fault on the user address to the
  > > caller, it's still just a short copy. So it makes copy_to_user() work
  > > for the wrong reason relative to the name.
  >
  > Right.
  >
  > And it won't work that way on other architectures. On x86, we have a
  > generic function that can take faults on either side, and we use it
  > for both cases (and for the "in_user" case too), but that's an
  > artifact of the architecture oddity.
  >
  > In fact, it's probably wrong even on x86 - because it can hide bugs -
  > but writing those things is painful enough that everybody prefers
  > having just one function.

Replace a single top-level memcpy_mcsafe() with either
copy_mc_to_user(), or copy_mc_to_kernel().

Introduce an x86 copy_mc_fragile() name as the rename for the
low-level x86 implementation formerly named memcpy_mcsafe(). It is used
as the slow / careful backend that is supplanted by a fast
copy_mc_generic() in a follow-on patch.

One side-effect of this reorganization is that separating copy_mc_64.S
to its own file means that perf no longer needs to track dependencies
for its memcpy_64.S benchmarks.

 [ bp: Massage a bit. ]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com
Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
selftests/bpf: Fix test_sysctl_loop{1, 2} failure due to clang change 2020-10-29T09:08:26+00:00 Yonghong Song yhs@fb.com 2020-09-09T17:15:42+00:00 445359b326329d0f15454f2b7483cbbe6d6b28a6 [ Upstream commit 7fb5eefd76394cfefb380724a87ca40b47d44405 ] Andrii reported that with latest clang, when building selftests, we have error likes: error: progs/test_sysctl_loop1.c:23:16: in function sysctl_tcp_mem i32 (%struct.bpf_sysctl*): Looks like the BPF stack limit of 512 bytes is exceeded. Please move large on stack variables into BPF per-cpu array map. The error is triggered by the following LLVM patch: https://reviews.llvm.org/D87134 For example, the following code is from test_sysctl_loop1.c: static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx) { volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string"; ... } Without the above LLVM patch, the compiler did optimization to load the string (59 bytes long) with 7 64bit loads, 1 8bit load and 1 16bit load, occupying 64 byte stack size. With the above LLVM patch, the compiler only uses 8bit loads, but subregister is 32bit. So stack requirements become 4 * 59 = 236 bytes. Together with other stuff on the stack, total stack size exceeds 512 bytes, hence compiler complains and quits. To fix the issue, removing "volatile" key word or changing "volatile" to "const"/"static const" does not work, the string is put in .rodata.str1.1 section, which libbpf did not process it and errors out with libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1 libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name' in section '.rodata.str1.1' Defining the string const as global variable can fix the issue as it puts the string constant in '.rodata' section which is recognized by libbpf. In the future, when libbpf can process '.rodata.str*.*' properly, the global definition can be changed back to local definition. Defining tcp_mem_name as a global, however, triggered a verifier failure. ./test_progs -n 7/21 libbpf: load bpf program failed: Permission denied libbpf: -- BEGIN DUMP LOG --- libbpf: invalid stack off=0 size=1 verification time 6975 usec stack depth 160+64 processed 889 insns (limit 1000000) max_states_per_insn 4 total_states 14 peak_states 14 mark_read 10 libbpf: -- END LOG -- libbpf: failed to load program 'sysctl_tcp_mem' libbpf: failed to load object 'test_sysctl_loop2.o' test_bpf_verif_scale:FAIL:114 #7/21 test_sysctl_loop2.o:FAIL This actually exposed a bpf program bug. In test_sysctl_loop{1,2}, we have code like const char tcp_mem_name[] = "<...long string...>"; ... char name[64]; ... for (i = 0; i < sizeof(tcp_mem_name); ++i) if (name[i] != tcp_mem_name[i]) return 0; In the above code, if sizeof(tcp_mem_name) > 64, name[i] access may be out of bound. The sizeof(tcp_mem_name) is 59 for test_sysctl_loop1.c and 79 for test_sysctl_loop2.c. Without promotion-to-global change, old compiler generates code where the overflowed stack access is actually filled with valid value, so hiding the bpf program bug. With promotion-to-global change, the code is different, more specifically, the previous loading constants to stack is gone, and "name" occupies stack[-64:0] and overflow access triggers a verifier error. To fix the issue, adjust "name" buffer size properly. Reported-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200909171542.3673449-1-yhs@fb.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7fb5eefd76394cfefb380724a87ca40b47d44405 ]

Andrii reported that with latest clang, when building selftests, we have
error likes:
  error: progs/test_sysctl_loop1.c:23:16: in function sysctl_tcp_mem i32 (%struct.bpf_sysctl*):
  Looks like the BPF stack limit of 512 bytes is exceeded.
  Please move large on stack variables into BPF per-cpu array map.

The error is triggered by the following LLVM patch:
  https://reviews.llvm.org/D87134

For example, the following code is from test_sysctl_loop1.c:
  static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
  {
    volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string";
    ...
  }
Without the above LLVM patch, the compiler did optimization to load the string
(59 bytes long) with 7 64bit loads, 1 8bit load and 1 16bit load,
occupying 64 byte stack size.

With the above LLVM patch, the compiler only uses 8bit loads, but subregister is 32bit.
So stack requirements become 4 * 59 = 236 bytes. Together with other stuff on
the stack, total stack size exceeds 512 bytes, hence compiler complains and quits.

To fix the issue, removing "volatile" key word or changing "volatile" to
"const"/"static const" does not work, the string is put in .rodata.str1.1 section,
which libbpf did not process it and errors out with
  libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1
  libbpf: prog 'sysctl_tcp_mem': bad map relo against '.L__const.is_tcp_mem.tcp_mem_name'
          in section '.rodata.str1.1'

Defining the string const as global variable can fix the issue as it puts the string constant
in '.rodata' section which is recognized by libbpf. In the future, when libbpf can process
'.rodata.str*.*' properly, the global definition can be changed back to local definition.

Defining tcp_mem_name as a global, however, triggered a verifier failure.
   ./test_progs -n 7/21
  libbpf: load bpf program failed: Permission denied
  libbpf: -- BEGIN DUMP LOG ---
  libbpf:
  invalid stack off=0 size=1
  verification time 6975 usec
  stack depth 160+64
  processed 889 insns (limit 1000000) max_states_per_insn 4 total_states
  14 peak_states 14 mark_read 10

  libbpf: -- END LOG --
  libbpf: failed to load program 'sysctl_tcp_mem'
  libbpf: failed to load object 'test_sysctl_loop2.o'
  test_bpf_verif_scale:FAIL:114
  #7/21 test_sysctl_loop2.o:FAIL
This actually exposed a bpf program bug. In test_sysctl_loop{1,2}, we have code
like
  const char tcp_mem_name[] = "<...long string...>";
  ...
  char name[64];
  ...
  for (i = 0; i < sizeof(tcp_mem_name); ++i)
      if (name[i] != tcp_mem_name[i])
          return 0;
In the above code, if sizeof(tcp_mem_name) > 64, name[i] access may be
out of bound. The sizeof(tcp_mem_name) is 59 for test_sysctl_loop1.c and
79 for test_sysctl_loop2.c.

Without promotion-to-global change, old compiler generates code where
the overflowed stack access is actually filled with valid value, so hiding
the bpf program bug. With promotion-to-global change, the code is different,
more specifically, the previous loading constants to stack is gone, and
"name" occupies stack[-64:0] and overflow access triggers a verifier error.
To fix the issue, adjust "name" buffer size properly.

Reported-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909171542.3673449-1-yhs@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
libbpf: Close map fd if init map slots failed 2020-10-29T09:08:21+00:00 Hangbin Liu liuhangbin@gmail.com 2020-10-06T02:13:43+00:00 6afdaf29e4c2394e94a5df5c747673c2343d9764 [ Upstream commit a0f2b7acb4b1d29127ff99c714233b973afd1411 ] Previously we forgot to close the map fd if bpf_map_update_elem() failed during map slot init, which will leak map fd. Let's move map slot initialization to new function init_map_slots() to simplify the code. And close the map fd if init slot failed. Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201006021345.3817033-2-liuhangbin@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit a0f2b7acb4b1d29127ff99c714233b973afd1411 ]

Previously we forgot to close the map fd if bpf_map_update_elem()
failed during map slot init, which will leak map fd.

Let's move map slot initialization to new function init_map_slots() to
simplify the code. And close the map fd if init slot failed.

Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201006021345.3817033-2-liuhangbin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
selftests/powerpc: Fix eeh-basic.sh exit codes 2020-10-29T09:08:02+00:00 Oliver O'Halloran oohall@gmail.com 2020-10-14T02:47:11+00:00 a08401b32a3a5bfd186aa30a182dc98d1b9936a2 [ Upstream commit 996f9e0f93f16211945c8d5f18f296a88cb32f91 ] The kselftests test running infrastructure expects tests to finish with an exit code of 4 if the test decided it should be skipped. Currently eeh-basic.sh exits with the number of devices that failed to recover, so if four devices didn't recover we'll report a skip instead of a fail. Fix this by checking if the return code is non-zero and report success and failure by returning 0 or 1 respectively. For the cases where should actually skip return 4. Fixes: 85d86c8aa52e ("selftests/powerpc: Add basic EEH selftest") Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201014024711.1138386-1-oohall@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 996f9e0f93f16211945c8d5f18f296a88cb32f91 ]

The kselftests test running infrastructure expects tests to finish with an
exit code of 4 if the test decided it should be skipped. Currently
eeh-basic.sh exits with the number of devices that failed to recover, so if
four devices didn't recover we'll report a skip instead of a fail.

Fix this by checking if the return code is non-zero and report success
and failure by returning 0 or 1 respectively. For the cases where should
actually skip return 4.

Fixes: 85d86c8aa52e ("selftests/powerpc: Add basic EEH selftest")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201014024711.1138386-1-oohall@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
perf trace: Fix off by ones in memset() after realloc() in arches using libaudit 2020-10-29T09:08:02+00:00 Jiri Slaby jslaby@suse.cz 2020-10-01T09:34:19+00:00 bb24e3cb31cde6ce5175146b594b7ca159c1f0e7 [ Upstream commit f3013f7ed465479e60c1ab1921a5718fc541cc3b ] 'perf trace ls' started crashing after commit d21cb73a9025 on !HAVE_SYSCALL_TABLE_SUPPORT configs (armv7l here) like this: 0 strlen () at ../sysdeps/arm/armv6t2/strlen.S:126 1 0xb6800780 in __vfprintf_internal (s=0xbeff9908, s@entry=0xbeff9900, format=0xa27160 "]: %s()", ap=..., mode_flags=<optimized out>) at vfprintf-internal.c:1688 ... 5 0x0056ecdc in fprintf (__fmt=0xa27160 "]: %s()", __stream=<optimized out>) at /usr/include/bits/stdio2.h:100 6 trace__sys_exit (trace=trace@entry=0xbeffc710, evsel=evsel@entry=0xd968d0, event=<optimized out>, sample=sample@entry=0xbeffc3e8) at builtin-trace.c:2475 7 0x00566d40 in trace__handle_event (sample=0xbeffc3e8, event=<optimized out>, trace=0xbeffc710) at builtin-trace.c:3122 ... 15 main (argc=2, argv=0xbefff6e8) at perf.c:538 It is because memset in trace__read_syscall_info zeroes wrong memory: 1) when initializing for the first time, it does not reset the last id. 2) in other cases, it resets the last id of previous buffer. ad 1) it causes the crash above as sc->name used in the fprintf above contains garbage. ad 2) it sets nonexistent from true back to false for id 11 here. Not sure, what the consequences are. So fix it by introducing a special case for the initial initialization and do the right +1 in both cases. Fixes: d21cb73a9025 ("perf trace: Grow the syscall table as needed when using libaudit") Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lore.kernel.org/lkml/20201001093419.15761-1-jslaby@suse.cz Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f3013f7ed465479e60c1ab1921a5718fc541cc3b ]

'perf trace ls' started crashing after commit d21cb73a9025 on
!HAVE_SYSCALL_TABLE_SUPPORT configs (armv7l here) like this:

  0  strlen () at ../sysdeps/arm/armv6t2/strlen.S:126
  1  0xb6800780 in __vfprintf_internal (s=0xbeff9908, s@entry=0xbeff9900, format=0xa27160 "]: %s()", ap=..., mode_flags=<optimized out>) at vfprintf-internal.c:1688
  ...
  5  0x0056ecdc in fprintf (__fmt=0xa27160 "]: %s()", __stream=<optimized out>) at /usr/include/bits/stdio2.h:100
  6  trace__sys_exit (trace=trace@entry=0xbeffc710, evsel=evsel@entry=0xd968d0, event=<optimized out>, sample=sample@entry=0xbeffc3e8) at builtin-trace.c:2475
  7  0x00566d40 in trace__handle_event (sample=0xbeffc3e8, event=<optimized out>, trace=0xbeffc710) at builtin-trace.c:3122
  ...
  15 main (argc=2, argv=0xbefff6e8) at perf.c:538

It is because memset in trace__read_syscall_info zeroes wrong memory:

1) when initializing for the first time, it does not reset the last id.

2) in other cases, it resets the last id of previous buffer.

ad 1) it causes the crash above as sc->name used in the fprintf above
      contains garbage.

ad 2) it sets nonexistent from true back to false for id 11 here. Not
      sure, what the consequences are.

So fix it by introducing a special case for the initial initialization
and do the right +1 in both cases.

Fixes: d21cb73a9025 ("perf trace: Grow the syscall table as needed when using libaudit")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20201001093419.15761-1-jslaby@suse.cz
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
perf stat: Fix out of bounds CPU map access when handling armv8_pmu events 2020-10-29T09:08:00+00:00 Namhyung Kim namhyung@kernel.org 2020-10-07T08:13:11+00:00 69a4718cb2bc1b306dffe87240eb0c4738bcfea2 [ Upstream commit bef69bd7cfc363ab94b84ea29102f3e913ed3c6c ] It was reported that 'perf stat' crashed when using with armv8_pmu (CPU) events with the task mode. As 'perf stat' uses an empty cpu map for task mode but armv8_pmu has its own cpu mask, it has confused which map it should use when accessing file descriptors and this causes segfaults: (gdb) bt #0 0x0000000000603fc8 in perf_evsel__close_fd_cpu (evsel=<optimized out>, cpu=<optimized out>) at evsel.c:122 #1 perf_evsel__close_cpu (evsel=evsel@entry=0x716e950, cpu=7) at evsel.c:156 #2 0x00000000004d4718 in evlist__close (evlist=0x70a7cb0) at util/evlist.c:1242 #3 0x0000000000453404 in __run_perf_stat (argc=3, argc@entry=1, argv=0x30, argv@entry=0xfffffaea2f90, run_idx=119, run_idx@entry=1701998435) at builtin-stat.c:929 #4 0x0000000000455058 in run_perf_stat (run_idx=1701998435, argv=0xfffffaea2f90, argc=1) at builtin-stat.c:947 #5 cmd_stat (argc=1, argv=0xfffffaea2f90) at builtin-stat.c:2357 #6 0x00000000004bb888 in run_builtin (p=p@entry=0x9764b8 <commands+288>, argc=argc@entry=4, argv=argv@entry=0xfffffaea2f90) at perf.c:312 #7 0x00000000004bbb54 in handle_internal_command (argc=argc@entry=4, argv=argv@entry=0xfffffaea2f90) at perf.c:364 #8 0x0000000000435378 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:408 #9 main (argc=4, argv=0xfffffaea2f90) at perf.c:538 To fix this, I simply used the given cpu map unless the evsel actually is not a system-wide event (like uncore events). Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors") Reported-by: Wei Li <liwei391@huawei.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Barry Song <song.bao.hua@hisilicon.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20201007081311.1831003-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit bef69bd7cfc363ab94b84ea29102f3e913ed3c6c ]

It was reported that 'perf stat' crashed when using with armv8_pmu (CPU)
events with the task mode.  As 'perf stat' uses an empty cpu map for
task mode but armv8_pmu has its own cpu mask, it has confused which map
it should use when accessing file descriptors and this causes segfaults:

  (gdb) bt
  #0  0x0000000000603fc8 in perf_evsel__close_fd_cpu (evsel=<optimized out>,
      cpu=<optimized out>) at evsel.c:122
  #1  perf_evsel__close_cpu (evsel=evsel@entry=0x716e950, cpu=7) at evsel.c:156
  #2  0x00000000004d4718 in evlist__close (evlist=0x70a7cb0) at util/evlist.c:1242
  #3  0x0000000000453404 in __run_perf_stat (argc=3, argc@entry=1, argv=0x30,
      argv@entry=0xfffffaea2f90, run_idx=119, run_idx@entry=1701998435)
      at builtin-stat.c:929
  #4  0x0000000000455058 in run_perf_stat (run_idx=1701998435, argv=0xfffffaea2f90,
      argc=1) at builtin-stat.c:947
  #5  cmd_stat (argc=1, argv=0xfffffaea2f90) at builtin-stat.c:2357
  #6  0x00000000004bb888 in run_builtin (p=p@entry=0x9764b8 <commands+288>,
      argc=argc@entry=4, argv=argv@entry=0xfffffaea2f90) at perf.c:312
  #7  0x00000000004bbb54 in handle_internal_command (argc=argc@entry=4,
      argv=argv@entry=0xfffffaea2f90) at perf.c:364
  #8  0x0000000000435378 in run_argv (argcp=<synthetic pointer>,
      argv=<synthetic pointer>) at perf.c:408
  #9  main (argc=4, argv=0xfffffaea2f90) at perf.c:538

To fix this, I simply used the given cpu map unless the evsel actually
is not a system-wide event (like uncore events).

Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors")
Reported-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Barry Song <song.bao.hua@hisilicon.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201007081311.1831003-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
perf stat: Skip duration_time in setup_system_wide 2020-10-29T09:07:58+00:00 Jin Yao yao.jin@linux.intel.com 2020-09-22T01:50:04+00:00 939faf1216321942e5c6124fda0bbee0657eecab [ Upstream commit 002a3d690f95804bdef6b70b26154103518e13d9 ] Some metrics (such as DRAM_BW_Use) consists of uncore events and duration_time. For uncore events, counter->core.system_wide is true. But for duration_time, counter->core.system_wide is false so target.system_wide is set to false. Then 'enable_on_exec' is set in perf_event_attr of uncore event. Kernel will return error when trying to open the uncore event. This patch skips the duration_time in setup_system_wide then target.system_wide will be set to true for the evlist of uncore events + duration_time. Before (tested on skylake desktop): # perf stat -M DRAM_BW_Use -- sleep 1 Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (arb/event=0x84,umask=0x1/). /bin/dmesg | grep -i perf may provide additional information. After: # perf stat -M DRAM_BW_Use -- sleep 1 Performance counter stats for 'system wide': 169 arb/event=0x84,umask=0x1/ # 0.00 DRAM_BW_Use 40,427 arb/event=0x81,umask=0x1/ 1,000,902,197 ns duration_time 1.000902197 seconds time elapsed Fixes: e3ba76deef23064f ("perf tools: Force uncore events to system wide monitoring") Signed-off-by: Jin Yao <yao.jin@linux.intel.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jin Yao <yao.jin@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lore.kernel.org/lkml/20200922015004.30114-1-yao.jin@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 002a3d690f95804bdef6b70b26154103518e13d9 ]

Some metrics (such as DRAM_BW_Use) consists of uncore events and
duration_time. For uncore events, counter->core.system_wide is true. But
for duration_time, counter->core.system_wide is false so
target.system_wide is set to false.

Then 'enable_on_exec' is set in perf_event_attr of uncore event.  Kernel
will return error when trying to open the uncore event.

This patch skips the duration_time in setup_system_wide then
target.system_wide will be set to true for the evlist of uncore events +
duration_time.

Before (tested on skylake desktop):

  # perf stat -M DRAM_BW_Use -- sleep 1
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (arb/event=0x84,umask=0x1/).
  /bin/dmesg | grep -i perf may provide additional information.

After:

  # perf stat -M DRAM_BW_Use -- sleep 1

   Performance counter stats for 'system wide':

                169      arb/event=0x84,umask=0x1/ #     0.00 DRAM_BW_Use
             40,427      arb/event=0x81,umask=0x1/
      1,000,902,197 ns   duration_time

        1.000902197 seconds time elapsed

Fixes: e3ba76deef23064f ("perf tools: Force uncore events to system wide monitoring")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200922015004.30114-1-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
perf intel-pt: Fix "context_switch event has no tid" error 2020-10-29T09:07:57+00:00 Adrian Hunter adrian.hunter@intel.com 2020-09-09T08:49:23+00:00 be825f704b2f99b8519dc3299d7ad4e01cc7f770 [ Upstream commit 7d537a8d2e76bc4fc71e34545ceaa463ac2cd928 ] A context_switch event can have no tid because pids can be detached from a task while the task is still running (in do_exit()). Note this won't happen with per-task contexts because then tracing stops at perf_event_exit_task() If a task with no tid gets preempted, or a dying task gets preempted and its parent releases it, when it subsequently gets switched back in, Intel PT will not be able to determine what task is running and prints an error "context_switch event has no tid". However, it is not really an error because the task is in kernel space and the decoder can continue to decode successfully. Fix by changing the error to be only a logged message, and make allowance for tid == -1. Example: Using 5.9-rc4 with Preemptible Kernel (Low-Latency Desktop) e.g. $ uname -r 5.9.0-rc4 $ grep PREEMPT .config # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set CONFIG_PREEMPT=y CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_NOTIFIERS=y CONFIG_DRM_I915_PREEMPT_TIMEOUT=640 CONFIG_DEBUG_PREEMPT=y # CONFIG_PREEMPT_TRACER is not set # CONFIG_PREEMPTIRQ_DELAY_TEST is not set Before: $ cat forkit.c #include <sys/types.h> #include <unistd.h> #include <sys/wait.h> int main() { pid_t child; int status = 0; child = fork(); if (child == 0) return 123; wait(&status); return 0; } $ gcc -o forkit forkit.c $ sudo ~/bin/perf record --kcore -a -m,64M -e intel_pt/cyc/k & [1] 11016 $ taskset 2 ./forkit $ sudo pkill perf $ [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 17.262 MB perf.data ] [1]+ Terminated sudo ~/bin/perf record --kcore -a -m,64M -e intel_pt/cyc/k $ sudo ~/bin/perf script --show-task-events --show-switch-events --itrace=iqqe-o -C 1 --ns | grep -C 2 forkit context_switch event has no tid taskset 11019 [001] 66663.270045029: 1 instructions:k: ffffffffb1d9f844 strnlen_user+0xb4 ([kernel.kallsyms]) taskset 11019 [001] 66663.270201816: 1 instructions:k: ffffffffb1a83121 unmap_page_range+0x561 ([kernel.kallsyms]) forkit 11019 [001] 66663.270327553: PERF_RECORD_COMM exec: forkit:11019/11019 forkit 11019 [001] 66663.270420028: 1 instructions:k: ffffffffb1db9537 __clear_user+0x27 ([kernel.kallsyms]) forkit 11019 [001] 66663.270648704: 1 instructions:k: ffffffffb18829e6 do_user_addr_fault+0xf6 ([kernel.kallsyms]) forkit 11019 [001] 66663.270833163: 1 instructions:k: ffffffffb230a825 irqentry_exit_to_user_mode+0x15 ([kernel.kallsyms]) forkit 11019 [001] 66663.271092359: 1 instructions:k: ffffffffb1aea3d9 lock_page_memcg+0x9 ([kernel.kallsyms]) forkit 11019 [001] 66663.271207092: PERF_RECORD_FORK(11020:11020):(11019:11019) forkit 11019 [001] 66663.271234775: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 11020/11020 forkit 11020 [001] 66663.271238407: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11019/11019 forkit 11020 [001] 66663.271312066: 1 instructions:k: ffffffffb1a88140 handle_mm_fault+0x10 ([kernel.kallsyms]) forkit 11020 [001] 66663.271476225: PERF_RECORD_EXIT(11020:11020):(11019:11019) forkit 11020 [001] 66663.271497488: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11019/11019 forkit 11019 [001] 66663.271500523: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11020/11020 forkit 11019 [001] 66663.271517241: 1 instructions:k: ffffffffb24012cd error_entry+0x6d ([kernel.kallsyms]) forkit 11019 [001] 66663.271664080: PERF_RECORD_EXIT(11019:11019):(1386:1386) After: $ sudo ~/bin/perf script --show-task-events --show-switch-events --itrace=iqqe-o -C 1 --ns | grep -C 2 forkit taskset 11019 [001] 66663.270045029: 1 instructions:k: ffffffffb1d9f844 strnlen_user+0xb4 ([kernel.kallsyms]) taskset 11019 [001] 66663.270201816: 1 instructions:k: ffffffffb1a83121 unmap_page_range+0x561 ([kernel.kallsyms]) forkit 11019 [001] 66663.270327553: PERF_RECORD_COMM exec: forkit:11019/11019 forkit 11019 [001] 66663.270420028: 1 instructions:k: ffffffffb1db9537 __clear_user+0x27 ([kernel.kallsyms]) forkit 11019 [001] 66663.270648704: 1 instructions:k: ffffffffb18829e6 do_user_addr_fault+0xf6 ([kernel.kallsyms]) forkit 11019 [001] 66663.270833163: 1 instructions:k: ffffffffb230a825 irqentry_exit_to_user_mode+0x15 ([kernel.kallsyms]) forkit 11019 [001] 66663.271092359: 1 instructions:k: ffffffffb1aea3d9 lock_page_memcg+0x9 ([kernel.kallsyms]) forkit 11019 [001] 66663.271207092: PERF_RECORD_FORK(11020:11020):(11019:11019) forkit 11019 [001] 66663.271234775: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 11020/11020 forkit 11020 [001] 66663.271238407: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11019/11019 forkit 11020 [001] 66663.271312066: 1 instructions:k: ffffffffb1a88140 handle_mm_fault+0x10 ([kernel.kallsyms]) forkit 11020 [001] 66663.271476225: PERF_RECORD_EXIT(11020:11020):(11019:11019) forkit 11020 [001] 66663.271497488: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11019/11019 forkit 11019 [001] 66663.271500523: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11020/11020 forkit 11019 [001] 66663.271517241: 1 instructions:k: ffffffffb24012cd error_entry+0x6d ([kernel.kallsyms]) forkit 11019 [001] 66663.271664080: PERF_RECORD_EXIT(11019:11019):(1386:1386) forkit 11019 [001] 66663.271688752: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: -1/-1 :-1 -1 [001] 66663.271692086: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11019/11019 :-1 -1 [001] 66663.271707466: 1 instructions:k: ffffffffb18eb096 update_load_avg+0x306 ([kernel.kallsyms]) Fixes: 86c2786994bd7c ("perf intel-pt: Add support for PERF_RECORD_SWITCH") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Yu-cheng Yu <yu-cheng.yu@intel.com> Link: http://lore.kernel.org/lkml/20200909084923.9096-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7d537a8d2e76bc4fc71e34545ceaa463ac2cd928 ]

A context_switch event can have no tid because pids can be detached from
a task while the task is still running (in do_exit()). Note this won't
happen with per-task contexts because then tracing stops at
perf_event_exit_task()

If a task with no tid gets preempted, or a dying task gets preempted and
its parent releases it, when it subsequently gets switched back in,
Intel PT will not be able to determine what task is running and prints
an error "context_switch event has no tid". However, it is not really an
error because the task is in kernel space and the decoder can continue
to decode successfully. Fix by changing the error to be only a logged
message, and make allowance for tid == -1.

Example:

  Using 5.9-rc4 with Preemptible Kernel (Low-Latency Desktop) e.g.
  $ uname -r
  5.9.0-rc4
  $ grep PREEMPT .config
  # CONFIG_PREEMPT_NONE is not set
  # CONFIG_PREEMPT_VOLUNTARY is not set
  CONFIG_PREEMPT=y
  CONFIG_PREEMPT_COUNT=y
  CONFIG_PREEMPTION=y
  CONFIG_PREEMPT_RCU=y
  CONFIG_PREEMPT_NOTIFIERS=y
  CONFIG_DRM_I915_PREEMPT_TIMEOUT=640
  CONFIG_DEBUG_PREEMPT=y
  # CONFIG_PREEMPT_TRACER is not set
  # CONFIG_PREEMPTIRQ_DELAY_TEST is not set

Before:

  $ cat forkit.c

  #include <sys/types.h>
  #include <unistd.h>
  #include <sys/wait.h>

  int main()
  {
          pid_t child;
          int status = 0;

          child = fork();
          if (child == 0)
                  return 123;
          wait(&status);
          return 0;
  }

  $ gcc -o forkit forkit.c
  $ sudo ~/bin/perf record --kcore -a -m,64M -e intel_pt/cyc/k &
  [1] 11016
  $ taskset 2 ./forkit
  $ sudo pkill perf
  $ [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 17.262 MB perf.data ]

  [1]+  Terminated              sudo ~/bin/perf record --kcore -a -m,64M -e intel_pt/cyc/k
  $ sudo ~/bin/perf script --show-task-events --show-switch-events --itrace=iqqe-o -C 1 --ns | grep -C 2 forkit
  context_switch event has no tid
           taskset 11019 [001] 66663.270045029:          1 instructions:k:  ffffffffb1d9f844 strnlen_user+0xb4 ([kernel.kallsyms])
           taskset 11019 [001] 66663.270201816:          1 instructions:k:  ffffffffb1a83121 unmap_page_range+0x561 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270327553: PERF_RECORD_COMM exec: forkit:11019/11019
            forkit 11019 [001] 66663.270420028:          1 instructions:k:  ffffffffb1db9537 __clear_user+0x27 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270648704:          1 instructions:k:  ffffffffb18829e6 do_user_addr_fault+0xf6 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270833163:          1 instructions:k:  ffffffffb230a825 irqentry_exit_to_user_mode+0x15 ([kernel.kallsyms])
            forkit 11019 [001] 66663.271092359:          1 instructions:k:  ffffffffb1aea3d9 lock_page_memcg+0x9 ([kernel.kallsyms])
            forkit 11019 [001] 66663.271207092: PERF_RECORD_FORK(11020:11020):(11019:11019)
            forkit 11019 [001] 66663.271234775: PERF_RECORD_SWITCH_CPU_WIDE OUT          next pid/tid: 11020/11020
            forkit 11020 [001] 66663.271238407: PERF_RECORD_SWITCH_CPU_WIDE IN           prev pid/tid: 11019/11019
            forkit 11020 [001] 66663.271312066:          1 instructions:k:  ffffffffb1a88140 handle_mm_fault+0x10 ([kernel.kallsyms])
            forkit 11020 [001] 66663.271476225: PERF_RECORD_EXIT(11020:11020):(11019:11019)
            forkit 11020 [001] 66663.271497488: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt  next pid/tid: 11019/11019
            forkit 11019 [001] 66663.271500523: PERF_RECORD_SWITCH_CPU_WIDE IN           prev pid/tid: 11020/11020
            forkit 11019 [001] 66663.271517241:          1 instructions:k:  ffffffffb24012cd error_entry+0x6d ([kernel.kallsyms])
            forkit 11019 [001] 66663.271664080: PERF_RECORD_EXIT(11019:11019):(1386:1386)

After:

  $ sudo ~/bin/perf script --show-task-events --show-switch-events --itrace=iqqe-o -C 1 --ns | grep -C 2 forkit
           taskset 11019 [001] 66663.270045029:          1 instructions:k:  ffffffffb1d9f844 strnlen_user+0xb4 ([kernel.kallsyms])
           taskset 11019 [001] 66663.270201816:          1 instructions:k:  ffffffffb1a83121 unmap_page_range+0x561 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270327553: PERF_RECORD_COMM exec: forkit:11019/11019
            forkit 11019 [001] 66663.270420028:          1 instructions:k:  ffffffffb1db9537 __clear_user+0x27 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270648704:          1 instructions:k:  ffffffffb18829e6 do_user_addr_fault+0xf6 ([kernel.kallsyms])
            forkit 11019 [001] 66663.270833163:          1 instructions:k:  ffffffffb230a825 irqentry_exit_to_user_mode+0x15 ([kernel.kallsyms])
            forkit 11019 [001] 66663.271092359:          1 instructions:k:  ffffffffb1aea3d9 lock_page_memcg+0x9 ([kernel.kallsyms])
            forkit 11019 [001] 66663.271207092: PERF_RECORD_FORK(11020:11020):(11019:11019)
            forkit 11019 [001] 66663.271234775: PERF_RECORD_SWITCH_CPU_WIDE OUT          next pid/tid: 11020/11020
            forkit 11020 [001] 66663.271238407: PERF_RECORD_SWITCH_CPU_WIDE IN           prev pid/tid: 11019/11019
            forkit 11020 [001] 66663.271312066:          1 instructions:k:  ffffffffb1a88140 handle_mm_fault+0x10 ([kernel.kallsyms])
            forkit 11020 [001] 66663.271476225: PERF_RECORD_EXIT(11020:11020):(11019:11019)
            forkit 11020 [001] 66663.271497488: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt  next pid/tid: 11019/11019
            forkit 11019 [001] 66663.271500523: PERF_RECORD_SWITCH_CPU_WIDE IN           prev pid/tid: 11020/11020
            forkit 11019 [001] 66663.271517241:          1 instructions:k:  ffffffffb24012cd error_entry+0x6d ([kernel.kallsyms])
            forkit 11019 [001] 66663.271664080: PERF_RECORD_EXIT(11019:11019):(1386:1386)
            forkit 11019 [001] 66663.271688752: PERF_RECORD_SWITCH_CPU_WIDE OUT          next pid/tid:    -1/-1
               :-1    -1 [001] 66663.271692086: PERF_RECORD_SWITCH_CPU_WIDE IN           prev pid/tid: 11019/11019
                :-1    -1 [001] 66663.271707466:          1 instructions:k:  ffffffffb18eb096 update_load_avg+0x306 ([kernel.kallsyms])

Fixes: 86c2786994bd7c ("perf intel-pt: Add support for PERF_RECORD_SWITCH")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lore.kernel.org/lkml/20200909084923.9096-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>