linux-toradex.git/tools/perf/util/symbol.c, branch v6.3

perf symbols: Symbol lookup with kcore can fail if multiple segments match stext

2023-02-02T19:32:19+00:00

This problem was encountered on an arm64 system with a lot of memory.
Without kernel debug symbols installed, and with both kcore and kallsyms
available, perf managed to get confused and returned "unknown" for all
of the kernel symbols that it tried to look up.

On this system, stext fell within the vmalloc segment.  The kcore symbol
matching code tries to find the first segment that contains stext and
uses that to replace the segment generated from just the kallsyms
information.  In this case, however, there were two: a very large
vmalloc segment, and the text segment.  This caused perf to get confused
because multiple overlapping segments were inserted into the RB tree
that holds the discovered segments.  However, that alone wasn't
sufficient to cause the problem. Even when we could find the segment,
the offsets were adjusted in such a way that the newly generated symbols
didn't line up with the instruction addresses in the trace.  The most
obvious solution would be to consult which segment type is text from
kcore, but this information is not exposed to users.

Instead, select the smallest matching segment that contains stext
instead of the first matching segment.  This allows us to match the text
segment instead of vmalloc, if one is contained within the other.

Reviewed-by: Adrian Hunter 
Signed-off-by: Krister Johansen 
Cc: Alexander Shishkin 
Cc: David Reaver 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Michael Petlan 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lore.kernel.org/lkml/20230125183418.GD1963@templeofstupid.com
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Record whether a symbol is an alias for an IFUNC symbol

2023-02-02T00:49:29+00:00

To assist with synthesizing plt symbols for IFUNCs, record whether a
symbol is an alias of an IFUNC symbol.

Reviewed-by: Namhyung Kim 
Signed-off-by: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Link: https://lore.kernel.org/r/20230131131625.6964-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf symbols: Add dso__find_symbol_nocache()

2023-01-22T21:10:12+00:00

Symbols should not be cached when there are more symbols still to add.

Add dso__find_symbol_nocache() to facilitate that.

Signed-off-by: Adrian Hunter 
Acked-by: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/r/20230120123456.12449-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf dso: Hold lock when accessing nsinfo

2022-10-04T11:55:20+00:00

There may be threads racing to update dso->nsinfo:

  https://lore.kernel.org/linux-perf-users/CAP-5=fWZH20L4kv-BwVtGLwR=Em3AOOT+Q4QGivvQuYn5AsPRg@mail.gmail.com/

Holding the dso->lock avoids use-after-free, memory leaks and other such
bugs. Apply the fix in:

  https://lore.kernel.org/linux-perf-users/20211118193714.2293728-1-irogers@google.com/

of there being a missing nsinfo__put now that the accesses are data race
free. Fixes test "Lookup mmap thread" when compiled with address
sanitizer.

Signed-off-by: Ian Rogers 
Reviewed-by: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Alexandre Truong 
Cc: Alexey Bayduraev 
Cc: Andi Kleen 
Cc: Andres Freund 
Cc: Andrii Nakryiko 
Cc: André Almeida 
Cc: Athira Jajeev 
Cc: Christophe JAILLET 
Cc: Colin Ian King 
Cc: Dario Petrillo 
Cc: Darren Hart 
Cc: Dave Marchevsky 
Cc: Davidlohr Bueso 
Cc: Fangrui Song 
Cc: Hewenliang 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jason Wang 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Kim Phillips 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Martin Liška 
Cc: Masami Hiramatsu 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Pavithra Gurushankar 
Cc: Peter Zijlstra 
Cc: Quentin Monnet 
Cc: Ravi Bangoria 
Cc: Remi Bernon 
Cc: Riccardo Mancini 
Cc: Song Liu 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Thomas Richter 
Cc: Tom Rix 
Cc: Weiguo Li 
Cc: Wenyu Liu 
Cc: William Cohen 
Cc: Zechuan Chen 
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Cc: yaowenbin 
Link: https://lore.kernel.org/r/20220826164242.43412-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf dso: Update use of pthread mutex

2022-10-04T11:55:20+00:00

Switch to the use of mutex wrappers that provide better error checking.

Signed-off-by: Ian Rogers 
Reviewed-by: Adrian Hunter 
Acked-by: Namhyung Kim 
Cc: Alexander Shishkin 
Cc: Alexandre Truong 
Cc: Alexey Bayduraev 
Cc: Andi Kleen 
Cc: Andres Freund 
Cc: Andrii Nakryiko 
Cc: André Almeida 
Cc: Athira Jajeev 
Cc: Christophe JAILLET 
Cc: Colin Ian King 
Cc: Dario Petrillo 
Cc: Darren Hart 
Cc: Dave Marchevsky 
Cc: Davidlohr Bueso 
Cc: Fangrui Song 
Cc: Hewenliang 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jason Wang 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Kim Phillips 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Martin Liška 
Cc: Masami Hiramatsu 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Pavithra Gurushankar 
Cc: Peter Zijlstra 
Cc: Quentin Monnet 
Cc: Ravi Bangoria 
Cc: Remi Bernon 
Cc: Riccardo Mancini 
Cc: Song Liu 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Thomas Richter 
Cc: Tom Rix 
Cc: Weiguo Li 
Cc: Wenyu Liu 
Cc: William Cohen 
Cc: Zechuan Chen 
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Cc: yaowenbin 
Link: https://lore.kernel.org/r/20220826164242.43412-12-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Automatically use guest kcore_dir if present

2022-07-20T14:08:37+00:00

When registering a guest machine using machine_pid from the id index,
check perf.data for a matching kcore_dir subdirectory and set the
kallsyms file name accordingly. If set, use it to find the machine's
kernel symbols and object code (from kcore).

Signed-off-by: Adrian Hunter 
Cc: Andi Kleen 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-23-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf symbol: Remove archsymbolsfixup_end()

2022-04-28T13:51:40+00:00

Now the generic code can handle kallsyms fixup properly so no need to
keep the arch-functions anymore.

Fixes: 3cf6a32f3f2a4594 ("perf symbols: Fix symbol size calculation condition")
Signed-off-by: Namhyung Kim 
Acked-by: Ian Rogers 
Cc: Heiko Carstens 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Masami Hiramatsu 
Cc: Mathieu Poirier 
Cc: Michael Ellerman 
Cc: Michael Petlan 
Cc: Peter Zijlstra 
Cc: Song Liu 
Cc: Will Deacon 
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20220416004048.1514900-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf symbol: Update symbols__fixup_end()

2022-04-28T13:51:33+00:00

Now arch-specific functions all do the same thing.  When it fixes the
symbol address it needs to check the boundary between the kernel image
and modules.  For the last symbol in the previous region, it cannot
know the exact size as it's discarded already.  Thus it just uses a
small page size (4096) and rounds it up like the last symbol.

Fixes: 3cf6a32f3f2a4594 ("perf symbols: Fix symbol size calculation condition")
Signed-off-by: Namhyung Kim 
Acked-by: Ian Rogers 
Cc: Heiko Carstens 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Masami Hiramatsu 
Cc: Mathieu Poirier 
Cc: Michael Ellerman 
Cc: Michael Petlan 
Cc: Peter Zijlstra 
Cc: Song Liu 
Cc: Will Deacon 
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20220416004048.1514900-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf symbol: Pass is_kallsyms to symbols__fixup_end()

2022-04-28T13:51:20+00:00

The symbol fixup is necessary for symbols in kallsyms since they don't
have size info.  So we use the next symbol's address to calculate the
size.  Now it's also used for user binaries because sometimes they miss
size for hand-written asm functions.

There's a arch-specific function to handle kallsyms differently but
currently it cannot distinguish kallsyms from others.  Pass this
information explicitly to handle it properly.  Note that those arch
functions will be moved to the generic function so I didn't added it to
the arch-functions.

Fixes: 3cf6a32f3f2a4594 ("perf symbols: Fix symbol size calculation condition")
Signed-off-by: Namhyung Kim 
Acked-by: Ian Rogers 
Cc: Heiko Carstens 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Masami Hiramatsu 
Cc: Mathieu Poirier 
Cc: Michael Ellerman 
Cc: Michael Petlan 
Cc: Peter Zijlstra 
Cc: Song Liu 
Cc: Will Deacon 
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20220416004048.1514900-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

Merge remote-tracking branch 'torvalds/master' into perf/core

2022-03-22T20:52:10+00:00

To pick up fixes that went thru perf/urgent and now are fixed by an
upcoming patch.

Signed-off-by: Arnaldo Carvalho de Melo