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63 lines
1.9 KiB
ReStructuredText
63 lines
1.9 KiB
ReStructuredText
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SanitizerStats
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==============
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.. contents::
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:local:
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Introduction
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============
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The sanitizers support a simple mechanism for gathering profiling statistics
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to help understand the overhead associated with sanitizers.
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How to build and run
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====================
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SanitizerStats can currently only be used with :doc:`ControlFlowIntegrity`.
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In addition to ``-fsanitize=cfi*``, pass the ``-fsanitize-stats`` flag.
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This will cause the program to count the number of times that each control
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flow integrity check in the program fires.
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At run time, set the ``SANITIZER_STATS_PATH`` environment variable to direct
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statistics output to a file. The file will be written on process exit.
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The following substitutions will be applied to the environment variable:
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- ``%b`` -- The executable basename.
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- ``%p`` -- The process ID.
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You can also send the ``SIGUSR2`` signal to a process to make it write
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sanitizer statistics immediately.
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The ``sanstats`` program can be used to dump statistics. It takes as a
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command line argument the path to a statistics file produced by a program
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compiled with ``-fsanitize-stats``.
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The output of ``sanstats`` is in four columns, separated by spaces. The first
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column is the file and line number of the call site. The second column is
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the function name. The third column is the type of statistic gathered (in
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this case, the type of control flow integrity check). The fourth column is
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the call count.
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Example:
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.. code-block:: console
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$ cat -n vcall.cc
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1 struct A {
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2 virtual void f() {}
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3 };
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4
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5 __attribute__((noinline)) void g(A *a) {
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6 a->f();
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7 }
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8
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9 int main() {
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10 A a;
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11 g(&a);
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12 }
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$ clang++ -fsanitize=cfi -flto -fuse-ld=gold vcall.cc -fsanitize-stats -g
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$ SANITIZER_STATS_PATH=a.stats ./a.out
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$ sanstats a.stats
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vcall.cc:6 _Z1gP1A cfi-vcall 1
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