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// SPDX-License-Identifier: GPL-2.0
/*
* A translation unit built with UBSAN, where only one of two functions is
* patched.
*
* Every instrumented operation gets a per-callsite metadata object in an
* anonymous data section -- .data..Lubsan_data and .data..Lubsan_type from
* GCC, .data..L__unnamed_ from Clang -- and a call to a __ubsan_handle_*
* routine. The names are compiler-generated and carry no meaning across a
* rebuild, so klp diff has to treat those sections as uncorrelated rather than
* pairing them up by name.
*
* untouched() is byte-identical in both builds and exists to catch the false
* positive: if the metadata were correlated by name, its shifts would look
* changed and it would be dragged into the patch.
*
* The shifts are what draw the instrumentation. A bounds check would do as
* well but neither compiler emits one for an index it can prove in range.
*/
static const char __modinfo[]
__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
int shift_by(int v, int n);
int untouched(int v, int n)
{
int s = 0;
s += v << (n & 31);
s += v << ((n + 1) & 31);
s += shift_by(v, n);
return s;
}
int touched(int v, int n)
{
int s = 0;
s += v << (n & 31);
#ifdef PATCHED
s += v << ((n + 3) & 31);
#else
s += v << ((n + 2) & 31);
#endif
return s;
}
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