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// SPDX-License-Identifier: GPL-2.0
/*
* Instruction operands whose change must move a function's checksum even
* though the instruction bytes themselves do not.
*
* checksum_update_insn() hashes the raw bytes and then, when the instruction
* carries a relocation, what that relocation refers to: a string section
* contributes the string's contents, anything else the target symbol's name
* and the adjusted addend. A reference to a static arrives as a section
* symbol and has to be resolved back to the object first.
*
* The bytes are identical in every case below -- a rel32 operand is zero in
* the object and supplied by the relocation -- so a checksum that stopped at
* the bytes would call all of these unchanged.
*
* Each variant applies to the patched build only:
*
* WHICH_CALL calls a different function
* STR_CONTENT passes a literal whose text was edited
* WHICH_SLOT reads a different index of a global array: addend only
* WHICH_PRIV the same, for a static, reached through its section symbol
*/
static const char __modinfo[]
__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
int callee_a(int x);
int callee_b(int x);
int sink(const char *s);
int slots[4];
/*
* A file-local array, plus a writer the compiler cannot see through. Without
* one it can prove the array is never written, folds every read to zero, and
* emits no relocation at all -- so the reference this is here to exercise does
* not exist.
*/
static int priv_slots[4];
void set_priv(int i, int v);
void set_priv(int i, int v)
{
priv_slots[i] = v;
}
#if defined(PATCHED) && defined(STR_CONTENT)
#define MESSAGE "edited"
#else
#define MESSAGE "original"
#endif
int target(int x)
{
int r;
#if defined(PATCHED) && defined(WHICH_CALL)
r = callee_b(x);
#else
r = callee_a(x);
#endif
r += sink(MESSAGE);
#if defined(PATCHED) && defined(WHICH_SLOT)
r += slots[2];
#else
r += slots[1];
#endif
#if defined(PATCHED) && defined(WHICH_PRIV)
r += priv_slots[3];
#else
r += priv_slots[1];
#endif
return r;
}
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