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// SPDX-License-Identifier: GPL-2.0
/*
* A special section entry belonging to a patched function. SPECIAL_SEC picks
* which section, since klp diff treats eight of them alike and each needs
* extracting for the patched function and no other.
*
* The entry is written out by hand so the fixture builds without kernel
* headers. Only the leading relocation matters to klp diff; the rest is
* padded to the section's real entry size, because the entries have to be the
* right length for the boundaries between them to fall in the right places.
*
* SPECIAL_RELOCS covers __ex_table, whose entries relocate both the faulting
* instruction and its fixup; objtool rejects one with only the first.
*/
#ifndef SPECIAL_SEC
#define SPECIAL_SEC "__bug_table"
#endif
#ifndef SPECIAL_ENTSIZE
#define SPECIAL_ENTSIZE 12
#endif
#ifndef SPECIAL_RELOCS
#define SPECIAL_RELOCS 1
#endif
#define STR_(x) #x
#define STR(x) STR_(x)
static const char __modinfo[]
__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
/*
* other() gets an entry of its own, so that "the untouched function's entry
* was not dragged in" is a question the section can actually answer. With
* only target() contributing, there is nothing for klp diff to leave behind
* and the negative assertion holds however the extraction behaves.
*/
int other(int x)
{
asm volatile(
"3: nop\n\t"
"4:\n\t"
".pushsection " SPECIAL_SEC ", \"aM\", @progbits, "
STR(SPECIAL_ENTSIZE) "\n\t"
".long 3b - .\n\t"
#if SPECIAL_RELOCS > 1
".long 4b - .\n\t"
".fill " STR(SPECIAL_ENTSIZE) " - 8, 1, 0\n\t"
#else
".fill " STR(SPECIAL_ENTSIZE) " - 4, 1, 0\n\t"
#endif
".popsection\n\t");
return x + 9;
}
int target(int x)
{
asm volatile(
"1: nop\n\t"
"2:\n\t"
".pushsection " SPECIAL_SEC ", \"aM\", @progbits, "
STR(SPECIAL_ENTSIZE) "\n\t"
".long 1b - .\n\t"
#if SPECIAL_RELOCS > 1
".long 2b - .\n\t"
".fill " STR(SPECIAL_ENTSIZE) " - 8, 1, 0\n\t"
#else
".fill " STR(SPECIAL_ENTSIZE) " - 4, 1, 0\n\t"
#endif
".popsection\n\t");
#ifdef PATCHED
return x + 2;
#else
return x + 1;
#endif
}
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