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// SPDX-License-Identifier: GPL-2.0
#include <linux/static_call.h>
#include <linux/memory.h>
#include <linux/bug.h>
#include <asm/text-patching.h>
enum insn_type {
CALL = 0, /* site call */
NOP = 1, /* site cond-call */
JMP = 2, /* tramp / site tail-call */
RET = 3, /* tramp / site cond-tail-call */
};
static void __static_call_transform(void *insn, enum insn_type type, void *func)
{
int size = CALL_INSN_SIZE;
const void *code;
switch (type) {
case CALL:
code = text_gen_insn(CALL_INSN_OPCODE, insn, func);
break;
case NOP:
code = ideal_nops[NOP_ATOMIC5];
break;
case JMP:
code = text_gen_insn(JMP32_INSN_OPCODE, insn, func);
break;
case RET:
code = text_gen_insn(RET_INSN_OPCODE, insn, func);
size = RET_INSN_SIZE;
break;
}
if (memcmp(insn, code, size) == 0)
return;
text_poke_bp(insn, code, size, NULL);
}
static inline enum insn_type __sc_insn(bool null, bool tail)
{
/*
* Encode the following table without branches:
*
* tail null insn
* -----+-------+------
* 0 | 0 | CALL
* 0 | 1 | NOP
* 1 | 0 | JMP
* 1 | 1 | RET
*/
return 2*tail + null;
}
void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
{
mutex_lock(&text_mutex);
if (tramp)
__static_call_transform(tramp, __sc_insn(!func, true), func);
if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site)
__static_call_transform(site, __sc_insn(!func, tail), func);
mutex_unlock(&text_mutex);
}
EXPORT_SYMBOL_GPL(arch_static_call_transform);
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