linux/arch/x86/kernel/rethook.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c.
 */
#include <linux/bug.h>
#include <linux/rethook.h>
#include <linux/kprobes.h>
#include <linux/objtool.h>

#include "kprobes/common.h"

__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);

#ifndef ANNOTATE_NOENDBR
#define ANNOTATE_NOENDBR
#endif

/*
 * When a target function returns, this code saves registers and calls
 * arch_rethook_trampoline_callback(), which calls the rethook handler.
 */
asm …;
NOKPROBE_SYMBOL(arch_rethook_trampoline);

/*
 * Called from arch_rethook_trampoline
 */
__used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs)
{ … }
NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);

/*
 * arch_rethook_trampoline() skips updating frame pointer. The frame pointer
 * saved in arch_rethook_trampoline_callback() points to the real caller
 * function's frame pointer. Thus the arch_rethook_trampoline() doesn't have
 * a standard stack frame with CONFIG_FRAME_POINTER=y.
 * Let's mark it non-standard function. Anyway, FP unwinder can correctly
 * unwind without the hint.
 */
STACK_FRAME_NON_STANDARD_FP(arch_rethook_trampoline);

/* This is called from rethook_trampoline_handler(). */
void arch_rethook_fixup_return(struct pt_regs *regs,
			       unsigned long correct_ret_addr)
{ … }
NOKPROBE_SYMBOL(arch_rethook_fixup_return);

void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
{ … }
NOKPROBE_SYMBOL(arch_rethook_prepare);