cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ftrace-direct-modify.c (3270B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2#include <linux/module.h>
      3#include <linux/kthread.h>
      4#include <linux/ftrace.h>
      5#include <asm/asm-offsets.h>
      6
      7extern void my_direct_func1(void);
      8extern void my_direct_func2(void);
      9
     10void my_direct_func1(void)
     11{
     12	trace_printk("my direct func1\n");
     13}
     14
     15void my_direct_func2(void)
     16{
     17	trace_printk("my direct func2\n");
     18}
     19
     20extern void my_tramp1(void *);
     21extern void my_tramp2(void *);
     22
     23static unsigned long my_ip = (unsigned long)schedule;
     24
     25#ifdef CONFIG_X86_64
     26
     27#include <asm/ibt.h>
     28
     29asm (
     30"	.pushsection    .text, \"ax\", @progbits\n"
     31"	.type		my_tramp1, @function\n"
     32"	.globl		my_tramp1\n"
     33"   my_tramp1:"
     34	ASM_ENDBR
     35"	pushq %rbp\n"
     36"	movq %rsp, %rbp\n"
     37"	call my_direct_func1\n"
     38"	leave\n"
     39"	.size		my_tramp1, .-my_tramp1\n"
     40	ASM_RET
     41
     42"	.type		my_tramp2, @function\n"
     43"	.globl		my_tramp2\n"
     44"   my_tramp2:"
     45	ASM_ENDBR
     46"	pushq %rbp\n"
     47"	movq %rsp, %rbp\n"
     48"	call my_direct_func2\n"
     49"	leave\n"
     50	ASM_RET
     51"	.size		my_tramp2, .-my_tramp2\n"
     52"	.popsection\n"
     53);
     54
     55#endif /* CONFIG_X86_64 */
     56
     57#ifdef CONFIG_S390
     58
     59asm (
     60"	.pushsection	.text, \"ax\", @progbits\n"
     61"	.type		my_tramp1, @function\n"
     62"	.globl		my_tramp1\n"
     63"   my_tramp1:"
     64"	lgr		%r1,%r15\n"
     65"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
     66"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
     67"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
     68"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
     69"	brasl		%r14,my_direct_func1\n"
     70"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
     71"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
     72"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
     73"	lgr		%r1,%r0\n"
     74"	br		%r1\n"
     75"	.size		my_tramp1, .-my_tramp1\n"
     76"	.type		my_tramp2, @function\n"
     77"	.globl		my_tramp2\n"
     78"   my_tramp2:"
     79"	lgr		%r1,%r15\n"
     80"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
     81"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
     82"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
     83"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
     84"	brasl		%r14,my_direct_func2\n"
     85"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
     86"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
     87"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
     88"	lgr		%r1,%r0\n"
     89"	br		%r1\n"
     90"	.size		my_tramp2, .-my_tramp2\n"
     91"	.popsection\n"
     92);
     93
     94#endif /* CONFIG_S390 */
     95
     96static unsigned long my_tramp = (unsigned long)my_tramp1;
     97static unsigned long tramps[2] = {
     98	(unsigned long)my_tramp1,
     99	(unsigned long)my_tramp2,
    100};
    101
    102static int simple_thread(void *arg)
    103{
    104	static int t;
    105	int ret = 0;
    106
    107	while (!kthread_should_stop()) {
    108		set_current_state(TASK_INTERRUPTIBLE);
    109		schedule_timeout(2 * HZ);
    110
    111		if (ret)
    112			continue;
    113		t ^= 1;
    114		ret = modify_ftrace_direct(my_ip, my_tramp, tramps[t]);
    115		if (!ret)
    116			my_tramp = tramps[t];
    117		WARN_ON_ONCE(ret);
    118	}
    119
    120	return 0;
    121}
    122
    123static struct task_struct *simple_tsk;
    124
    125static int __init ftrace_direct_init(void)
    126{
    127	int ret;
    128
    129	ret = register_ftrace_direct(my_ip, my_tramp);
    130	if (!ret)
    131		simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
    132	return ret;
    133}
    134
    135static void __exit ftrace_direct_exit(void)
    136{
    137	kthread_stop(simple_tsk);
    138	unregister_ftrace_direct(my_ip, my_tramp);
    139}
    140
    141module_init(ftrace_direct_init);
    142module_exit(ftrace_direct_exit);
    143
    144MODULE_AUTHOR("Steven Rostedt");
    145MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
    146MODULE_LICENSE("GPL");