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.c (2224B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Simple kernel driver to link kernel Ftrace and an STM device
      4 * Copyright (c) 2016, Linaro Ltd.
      5 *
      6 * STM Ftrace will be registered as a trace_export.
      7 */
      8
      9#include <linux/module.h>
     10#include <linux/stm.h>
     11#include <linux/trace.h>
     12
     13#define STM_FTRACE_NR_CHANNELS 1
     14#define STM_FTRACE_CHAN 0
     15
     16static int stm_ftrace_link(struct stm_source_data *data);
     17static void stm_ftrace_unlink(struct stm_source_data *data);
     18
     19static struct stm_ftrace {
     20	struct stm_source_data	data;
     21	struct trace_export	ftrace;
     22} stm_ftrace = {
     23	.data	= {
     24		.name		= "ftrace",
     25		.nr_chans	= STM_FTRACE_NR_CHANNELS,
     26		.link		= stm_ftrace_link,
     27		.unlink		= stm_ftrace_unlink,
     28	},
     29};
     30
     31/**
     32 * stm_ftrace_write() - write data to STM via 'stm_ftrace' source
     33 * @buf:	buffer containing the data packet
     34 * @len:	length of the data packet
     35 */
     36static void notrace
     37stm_ftrace_write(struct trace_export *export, const void *buf, unsigned int len)
     38{
     39	struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace);
     40	/* This is called from trace system with preemption disabled */
     41	unsigned int cpu = smp_processor_id();
     42
     43	stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, buf, len);
     44}
     45
     46static int stm_ftrace_link(struct stm_source_data *data)
     47{
     48	struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
     49
     50	sf->ftrace.write = stm_ftrace_write;
     51	sf->ftrace.flags = TRACE_EXPORT_FUNCTION | TRACE_EXPORT_EVENT
     52			| TRACE_EXPORT_MARKER;
     53
     54	return register_ftrace_export(&sf->ftrace);
     55}
     56
     57static void stm_ftrace_unlink(struct stm_source_data *data)
     58{
     59	struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
     60
     61	unregister_ftrace_export(&sf->ftrace);
     62}
     63
     64static int __init stm_ftrace_init(void)
     65{
     66	int ret;
     67
     68	stm_ftrace.data.nr_chans = roundup_pow_of_two(num_possible_cpus());
     69	ret = stm_source_register_device(NULL, &stm_ftrace.data);
     70	if (ret)
     71		pr_err("Failed to register stm_source - ftrace.\n");
     72
     73	return ret;
     74}
     75
     76static void __exit stm_ftrace_exit(void)
     77{
     78	stm_source_unregister_device(&stm_ftrace.data);
     79}
     80
     81module_init(stm_ftrace_init);
     82module_exit(stm_ftrace_exit);
     83
     84MODULE_LICENSE("GPL v2");
     85MODULE_DESCRIPTION("stm_ftrace driver");
     86MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");