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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opal-msglog.c (3571B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * PowerNV OPAL in-memory console interface
      4 *
      5 * Copyright 2014 IBM Corp.
      6 */
      7
      8#include <asm/io.h>
      9#include <asm/opal.h>
     10#include <linux/debugfs.h>
     11#include <linux/of.h>
     12#include <linux/types.h>
     13#include <asm/barrier.h>
     14
     15#include "powernv.h"
     16
     17/* OPAL in-memory console. Defined in OPAL source at core/console.c */
     18struct memcons {
     19	__be64 magic;
     20#define MEMCONS_MAGIC	0x6630696567726173L
     21	__be64 obuf_phys;
     22	__be64 ibuf_phys;
     23	__be32 obuf_size;
     24	__be32 ibuf_size;
     25	__be32 out_pos;
     26#define MEMCONS_OUT_POS_WRAP	0x80000000u
     27#define MEMCONS_OUT_POS_MASK	0x00ffffffu
     28	__be32 in_prod;
     29	__be32 in_cons;
     30};
     31
     32static struct memcons *opal_memcons = NULL;
     33
     34ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count)
     35{
     36	const char *conbuf;
     37	ssize_t ret;
     38	size_t first_read = 0;
     39	uint32_t out_pos, avail;
     40
     41	if (!mc)
     42		return -ENODEV;
     43
     44	out_pos = be32_to_cpu(READ_ONCE(mc->out_pos));
     45
     46	/* Now we've read out_pos, put a barrier in before reading the new
     47	 * data it points to in conbuf. */
     48	smp_rmb();
     49
     50	conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
     51
     52	/* When the buffer has wrapped, read from the out_pos marker to the end
     53	 * of the buffer, and then read the remaining data as in the un-wrapped
     54	 * case. */
     55	if (out_pos & MEMCONS_OUT_POS_WRAP) {
     56
     57		out_pos &= MEMCONS_OUT_POS_MASK;
     58		avail = be32_to_cpu(mc->obuf_size) - out_pos;
     59
     60		ret = memory_read_from_buffer(to, count, &pos,
     61				conbuf + out_pos, avail);
     62
     63		if (ret < 0)
     64			goto out;
     65
     66		first_read = ret;
     67		to += first_read;
     68		count -= first_read;
     69		pos -= avail;
     70
     71		if (count <= 0)
     72			goto out;
     73	}
     74
     75	/* Sanity check. The firmware should not do this to us. */
     76	if (out_pos > be32_to_cpu(mc->obuf_size)) {
     77		pr_err("OPAL: memory console corruption. Aborting read.\n");
     78		return -EINVAL;
     79	}
     80
     81	ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos);
     82
     83	if (ret < 0)
     84		goto out;
     85
     86	ret += first_read;
     87out:
     88	return ret;
     89}
     90
     91ssize_t opal_msglog_copy(char *to, loff_t pos, size_t count)
     92{
     93	return memcons_copy(opal_memcons, to, pos, count);
     94}
     95
     96static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj,
     97				struct bin_attribute *bin_attr, char *to,
     98				loff_t pos, size_t count)
     99{
    100	return opal_msglog_copy(to, pos, count);
    101}
    102
    103static struct bin_attribute opal_msglog_attr = {
    104	.attr = {.name = "msglog", .mode = 0400},
    105	.read = opal_msglog_read
    106};
    107
    108struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name)
    109{
    110	u64 mcaddr;
    111	struct memcons *mc;
    112
    113	if (of_property_read_u64(node, mc_prop_name, &mcaddr)) {
    114		pr_warn("%s property not found, no message log\n",
    115			mc_prop_name);
    116		goto out_err;
    117	}
    118
    119	mc = phys_to_virt(mcaddr);
    120	if (!mc) {
    121		pr_warn("memory console address is invalid\n");
    122		goto out_err;
    123	}
    124
    125	if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
    126		pr_warn("memory console version is invalid\n");
    127		goto out_err;
    128	}
    129
    130	return mc;
    131
    132out_err:
    133	return NULL;
    134}
    135
    136u32 __init memcons_get_size(struct memcons *mc)
    137{
    138	return be32_to_cpu(mc->ibuf_size) + be32_to_cpu(mc->obuf_size);
    139}
    140
    141void __init opal_msglog_init(void)
    142{
    143	opal_memcons = memcons_init(opal_node, "ibm,opal-memcons");
    144	if (!opal_memcons) {
    145		pr_warn("OPAL: memcons failed to load from ibm,opal-memcons\n");
    146		return;
    147	}
    148
    149	opal_msglog_attr.size = memcons_get_size(opal_memcons);
    150}
    151
    152void __init opal_msglog_sysfs_init(void)
    153{
    154	if (!opal_memcons) {
    155		pr_warn("OPAL: message log initialisation failed, not creating sysfs entry\n");
    156		return;
    157	}
    158
    159	if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0)
    160		pr_warn("OPAL: sysfs file creation failed\n");
    161}