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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ram_core.c (15298B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2012 Google, Inc.
      4 */
      5
      6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      7
      8#include <linux/device.h>
      9#include <linux/err.h>
     10#include <linux/errno.h>
     11#include <linux/init.h>
     12#include <linux/io.h>
     13#include <linux/kernel.h>
     14#include <linux/list.h>
     15#include <linux/memblock.h>
     16#include <linux/pstore_ram.h>
     17#include <linux/rslib.h>
     18#include <linux/slab.h>
     19#include <linux/uaccess.h>
     20#include <linux/vmalloc.h>
     21#include <asm/page.h>
     22
     23/**
     24 * struct persistent_ram_buffer - persistent circular RAM buffer
     25 *
     26 * @sig:
     27 *	signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
     28 * @start:
     29 *	offset into @data where the beginning of the stored bytes begin
     30 * @size:
     31 *	number of valid bytes stored in @data
     32 */
     33struct persistent_ram_buffer {
     34	uint32_t    sig;
     35	atomic_t    start;
     36	atomic_t    size;
     37	uint8_t     data[];
     38};
     39
     40#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
     41
     42static inline size_t buffer_size(struct persistent_ram_zone *prz)
     43{
     44	return atomic_read(&prz->buffer->size);
     45}
     46
     47static inline size_t buffer_start(struct persistent_ram_zone *prz)
     48{
     49	return atomic_read(&prz->buffer->start);
     50}
     51
     52/* increase and wrap the start pointer, returning the old value */
     53static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
     54{
     55	int old;
     56	int new;
     57	unsigned long flags = 0;
     58
     59	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
     60		raw_spin_lock_irqsave(&prz->buffer_lock, flags);
     61
     62	old = atomic_read(&prz->buffer->start);
     63	new = old + a;
     64	while (unlikely(new >= prz->buffer_size))
     65		new -= prz->buffer_size;
     66	atomic_set(&prz->buffer->start, new);
     67
     68	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
     69		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
     70
     71	return old;
     72}
     73
     74/* increase the size counter until it hits the max size */
     75static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
     76{
     77	size_t old;
     78	size_t new;
     79	unsigned long flags = 0;
     80
     81	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
     82		raw_spin_lock_irqsave(&prz->buffer_lock, flags);
     83
     84	old = atomic_read(&prz->buffer->size);
     85	if (old == prz->buffer_size)
     86		goto exit;
     87
     88	new = old + a;
     89	if (new > prz->buffer_size)
     90		new = prz->buffer_size;
     91	atomic_set(&prz->buffer->size, new);
     92
     93exit:
     94	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
     95		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
     96}
     97
     98static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
     99	uint8_t *data, size_t len, uint8_t *ecc)
    100{
    101	int i;
    102
    103	/* Initialize the parity buffer */
    104	memset(prz->ecc_info.par, 0,
    105	       prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
    106	encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
    107	for (i = 0; i < prz->ecc_info.ecc_size; i++)
    108		ecc[i] = prz->ecc_info.par[i];
    109}
    110
    111static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
    112	void *data, size_t len, uint8_t *ecc)
    113{
    114	int i;
    115
    116	for (i = 0; i < prz->ecc_info.ecc_size; i++)
    117		prz->ecc_info.par[i] = ecc[i];
    118	return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
    119				NULL, 0, NULL, 0, NULL);
    120}
    121
    122static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
    123	unsigned int start, unsigned int count)
    124{
    125	struct persistent_ram_buffer *buffer = prz->buffer;
    126	uint8_t *buffer_end = buffer->data + prz->buffer_size;
    127	uint8_t *block;
    128	uint8_t *par;
    129	int ecc_block_size = prz->ecc_info.block_size;
    130	int ecc_size = prz->ecc_info.ecc_size;
    131	int size = ecc_block_size;
    132
    133	if (!ecc_size)
    134		return;
    135
    136	block = buffer->data + (start & ~(ecc_block_size - 1));
    137	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
    138
    139	do {
    140		if (block + ecc_block_size > buffer_end)
    141			size = buffer_end - block;
    142		persistent_ram_encode_rs8(prz, block, size, par);
    143		block += ecc_block_size;
    144		par += ecc_size;
    145	} while (block < buffer->data + start + count);
    146}
    147
    148static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
    149{
    150	struct persistent_ram_buffer *buffer = prz->buffer;
    151
    152	if (!prz->ecc_info.ecc_size)
    153		return;
    154
    155	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
    156				  prz->par_header);
    157}
    158
    159static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
    160{
    161	struct persistent_ram_buffer *buffer = prz->buffer;
    162	uint8_t *block;
    163	uint8_t *par;
    164
    165	if (!prz->ecc_info.ecc_size)
    166		return;
    167
    168	block = buffer->data;
    169	par = prz->par_buffer;
    170	while (block < buffer->data + buffer_size(prz)) {
    171		int numerr;
    172		int size = prz->ecc_info.block_size;
    173		if (block + size > buffer->data + prz->buffer_size)
    174			size = buffer->data + prz->buffer_size - block;
    175		numerr = persistent_ram_decode_rs8(prz, block, size, par);
    176		if (numerr > 0) {
    177			pr_devel("error in block %p, %d\n", block, numerr);
    178			prz->corrected_bytes += numerr;
    179		} else if (numerr < 0) {
    180			pr_devel("uncorrectable error in block %p\n", block);
    181			prz->bad_blocks++;
    182		}
    183		block += prz->ecc_info.block_size;
    184		par += prz->ecc_info.ecc_size;
    185	}
    186}
    187
    188static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
    189				   struct persistent_ram_ecc_info *ecc_info)
    190{
    191	int numerr;
    192	struct persistent_ram_buffer *buffer = prz->buffer;
    193	int ecc_blocks;
    194	size_t ecc_total;
    195
    196	if (!ecc_info || !ecc_info->ecc_size)
    197		return 0;
    198
    199	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
    200	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
    201	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
    202	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
    203
    204	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
    205				  prz->ecc_info.block_size +
    206				  prz->ecc_info.ecc_size);
    207	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
    208	if (ecc_total >= prz->buffer_size) {
    209		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
    210		       __func__, prz->ecc_info.ecc_size,
    211		       ecc_total, prz->buffer_size);
    212		return -EINVAL;
    213	}
    214
    215	prz->buffer_size -= ecc_total;
    216	prz->par_buffer = buffer->data + prz->buffer_size;
    217	prz->par_header = prz->par_buffer +
    218			  ecc_blocks * prz->ecc_info.ecc_size;
    219
    220	/*
    221	 * first consecutive root is 0
    222	 * primitive element to generate roots = 1
    223	 */
    224	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
    225				  0, 1, prz->ecc_info.ecc_size);
    226	if (prz->rs_decoder == NULL) {
    227		pr_info("init_rs failed\n");
    228		return -EINVAL;
    229	}
    230
    231	/* allocate workspace instead of using stack VLA */
    232	prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
    233					  sizeof(*prz->ecc_info.par),
    234					  GFP_KERNEL);
    235	if (!prz->ecc_info.par) {
    236		pr_err("cannot allocate ECC parity workspace\n");
    237		return -ENOMEM;
    238	}
    239
    240	prz->corrected_bytes = 0;
    241	prz->bad_blocks = 0;
    242
    243	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
    244					   prz->par_header);
    245	if (numerr > 0) {
    246		pr_info("error in header, %d\n", numerr);
    247		prz->corrected_bytes += numerr;
    248	} else if (numerr < 0) {
    249		pr_info_ratelimited("uncorrectable error in header\n");
    250		prz->bad_blocks++;
    251	}
    252
    253	return 0;
    254}
    255
    256ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
    257	char *str, size_t len)
    258{
    259	ssize_t ret;
    260
    261	if (!prz->ecc_info.ecc_size)
    262		return 0;
    263
    264	if (prz->corrected_bytes || prz->bad_blocks)
    265		ret = snprintf(str, len, ""
    266			"\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
    267			prz->corrected_bytes, prz->bad_blocks);
    268	else
    269		ret = snprintf(str, len, "\nECC: No errors detected\n");
    270
    271	return ret;
    272}
    273
    274static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
    275	const void *s, unsigned int start, unsigned int count)
    276{
    277	struct persistent_ram_buffer *buffer = prz->buffer;
    278	memcpy_toio(buffer->data + start, s, count);
    279	persistent_ram_update_ecc(prz, start, count);
    280}
    281
    282static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
    283	const void __user *s, unsigned int start, unsigned int count)
    284{
    285	struct persistent_ram_buffer *buffer = prz->buffer;
    286	int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
    287		-EFAULT : 0;
    288	persistent_ram_update_ecc(prz, start, count);
    289	return ret;
    290}
    291
    292void persistent_ram_save_old(struct persistent_ram_zone *prz)
    293{
    294	struct persistent_ram_buffer *buffer = prz->buffer;
    295	size_t size = buffer_size(prz);
    296	size_t start = buffer_start(prz);
    297
    298	if (!size)
    299		return;
    300
    301	if (!prz->old_log) {
    302		persistent_ram_ecc_old(prz);
    303		prz->old_log = kmalloc(size, GFP_KERNEL);
    304	}
    305	if (!prz->old_log) {
    306		pr_err("failed to allocate buffer\n");
    307		return;
    308	}
    309
    310	prz->old_log_size = size;
    311	memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
    312	memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
    313}
    314
    315int notrace persistent_ram_write(struct persistent_ram_zone *prz,
    316	const void *s, unsigned int count)
    317{
    318	int rem;
    319	int c = count;
    320	size_t start;
    321
    322	if (unlikely(c > prz->buffer_size)) {
    323		s += c - prz->buffer_size;
    324		c = prz->buffer_size;
    325	}
    326
    327	buffer_size_add(prz, c);
    328
    329	start = buffer_start_add(prz, c);
    330
    331	rem = prz->buffer_size - start;
    332	if (unlikely(rem < c)) {
    333		persistent_ram_update(prz, s, start, rem);
    334		s += rem;
    335		c -= rem;
    336		start = 0;
    337	}
    338	persistent_ram_update(prz, s, start, c);
    339
    340	persistent_ram_update_header_ecc(prz);
    341
    342	return count;
    343}
    344
    345int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
    346	const void __user *s, unsigned int count)
    347{
    348	int rem, ret = 0, c = count;
    349	size_t start;
    350
    351	if (unlikely(c > prz->buffer_size)) {
    352		s += c - prz->buffer_size;
    353		c = prz->buffer_size;
    354	}
    355
    356	buffer_size_add(prz, c);
    357
    358	start = buffer_start_add(prz, c);
    359
    360	rem = prz->buffer_size - start;
    361	if (unlikely(rem < c)) {
    362		ret = persistent_ram_update_user(prz, s, start, rem);
    363		s += rem;
    364		c -= rem;
    365		start = 0;
    366	}
    367	if (likely(!ret))
    368		ret = persistent_ram_update_user(prz, s, start, c);
    369
    370	persistent_ram_update_header_ecc(prz);
    371
    372	return unlikely(ret) ? ret : count;
    373}
    374
    375size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
    376{
    377	return prz->old_log_size;
    378}
    379
    380void *persistent_ram_old(struct persistent_ram_zone *prz)
    381{
    382	return prz->old_log;
    383}
    384
    385void persistent_ram_free_old(struct persistent_ram_zone *prz)
    386{
    387	kfree(prz->old_log);
    388	prz->old_log = NULL;
    389	prz->old_log_size = 0;
    390}
    391
    392void persistent_ram_zap(struct persistent_ram_zone *prz)
    393{
    394	atomic_set(&prz->buffer->start, 0);
    395	atomic_set(&prz->buffer->size, 0);
    396	persistent_ram_update_header_ecc(prz);
    397}
    398
    399#define MEM_TYPE_WCOMBINE	0
    400#define MEM_TYPE_NONCACHED	1
    401#define MEM_TYPE_NORMAL		2
    402
    403static void *persistent_ram_vmap(phys_addr_t start, size_t size,
    404		unsigned int memtype)
    405{
    406	struct page **pages;
    407	phys_addr_t page_start;
    408	unsigned int page_count;
    409	pgprot_t prot;
    410	unsigned int i;
    411	void *vaddr;
    412
    413	page_start = start - offset_in_page(start);
    414	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
    415
    416	switch (memtype) {
    417	case MEM_TYPE_NORMAL:
    418		prot = PAGE_KERNEL;
    419		break;
    420	case MEM_TYPE_NONCACHED:
    421		prot = pgprot_noncached(PAGE_KERNEL);
    422		break;
    423	case MEM_TYPE_WCOMBINE:
    424		prot = pgprot_writecombine(PAGE_KERNEL);
    425		break;
    426	default:
    427		pr_err("invalid mem_type=%d\n", memtype);
    428		return NULL;
    429	}
    430
    431	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
    432	if (!pages) {
    433		pr_err("%s: Failed to allocate array for %u pages\n",
    434		       __func__, page_count);
    435		return NULL;
    436	}
    437
    438	for (i = 0; i < page_count; i++) {
    439		phys_addr_t addr = page_start + i * PAGE_SIZE;
    440		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
    441	}
    442	vaddr = vmap(pages, page_count, VM_MAP, prot);
    443	kfree(pages);
    444
    445	/*
    446	 * Since vmap() uses page granularity, we must add the offset
    447	 * into the page here, to get the byte granularity address
    448	 * into the mapping to represent the actual "start" location.
    449	 */
    450	return vaddr + offset_in_page(start);
    451}
    452
    453static void *persistent_ram_iomap(phys_addr_t start, size_t size,
    454		unsigned int memtype, char *label)
    455{
    456	void *va;
    457
    458	if (!request_mem_region(start, size, label ?: "ramoops")) {
    459		pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
    460			label ?: "ramoops",
    461			(unsigned long long)size, (unsigned long long)start);
    462		return NULL;
    463	}
    464
    465	if (memtype)
    466		va = ioremap(start, size);
    467	else
    468		va = ioremap_wc(start, size);
    469
    470	/*
    471	 * Since request_mem_region() and ioremap() are byte-granularity
    472	 * there is no need handle anything special like we do when the
    473	 * vmap() case in persistent_ram_vmap() above.
    474	 */
    475	return va;
    476}
    477
    478static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
    479		struct persistent_ram_zone *prz, int memtype)
    480{
    481	prz->paddr = start;
    482	prz->size = size;
    483
    484	if (pfn_valid(start >> PAGE_SHIFT))
    485		prz->vaddr = persistent_ram_vmap(start, size, memtype);
    486	else
    487		prz->vaddr = persistent_ram_iomap(start, size, memtype,
    488						  prz->label);
    489
    490	if (!prz->vaddr) {
    491		pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
    492			(unsigned long long)size, (unsigned long long)start);
    493		return -ENOMEM;
    494	}
    495
    496	prz->buffer = prz->vaddr;
    497	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
    498
    499	return 0;
    500}
    501
    502static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
    503				    struct persistent_ram_ecc_info *ecc_info)
    504{
    505	int ret;
    506	bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
    507
    508	ret = persistent_ram_init_ecc(prz, ecc_info);
    509	if (ret) {
    510		pr_warn("ECC failed %s\n", prz->label);
    511		return ret;
    512	}
    513
    514	sig ^= PERSISTENT_RAM_SIG;
    515
    516	if (prz->buffer->sig == sig) {
    517		if (buffer_size(prz) == 0) {
    518			pr_debug("found existing empty buffer\n");
    519			return 0;
    520		}
    521
    522		if (buffer_size(prz) > prz->buffer_size ||
    523		    buffer_start(prz) > buffer_size(prz)) {
    524			pr_info("found existing invalid buffer, size %zu, start %zu\n",
    525				buffer_size(prz), buffer_start(prz));
    526			zap = true;
    527		} else {
    528			pr_debug("found existing buffer, size %zu, start %zu\n",
    529				 buffer_size(prz), buffer_start(prz));
    530			persistent_ram_save_old(prz);
    531		}
    532	} else {
    533		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
    534			 prz->buffer->sig);
    535		prz->buffer->sig = sig;
    536		zap = true;
    537	}
    538
    539	/* Reset missing, invalid, or single-use memory area. */
    540	if (zap)
    541		persistent_ram_zap(prz);
    542
    543	return 0;
    544}
    545
    546void persistent_ram_free(struct persistent_ram_zone *prz)
    547{
    548	if (!prz)
    549		return;
    550
    551	if (prz->vaddr) {
    552		if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
    553			/* We must vunmap() at page-granularity. */
    554			vunmap(prz->vaddr - offset_in_page(prz->paddr));
    555		} else {
    556			iounmap(prz->vaddr);
    557			release_mem_region(prz->paddr, prz->size);
    558		}
    559		prz->vaddr = NULL;
    560	}
    561	if (prz->rs_decoder) {
    562		free_rs(prz->rs_decoder);
    563		prz->rs_decoder = NULL;
    564	}
    565	kfree(prz->ecc_info.par);
    566	prz->ecc_info.par = NULL;
    567
    568	persistent_ram_free_old(prz);
    569	kfree(prz->label);
    570	kfree(prz);
    571}
    572
    573struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
    574			u32 sig, struct persistent_ram_ecc_info *ecc_info,
    575			unsigned int memtype, u32 flags, char *label)
    576{
    577	struct persistent_ram_zone *prz;
    578	int ret = -ENOMEM;
    579
    580	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
    581	if (!prz) {
    582		pr_err("failed to allocate persistent ram zone\n");
    583		goto err;
    584	}
    585
    586	/* Initialize general buffer state. */
    587	raw_spin_lock_init(&prz->buffer_lock);
    588	prz->flags = flags;
    589	prz->label = kstrdup(label, GFP_KERNEL);
    590
    591	ret = persistent_ram_buffer_map(start, size, prz, memtype);
    592	if (ret)
    593		goto err;
    594
    595	ret = persistent_ram_post_init(prz, sig, ecc_info);
    596	if (ret)
    597		goto err;
    598
    599	pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
    600		prz->label, prz->size, (unsigned long long)prz->paddr,
    601		sizeof(*prz->buffer), prz->buffer_size,
    602		prz->size - sizeof(*prz->buffer) - prz->buffer_size,
    603		prz->ecc_info.ecc_size, prz->ecc_info.block_size);
    604
    605	return prz;
    606err:
    607	persistent_ram_free(prz);
    608	return ERR_PTR(ret);
    609}