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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memtest.c (2851B)


      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/kernel.h>
      3#include <linux/types.h>
      4#include <linux/init.h>
      5#include <linux/memblock.h>
      6
      7static u64 patterns[] __initdata = {
      8	/* The first entry has to be 0 to leave memtest with zeroed memory */
      9	0,
     10	0xffffffffffffffffULL,
     11	0x5555555555555555ULL,
     12	0xaaaaaaaaaaaaaaaaULL,
     13	0x1111111111111111ULL,
     14	0x2222222222222222ULL,
     15	0x4444444444444444ULL,
     16	0x8888888888888888ULL,
     17	0x3333333333333333ULL,
     18	0x6666666666666666ULL,
     19	0x9999999999999999ULL,
     20	0xccccccccccccccccULL,
     21	0x7777777777777777ULL,
     22	0xbbbbbbbbbbbbbbbbULL,
     23	0xddddddddddddddddULL,
     24	0xeeeeeeeeeeeeeeeeULL,
     25	0x7a6c7258554e494cULL, /* yeah ;-) */
     26};
     27
     28static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
     29{
     30	pr_info("  %016llx bad mem addr %pa - %pa reserved\n",
     31		cpu_to_be64(pattern), &start_bad, &end_bad);
     32	memblock_reserve(start_bad, end_bad - start_bad);
     33}
     34
     35static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
     36{
     37	u64 *p, *start, *end;
     38	phys_addr_t start_bad, last_bad;
     39	phys_addr_t start_phys_aligned;
     40	const size_t incr = sizeof(pattern);
     41
     42	start_phys_aligned = ALIGN(start_phys, incr);
     43	start = __va(start_phys_aligned);
     44	end = start + (size - (start_phys_aligned - start_phys)) / incr;
     45	start_bad = 0;
     46	last_bad = 0;
     47
     48	for (p = start; p < end; p++)
     49		*p = pattern;
     50
     51	for (p = start; p < end; p++, start_phys_aligned += incr) {
     52		if (*p == pattern)
     53			continue;
     54		if (start_phys_aligned == last_bad + incr) {
     55			last_bad += incr;
     56			continue;
     57		}
     58		if (start_bad)
     59			reserve_bad_mem(pattern, start_bad, last_bad + incr);
     60		start_bad = last_bad = start_phys_aligned;
     61	}
     62	if (start_bad)
     63		reserve_bad_mem(pattern, start_bad, last_bad + incr);
     64}
     65
     66static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
     67{
     68	u64 i;
     69	phys_addr_t this_start, this_end;
     70
     71	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
     72				&this_end, NULL) {
     73		this_start = clamp(this_start, start, end);
     74		this_end = clamp(this_end, start, end);
     75		if (this_start < this_end) {
     76			pr_info("  %pa - %pa pattern %016llx\n",
     77				&this_start, &this_end, cpu_to_be64(pattern));
     78			memtest(pattern, this_start, this_end - this_start);
     79		}
     80	}
     81}
     82
     83/* default is disabled */
     84static unsigned int memtest_pattern __initdata;
     85
     86static int __init parse_memtest(char *arg)
     87{
     88	int ret = 0;
     89
     90	if (arg)
     91		ret = kstrtouint(arg, 0, &memtest_pattern);
     92	else
     93		memtest_pattern = ARRAY_SIZE(patterns);
     94
     95	return ret;
     96}
     97
     98early_param("memtest", parse_memtest);
     99
    100void __init early_memtest(phys_addr_t start, phys_addr_t end)
    101{
    102	unsigned int i;
    103	unsigned int idx = 0;
    104
    105	if (!memtest_pattern)
    106		return;
    107
    108	pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
    109	for (i = memtest_pattern-1; i < UINT_MAX; --i) {
    110		idx = i % ARRAY_SIZE(patterns);
    111		do_one_pass(patterns[idx], start, end);
    112	}
    113}