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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2019
*/
#include <linux/pgtable.h>
#include <asm/physmem_info.h>
#include <asm/cpacf.h>
#include <asm/timex.h>
#include <asm/sclp.h>
#include <asm/kasan.h>
#include "decompressor.h"
#include "boot.h"
#define PRNG_MODE_TDES 1
#define PRNG_MODE_SHA512 2
#define PRNG_MODE_TRNG 3
struct prno_parm {
u32 res;
u32 reseed_counter;
u64 stream_bytes;
u8 V[112];
u8 C[112];
};
struct prng_parm {
u8 parm_block[32];
u32 reseed_counter;
u64 byte_counter;
};
static int check_prng(void)
{
if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) {
sclp_early_printk("KASLR disabled: CPU has no PRNG\n");
return 0;
}
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
return PRNG_MODE_TRNG;
if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN))
return PRNG_MODE_SHA512;
else
return PRNG_MODE_TDES;
}
int get_random(unsigned long limit, unsigned long *value)
{
struct prng_parm prng = {
/* initial parameter block for tdes mode, copied from libica */
.parm_block = {
0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0
},
};
unsigned long seed, random;
struct prno_parm prno;
__u64 entropy[4];
int mode, i;
mode = check_prng();
seed = get_tod_clock_fast();
switch (mode) {
case PRNG_MODE_TRNG:
cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random));
break;
case PRNG_MODE_SHA512:
cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0,
(u8 *) &seed, sizeof(seed));
cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random,
sizeof(random), NULL, 0);
break;
case PRNG_MODE_TDES:
/* add entropy */
*(unsigned long *) prng.parm_block ^= seed;
for (i = 0; i < 16; i++) {
cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block,
(u8 *) entropy, (u8 *) entropy,
sizeof(entropy));
memcpy(prng.parm_block, entropy, sizeof(entropy));
}
random = seed;
cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random,
(u8 *) &random, sizeof(random));
break;
default:
return -1;
}
*value = random % limit;
return 0;
}
static void sort_reserved_ranges(struct reserved_range *res, unsigned long size)
{
struct reserved_range tmp;
int i, j;
for (i = 1; i < size; i++) {
tmp = res[i];
for (j = i - 1; j >= 0 && res[j].start > tmp.start; j--)
res[j + 1] = res[j];
res[j + 1] = tmp;
}
}
static unsigned long iterate_valid_positions(unsigned long size, unsigned long align,
unsigned long _min, unsigned long _max,
struct reserved_range *res, size_t res_count,
bool pos_count, unsigned long find_pos)
{
unsigned long start, end, tmp_end, range_pos, pos = 0;
struct reserved_range *res_end = res + res_count;
struct reserved_range *skip_res;
int i;
align = max(align, 8UL);
_min = round_up(_min, align);
for_each_physmem_usable_range(i, &start, &end) {
if (_min >= end)
continue;
start = round_up(start, align);
if (start >= _max)
break;
start = max(_min, start);
end = min(_max, end);
while (start + size <= end) {
/* skip reserved ranges below the start */
while (res && res->end <= start) {
res++;
if (res >= res_end)
res = NULL;
}
skip_res = NULL;
tmp_end = end;
/* has intersecting reserved range */
if (res && res->start < end) {
skip_res = res;
tmp_end = res->start;
}
if (start + size <= tmp_end) {
range_pos = (tmp_end - start - size) / align + 1;
if (pos_count) {
pos += range_pos;
} else {
if (range_pos >= find_pos)
return start + (find_pos - 1) * align;
find_pos -= range_pos;
}
}
if (!skip_res)
break;
start = round_up(skip_res->end, align);
}
}
return pos_count ? pos : 0;
}
/*
* Two types of decompressor memory allocations/reserves are considered
* differently.
*
* "Static" or "single" allocations are done via physmem_alloc_range() and
* physmem_reserve(), and they are listed in physmem_info.reserved[]. Each
* type of "static" allocation can only have one allocation per type and
* cannot have chains.
*
* On the other hand, "dynamic" or "repetitive" allocations are done via
* physmem_alloc_top_down(). These allocations are tightly packed together
* top down from the end of online memory. physmem_alloc_pos represents
* current position where those allocations start.
*
* Functions randomize_within_range() and iterate_valid_positions()
* only consider "dynamic" allocations by never looking above
* physmem_alloc_pos. "Static" allocations, however, are explicitly
* considered by checking the "res" (reserves) array. The first
* reserved_range of a "dynamic" allocation may also be checked along the
* way, but it will always be above the maximum value anyway.
*/
unsigned long randomize_within_range(unsigned long size, unsigned long align,
unsigned long min, unsigned long max)
{
struct reserved_range res[RR_MAX];
unsigned long max_pos, pos;
memcpy(res, physmem_info.reserved, sizeof(res));
sort_reserved_ranges(res, ARRAY_SIZE(res));
max = min(max, get_physmem_alloc_pos());
max_pos = iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), true, 0);
if (!max_pos)
return 0;
if (get_random(max_pos, &pos))
return 0;
return iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), false, pos + 1);
}
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