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// SPDX-License-Identifier: GPL-2.0
#include <linux/errno.h>
#include <linux/init.h>
#include <asm/sclp.h>
#include <asm/sections.h>
#include <asm/mem_detect.h>
#include <asm/sparsemem.h>
#include "compressed/decompressor.h"
#include "boot.h"
struct mem_detect_info __bootdata(mem_detect);
/* up to 256 storage elements, 1020 subincrements each */
#define ENTRIES_EXTENDED_MAX \
(256 * (1020 / 2) * sizeof(struct mem_detect_block))
/*
* To avoid corrupting old kernel memory during dump, find lowest memory
* chunk possible either right after the kernel end (decompressed kernel) or
* after initrd (if it is present and there is no hole between the kernel end
* and initrd)
*/
static void *mem_detect_alloc_extended(void)
{
unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE &&
INITRD_START < offset + ENTRIES_EXTENDED_MAX)
offset = ALIGN(INITRD_START + INITRD_SIZE, sizeof(u64));
return (void *)offset;
}
static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
{
if (n < MEM_INLINED_ENTRIES)
return &mem_detect.entries[n];
if (unlikely(!mem_detect.entries_extended))
mem_detect.entries_extended = mem_detect_alloc_extended();
return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
}
/*
* sequential calls to add_mem_detect_block with adjacent memory areas
* are merged together into single memory block.
*/
void add_mem_detect_block(u64 start, u64 end)
{
struct mem_detect_block *block;
if (mem_detect.count) {
block = __get_mem_detect_block_ptr(mem_detect.count - 1);
if (block->end == start) {
block->end = end;
return;
}
}
block = __get_mem_detect_block_ptr(mem_detect.count);
block->start = start;
block->end = end;
mem_detect.count++;
}
static int __diag260(unsigned long rx1, unsigned long rx2)
{
unsigned long reg1, reg2, ry;
union register_pair rx;
psw_t old;
int rc;
rx.even = rx1;
rx.odd = rx2;
ry = 0x10; /* storage configuration */
rc = -1; /* fail */
asm volatile(
" mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
" epsw %[reg1],%[reg2]\n"
" st %[reg1],0(%[psw_pgm])\n"
" st %[reg2],4(%[psw_pgm])\n"
" larl %[reg1],1f\n"
" stg %[reg1],8(%[psw_pgm])\n"
" diag %[rx],%[ry],0x260\n"
" ipm %[rc]\n"
" srl %[rc],28\n"
"1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
: [reg1] "=&d" (reg1),
[reg2] "=&a" (reg2),
[rc] "+&d" (rc),
[ry] "+&d" (ry),
"+Q" (S390_lowcore.program_new_psw),
"=Q" (old)
: [rx] "d" (rx.pair),
[psw_old] "a" (&old),
[psw_pgm] "a" (&S390_lowcore.program_new_psw)
: "cc", "memory");
return rc == 0 ? ry : -1;
}
static int diag260(void)
{
int rc, i;
struct {
unsigned long start;
unsigned long end;
} storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
memset(storage_extents, 0, sizeof(storage_extents));
rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
if (rc == -1)
return -1;
for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
return 0;
}
static int tprot(unsigned long addr)
{
unsigned long reg1, reg2;
int rc = -EFAULT;
psw_t old;
asm volatile(
" mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
" epsw %[reg1],%[reg2]\n"
" st %[reg1],0(%[psw_pgm])\n"
" st %[reg2],4(%[psw_pgm])\n"
" larl %[reg1],1f\n"
" stg %[reg1],8(%[psw_pgm])\n"
" tprot 0(%[addr]),0\n"
" ipm %[rc]\n"
" srl %[rc],28\n"
"1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
: [reg1] "=&d" (reg1),
[reg2] "=&a" (reg2),
[rc] "+&d" (rc),
"=Q" (S390_lowcore.program_new_psw.addr),
"=Q" (old)
: [psw_old] "a" (&old),
[psw_pgm] "a" (&S390_lowcore.program_new_psw),
[addr] "a" (addr)
: "cc", "memory");
return rc;
}
static void search_mem_end(void)
{
unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
unsigned long offset = 0;
unsigned long pivot;
while (range > 1) {
range >>= 1;
pivot = offset + range;
if (!tprot(pivot << 20))
offset = pivot;
}
add_mem_detect_block(0, (offset + 1) << 20);
}
unsigned long detect_memory(void)
{
unsigned long max_physmem_end;
sclp_early_get_memsize(&max_physmem_end);
if (!sclp_early_read_storage_info()) {
mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
return max_physmem_end;
}
if (!diag260()) {
mem_detect.info_source = MEM_DETECT_DIAG260;
return max_physmem_end;
}
if (max_physmem_end) {
add_mem_detect_block(0, max_physmem_end);
mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
return max_physmem_end;
}
search_mem_end();
mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
return get_mem_detect_end();
}
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