diff options
Diffstat (limited to 'arch/s390/boot/mem_detect.c')
| -rw-r--r-- | arch/s390/boot/mem_detect.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/arch/s390/boot/mem_detect.c b/arch/s390/boot/mem_detect.c new file mode 100644 index 000000000000..4cb771ba13fa --- /dev/null +++ b/arch/s390/boot/mem_detect.c @@ -0,0 +1,182 @@ +// 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" + +unsigned long __bootdata(max_physmem_end); +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(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 unsigned long get_mem_detect_end(void) +{ + if (mem_detect.count) + return __get_mem_detect_block_ptr(mem_detect.count - 1)->end; + return 0; +} + +static int __diag260(unsigned long rx1, unsigned long rx2) +{ + register unsigned long _rx1 asm("2") = rx1; + register unsigned long _rx2 asm("3") = rx2; + register unsigned long _ry asm("4") = 0x10; /* storage configuration */ + int rc = -1; /* fail */ + unsigned long reg1, reg2; + psw_t old = S390_lowcore.program_new_psw; + + asm volatile( + " epsw %0,%1\n" + " st %0,%[psw_pgm]\n" + " st %1,%[psw_pgm]+4\n" + " larl %0,1f\n" + " stg %0,%[psw_pgm]+8\n" + " diag %[rx],%[ry],0x260\n" + " ipm %[rc]\n" + " srl %[rc],28\n" + "1:\n" + : "=&d" (reg1), "=&a" (reg2), + [psw_pgm] "=Q" (S390_lowcore.program_new_psw), + [rc] "+&d" (rc), [ry] "+d" (_ry) + : [rx] "d" (_rx1), "d" (_rx2) + : "cc", "memory"); + S390_lowcore.program_new_psw = old; + 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 pgm_addr; + int rc = -EFAULT; + psw_t old = S390_lowcore.program_new_psw; + + S390_lowcore.program_new_psw.mask = __extract_psw(); + asm volatile( + " larl %[pgm_addr],1f\n" + " stg %[pgm_addr],%[psw_pgm_addr]\n" + " tprot 0(%[addr]),0\n" + " ipm %[rc]\n" + " srl %[rc],28\n" + "1:\n" + : [pgm_addr] "=&d"(pgm_addr), + [psw_pgm_addr] "=Q"(S390_lowcore.program_new_psw.addr), + [rc] "+&d"(rc) + : [addr] "a"(addr) + : "cc", "memory"); + S390_lowcore.program_new_psw = old; + 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); +} + +void detect_memory(void) +{ + sclp_early_get_memsize(&max_physmem_end); + + if (!sclp_early_read_storage_info()) { + mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO; + return; + } + + if (!diag260()) { + mem_detect.info_source = MEM_DETECT_DIAG260; + return; + } + + if (max_physmem_end) { + add_mem_detect_block(0, max_physmem_end); + mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO; + return; + } + + search_mem_end(); + mem_detect.info_source = MEM_DETECT_BIN_SEARCH; + max_physmem_end = get_mem_detect_end(); +} |