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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memory.c (2893B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * memory.c: memory initialisation code.
      4 *
      5 * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
      6 * Copyright (C) 2000, 2002  Maciej W. Rozycki
      7 */
      8#include <linux/init.h>
      9#include <linux/kernel.h>
     10#include <linux/mm.h>
     11#include <linux/memblock.h>
     12#include <linux/types.h>
     13
     14#include <asm/addrspace.h>
     15#include <asm/dec/machtype.h>
     16#include <asm/dec/prom.h>
     17#include <asm/page.h>
     18#include <asm/sections.h>
     19
     20
     21volatile unsigned long mem_err;		/* So we know an error occurred */
     22
     23/*
     24 * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
     25 * off the end of real memory.  Only suitable for the 2100/3100's (PMAX).
     26 */
     27
     28#define CHUNK_SIZE 0x400000
     29
     30static __init void pmax_setup_memory_region(void)
     31{
     32	volatile unsigned char *memory_page, dummy;
     33	char old_handler[0x80];
     34	extern char genexcept_early;
     35
     36	/* Install exception handler */
     37	memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
     38	memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80);
     39
     40	/* read unmapped and uncached (KSEG1)
     41	 * DECstations have at least 4MB RAM
     42	 * Assume less than 480MB of RAM, as this is max for 5000/2xx
     43	 * FIXME this should be replaced by the first free page!
     44	 */
     45	for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
     46	     mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
     47	     memory_page += CHUNK_SIZE) {
     48		dummy = *memory_page;
     49	}
     50	memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
     51
     52	memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
     53}
     54
     55/*
     56 * Use the REX prom calls to get hold of the memory bitmap, and thence
     57 * determine memory size.
     58 */
     59static __init void rex_setup_memory_region(void)
     60{
     61	int i, bitmap_size;
     62	unsigned long mem_start = 0, mem_size = 0;
     63	memmap *bm;
     64
     65	/* some free 64k */
     66	bm = (memmap *)CKSEG0ADDR(0x28000);
     67
     68	bitmap_size = rex_getbitmap(bm);
     69
     70	for (i = 0; i < bitmap_size; i++) {
     71		/* FIXME: very simplistically only add full sets of pages */
     72		if (bm->bitmap[i] == 0xff)
     73			mem_size += (8 * bm->pagesize);
     74		else if (!mem_size)
     75			mem_start += (8 * bm->pagesize);
     76		else {
     77			memblock_add(mem_start, mem_size);
     78			mem_start += mem_size + (8 * bm->pagesize);
     79			mem_size = 0;
     80		}
     81	}
     82	if (mem_size)
     83		memblock_add(mem_start, mem_size);
     84}
     85
     86void __init prom_meminit(u32 magic)
     87{
     88	if (!prom_is_rex(magic))
     89		pmax_setup_memory_region();
     90	else
     91		rex_setup_memory_region();
     92}
     93
     94void __init prom_free_prom_memory(void)
     95{
     96	unsigned long end;
     97
     98	/*
     99	 * Free everything below the kernel itself but leave
    100	 * the first page reserved for the exception handlers.
    101	 */
    102
    103#if IS_ENABLED(CONFIG_DECLANCE)
    104	/*
    105	 * Leave 128 KB reserved for Lance memory for
    106	 * IOASIC DECstations.
    107	 *
    108	 * XXX: save this address for use in dec_lance.c?
    109	 */
    110	if (IOASIC)
    111		end = __pa(&_text) - 0x00020000;
    112	else
    113#endif
    114		end = __pa(&_text);
    115
    116	free_init_pages("unused PROM memory", PAGE_SIZE, end);
    117}