![Julia Lawall](/assets/img/avatar_default.png)
As noted by Akinobu Mita in patch b1fceac2b9
,
alloc_bootmem and related functions never return NULL and always return a
zeroed region of memory. Thus a NULL test or memset after calls to these
functions is unnecessary.
This was fixed using the following semantic patch.
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@@
expression E;
statement S;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\|alloc_bootmem_node\|alloc_bootmem_low_pages_node\|alloc_bootmem_pages_node\)(...)
... when != E
(
- BUG_ON (E == NULL);
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- if (E == NULL) S
)
@@
expression E,E1;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\|alloc_bootmem_node\|alloc_bootmem_low_pages_node\|alloc_bootmem_pages_node\)(...)
... when != E
- memset(E,0,E1);
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
183 lines
4.5 KiB
C
183 lines
4.5 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/init.h>
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#include <linux/mmzone.h>
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#include <linux/module.h>
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#include <linux/bootmem.h>
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#include <linux/pagemap.h>
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#include <linux/nodemask.h>
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#include <asm/page.h>
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#include <asm/mmu_context.h>
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#include <asm/tlb.h>
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#include <asm/io.h>
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#include <asm/dma.h>
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#include <asm/setup.h>
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#include <asm/sections.h>
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#define __page_aligned __attribute__((section(".data.page_aligned")))
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DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
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pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned;
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struct page *empty_zero_page;
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EXPORT_SYMBOL(empty_zero_page);
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/*
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* Cache of MMU context last used.
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*/
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unsigned long mmu_context_cache = NO_CONTEXT;
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/*
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* paging_init() sets up the page tables
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*
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* This routine also unmaps the page at virtual kernel address 0, so
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* that we can trap those pesky NULL-reference errors in the kernel.
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*/
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void __init paging_init(void)
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{
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extern unsigned long _evba;
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void *zero_page;
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int nid;
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/*
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* Make sure we can handle exceptions before enabling
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* paging. Not that we should ever _get_ any exceptions this
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* early, but you never know...
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*/
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printk("Exception vectors start at %p\n", &_evba);
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sysreg_write(EVBA, (unsigned long)&_evba);
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/*
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* Since we are ready to handle exceptions now, we should let
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* the CPU generate them...
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*/
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__asm__ __volatile__ ("csrf %0" : : "i"(SR_EM_BIT));
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/*
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* Allocate the zero page. The allocator will panic if it
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* can't satisfy the request, so no need to check.
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*/
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zero_page = alloc_bootmem_low_pages_node(NODE_DATA(0),
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PAGE_SIZE);
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sysreg_write(PTBR, (unsigned long)swapper_pg_dir);
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enable_mmu();
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printk ("CPU: Paging enabled\n");
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for_each_online_node(nid) {
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pg_data_t *pgdat = NODE_DATA(nid);
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unsigned long zones_size[MAX_NR_ZONES];
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unsigned long low, start_pfn;
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start_pfn = pgdat->bdata->node_min_pfn;
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low = pgdat->bdata->node_low_pfn;
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memset(zones_size, 0, sizeof(zones_size));
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zones_size[ZONE_NORMAL] = low - start_pfn;
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printk("Node %u: start_pfn = 0x%lx, low = 0x%lx\n",
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nid, start_pfn, low);
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free_area_init_node(nid, zones_size, start_pfn, NULL);
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printk("Node %u: mem_map starts at %p\n",
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pgdat->node_id, pgdat->node_mem_map);
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}
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mem_map = NODE_DATA(0)->node_mem_map;
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empty_zero_page = virt_to_page(zero_page);
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flush_dcache_page(empty_zero_page);
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}
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void __init mem_init(void)
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{
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int codesize, reservedpages, datasize, initsize;
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int nid, i;
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reservedpages = 0;
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high_memory = NULL;
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/* this will put all low memory onto the freelists */
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for_each_online_node(nid) {
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pg_data_t *pgdat = NODE_DATA(nid);
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unsigned long node_pages = 0;
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void *node_high_memory;
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num_physpages += pgdat->node_present_pages;
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if (pgdat->node_spanned_pages != 0)
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node_pages = free_all_bootmem_node(pgdat);
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totalram_pages += node_pages;
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for (i = 0; i < node_pages; i++)
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if (PageReserved(pgdat->node_mem_map + i))
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reservedpages++;
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node_high_memory = (void *)((pgdat->node_start_pfn
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+ pgdat->node_spanned_pages)
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<< PAGE_SHIFT);
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if (node_high_memory > high_memory)
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high_memory = node_high_memory;
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}
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max_mapnr = MAP_NR(high_memory);
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codesize = (unsigned long)_etext - (unsigned long)_text;
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datasize = (unsigned long)_edata - (unsigned long)_data;
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initsize = (unsigned long)__init_end - (unsigned long)__init_begin;
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printk ("Memory: %luk/%luk available (%dk kernel code, "
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"%dk reserved, %dk data, %dk init)\n",
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(unsigned long)nr_free_pages() << (PAGE_SHIFT - 10),
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totalram_pages << (PAGE_SHIFT - 10),
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codesize >> 10,
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reservedpages << (PAGE_SHIFT - 10),
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datasize >> 10,
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initsize >> 10);
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}
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static inline void free_area(unsigned long addr, unsigned long end, char *s)
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{
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unsigned int size = (end - addr) >> 10;
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for (; addr < end; addr += PAGE_SIZE) {
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struct page *page = virt_to_page(addr);
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ClearPageReserved(page);
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init_page_count(page);
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free_page(addr);
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totalram_pages++;
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}
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if (size && s)
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printk(KERN_INFO "Freeing %s memory: %dK (%lx - %lx)\n",
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s, size, end - (size << 10), end);
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}
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void free_initmem(void)
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{
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free_area((unsigned long)__init_begin, (unsigned long)__init_end,
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"init");
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}
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#ifdef CONFIG_BLK_DEV_INITRD
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void free_initrd_mem(unsigned long start, unsigned long end)
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{
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free_area(start, end, "initrd");
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}
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#endif
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