一个2.4.21版本的嵌入式linux内核

				/*				 * IA-32 ELF support.				 *				 * Copyright (C) 1999 Arun Sharma 				 * Copyright (C) 2001 Hewlett-Packard Co				 *	David Mosberger-Tang 				 *				 * 06/16/00	A. Mallick	initialize csd/ssd/tssd/cflg for ia32_load_state				 * 04/13/01	D. Mosberger	dropped saving tssd in ar.k1---it's not needed				 * 09/14/01	D. Mosberger	fixed memory management for gdt/tss page				 */				#include 								#include 								#include 				#include 				#include 								#define CONFIG_BINFMT_ELF32								/* Override some function names */				#undef start_thread				#define start_thread			ia32_start_thread				#define elf_format			elf32_format				#define init_elf_binfmt			init_elf32_binfmt				#define exit_elf_binfmt			exit_elf32_binfmt								#undef CONFIG_BINFMT_ELF				#ifdef CONFIG_BINFMT_ELF32				# define CONFIG_BINFMT_ELF		CONFIG_BINFMT_ELF32				#endif								#undef CONFIG_BINFMT_ELF_MODULE				#ifdef CONFIG_BINFMT_ELF32_MODULE				# define CONFIG_BINFMT_ELF_MODULE	CONFIG_BINFMT_ELF32_MODULE				#endif								#undef CLOCKS_PER_SEC				#define CLOCKS_PER_SEC	IA32_CLOCKS_PER_SEC								extern void ia64_elf32_init (struct pt_regs *regs);				extern void put_dirty_page (struct task_struct * tsk, struct page *page, unsigned long address);								static void elf32_set_personality (void);								#define ELF_PLAT_INIT(_r)		ia64_elf32_init(_r)				#define setup_arg_pages(bprm)		ia32_setup_arg_pages(bprm)				#define elf_map				elf32_map								#undef SET_PERSONALITY				#define SET_PERSONALITY(ex, ibcs2)	elf32_set_personality()								/* Ugly but avoids duplication */				#include "../../../fs/binfmt_elf.c"								extern struct page *ia32_shared_page[];				extern unsigned long *ia32_gdt;								struct page *				ia32_install_shared_page (struct vm_area_struct *vma, unsigned long address, int no_share)				{					struct page *pg = ia32_shared_page[(address - vma->vm_start)/PAGE_SIZE];									get_page(pg);					return pg;				}								static struct vm_operations_struct ia32_shared_page_vm_ops = {					nopage:	ia32_install_shared_page				};								void				ia64_elf32_init (struct pt_regs *regs)				{					struct vm_area_struct *vma;									/*					 * Map GDT and TSS below 4GB, where the processor can find them.  We need to map					 * it with privilege level 3 because the IVE uses non-privileged accesses to these					 * tables.  IA-32 segmentation is used to protect against IA-32 accesses to them.					 */					vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);					if (vma) {						vma->vm_mm = current->mm;						vma->vm_start = IA32_GDT_OFFSET;						vma->vm_end = vma->vm_start + max(PAGE_SIZE, 2*IA32_PAGE_SIZE);						vma->vm_page_prot = PAGE_SHARED;						vma->vm_flags = VM_READ|VM_MAYREAD;						vma->vm_ops = &ia32_shared_page_vm_ops;						vma->vm_pgoff = 0;						vma->vm_file = NULL;						vma->vm_private_data = NULL;						down_write(¤t->mm->mmap_sem);						{							insert_vm_struct(current->mm, vma);						}						up_write(¤t->mm->mmap_sem);					}									/*					 * Install LDT as anonymous memory.  This gives us all-zero segment descriptors					 * until a task modifies them via modify_ldt().					 */					vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);					if (vma) {						vma->vm_mm = current->mm;						vma->vm_start = IA32_LDT_OFFSET;						vma->vm_end = vma->vm_start + PAGE_ALIGN(IA32_LDT_ENTRIES*IA32_LDT_ENTRY_SIZE);						vma->vm_page_prot = PAGE_SHARED;						vma->vm_flags = VM_READ|VM_WRITE|VM_MAYREAD|VM_MAYWRITE;						vma->vm_ops = NULL;						vma->vm_pgoff = 0;						vma->vm_file = NULL;						vma->vm_private_data = NULL;						down_write(¤t->mm->mmap_sem);						{							insert_vm_struct(current->mm, vma);						}						up_write(¤t->mm->mmap_sem);					}									ia64_psr(regs)->ac = 0;		/* turn off alignment checking */					regs->loadrs = 0;					/*					 *  According to the ABI %edx points to an `atexit' handler.  Since we don't have					 *  one we'll set it to 0 and initialize all the other registers just to make					 *  things more deterministic, ala the i386 implementation.					 */					regs->r8 = 0;	/* %eax */					regs->r11 = 0;	/* %ebx */					regs->r9 = 0;	/* %ecx */					regs->r10 = 0;	/* %edx */					regs->r13 = 0;	/* %ebp */					regs->r14 = 0;	/* %esi */					regs->r15 = 0;	/* %edi */									current->thread.eflag = IA32_EFLAG;					current->thread.fsr = IA32_FSR_DEFAULT;					current->thread.fcr = IA32_FCR_DEFAULT;					current->thread.fir = 0;					current->thread.fdr = 0;									/*					 * Setup GDTD.  Note: GDTD is the descrambled version of the pseudo-descriptor					 * format defined by Figure 3-11 "Pseudo-Descriptor Format" in the IA-32					 * architecture manual. Also note that the only fields that are not ignored are					 * `base', `limit', 'G', `P' (must be 1) and `S' (must be 0).					 */					regs->r31 = IA32_SEG_UNSCRAMBLE(IA32_SEG_DESCRIPTOR(IA32_GDT_OFFSET, IA32_PAGE_SIZE - 1,											    0, 0, 0, 1, 0, 0, 0));					/* Setup the segment selectors */					regs->r16 = (__USER_DS 					regs->r17 = (__USER_DS 									ia32_load_segment_descriptors(current);					ia32_load_state(current);				}								int				ia32_setup_arg_pages (struct linux_binprm *bprm)				{					unsigned long stack_base;					struct vm_area_struct *mpnt;					int i;									stack_base = IA32_STACK_TOP - MAX_ARG_PAGES*PAGE_SIZE;									bprm->p += stack_base;					if (bprm->loader)						bprm->loader += stack_base;					bprm->exec += stack_base;									mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);					if (!mpnt)						return -ENOMEM;									down_write(¤t->mm->mmap_sem);					{						mpnt->vm_mm = current->mm;						mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;						mpnt->vm_end = IA32_STACK_TOP;						mpnt->vm_page_prot = PAGE_COPY;						mpnt->vm_flags = VM_STACK_FLAGS;						mpnt->vm_ops = NULL;						mpnt->vm_pgoff = 0;						mpnt->vm_file = NULL;						mpnt->vm_private_data = 0;						insert_vm_struct(current->mm, mpnt);						current->mm->total_vm = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;					}									for (i = 0 ; i < MAX_ARG_PAGES ; i++) {						struct page *page = bprm->page[i];						if (page) {							bprm->page[i] = NULL;							put_dirty_page(current, page, stack_base);						}						stack_base += PAGE_SIZE;					}					up_write(¤t->mm->mmap_sem);									return 0;				}								static void				elf32_set_personality (void)				{					set_personality(PER_LINUX32);					current->thread.map_base  = IA32_PAGE_OFFSET/3;					current->thread.task_size = IA32_PAGE_OFFSET;	/* use what Linux/x86 uses... */					current->thread.flags |= IA64_THREAD_XSTACK;	/* data must be executable */					set_fs(USER_DS);				/* set addr limit for new TASK_SIZE */				}								static unsigned long				elf32_map (struct file *filep, unsigned long addr, struct elf_phdr *eppnt, int prot, int type)				{					unsigned long pgoff = (eppnt->p_vaddr) & ~IA32_PAGE_MASK;									return ia32_do_mmap(filep, (addr & IA32_PAGE_MASK), eppnt->p_filesz + pgoff, prot, type,							    eppnt->p_offset - pgoff);				}