vdso.c

linux 内核源代码

	for (i = 0; i < (lib->dynsymsize / sizeof(Elf64_Sym)); i++) {
		if (lib->dynsym[i].st_name == 0)
			continue;
		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
			MAX_SYMNAME);
		c = strchr(name, '@');
		if (c)
			*c = 0;
		if (strcmp(symname, name) == 0)
			return &lib->dynsym[i];
	}
	return NULL;
}

/* Note that we assume the section is .text and the symbol is relative to
 * the library base
 */
static unsigned long __init find_function64(struct lib64_elfinfo *lib,
					    const char *symname)
{
	Elf64_Sym *sym = find_symbol64(lib, symname);

	if (sym == NULL) {
		printk(KERN_WARNING "vDSO64: function %s not found !\n",
		       symname);
		return 0;
	}
#ifdef VDS64_HAS_DESCRIPTORS
	return *((u64 *)(vdso64_kbase + sym->st_value - VDSO64_LBASE)) -
		VDSO64_LBASE;
#else
	return sym->st_value - VDSO64_LBASE;
#endif
}

static int vdso_do_func_patch64(struct lib32_elfinfo *v32,
				struct lib64_elfinfo *v64,
				const char *orig, const char *fix)
{
	Elf64_Sym *sym64_gen, *sym64_fix;

	sym64_gen = find_symbol64(v64, orig);
	if (sym64_gen == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", orig);
		return -1;
	}
	if (fix == NULL) {
		sym64_gen->st_name = 0;
		return 0;
	}
	sym64_fix = find_symbol64(v64, fix);
	if (sym64_fix == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", fix);
		return -1;
	}
	sym64_gen->st_value = sym64_fix->st_value;
	sym64_gen->st_size = sym64_fix->st_size;
	sym64_gen->st_info = sym64_fix->st_info;
	sym64_gen->st_other = sym64_fix->st_other;
	sym64_gen->st_shndx = sym64_fix->st_shndx;

	return 0;
}

#endif /* CONFIG_PPC64 */


static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
					struct lib64_elfinfo *v64)
{
	void *sect;

	/*
	 * Locate symbol tables & text section
	 */

	v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize);
	v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
	if (v32->dynsym == NULL || v32->dynstr == NULL) {
		printk(KERN_ERR "vDSO32: required symbol section not found\n");
		return -1;
	}
	sect = find_section32(v32->hdr, ".text", NULL);
	if (sect == NULL) {
		printk(KERN_ERR "vDSO32: the .text section was not found\n");
		return -1;
	}
	v32->text = sect - vdso32_kbase;

#ifdef CONFIG_PPC64
	v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize);
	v64->dynstr = find_section64(v64->hdr, ".dynstr", NULL);
	if (v64->dynsym == NULL || v64->dynstr == NULL) {
		printk(KERN_ERR "vDSO64: required symbol section not found\n");
		return -1;
	}
	sect = find_section64(v64->hdr, ".text", NULL);
	if (sect == NULL) {
		printk(KERN_ERR "vDSO64: the .text section was not found\n");
		return -1;
	}
	v64->text = sect - vdso64_kbase;
#endif /* CONFIG_PPC64 */

	return 0;
}

static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
					  struct lib64_elfinfo *v64)
{
	/*
	 * Find signal trampolines
	 */

#ifdef CONFIG_PPC64
	vdso64_rt_sigtramp = find_function64(v64, "__kernel_sigtramp_rt64");
#endif
	vdso32_sigtramp	   = find_function32(v32, "__kernel_sigtramp32");
	vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32");
}

static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
				       struct lib64_elfinfo *v64)
{
	Elf32_Sym *sym32;
#ifdef CONFIG_PPC64
	Elf64_Sym *sym64;

       	sym64 = find_symbol64(v64, "__kernel_datapage_offset");
	if (sym64 == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol "
		       "__kernel_datapage_offset !\n");
		return -1;
	}
	*((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
		(vdso64_pages << PAGE_SHIFT) -
		(sym64->st_value - VDSO64_LBASE);
#endif /* CONFIG_PPC64 */

	sym32 = find_symbol32(v32, "__kernel_datapage_offset");
	if (sym32 == NULL) {
		printk(KERN_ERR "vDSO32: Can't find symbol "
		       "__kernel_datapage_offset !\n");
		return -1;
	}
	*((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
		(vdso32_pages << PAGE_SHIFT) -
		(sym32->st_value - VDSO32_LBASE);

	return 0;
}


static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
				      struct lib64_elfinfo *v64)
{
	void *start32;
	unsigned long size32;

#ifdef CONFIG_PPC64
	void *start64;
	unsigned long size64;

	start64 = find_section64(v64->hdr, "__ftr_fixup", &size64);
	if (start64)
		do_feature_fixups(cur_cpu_spec->cpu_features,
				  start64, start64 + size64);

	start64 = find_section64(v64->hdr, "__fw_ftr_fixup", &size64);
	if (start64)
		do_feature_fixups(powerpc_firmware_features,
				  start64, start64 + size64);
#endif /* CONFIG_PPC64 */

	start32 = find_section32(v32->hdr, "__ftr_fixup", &size32);
	if (start32)
		do_feature_fixups(cur_cpu_spec->cpu_features,
				  start32, start32 + size32);

#ifdef CONFIG_PPC64
	start32 = find_section32(v32->hdr, "__fw_ftr_fixup", &size32);
	if (start32)
		do_feature_fixups(powerpc_firmware_features,
				  start32, start32 + size32);
#endif /* CONFIG_PPC64 */

	return 0;
}

static __init int vdso_fixup_alt_funcs(struct lib32_elfinfo *v32,
				       struct lib64_elfinfo *v64)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(vdso_patches); i++) {
		struct vdso_patch_def *patch = &vdso_patches[i];
		int match = (cur_cpu_spec->cpu_features & patch->ftr_mask)
			== patch->ftr_value;
		if (!match)
			continue;

		DBG("replacing %s with %s...\n", patch->gen_name,
		    patch->fix_name ? "NONE" : patch->fix_name);

		/*
		 * Patch the 32 bits and 64 bits symbols. Note that we do not
		 * patch the "." symbol on 64 bits.
		 * It would be easy to do, but doesn't seem to be necessary,
		 * patching the OPD symbol is enough.
		 */
		vdso_do_func_patch32(v32, v64, patch->gen_name,
				     patch->fix_name);
#ifdef CONFIG_PPC64
		vdso_do_func_patch64(v32, v64, patch->gen_name,
				     patch->fix_name);
#endif /* CONFIG_PPC64 */
	}

	return 0;
}


static __init int vdso_setup(void)
{
	struct lib32_elfinfo	v32;
	struct lib64_elfinfo	v64;

	v32.hdr = vdso32_kbase;
#ifdef CONFIG_PPC64
	v64.hdr = vdso64_kbase;
#endif
	if (vdso_do_find_sections(&v32, &v64))
		return -1;

	if (vdso_fixup_datapage(&v32, &v64))
		return -1;

	if (vdso_fixup_features(&v32, &v64))
		return -1;

	if (vdso_fixup_alt_funcs(&v32, &v64))
		return -1;

	vdso_setup_trampolines(&v32, &v64);

	return 0;
}

/*
 * Called from setup_arch to initialize the bitmap of available
 * syscalls in the systemcfg page
 */
static void __init vdso_setup_syscall_map(void)
{
	unsigned int i;
	extern unsigned long *sys_call_table;
	extern unsigned long sys_ni_syscall;


	for (i = 0; i < __NR_syscalls; i++) {
#ifdef CONFIG_PPC64
		if (sys_call_table[i*2] != sys_ni_syscall)
			vdso_data->syscall_map_64[i >> 5] |=
				0x80000000UL >> (i & 0x1f);
		if (sys_call_table[i*2+1] != sys_ni_syscall)
			vdso_data->syscall_map_32[i >> 5] |=
				0x80000000UL >> (i & 0x1f);
#else /* CONFIG_PPC64 */
		if (sys_call_table[i] != sys_ni_syscall)
			vdso_data->syscall_map_32[i >> 5] |=
				0x80000000UL >> (i & 0x1f);
#endif /* CONFIG_PPC64 */
	}
}


static int __init vdso_init(void)
{
	int i;

#ifdef CONFIG_PPC64
	/*
	 * Fill up the "systemcfg" stuff for backward compatiblity
	 */
	strcpy((char *)vdso_data->eye_catcher, "SYSTEMCFG:PPC64");
	vdso_data->version.major = SYSTEMCFG_MAJOR;
	vdso_data->version.minor = SYSTEMCFG_MINOR;
	vdso_data->processor = mfspr(SPRN_PVR);
	/*
	 * Fake the old platform number for pSeries and iSeries and add
	 * in LPAR bit if necessary
	 */
	vdso_data->platform = machine_is(iseries) ? 0x200 : 0x100;
	if (firmware_has_feature(FW_FEATURE_LPAR))
		vdso_data->platform |= 1;
	vdso_data->physicalMemorySize = lmb_phys_mem_size();
	vdso_data->dcache_size = ppc64_caches.dsize;
	vdso_data->dcache_line_size = ppc64_caches.dline_size;
	vdso_data->icache_size = ppc64_caches.isize;
	vdso_data->icache_line_size = ppc64_caches.iline_size;

	/* XXXOJN: Blocks should be added to ppc64_caches and used instead */
	vdso_data->dcache_block_size = ppc64_caches.dline_size;
	vdso_data->icache_block_size = ppc64_caches.iline_size;
	vdso_data->dcache_log_block_size = ppc64_caches.log_dline_size;
	vdso_data->icache_log_block_size = ppc64_caches.log_iline_size;

	/*
	 * Calculate the size of the 64 bits vDSO
	 */
	vdso64_pages = (&vdso64_end - &vdso64_start) >> PAGE_SHIFT;
	DBG("vdso64_kbase: %p, 0x%x pages\n", vdso64_kbase, vdso64_pages);
#else
	vdso_data->dcache_block_size = L1_CACHE_BYTES;
	vdso_data->dcache_log_block_size = L1_CACHE_SHIFT;
	vdso_data->icache_block_size = L1_CACHE_BYTES;
	vdso_data->icache_log_block_size = L1_CACHE_SHIFT;
#endif /* CONFIG_PPC64 */


	/*
	 * Calculate the size of the 32 bits vDSO
	 */
	vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;
	DBG("vdso32_kbase: %p, 0x%x pages\n", vdso32_kbase, vdso32_pages);


	/*
	 * Setup the syscall map in the vDOS
	 */
	vdso_setup_syscall_map();

	/*
	 * Initialize the vDSO images in memory, that is do necessary
	 * fixups of vDSO symbols, locate trampolines, etc...
	 */
	if (vdso_setup()) {
		printk(KERN_ERR "vDSO setup failure, not enabled !\n");
		vdso32_pages = 0;
#ifdef CONFIG_PPC64
		vdso64_pages = 0;
#endif
		return 0;
	}

	/* Make sure pages are in the correct state */
	vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 2),
				  GFP_KERNEL);
	BUG_ON(vdso32_pagelist == NULL);
	for (i = 0; i < vdso32_pages; i++) {
		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
		vdso32_pagelist[i] = pg;
	}
	vdso32_pagelist[i++] = virt_to_page(vdso_data);
	vdso32_pagelist[i] = NULL;

#ifdef CONFIG_PPC64
	vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 2),
				  GFP_KERNEL);
	BUG_ON(vdso64_pagelist == NULL);
	for (i = 0; i < vdso64_pages; i++) {
		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
		vdso64_pagelist[i] = pg;
	}
	vdso64_pagelist[i++] = virt_to_page(vdso_data);
	vdso64_pagelist[i] = NULL;
#endif /* CONFIG_PPC64 */

	get_page(virt_to_page(vdso_data));

	smp_wmb();
	vdso_ready = 1;

	return 0;
}
#ifdef CONFIG_PPC_MERGE
arch_initcall(vdso_init);
#endif

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}

int in_gate_area(struct task_struct *task, unsigned long addr)
{
	return 0;
}

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
	return NULL;
}