// SPDX-License-Identifier: GPL-2.0-or-later /* *    Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. *			 <benh@kernel.crashing.org> */ #include <linux/errno.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/mm.h>#include <linux/smp.h>#include <linux/stddef.h>#include <linux/unistd.h>#include <linux/slab.h>#include <linux/user.h>#include <linux/elf.h>#include <linux/security.h>#include <linux/syscalls.h>#include <linux/vdso_datastore.h>#include <vdso/datapage.h> #include <asm/syscall.h>#include <asm/syscalls.h>#include <asm/processor.h>#include <asm/mmu.h>#include <asm/mmu_context.h>#include <asm/machdep.h>#include <asm/cputable.h>#include <asm/sections.h>#include <asm/firmware.h>#include <asm/vdso.h>#include <asm/vdso_datapage.h>#include <asm/setup.h> static_assert(__VDSO_PAGES == VDSO_NR_PAGES); /* The alignment of the vDSO */#define VDSO_ALIGNMENT	(1 << 16) extern char vdso32_start, vdso32_end;extern char vdso64_start, vdso64_end; static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma,		       unsigned long text_size){	unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 	if (new_size != text_size)		return -EINVAL; 	current->mm->context.vdso = (void __user *)new_vma->vm_start; 	return 0;} static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma){	return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start);} static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma){	return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start);} static void vdso_close(const struct vm_special_mapping *sm, struct vm_area_struct *vma){	struct mm_struct *mm = vma->vm_mm; 	/*	 * close() is called for munmap() but also for mremap(). In the mremap()	 * case the vdso pointer has already been updated by the mremap() hook	 * above, so it must not be set to NULL here.	 */	if (vma->vm_start != (unsigned long)mm->context.vdso)		return; 	mm->context.vdso = NULL;} static struct vm_special_mapping vdso32_spec __ro_after_init = {	.name = "[vdso]",	.mremap = vdso32_mremap,	.close = vdso_close,}; static struct vm_special_mapping vdso64_spec __ro_after_init = {	.name = "[vdso]",	.mremap = vdso64_mremap,	.close = vdso_close,}; /* * This is called from binfmt_elf, we create the special vma for the * vDSO and insert it into the mm struct tree */static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp){	unsigned long vdso_size, vdso_base, mappings_size;	struct vm_special_mapping *vdso_spec;	unsigned long vvar_size = VDSO_NR_PAGES * PAGE_SIZE;	struct mm_struct *mm = current->mm;	struct vm_area_struct *vma; 	if (is_32bit_task()) {		vdso_spec = &vdso32_spec;		vdso_size = &vdso32_end - &vdso32_start;	} else {		vdso_spec = &vdso64_spec;		vdso_size = &vdso64_end - &vdso64_start;	} 	mappings_size = vdso_size + vvar_size;	mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK; 	/*	 * Pick a base address for the vDSO in process space.	 * Add enough to the size so that the result can be aligned.	 */	vdso_base = get_unmapped_area(NULL, 0, mappings_size, 0, 0);	if (IS_ERR_VALUE(vdso_base))		return vdso_base; 	/* Add required alignment. */	vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); 	vma = vdso_install_vvar_mapping(mm, vdso_base);	if (IS_ERR(vma))		return PTR_ERR(vma); 	/*	 * our vma flags don't have VM_WRITE so by default, the process isn't	 * allowed to write those pages.	 * gdb can break that with ptrace interface, and thus trigger COW on	 * those pages but it's then your responsibility to never do that on	 * the "data" page of the vDSO or you'll stop getting kernel updates	 * and your nice userland gettimeofday will be totally dead.	 * It's fine to use that for setting breakpoints in the vDSO code	 * pages though.	 */	vma = _install_special_mapping(mm, vdso_base + vvar_size, vdso_size,				       VM_READ | VM_EXEC | VM_MAYREAD |				       VM_MAYWRITE | VM_MAYEXEC, vdso_spec);	if (IS_ERR(vma)) {		do_munmap(mm, vdso_base, vvar_size, NULL);		return PTR_ERR(vma);	} 	// Now that the mappings are in place, set the mm VDSO pointer	mm->context.vdso = (void __user *)vdso_base + vvar_size; 	return 0;} int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp){	struct mm_struct *mm = current->mm;	int rc; 	mm->context.vdso = NULL; 	if (mmap_write_lock_killable(mm))		return -EINTR; 	rc = __arch_setup_additional_pages(bprm, uses_interp); 	mmap_write_unlock(mm);	return rc;} #define VDSO_DO_FIXUPS(type, value, bits, sec) do {					\	void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start);	\	void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end);	\											\	do_##type##_fixups((value), __start, __end);					\} while (0) static void __init vdso_fixup_features(void){#ifdef CONFIG_PPC64	VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup);	VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup);	VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup);	VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup);#endif /* CONFIG_PPC64 */ #ifdef CONFIG_VDSO32	VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup);	VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup);#ifdef CONFIG_PPC64	VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup);#endif /* CONFIG_PPC64 */	VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup);#endif} /* * 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; 	for (i = 0; i < NR_syscalls; i++) {		if (sys_call_table[i] != (void *)&sys_ni_syscall)			vdso_k_arch_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);		if (IS_ENABLED(CONFIG_COMPAT) &&		    compat_sys_call_table[i] != (void *)&sys_ni_syscall)			vdso_k_arch_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);	}} #ifdef CONFIG_PPC64int vdso_getcpu_init(void){	unsigned long cpu, node, val; 	/*	 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node	 * in the next 16 bits.  The VDSO uses this to implement getcpu().	 */	cpu = get_cpu();	WARN_ON_ONCE(cpu > 0xffff); 	node = cpu_to_node(cpu);	WARN_ON_ONCE(node > 0xffff); 	val = (cpu & 0xffff) | ((node & 0xffff) << 16);	mtspr(SPRN_SPRG_VDSO_WRITE, val);	get_paca()->sprg_vdso = val; 	put_cpu(); 	return 0;}/* We need to call this before SMP init */early_initcall(vdso_getcpu_init);#endif static struct page ** __init vdso_setup_pages(void *start, void *end){	int i;	struct page **pagelist;	int pages = (end - start) >> PAGE_SHIFT; 	pagelist = kzalloc_objs(struct page *, pages + 1);	if (!pagelist)		panic("%s: Cannot allocate page list for VDSO", __func__); 	for (i = 0; i < pages; i++)		pagelist[i] = virt_to_page(start + i * PAGE_SIZE); 	return pagelist;} static int __init vdso_init(void){#ifdef CONFIG_PPC64	vdso_k_arch_data->dcache_block_size = ppc64_caches.l1d.block_size;	vdso_k_arch_data->icache_block_size = ppc64_caches.l1i.block_size;	vdso_k_arch_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size;	vdso_k_arch_data->icache_log_block_size = ppc64_caches.l1i.log_block_size;#endif /* CONFIG_PPC64 */ 	vdso_setup_syscall_map(); 	vdso_fixup_features(); 	if (IS_ENABLED(CONFIG_VDSO32))		vdso32_spec.pages = vdso_setup_pages(&vdso32_start, &vdso32_end); 	if (IS_ENABLED(CONFIG_PPC64))		vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end); 	smp_wmb(); 	return 0;}arch_initcall(vdso_init);