1 files changed, 378 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
new file mode 100644
index 000000000..7a2ff9010
--- /dev/null
+++ b/arch/powerpc/kernel/vdso.c
@@ -0,0 +1,378 @@
+// 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/memblock.h>
+#include <linux/syscalls.h>
+#include <linux/time_namespace.h>
+#include <vdso/datapage.h>
+
+#include <asm/syscall.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>
+
+/* The alignment of the vDSO */
+#define VDSO_ALIGNMENT	(1 << 16)
+
+extern char vdso32_start, vdso32_end;
+extern char vdso64_start, vdso64_end;
+
+long sys_ni_syscall(void);
+
+/*
+ * The vdso data page (aka. systemcfg for old ppc64 fans) is here.
+ * Once the early boot kernel code no longer needs to muck around
+ * with it, it will become dynamically allocated
+ */
+static union {
+	struct vdso_arch_data	data;
+	u8			page[PAGE_SIZE];
+} vdso_data_store __page_aligned_data;
+struct vdso_arch_data *vdso_data = &vdso_data_store.data;
+
+enum vvar_pages {
+	VVAR_DATA_PAGE_OFFSET,
+	VVAR_TIMENS_PAGE_OFFSET,
+	VVAR_NR_PAGES,
+};
+
+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 vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
+			     struct vm_area_struct *vma, struct vm_fault *vmf);
+
+static struct vm_special_mapping vvar_spec __ro_after_init = {
+	.name = "[vvar]",
+	.fault = vvar_fault,
+};
+
+static struct vm_special_mapping vdso32_spec __ro_after_init = {
+	.name = "[vdso]",
+	.mremap = vdso32_mremap,
+};
+
+static struct vm_special_mapping vdso64_spec __ro_after_init = {
+	.name = "[vdso]",
+	.mremap = vdso64_mremap,
+};
+
+#ifdef CONFIG_TIME_NS
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+	return ((struct vdso_arch_data *)vvar_page)->data;
+}
+
+/*
+ * The vvar mapping contains data for a specific time namespace, so when a task
+ * changes namespace we must unmap its vvar data for the old namespace.
+ * Subsequent faults will map in data for the new namespace.
+ *
+ * For more details see timens_setup_vdso_data().
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+	struct mm_struct *mm = task->mm;
+	VMA_ITERATOR(vmi, mm, 0);
+	struct vm_area_struct *vma;
+
+	mmap_read_lock(mm);
+	for_each_vma(vmi, vma) {
+		if (vma_is_special_mapping(vma, &vvar_spec))
+			zap_vma_pages(vma);
+	}
+	mmap_read_unlock(mm);
+
+	return 0;
+}
+#endif
+
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
+			     struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *timens_page = find_timens_vvar_page(vma);
+	unsigned long pfn;
+
+	switch (vmf->pgoff) {
+	case VVAR_DATA_PAGE_OFFSET:
+		if (timens_page)
+			pfn = page_to_pfn(timens_page);
+		else
+			pfn = virt_to_pfn(vdso_data);
+		break;
+#ifdef CONFIG_TIME_NS
+	case VVAR_TIMENS_PAGE_OFFSET:
+		/*
+		 * If a task belongs to a time namespace then a namespace
+		 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
+		 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
+		 * offset.
+		 * See also the comment near timens_setup_vdso_data().
+		 */
+		if (!timens_page)
+			return VM_FAULT_SIGBUS;
+		pfn = virt_to_pfn(vdso_data);
+		break;
+#endif /* CONFIG_TIME_NS */
+	default:
+		return VM_FAULT_SIGBUS;
+	}
+
+	return vmf_insert_pfn(vma, vmf->address, pfn);
+}
+
+/*
+ * 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 = VVAR_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);
+
+	/*
+	 * Put vDSO base into mm struct. We need to do this before calling
+	 * install_special_mapping or the perf counter mmap tracking code
+	 * will fail to recognise it as a vDSO.
+	 */
+	mm->context.vdso = (void __user *)vdso_base + vvar_size;
+
+	vma = _install_special_mapping(mm, vdso_base, vvar_size,
+				       VM_READ | VM_MAYREAD | VM_IO |
+				       VM_DONTDUMP | VM_PFNMAP, &vvar_spec);
+	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_OR_ZERO(vma);
+}
+
+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);
+	if (rc)
+		mm->context.vdso = NULL;
+
+	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_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
+		if (IS_ENABLED(CONFIG_COMPAT) &&
+		    compat_sys_call_table[i] != (void *)&sys_ni_syscall)
+			vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
+	}
+}
+
+#ifdef CONFIG_PPC64
+int 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 = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL);
+	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
+	/*
+	 * Fill up the "systemcfg" stuff for backward compatibility
+	 */
+	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 add
+	 * in LPAR bit if necessary
+	 */
+	vdso_data->platform = 0x100;
+	if (firmware_has_feature(FW_FEATURE_LPAR))
+		vdso_data->platform |= 1;
+	vdso_data->physicalMemorySize = memblock_phys_mem_size();
+	vdso_data->dcache_size = ppc64_caches.l1d.size;
+	vdso_data->dcache_line_size = ppc64_caches.l1d.line_size;
+	vdso_data->icache_size = ppc64_caches.l1i.size;
+	vdso_data->icache_line_size = ppc64_caches.l1i.line_size;
+	vdso_data->dcache_block_size = ppc64_caches.l1d.block_size;
+	vdso_data->icache_block_size = ppc64_caches.l1i.block_size;
+	vdso_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size;
+	vdso_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);