// 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/prom.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;

/*
 * 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;
        struct vm_area_struct *vma;

        mmap_read_lock(mm);

        for (vma = mm->mmap; vma; vma = vma->vm_next) {
                unsigned long size = vma->vm_end - vma->vm_start;

                if (vma_is_special_mapping(vma, &vvar_spec))
                        zap_page_range(vma, vma->vm_start, size);
        }

        mmap_read_unlock(mm);
        return 0;
}

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
        if (likely(vma->vm_mm == current->mm))
                return current->nsproxy->time_ns->vvar_page;

        /*
         * VM_PFNMAP | VM_IO protect .fault() handler from being called
         * through interfaces like /proc/$pid/mem or
         * process_vm_{readv,writev}() as long as there's no .access()
         * in special_mapping_vmops.
         * For more details check_vma_flags() and __access_remote_vm()
         */
        WARN(1, "vvar_page accessed remotely");

        return NULL;
}
#else
static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
{
        return NULL;
}
#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;
                vdso_base = VDSO32_MBASE;
        } else {
                vdso_spec = &vdso64_spec;
                vdso_size = &vdso64_end - &vdso64_start;
                /*
                 * On 64bit we don't have a preferred map address. This
                 * allows get_unmapped_area to find an area near other mmaps
                 * and most likely share a SLB entry.
                 */
                vdso_base = 0;
        }

        mappings_size = vdso_size + vvar_size;
        mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK;

        /*
         * pick a base address for the vDSO in process space. We try to put it
         * at vdso_base which is the "natural" base for it, but we might fail
         * and end up putting it elsewhere.
         * Add enough to the size so that the result can be aligned.
         */
        vdso_base = get_unmapped_area(NULL, vdso_base, 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] != (unsigned long)&sys_ni_syscall)
                        vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f);
                if (IS_ENABLED(CONFIG_COMPAT) &&
                    compat_sys_call_table[i] != (unsigned long)&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);