arch/powerpc/kernel/vdso.c - linux - Git at Google

 // 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 <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;

 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 + PAGE_SIZE)
 		return -EINVAL;

 	current->mm->context.vdso = (void __user *)new_vma->vm_start + PAGE_SIZE;

 	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 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,
 };

 /*
  * 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)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_special_mapping *vdso_spec;
 	struct vm_area_struct *vma;
 	unsigned long vdso_size;
 	unsigned long vdso_base;

 	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;
 	}

 	/* Add a page to the vdso size for the data page */
 	vdso_size += PAGE_SIZE;

 	/*
 	 * 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,
 				      vdso_size + ((VDSO_ALIGNMENT - 1) & PAGE_MASK),
 				      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 + PAGE_SIZE;

 	/*
 	 * 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, vdso_size,
 				       VM_READ | VM_EXEC | VM_MAYREAD |
 				       VM_MAYWRITE | VM_MAYEXEC, vdso_spec);
 	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__);

 	pagelist[0] = virt_to_page(vdso_data);

 	for (i = 0; i < pages; i++)
 		pagelist[i + 1] = 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);
	// 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 <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;

	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 + PAGE_SIZE)
	return -EINVAL;

	current->mm->context.vdso = (void __user *)new_vma->vm_start + PAGE_SIZE;

	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 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,
	};

	/*
	* 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)
	{
	struct mm_struct *mm = current->mm;
	struct vm_special_mapping *vdso_spec;
	struct vm_area_struct *vma;
	unsigned long vdso_size;
	unsigned long vdso_base;

	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;
	}

	/* Add a page to the vdso size for the data page */
	vdso_size += PAGE_SIZE;

	/*
	* 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,
	vdso_size + ((VDSO_ALIGNMENT - 1) & PAGE_MASK),
	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 + PAGE_SIZE;

	/*
	* 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, vdso_size,
	VM_READ \| VM_EXEC \| VM_MAYREAD \|
	VM_MAYWRITE \| VM_MAYEXEC, vdso_spec);
	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__);

	pagelist[0] = virt_to_page(vdso_data);

	for (i = 0; i < pages; i++)
	pagelist[i + 1] = 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);