alistair23-linux/arch/parisc/kernel/sys_parisc.c

// SPDX-License-Identifier: GPL-2.0-or-later

/*
 *    PARISC specific syscalls
 *
 *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
 *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
 *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
 *    Copyright (C) 1999-2014 Helge Deller <deller@gmx.de>
 */

#include <linux/uaccess.h>
#include <asm/elf.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/linkage.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/shm.h>
#include <linux/syscalls.h>
#include <linux/utsname.h>
#include <linux/personality.h>
#include <linux/random.h>

/* we construct an artificial offset for the mapping based on the physical
 * address of the kernel mapping variable */
#define GET_LAST_MMAP(filp)		\
	(filp ? ((unsigned long) filp->f_mapping) >> 8 : 0UL)
#define SET_LAST_MMAP(filp, val)	\
	 { /* nothing */ }

static int get_offset(unsigned int last_mmap)
{
	return (last_mmap & (SHM_COLOUR-1)) >> PAGE_SHIFT;
}

static unsigned long shared_align_offset(unsigned int last_mmap,
					 unsigned long pgoff)
{
	return (get_offset(last_mmap) + pgoff) << PAGE_SHIFT;
}

static inline unsigned long COLOR_ALIGN(unsigned long addr,
			 unsigned int last_mmap, unsigned long pgoff)
{
	unsigned long base = (addr+SHM_COLOUR-1) & ~(SHM_COLOUR-1);
	unsigned long off  = (SHM_COLOUR-1) &
		(shared_align_offset(last_mmap, pgoff) << PAGE_SHIFT);

	return base + off;
}

/*
 * Top of mmap area (just below the process stack).
 */

/*
 * When called from arch_get_unmapped_area(), rlim_stack will be NULL,
 * indicating that "current" should be used instead of a passed-in
 * value from the exec bprm as done with arch_pick_mmap_layout().
 */
static unsigned long mmap_upper_limit(struct rlimit *rlim_stack)
{
	unsigned long stack_base;

	/* Limit stack size - see setup_arg_pages() in fs/exec.c */
	stack_base = rlim_stack ? rlim_stack->rlim_max
				: rlimit_max(RLIMIT_STACK);
	if (stack_base > STACK_SIZE_MAX)
		stack_base = STACK_SIZE_MAX;

	/* Add space for stack randomization. */
	if (current->flags & PF_RANDOMIZE)
		stack_base += (STACK_RND_MASK << PAGE_SHIFT);

	return PAGE_ALIGN(STACK_TOP - stack_base);
}


unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
	unsigned long task_size = TASK_SIZE;
	int do_color_align, last_mmap;
	struct vm_unmapped_area_info info;

	if (len > task_size)
		return -ENOMEM;

	do_color_align = 0;
	if (filp || (flags & MAP_SHARED))
		do_color_align = 1;
	last_mmap = GET_LAST_MMAP(filp);

	if (flags & MAP_FIXED) {
		if ((flags & MAP_SHARED) && last_mmap &&
		    (addr - shared_align_offset(last_mmap, pgoff))
				& (SHM_COLOUR - 1))
			return -EINVAL;
		goto found_addr;
	}

	if (addr) {
		if (do_color_align && last_mmap)
			addr = COLOR_ALIGN(addr, last_mmap, pgoff);
		else
			addr = PAGE_ALIGN(addr);

		vma = find_vma_prev(mm, addr, &prev);
		if (task_size - len >= addr &&
		    (!vma || addr + len <= vm_start_gap(vma)) &&
		    (!prev || addr >= vm_end_gap(prev)))
			goto found_addr;
	}

	info.flags = 0;
	info.length = len;
	info.low_limit = mm->mmap_legacy_base;
	info.high_limit = mmap_upper_limit(NULL);
	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
	info.align_offset = shared_align_offset(last_mmap, pgoff);
	addr = vm_unmapped_area(&info);

found_addr:
	if (do_color_align && !last_mmap && !(addr & ~PAGE_MASK))
		SET_LAST_MMAP(filp, addr - (pgoff << PAGE_SHIFT));

	return addr;
}

unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
			  const unsigned long len, const unsigned long pgoff,
			  const unsigned long flags)
{
	struct vm_area_struct *vma, *prev;
	struct mm_struct *mm = current->mm;
	unsigned long addr = addr0;
	int do_color_align, last_mmap;
	struct vm_unmapped_area_info info;

	/* requested length too big for entire address space */
	if (len > TASK_SIZE)
		return -ENOMEM;

	do_color_align = 0;
	if (filp || (flags & MAP_SHARED))
		do_color_align = 1;
	last_mmap = GET_LAST_MMAP(filp);

	if (flags & MAP_FIXED) {
		if ((flags & MAP_SHARED) && last_mmap &&
		    (addr - shared_align_offset(last_mmap, pgoff))
			& (SHM_COLOUR - 1))
			return -EINVAL;
		goto found_addr;
	}

	/* requesting a specific address */
	if (addr) {
		if (do_color_align && last_mmap)
			addr = COLOR_ALIGN(addr, last_mmap, pgoff);
		else
			addr = PAGE_ALIGN(addr);

		vma = find_vma_prev(mm, addr, &prev);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vm_start_gap(vma)) &&
		    (!prev || addr >= vm_end_gap(prev)))
			goto found_addr;
	}

	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = PAGE_SIZE;
	info.high_limit = mm->mmap_base;
	info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
	info.align_offset = shared_align_offset(last_mmap, pgoff);
	addr = vm_unmapped_area(&info);
	if (!(addr & ~PAGE_MASK))
		goto found_addr;
	VM_BUG_ON(addr != -ENOMEM);

	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
	return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);

found_addr:
	if (do_color_align && !last_mmap && !(addr & ~PAGE_MASK))
		SET_LAST_MMAP(filp, addr - (pgoff << PAGE_SHIFT));

	return addr;
}

static int mmap_is_legacy(void)
{
	if (current->personality & ADDR_COMPAT_LAYOUT)
		return 1;

	/* parisc stack always grows up - so a unlimited stack should
	 * not be an indicator to use the legacy memory layout.
	 * if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
	 *	return 1;
	 */

	return sysctl_legacy_va_layout;
}

static unsigned long mmap_rnd(void)
{
	unsigned long rnd = 0;

	if (current->flags & PF_RANDOMIZE)
		rnd = get_random_int() & MMAP_RND_MASK;

	return rnd << PAGE_SHIFT;
}

unsigned long arch_mmap_rnd(void)
{
	return (get_random_int() & MMAP_RND_MASK) << PAGE_SHIFT;
}

static unsigned long mmap_legacy_base(void)
{
	return TASK_UNMAPPED_BASE + mmap_rnd();
}

/*
 * This function, called very early during the creation of a new
 * process VM image, sets up which VM layout function to use:
 */
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
{
	mm->mmap_legacy_base = mmap_legacy_base();
	mm->mmap_base = mmap_upper_limit(rlim_stack);

	if (mmap_is_legacy()) {
		mm->mmap_base = mm->mmap_legacy_base;
		mm->get_unmapped_area = arch_get_unmapped_area;
	} else {
		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
	}
}


asmlinkage unsigned long sys_mmap2(unsigned long addr, unsigned long len,
	unsigned long prot, unsigned long flags, unsigned long fd,
	unsigned long pgoff)
{
	/* Make sure the shift for mmap2 is constant (12), no matter what PAGE_SIZE
	   we have. */
	return ksys_mmap_pgoff(addr, len, prot, flags, fd,
			       pgoff >> (PAGE_SHIFT - 12));
}

asmlinkage unsigned long sys_mmap(unsigned long addr, unsigned long len,
		unsigned long prot, unsigned long flags, unsigned long fd,
		unsigned long offset)
{
	if (!(offset & ~PAGE_MASK)) {
		return ksys_mmap_pgoff(addr, len, prot, flags, fd,
					offset >> PAGE_SHIFT);
	} else {
		return -EINVAL;
	}
}

/* Fucking broken ABI */

#ifdef CONFIG_64BIT
asmlinkage long parisc_truncate64(const char __user * path,
					unsigned int high, unsigned int low)
{
	return ksys_truncate(path, (long)high << 32 | low);
}

asmlinkage long parisc_ftruncate64(unsigned int fd,
					unsigned int high, unsigned int low)
{
	return ksys_ftruncate(fd, (long)high << 32 | low);
}

/* stubs for the benefit of the syscall_table since truncate64 and truncate 
 * are identical on LP64 */
asmlinkage long sys_truncate64(const char __user * path, unsigned long length)
{
	return ksys_truncate(path, length);
}
asmlinkage long sys_ftruncate64(unsigned int fd, unsigned long length)
{
	return ksys_ftruncate(fd, length);
}
asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg)
{
	return sys_fcntl(fd, cmd, arg);
}
#else

asmlinkage long parisc_truncate64(const char __user * path,
					unsigned int high, unsigned int low)
{
	return ksys_truncate(path, (loff_t)high << 32 | low);
}

asmlinkage long parisc_ftruncate64(unsigned int fd,
					unsigned int high, unsigned int low)
{
	return sys_ftruncate64(fd, (loff_t)high << 32 | low);
}
#endif

asmlinkage ssize_t parisc_pread64(unsigned int fd, char __user *buf, size_t count,
					unsigned int high, unsigned int low)
{
	return ksys_pread64(fd, buf, count, (loff_t)high << 32 | low);
}

asmlinkage ssize_t parisc_pwrite64(unsigned int fd, const char __user *buf,
			size_t count, unsigned int high, unsigned int low)
{
	return ksys_pwrite64(fd, buf, count, (loff_t)high << 32 | low);
}

asmlinkage ssize_t parisc_readahead(int fd, unsigned int high, unsigned int low,
		                    size_t count)
{
	return ksys_readahead(fd, (loff_t)high << 32 | low, count);
}

asmlinkage long parisc_fadvise64_64(int fd,
			unsigned int high_off, unsigned int low_off,
			unsigned int high_len, unsigned int low_len, int advice)
{
	return ksys_fadvise64_64(fd, (loff_t)high_off << 32 | low_off,
			(loff_t)high_len << 32 | low_len, advice);
}

asmlinkage long parisc_sync_file_range(int fd,
			u32 hi_off, u32 lo_off, u32 hi_nbytes, u32 lo_nbytes,
			unsigned int flags)
{
	return ksys_sync_file_range(fd, (loff_t)hi_off << 32 | lo_off,
			(loff_t)hi_nbytes << 32 | lo_nbytes, flags);
}

asmlinkage long parisc_fallocate(int fd, int mode, u32 offhi, u32 offlo,
				u32 lenhi, u32 lenlo)
{
	return ksys_fallocate(fd, mode, ((u64)offhi << 32) | offlo,
			      ((u64)lenhi << 32) | lenlo);
}

long parisc_personality(unsigned long personality)
{
	long err;

	if (personality(current->personality) == PER_LINUX32
	    && personality(personality) == PER_LINUX)
		personality = (personality & ~PER_MASK) | PER_LINUX32;

	err = sys_personality(personality);
	if (personality(err) == PER_LINUX32)
		err = (err & ~PER_MASK) | PER_LINUX;

	return err;
}