cregit-Linux how code gets into the kernel

Release 4.10 arch/x86/kernel/sys_x86_64.c

Directory: arch/x86/kernel
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/sem.h>
#include <linux/msg.h>
#include <linux/shm.h>
#include <linux/stat.h>
#include <linux/mman.h>
#include <linux/file.h>
#include <linux/utsname.h>
#include <linux/personality.h>
#include <linux/random.h>
#include <linux/uaccess.h>
#include <linux/elf.h>

#include <asm/ia32.h>
#include <asm/syscalls.h>

/*
 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
 */



static unsigned long get_align_mask(void)
{
	/* handle 32- and 64-bit case with a single conditional */
	if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
		return 0;

	if (!(current->flags & PF_RANDOMIZE))
		return 0;

	return va_align.mask;
}


Contributors
PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov4583.33%150.00%


michel lespinassemichel lespinasse916.67%150.00%


Total54100.00%2100.00%



/*
 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
 * va_align.bits, [12:upper_bit), are set to a random value instead of
 * zeroing them. This random value is computed once per boot. This form
 * of ASLR is known as "per-boot ASLR".
 *
 * To achieve this, the random value is added to the info.align_offset
 * value before calling vm_unmapped_area() or ORed directly to the
 * address.
 */



static unsigned long get_align_bits(void)
{
	return va_align.bits & get_align_mask();
}


Contributors
PersonTokensPropCommitsCommitProp
hector marco-gisberthector marco-gisbert17100.00%1100.00%


Total17100.00%1100.00%






unsigned long align_vdso_addr(unsigned long addr)
{
	unsigned long align_mask = get_align_mask();
	addr = (addr + align_mask) & ~align_mask;
	return addr | get_align_bits();
}


Contributors
PersonTokensPropCommitsCommitProp
michel lespinassemichel lespinasse2058.82%133.33%


hector marco-gisberthector marco-gisbert823.53%133.33%


borislav petkovborislav petkov617.65%133.33%


Total34100.00%3100.00%






static int __init control_va_addr_alignment(char *str)
{
	/* guard against enabling this on other CPU families */
	if (va_align.flags < 0)
		return 1;

	if (*str == 0)
		return 1;

	if (*str == '=')
		str++;

	if (!strcmp(str, "32"))
		va_align.flags = ALIGN_VA_32;
	else if (!strcmp(str, "64"))
		va_align.flags = ALIGN_VA_64;
	else if (!strcmp(str, "off"))
		va_align.flags = 0;
	else if (!strcmp(str, "on"))
		va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
	else
		return 0;

	return 1;
}

Contributors
PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov119100.00%1100.00%


Total119100.00%1100.00%



__setup("align_va_addr", control_va_addr_alignment);


SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, off)
{
	long error;
	error = -EINVAL;
	if (off & ~PAGE_MASK)
		goto out;

	error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
out:
	return error;
}




static void find_start_end(unsigned long flags, unsigned long *begin,
			   unsigned long *end)
{
	if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
		/* This is usually used needed to map code in small
                   model, so it needs to be in the first 31bit. Limit
                   it to that.  This means we need to move the
                   unmapped base down for this case. This can give
                   conflicts with the heap, but we assume that glibc
                   malloc knows how to fall back to mmap. Give it 1GB
                   of playground for now. -AK */
		*begin = 0x40000000;
		*end = 0x80000000;
		if (current->flags & PF_RANDOMIZE) {
			*begin = randomize_page(*begin, 0x02000000);
		}
	} else {
		*begin = current->mm->mmap_legacy_base;
		*end = TASK_SIZE;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
andi kleenandi kleen5463.53%444.44%


jiri kosinajiri kosina1821.18%111.11%


radu caragearadu caragea55.88%111.11%


suresh siddhasuresh siddha44.71%111.11%


jason cooperjason cooper33.53%111.11%


h. peter anvinh. peter anvin11.18%111.11%


Total85100.00%9100.00%





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;
	struct vm_unmapped_area_info info;
	unsigned long begin, end;

	if (flags & MAP_FIXED)
		return addr;

	find_start_end(flags, &begin, &end);

	if (len > end)
		return -ENOMEM;

	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (end - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}

	info.flags = 0;
	info.length = len;
	info.low_limit = begin;
	info.high_limit = end;
	info.align_mask = 0;
	info.align_offset = pgoff << PAGE_SHIFT;
	if (filp) {
		info.align_mask = get_align_mask();
		info.align_offset += get_align_bits();
	}
	return vm_unmapped_area(&info);
}


Contributors
PersonTokensPropCommitsCommitProp
andi kleenandi kleen12464.58%333.33%


michel lespinassemichel lespinasse2915.10%222.22%


hector marco-gisberthector marco-gisbert2010.42%111.11%


benjamin herrenschmidtbenjamin herrenschmidt94.69%111.11%


wolfgang wanderwolfgang wander63.12%111.11%


borislav petkovborislav petkov42.08%111.11%


Total192100.00%9100.00%





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;
	struct mm_struct *mm = current->mm;
	unsigned long addr = addr0;
	struct vm_unmapped_area_info info;

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

	if (flags & MAP_FIXED)
		return addr;

	/* for MAP_32BIT mappings we force the legacy mmap base */
	if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT))
		goto bottomup;

	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = PAGE_SIZE;
	info.high_limit = mm->mmap_base;
	info.align_mask = 0;
	info.align_offset = pgoff << PAGE_SHIFT;
	if (filp) {
		info.align_mask = get_align_mask();
		info.align_offset += get_align_bits();
	}
	addr = vm_unmapped_area(&info);
	if (!(addr & ~PAGE_MASK))
		return addr;
	VM_BUG_ON(addr != -ENOMEM);

bottomup:
	/*
         * 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);
}

Contributors
PersonTokensPropCommitsCommitProp
jiri kosinajiri kosina17169.51%112.50%


michel lespinassemichel lespinasse4819.51%225.00%


hector marco-gisberthector marco-gisbert208.13%112.50%


xiao guangrongxiao guangrong31.22%112.50%


borislav petkovborislav petkov20.81%112.50%


yuanhan liuyuanhan liu10.41%112.50%


h. peter anvinh. peter anvin10.41%112.50%


Total246100.00%8100.00%




Overall Contributors
PersonTokensPropCommitsCommitProp
andi kleenandi kleen26029.38%520.00%


jiri kosinajiri kosina19221.69%14.00%


borislav petkovborislav petkov18320.68%14.00%


michel lespinassemichel lespinasse10712.09%28.00%


hector marco-gisberthector marco-gisbert667.46%14.00%


jason baronjason baron283.16%14.00%


benjamin herrenschmidtbenjamin herrenschmidt91.02%14.00%


wolfgang wanderwolfgang wander60.68%14.00%


radu caragearadu caragea50.56%14.00%


suresh siddhasuresh siddha40.45%14.00%


jason cooperjason cooper30.34%14.00%


stephen rothwellstephen rothwell30.34%14.00%


alexey dobriyanalexey dobriyan30.34%14.00%


jaswinder singh rajputjaswinder singh rajput30.34%14.00%


xiao guangrongxiao guangrong30.34%14.00%


al viroal viro30.34%14.00%


andrew mortonandrew morton30.34%14.00%


h. peter anvinh. peter anvin20.23%14.00%


gustavo padovangustavo padovan10.11%14.00%


yuanhan liuyuanhan liu10.11%14.00%


Total885100.00%25100.00%


Directory: arch/x86/kernel



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