Fix compatible mmap() return pointer over 4Gb

Hi Dmitry,

[auto build test ERROR on tip/x86/core]
[also build test ERROR on v4.10-rc4 next-20170116]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Dmitry-Safonov/Fix-compatible-mmap-return-pointer-over-4Gb/20170116-204523
config: i386-randconfig-i1-201703 (attached as .config)
compiler: gcc-4.8 (Debian 4.8.4-1) 4.8.4 reproduce:

        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

mm/mmap.c: In function 'arch_get_unmapped_area_topdown':

>> mm/mmap.c:2039:20: error: 'TASK_UNMAPPED_BASE' undeclared (first use in this function)
      info.low_limit = TASK_UNMAPPED_BASE;
                       ^

mm/mmap.c:2039:20: note: each undeclared identifier is reported only once for each function it appears in

vim +/TASK_UNMAPPED_BASE +2039 mm/mmap.c

^1da177e Linus Torvalds     2005-04-16  2033  	 * can happen with large stack limits and large mmap()
^1da177e Linus Torvalds     2005-04-16  2034  	 * allocations.
^1da177e Linus Torvalds     2005-04-16  2035  	 */
de1741a1 Alexander Kuleshov 2015-11-05  2036  	if (offset_in_page(addr)) {
db4fbfb9 Michel Lespinasse  2012-12-11  2037  		VM_BUG_ON(addr != -ENOMEM);
db4fbfb9 Michel Lespinasse  2012-12-11  2038  		info.flags = 0;
db4fbfb9 Michel Lespinasse  2012-12-11 @2039  		info.low_limit = TASK_UNMAPPED_BASE;
db4fbfb9 Michel Lespinasse  2012-12-11  2040  		info.high_limit = TASK_SIZE;
db4fbfb9 Michel Lespinasse  2012-12-11  2041  		addr = vm_unmapped_area(&info);
db4fbfb9 Michel Lespinasse  2012-12-11  2042  	}

:::::: The code at line 2039 was first introduced by commit
:::::: db4fbfb9523c93583c339e66023506f651c1d54b mm: vm_unmapped_area() lookup function

:::::: TO: Michel Lespinasse <[email protected]> :::::: CC: Linus Torvalds <[email protected]>

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

Hi Dmitry,

[auto build test ERROR on tip/x86/core]
[also build test ERROR on v4.10-rc4 next-20170116]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Dmitry-Safonov/Fix-compatible-mmap-return-pointer-over-4Gb/20170116-204523
config: x86_64-randconfig-x001-201703 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 reproduce:

        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

arch/x86/kernel/sys_x86_64.c: In function 'find_start_end':

>> arch/x86/kernel/sys_x86_64.c:122:7: error: implicit declaration of function 'in_compat_syscall' [-Werror=implicit-function-declaration]
      if (in_compat_syscall()) {
          ^~~~~~~~~~~~~~~~~

cc1: some warnings being treated as errors

vim +/in_compat_syscall +122 arch/x86/kernel/sys_x86_64.c

116 return;
117 }
118
119 if (!test_thread_flag(TIF_ADDR32)) {
120 #ifdef CONFIG_COMPAT
121 /* 64-bit native binary doing compat 32-bit syscall */

 > 122			if (in_compat_syscall()) {

123 *begin = mmap_legacy_base(arch_compat_rnd(),
124 IA32_PAGE_OFFSET);
125 *end = IA32_PAGE_OFFSET;

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

Hi Dmitry,

[auto build test WARNING on tip/x86/core]
[also build test WARNING on v4.10-rc4 next-20170116]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Dmitry-Safonov/Fix-compatible-mmap-return-pointer-over-4Gb/20170116-204523
config: x86_64-randconfig-ne0-01162147 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 reproduce:

        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

In file included from include/uapi/linux/stddef.h:1:0,

                    from include/linux/stddef.h:4,
                    from include/uapi/linux/posix_types.h:4,
                    from include/uapi/linux/types.h:13,
                    from include/linux/types.h:5,
                    from include/uapi/linux/capability.h:16,
                    from include/linux/capability.h:15,
                    from include/linux/sched.h:15,
                    from arch/x86/kernel/sys_x86_64.c:2:
   arch/x86/kernel/sys_x86_64.c: In function 'find_start_end':
   arch/x86/kernel/sys_x86_64.c:131:8: error: implicit declaration of function 'in_compat_syscall' [-Werror=implicit-function-declaration]
      if (!in_compat_syscall()) {
           ^
   include/linux/compiler.h:149:30: note: in definition of macro '__trace_if'
     if (__builtin_constant_p(!!(cond)) ? !!(cond) :   \
                                 ^~~~
>> arch/x86/kernel/sys_x86_64.c:131:3: note: in expansion of macro 'if'
      if (!in_compat_syscall()) {
      ^~

cc1: some warnings being treated as errors

vim +/if +131 arch/x86/kernel/sys_x86_64.c

     1	#include <linux/errno.h>
   > 2	#include <linux/sched.h>
     3	#include <linux/syscalls.h>
     4	#include <linux/mm.h>
     5	#include <linux/fs.h>
     6	#include <linux/smp.h>
     7	#include <linux/sem.h>
     8	#include <linux/msg.h>
     9	#include <linux/shm.h>
    10	#include <linux/stat.h>
    11	#include <linux/mman.h>
    12	#include <linux/file.h>
    13	#include <linux/utsname.h>
    14	#include <linux/personality.h>
    15	#include <linux/random.h>
    16	#include <linux/uaccess.h>
    17	#include <linux/elf.h>
    18	
    19	#include <asm/ia32.h>
    20	#include <asm/syscalls.h>
    21	
    22	/*
    23	 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
    24	 */
    25	static unsigned long get_align_mask(void)
    26	{
    27		/* handle 32- and 64-bit case with a single conditional */
    28		if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
    29			return 0;
    30	
    31		if (!(current->flags & PF_RANDOMIZE))
    32			return 0;
    33	
    34		return va_align.mask;
    35	}
    36	
    37	/*
    38	 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
    39	 * va_align.bits, [12:upper_bit), are set to a random value instead of
    40	 * zeroing them. This random value is computed once per boot. This form
    41	 * of ASLR is known as "per-boot ASLR".
    42	 *
    43	 * To achieve this, the random value is added to the info.align_offset
    44	 * value before calling vm_unmapped_area() or ORed directly to the
    45	 * address.
    46	 */
    47	static unsigned long get_align_bits(void)
    48	{
    49		return va_align.bits & get_align_mask();
    50	}
    51	
    52	unsigned long align_vdso_addr(unsigned long addr)
    53	{
    54		unsigned long align_mask = get_align_mask();
    55		addr = (addr + align_mask) & ~align_mask;
    56		return addr | get_align_bits();
    57	}
    58	
    59	static int __init control_va_addr_alignment(char *str)
    60	{
    61		/* guard against enabling this on other CPU families */
    62		if (va_align.flags < 0)
    63			return 1;
    64	
    65		if (*str == 0)
    66			return 1;
    67	
    68		if (*str == '=')
    69			str++;
    70	
    71		if (!strcmp(str, "32"))
    72			va_align.flags = ALIGN_VA_32;
    73		else if (!strcmp(str, "64"))
    74			va_align.flags = ALIGN_VA_64;
    75		else if (!strcmp(str, "off"))
    76			va_align.flags = 0;
    77		else if (!strcmp(str, "on"))
    78			va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
    79		else
    80			return 0;
    81	
    82		return 1;
    83	}
    84	__setup("align_va_addr", control_va_addr_alignment);
    85	
    86	SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
    87			unsigned long, prot, unsigned long, flags,
    88			unsigned long, fd, unsigned long, off)
    89	{
    90		long error;
    91		error = -EINVAL;
    92		if (off & ~PAGE_MASK)
    93			goto out;
    94	
    95		error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
    96	out:
    97		return error;
    98	}
    99	
   100	static void find_start_end(unsigned long flags, unsigned long *begin,
   101				   unsigned long *end)
   102	{
   103		if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
   104			/* This is usually used needed to map code in small
   105			   model, so it needs to be in the first 31bit. Limit
   106			   it to that.  This means we need to move the
   107			   unmapped base down for this case. This can give
   108			   conflicts with the heap, but we assume that glibc
   109			   malloc knows how to fall back to mmap. Give it 1GB
   110			   of playground for now. -AK */
   111			*begin = 0x40000000;
   112			*end = 0x80000000;
   113			if (current->flags & PF_RANDOMIZE) {
   114				*begin = randomize_page(*begin, 0x02000000);
   115			}
   116			return;
   117		}
   118	
   119		if (!test_thread_flag(TIF_ADDR32)) {
   120	#ifdef CONFIG_COMPAT
   121			/* 64-bit native binary doing compat 32-bit syscall */
   122			if (in_compat_syscall()) {
   123				*begin = mmap_legacy_base(arch_compat_rnd(),
   124							IA32_PAGE_OFFSET);
   125				*end = IA32_PAGE_OFFSET;
   126				return;
   127			}
   128	#endif
   129		} else {
   130			/* 32-bit binary doing 64-bit syscall */
 > 131			if (!in_compat_syscall()) {

132 *begin = mmap_legacy_base(arch_native_rnd(),
133 IA32_PAGE_OFFSET);
134 *end = TASK_SIZE_MAX;

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