• Linus Torvalds's avatar
    Merge branch 'compat' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux · 190f9186
    Linus Torvalds authored
    Pull s390 compat wrapper rework from Heiko Carstens:
     "S390 compat system call wrapper simplification work.
    
      The intention of this work is to get rid of all hand written assembly
      compat system call wrappers on s390, which perform proper sign or zero
      extension, or pointer conversion of compat system call parameters.
      Instead all of this should be done with C code eg by using Al's
      COMPAT_SYSCALL_DEFINEx() macro.
    
      Therefore all common code and s390 specific compat system calls have
      been converted to the COMPAT_SYSCALL_DEFINEx() macro.
    
      In order to generate correct code all compat system calls may only
      have eg compat_ulong_t parameters, but no unsigned long parameters.
      Those patches which change parameter types from unsigned long to
      compat_ulong_t parameters are separate in this series, but shouldn't
      cause any harm.
    
      The only compat system calls which intentionally have 64 bit
      parameters (preadv64 and pwritev64) in support of the x86/32 ABI
      haven't been changed, but are now only available if an architecture
      defines __ARCH_WANT_COMPAT_SYS_PREADV64/PWRITEV64.
    
      System calls which do not have a compat variant but still need proper
      zero extension on s390, like eg "long sys_brk(unsigned long brk)" will
      get a proper wrapper function with the new s390 specific
      COMPAT_SYSCALL_WRAPx() macro:
    
         COMPAT_SYSCALL_WRAP1(brk, unsigned long, brk);
    
      which generates the following code (simplified):
    
         asmlinkage long sys_brk(unsigned long brk);
         asmlinkage long compat_sys_brk(long brk)
         {
             return sys_brk((u32)brk);
         }
    
      Given that the C file which contains all the COMPAT_SYSCALL_WRAP lines
      includes both linux/syscall.h and linux/compat.h, it will generate
      build errors, if the declaration of sys_brk() doesn't match, or if
      there exists a non-matching compat_sys_brk() declaration.
    
      In addition this will intentionally result in a link error if
      somewhere else a compat_sys_brk() function exists, which probably
      should have been used instead.  Two more BUILD_BUG_ONs make sure the
      size and type of each compat syscall parameter can be handled
      correctly with the s390 specific macros.
    
      I converted the compat system calls step by step to verify the
      generated code is correct and matches the previous code.  In fact it
      did not always match, however that was always a bug in the hand
      written asm code.
    
      In result we get less code, less bugs, and much more sanity checking"
    
    * 'compat' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (44 commits)
      s390/compat: add copyright statement
      compat: include linux/unistd.h within linux/compat.h
      s390/compat: get rid of compat wrapper assembly code
      s390/compat: build error for large compat syscall args
      mm/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types
      kexec/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types
      net/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types
      ipc/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types
      fs/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types
      ipc/compat: convert to COMPAT_SYSCALL_DEFINE
      fs/compat: convert to COMPAT_SYSCALL_DEFINE
      security/compat: convert to COMPAT_SYSCALL_DEFINE
      mm/compat: convert to COMPAT_SYSCALL_DEFINE
      net/compat: convert to COMPAT_SYSCALL_DEFINE
      kernel/compat: convert to COMPAT_SYSCALL_DEFINE
      fs/compat: optional preadv64/pwrite64 compat system calls
      ipc/compat_sys_msgrcv: change msgtyp type from long to compat_long_t
      s390/compat: partial parameter conversion within syscall wrappers
      s390/compat: automatic zero, sign and pointer conversion of syscalls
      s390/compat: add sync_file_range and fallocate compat syscalls
      ...
    190f9186
read_write.c 28.1 KB