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linux-user: remove useless padding in flock64 structure

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Since commit 8efb2ed5ec ("linux-user: Correct signedness of
target_flock l_start and l_len fields"), flock64 structure uses
abi_llong for l_start and l_len in place of "unsigned long long"
this should force them to be aligned accordingly to the target
rules. So we can remove the padding field and the QEMU_PACKED
attribute.

I have compared the result of the following program before and
after the change:

    cat -> flock64_dump  <<EOF
    p/d sizeof(struct target_flock64)
    p/d &((struct target_flock64 *)0)->l_type
    p/d &((struct target_flock64 *)0)->l_whence
    p/d &((struct target_flock64 *)0)->l_start
    p/d &((struct target_flock64 *)0)->l_len
    p/d &((struct target_flock64 *)0)->l_pid
    quit
    EOF

    for file in build/all/*-linux-user/qemu-* ; do
    echo $file
    gdb -batch -nx -x flock64_dump $file 2> /dev/null
    done

The sizeof() changes because we remove the QEMU_PACKED.
The new size is 32 (except for i386 and m68k) and this is
the real size of "struct flock64" on the target architecture.

The following architectures differ:
aarch64_be, aarch64, alpha, armeb, arm, cris, hppa, nios2, or1k,
riscv32, riscv64, s390x.

For a subset of these architectures, I have checked with the following
program the new structure is the correct one:

  #include <stdio.h>
  #define __USE_LARGEFILE64
  #include <fcntl.h>

  int main(void)
  {
	  printf("struct flock64 %d\n", sizeof(struct flock64));
	  printf("l_type %d\n", &((struct flock64 *)0)->l_type);
	  printf("l_whence %d\n", &((struct flock64 *)0)->l_whence);
	  printf("l_start %d\n", &((struct flock64 *)0)->l_start);
	  printf("l_len %d\n", &((struct flock64 *)0)->l_len);
	  printf("l_pid %d\n", &((struct flock64 *)0)->l_pid);
  }

[I have checked aarch64, alpha, hppa, s390x]

For ARM, the target_flock64 becomes the EABI definition, so we need to
define the OABI one in place of the EABI one and use it when it is
needed.

I have also fixed the alignment value for sh4 (to align llong on 4 bytes)
(see c2e3dee6e0 "linux-user: Define target alignment size")
[We should check alignment properties for cris, nios2 and or1k]

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180502215730.28162-1-laurent@vivier.eu>
This commit is contained in:
Laurent Vivier 2018-05-02 23:57:30 +02:00
parent 465e237bf7
commit 7f254c5cb8
4 changed files with 19 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

14
linux-user/syscall.c
View file

@ -6600,10 +6600,10 @@ typedef abi_long from_flock64_fn(struct flock64 *fl, abi_ulong target_addr);
typedef abi_long to_flock64_fn(abi_ulong target_addr, const struct flock64 *fl);
#if defined(TARGET_ARM) && TARGET_ABI_BITS == 32
static inline abi_long copy_from_user_eabi_flock64(struct flock64 *fl,
static inline abi_long copy_from_user_oabi_flock64(struct flock64 *fl,
abi_ulong target_flock_addr)
{
struct target_eabi_flock64 *target_fl;
struct target_oabi_flock64 *target_fl;
short l_type;
if (!lock_user_struct(VERIFY_READ, target_fl, target_flock_addr, 1)) {
@ -6620,10 +6620,10 @@ static inline abi_long copy_from_user_eabi_flock64(struct flock64 *fl,
return 0;
}
static inline abi_long copy_to_user_eabi_flock64(abi_ulong target_flock_addr,
static inline abi_long copy_to_user_oabi_flock64(abi_ulong target_flock_addr,
const struct flock64 *fl)
{
struct target_eabi_flock64 *target_fl;
struct target_oabi_flock64 *target_fl;
short l_type;
if (!lock_user_struct(VERIFY_WRITE, target_fl, target_flock_addr, 0)) {
@ -11629,9 +11629,9 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
to_flock64_fn *copyto = copy_to_user_flock64;
#ifdef TARGET_ARM
if (((CPUARMState *)cpu_env)->eabi) {
copyfrom = copy_from_user_eabi_flock64;
copyto = copy_to_user_eabi_flock64;
if (!((CPUARMState *)cpu_env)->eabi) {
copyfrom = copy_from_user_oabi_flock64;
copyto = copy_to_user_oabi_flock64;
}
#endif