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linux-next/arch/powerpc/kernel/vdso64
Anton Blanchard 5045ea3737 powerpc/vdso64: Use double word compare on pointers
__kernel_get_syscall_map() and __kernel_clock_getres() use cmpli to
check if the passed in pointer is non zero. cmpli maps to a 32 bit
compare on binutils, so we ignore the top 32 bits.

A simple test case can be created by passing in a bogus pointer with
the bottom 32 bits clear. Using a clk_id that is handled by the VDSO,
then one that is handled by the kernel shows the problem:

  printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000));
  printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000));

And we get:

  0
  -1

The bigger issue is if we pass a valid pointer with the bottom 32 bits
clear, in this case we will return success but won't write any data
to the pointer.

I stumbled across this issue because the LLVM integrated assembler
doesn't accept cmpli with 3 arguments. Fix this by converting them to
cmpldi.

Fixes: a7f290dad3 ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Cc: stable@vger.kernel.org # v2.6.15+
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-09-29 15:17:57 +10:00
..
.gitignore [POWERPC] Update .gitignore for new vdso generated files 2007-10-08 08:38:12 -05:00
cacheflush.S [POWERPC] vdso: Fixes for cache block sizes 2007-11-20 13:56:31 +11:00
datapage.S powerpc/vdso64: Use double word compare on pointers 2016-09-29 15:17:57 +10:00
getcpu.S powerpc/booke64: Use SPRG7 for VDSO 2014-03-19 19:57:14 -05:00
gettimeofday.S powerpc/vdso64: Use double word compare on pointers 2016-09-29 15:17:57 +10:00
Makefile powerpc/vdso64: Drop vdso64as 2016-09-13 17:37:05 +10:00
note.S
sigtramp.S powerpc: Wrong DWARF CFI in the kernel vdso for little-endian / ELFv2 2013-11-21 09:19:23 +11:00
vdso64_wrapper.S powerpc: Use unstripped VDSO image for more accurate profiling data 2014-02-17 11:19:37 +11:00
vdso64.lds.S powerpc: Add ability to build little endian kernels 2013-10-11 16:48:56 +11:00