x86/mm/kaslr: Use the _ASM_MUL macro for multiplication to work around Clang incompat...
authorMatthias Kaehlcke <mka@chromium.org>
Mon, 1 May 2017 22:47:41 +0000 (15:47 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 13 Apr 2018 17:47:50 +0000 (19:47 +0200)
commitc49892015f528ccf4d53d9e388a9ce0cdd1cba37
treefecef75ff0c018b74cda860abbb24e2fb6e13386
parent82652acdd73a0c2b0e1cddeccfc8ab9dc90e2432
x86/mm/kaslr: Use the _ASM_MUL macro for multiplication to work around Clang incompatibility

[ Upstream commit 121843eb02a6e2fa30aefab64bfe183c97230c75 ]

The constraint "rm" allows the compiler to put mix_const into memory.
When the input operand is a memory location then MUL needs an operand
size suffix, since Clang can't infer the multiplication width from the
operand.

Add and use the _ASM_MUL macro which determines the operand size and
resolves to the NUL instruction with the corresponding suffix.

This fixes the following error when building with clang:

  CC      arch/x86/lib/kaslr.o
  /tmp/kaslr-dfe1ad.s: Assembler messages:
  /tmp/kaslr-dfe1ad.s:182: Error: no instruction mnemonic suffix given and no register operands; can't size instruction

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Grant Grundler <grundler@chromium.org>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Davidson <md@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170501224741.133938-1-mka@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/include/asm/asm.h
arch/x86/lib/kaslr.c