objtool: Add mcsafe_handle_tail() to the uaccess safe list
authorJosh Poimboeuf <jpoimboe@redhat.com>
Thu, 18 Jul 2019 01:36:46 +0000 (20:36 -0500)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 18 Jul 2019 19:01:06 +0000 (21:01 +0200)
commita7e47f26039c26312a4144c3001b4e9fa886bd45
tree5cd47870c750d1701946c8d9cbd51448b8b0f1fe
parent3193c0836f203a91bef96d88c64cccf0be090d9c
objtool: Add mcsafe_handle_tail() to the uaccess safe list

After an objtool improvement, it's reporting that __memcpy_mcsafe() is
calling mcsafe_handle_tail() with AC=1:

  arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x13: call to mcsafe_handle_tail() with UACCESS enabled
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0x34: (alt)
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0xb: (branch)
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0x0: <=== (func)

mcsafe_handle_tail() is basically an extension of __memcpy_mcsafe(), so
AC=1 is supposed to be set.  Add mcsafe_handle_tail() to the uaccess
safe list.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/035c38f7eac845281d3c3d36749144982e06e58c.1563413318.git.jpoimboe@redhat.com
tools/objtool/check.c