[GIT PULL] objtool changes for v5.2: Add build-time uaccess permissions and DF validation

[Ingo Molnar]

Linus,

Please pull the latest core-objtool-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-objtool-for-linus

   # HEAD: 29da93fea3ea39ab9b12270cc6be1b70ef201c9e mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions

This is a series from Peter Zijlstra that adds x86 build-time uaccess 
validation of SMAP to objtool, which will detect and warn about the 
following uaccess API usage bugs and weirdnesses:

	call to %s() with UACCESS enabled
	return with UACCESS enabled
	return with UACCESS disabled from a UACCESS-safe function
	recursive UACCESS enable
	redundant UACCESS disable
	UACCESS-safe disables UACCESS

As it turns out not leaking uaccess permissions outside the intended 
uaccess functionality is hard when the interfaces are complex and when 
such bugs are mostly dormant.

As a bonus we now also check the DF flag. We had at least one 
high-profile bug in that area in the early days of Linux, and the 
checking is fairly simple. The checks performed and warnings emitted are:

	call to %s() with DF set
	return with DF set
	return with modified stack frame
	recursive STD
	redundant CLD

It's all x86-only for now, but later on this can also be used for PAN on 
ARM and objtool is fairly cross-platform in principle.

While all warnings emitted by this new checking facility that got 
reported to us were fixed, there might be GCC version dependent warnings 
that were not reported yet - which we'll address, should they trigger.

The warnings are non-fatal build warnings.

 Thanks,

	Ingo

------------------>
Josh Poimboeuf (1):
      tracing: Improve "if" macro code generation

Peter Zijlstra (26):
      sched/x86: Save [ER]FLAGS on context switch
      x86/ia32: Fix ia32_restore_sigcontext() AC leak
      i915, uaccess: Fix redundant CLAC
      x86/uaccess: Move copy_user_handle_tail() into asm
      x86/uaccess: Fix up the fixup
      x86/nospec, objtool: Introduce ANNOTATE_IGNORE_ALTERNATIVE
      x86/uaccess, xen: Suppress SMAP warnings
      x86/uaccess: Always inline user_access_begin()
      x86/uaccess, signal: Fix AC=1 bloat
      x86/uaccess: Introduce user_access_{save,restore}()
      x86/smap: Ditch __stringify()
      x86/uaccess, kasan: Fix KASAN vs SMAP
      x86/uaccess, ubsan: Fix UBSAN vs. SMAP
      x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
      x86/uaccess, kcov: Disable stack protector
      objtool: Set insn->func for alternatives
      objtool: Handle function aliases
      objtool: Rewrite add_ignores()
      objtool: Add --backtrace support
      objtool: Rewrite alt->skip_orig
      objtool: Fix sibling call detection
      objtool: Add UACCESS validation
      objtool: Add Direction Flag validation
      sched/x86_64: Don't save flags on context switch
      x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
      mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions


 arch/x86/entry/entry_32.S                  |   2 +
 arch/x86/ia32/ia32_signal.c                |  29 ++-
 arch/x86/include/asm/alternative-asm.h     |  11 +
 arch/x86/include/asm/alternative.h         |  10 +
 arch/x86/include/asm/asm.h                 |  24 --
 arch/x86/include/asm/nospec-branch.h       |  28 +-
 arch/x86/include/asm/smap.h                |  37 ++-
 arch/x86/include/asm/switch_to.h           |   1 +
 arch/x86/include/asm/uaccess.h             |  12 +-
 arch/x86/include/asm/uaccess_64.h          |   3 -
 arch/x86/include/asm/xen/hypercall.h       |  24 +-
 arch/x86/kernel/process_32.c               |   7 +
 arch/x86/kernel/process_64.c               |   1 +
 arch/x86/kernel/signal.c                   |  29 ++-
 arch/x86/lib/copy_user_64.S                |  48 ++++
 arch/x86/lib/memcpy_64.S                   |   3 +-
 arch/x86/lib/usercopy_64.c                 |  20 --
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   6 +-
 include/linux/compiler.h                   |   2 +-
 include/linux/uaccess.h                    |   2 +
 kernel/Makefile                            |   1 +
 kernel/trace/trace_branch.c                |   4 +
 lib/Makefile                               |   1 +
 lib/strncpy_from_user.c                    |   5 +-
 lib/strnlen_user.c                         |   4 +-
 lib/ubsan.c                                |   4 +
 mm/kasan/Makefile                          |   3 +
 mm/kasan/common.c                          |  10 +
 mm/kasan/report.c                          |   3 +-
 scripts/Makefile.build                     |   3 +
 tools/objtool/arch.h                       |   8 +-
 tools/objtool/arch/x86/decode.c            |  21 +-
 tools/objtool/builtin-check.c              |   4 +-
 tools/objtool/builtin.h                    |   2 +-
 tools/objtool/check.c                      | 400 ++++++++++++++++++++++-------
 tools/objtool/check.h                      |   4 +-
 tools/objtool/elf.c                        |  15 +-
 tools/objtool/elf.h                        |   3 +-
 tools/objtool/special.c                    |  18 ++
 tools/objtool/special.h                    |   1 +
 tools/objtool/warn.h                       |   8 +
 41 files changed, 602 insertions(+), 219 deletions(-)