linux-toradex.git/tools/objtool/check.c, branch v5.7-rc2

objtool: Make BP scratch register warning more robust

2020-04-14T10:24:22+00:00

If func is NULL, a seg fault can result.

This is a theoretical issue which was found by Coverity, ID: 1492002
("Dereference after null check").

Fixes: c705cecc8431 ("objtool: Track original function across branches")
Reported-by: Gustavo A. R. Silva 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.com

objtool: Fix switch table detection in .text.unlikely

2020-04-14T10:06:21+00:00

If a switch jump table's indirect branch is in a ".cold" subfunction in
.text.unlikely, objtool doesn't detect it, and instead prints a false
warning:

  drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame
  drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame
  drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame

Fix it by comparing the function, instead of the section and offset.

Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Reviewed-by: Miroslav Benes 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com

objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings

2020-04-14T09:55:09+00:00

CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an
unreachable code path.  This includes __builtin_unreachable().  Because
the BUG() macro uses __builtin_unreachable() after it emits its own UD2,
this results in a double UD2.  In this case objtool rightfully detects
that the second UD2 is unreachable:

  init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction

We weren't able to figure out a way to get rid of the double UD2s, so
just silence the warning.

Reported-by: Randy Dunlap 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Reviewed-by: Kees Cook 
Reviewed-by: Miroslav Benes 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-30T23:17:15+00:00

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Continued user-access cleanups in the futex code.

   - percpu-rwsem rewrite that uses its own waitqueue and atomic_t
     instead of an embedded rwsem. This addresses a couple of
     weaknesses, but the primary motivation was complications on the -rt
     kernel.

   - Introduce raw lock nesting detection on lockdep
     (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
     lock differences. This too originates from -rt.

   - Reuse lockdep zapped chain_hlocks entries, to conserve RAM
     footprint on distro-ish kernels running into the "BUG:
     MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
     chain-entries pool.

   - Misc cleanups, smaller fixes and enhancements - see the changelog
     for details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  Documentation/locking/locktypes: Minor copy editor fixes
  Documentation/locking/locktypes: Further clarifications and wordsmithing
  m68knommu: Remove mm.h include from uaccess_no.h
  x86: get rid of user_atomic_cmpxchg_inatomic()
  generic arch_futex_atomic_op_inuser() doesn't need access_ok()
  x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
  x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
  objtool: whitelist __sanitizer_cov_trace_switch()
  [parisc, s390, sparc64] no need for access_ok() in futex handling
  sh: no need of access_ok() in arch_futex_atomic_op_inuser()
  futex: arch_futex_atomic_op_inuser() calling conventions change
  completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
  lockdep: Add posixtimer context tracing bits
  lockdep: Annotate irq_work
  lockdep: Add hrtimer context tracing bits
  lockdep: Introduce wait-type checks
  completion: Use simple wait queues
  sched/swait: Prepare usage in completions
  ...

objtool: whitelist __sanitizer_cov_trace_switch()

2020-03-28T03:58:53+00:00

it's not really different from e.g. __sanitizer_cov_trace_cmp4();
as it is, the switches that generate an array of labels get
rejected by objtool, while slightly different set of cases
that gets compiled into a series of comparisons is accepted.

Signed-off-by: Al Viro

objtool: Re-arrange validate_functions()

2020-03-25T17:28:31+00:00

In preparation to adding a vmlinux.o specific pass, rearrange some
code. No functional changes intended.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20200324160924.924304616@infradead.org

objtool: Delete cleanup()

2020-03-25T17:28:30+00:00

Perf shows we spend a measurable amount of time spend cleaning up
right before we exit anyway. Avoid the needsless work and just
terminate.

This reduces objtool on vmlinux.o runtime from 5.4s to 4.8s

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20200324160924.800720170@infradead.org

objtool: Optimize read_sections()

2020-03-25T17:28:30+00:00

Perf showed that __hash_init() is a significant portion of
read_sections(), so instead of doing a per section rela_hash, use an
elf-wide rela_hash.

Statistics show us there are about 1.1 million relas, so size it
accordingly.

This reduces the objtool on vmlinux.o runtime to a third, from 15 to 5
seconds.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20200324160924.739153726@infradead.org

objtool: Add a statistics mode

2020-03-25T17:28:28+00:00

Have it print a few numbers which can be used to size the hashtables.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20200324160924.321381240@infradead.org

objtool: Rename func_for_each_insn_all()

2020-03-25T17:28:27+00:00

Now that func_for_each_insn() is available, rename
func_for_each_insn_all(). This gets us:

  sym_for_each_insn()  - iterate on symbol offset/len
  func_for_each_insn() - iterate on insn->func

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/20200324160924.083720147@infradead.org