linux.git/tools/objtool, branch v4.14.124

objtool: Allow AR to be overridden with HOSTAR

2019-05-25T16:25:26+00:00

commit 8ea58f1e8b11cca3087b294779bf5959bf89cc10 upstream.

Currently, this Makefile hardcodes GNU ar, meaning that if it is not
available, there is no way to supply a different one and the build will
fail.

  $ make AR=llvm-ar CC=clang LD=ld.lld HOSTAR=llvm-ar HOSTCC=clang \
         HOSTLD=ld.lld HOSTLDFLAGS=-fuse-ld=lld defconfig modules_prepare
  ...
    AR       /out/tools/objtool/libsubcmd.a
  /bin/sh: 1: ar: not found
  ...

Follow the logic of HOST{CC,LD} and allow the user to specify a
different ar tool via HOSTAR (which is used elsewhere in other
tools/ Makefiles).

Signed-off-by: Nathan Chancellor 
Signed-off-by: Josh Poimboeuf 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Mukesh Ojha 
Cc: 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/80822a9353926c38fd7a152991c6292491a9d0e8.1558028966.git.jpoimboe@redhat.com
Link: https://github.com/ClangBuiltLinux/linux/issues/481
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix function fallthrough detection

2019-05-21T16:50:13+00:00

commit e6f393bc939d566ce3def71232d8013de9aaadde upstream.

When a function falls through to the next function due to a compiler
bug, objtool prints some obscure warnings.  For example:

  drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame
  drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8

Instead it should be printing:

  drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages()

This used to work, but was broken by the following commit:

  13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")

The padding nops at the end of a function aren't actually part of the
function, as defined by the symbol table.  So the 'func' variable in
validate_branch() is getting cleared to NULL when a padding nop is
encountered, breaking the fallthrough detection.

If the current instruction doesn't have a function associated with it,
just consider it to be part of the previously detected function by not
overwriting the previous value of 'func'.

Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: 
Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

objtool: Move objtool_file struct off the stack

2019-03-27T05:13:52+00:00

commit 0c671812f152b628bd87c0af49da032cc2a2c319 upstream.

Objtool uses over 512k of stack, thanks to the hash table embedded in
the objtool_file struct.  This causes an unnecessarily large stack
allocation and breaks users with low stack limits.

Move the struct off the stack.

Fixes: 042ba73fe7eb ("objtool: Add several performance improvements")
Reported-by: Vassili Karpov 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/df92dcbc4b84b02ffa252f46876df125fb56e2d7.1552954176.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

objtool: Fix segfault in .cold detection with -ffunction-sections

2018-12-17T08:28:50+00:00

[ Upstream commit 22566c1603030f0a036ad564634b064ad1a55db2 ]

Because find_symbol_by_name() traverses the same lists as
read_symbols(), changing sym->name in place without copying it affects
the result of find_symbol_by_name().  In the case where a ".cold"
function precedes its parent in sec->symbol_list, it can result in a
function being considered a parent of itself. This leads to function
length being set to 0 and other consequent side-effects including a
segfault in add_switch_table().  The effects of this bug are only
visible when building with -ffunction-sections in KCFLAGS.

Fix by copying the search string instead of modifying it in place.

Signed-off-by: Artem Savkov 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/910abd6b5a4945130fd44f787c24e07b9e07c8da.1542736240.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

objtool: Fix double-free in .cold detection error path

2018-12-17T08:28:49+00:00

[ Upstream commit 0b9301fb632f7111a3293a30cc5b20f1b82ed08d ]

If read_symbols() fails during second list traversal (the one dealing
with ".cold" subfunctions) it frees the symbol, but never deletes it
from the list/hash_table resulting in symbol being freed again in
elf_close(). Fix it by just returning an error, leaving cleanup to
elf_close().

Signed-off-by: Artem Savkov 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/beac5a9b7da9e8be90223459dcbe07766ae437dd.1542736240.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

objtool: Support GCC 8 '-fnoreorder-functions'

2018-08-24T11:09:11+00:00

[ Upstream commit 08b393d01c88aff27347ed2b1b354eb4db2f1532 ]

Since the following commit:

  cd77849a69cf ("objtool: Fix GCC 8 cold subfunction detection for aliased functions")

... if the kernel is built with EXTRA_CFLAGS='-fno-reorder-functions',
objtool can get stuck in an infinite loop.

That flag causes the new GCC 8 cold subfunctions to be placed in .text
instead of .text.unlikely.  But it also has an unfortunate quirk: in the
symbol table, the subfunction (e.g., nmi_panic.cold.7) is nested inside
the parent (nmi_panic).

That function overlap confuses objtool, and causes it to get into an
infinite loop in next_insn_same_func().  Here's Allan's description of
the loop:

  "Objtool iterates through the instructions in nmi_panic using
  next_insn_same_func. Once it reaches the end of nmi_panic at 0x534 it
  jumps to 0x528 as that's the start of nmi_panic.cold.7. However, since
  the instructions starting at 0x528 are still associated with nmi_panic
  objtool will get stuck in a loop, continually jumping back to 0x528
  after reaching 0x534."

Fix it by shortening the length of the parent function so that the
functions no longer overlap.

Reported-and-analyzed-by: Allan Xavier 
Signed-off-by: Josh Poimboeuf 
Cc: Allan Xavier 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/9e704c52bee651129b036be14feda317ae5606ae.1530136978.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

Kbuild: fix # escaping in .cmd files for future Make

2018-07-11T14:29:21+00:00

commit 9564a8cf422d7b58f6e857e3546d346fa970191e upstream.

I tried building using a freshly built Make (4.2.1-69-g8a731d1), but
already the objtool build broke with

orc_dump.c: In function ‘orc_dump’:
orc_dump.c:106:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations]
  if (elf_getshdrnum(elf, &nr_sections)) {

Turns out that with that new Make, the backslash was not removed, so cpp
didn't see a #include directive, grep found nothing, and
-DLIBELF_USE_DEPRECATED was wrongly put in CFLAGS.

Now, that new Make behaviour is documented in their NEWS file:

  * WARNING: Backward-incompatibility!
    Number signs (#) appearing inside a macro reference or function invocation
    no longer introduce comments and should not be escaped with backslashes:
    thus a call such as:
      foo := $(shell echo '#')
    is legal.  Previously the number sign needed to be escaped, for example:
      foo := $(shell echo '\#')
    Now this latter will resolve to "\#".  If you want to write makefiles
    portable to both versions, assign the number sign to a variable:
      C := \#
      foo := $(shell echo '$C')
    This was claimed to be fixed in 3.81, but wasn't, for some reason.
    To detect this change search for 'nocomment' in the .FEATURES variable.

This also fixes up the two make-cmd instances to replace # with $(pound)
rather than with \#. There might very well be other places that need
similar fixup in preparation for whatever future Make release contains
the above change, but at least this builds an x86_64 defconfig with the
new make.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=197847
Cc: Randy Dunlap 
Signed-off-by: Rasmus Villemoes 
Signed-off-by: Masahiro Yamada 
Signed-off-by: Greg Kroah-Hartman

objtool, kprobes/x86: Sync the latest header with tools/objtool/arch/x86/include/asm/insn.h

2018-06-20T19:02:58+00:00

[ Upstream commit 4fe875e4bd3cae85ae6f6eaf77f63fabe613b66e ]

The following commit:

  ee6a7354a362: kprobes/x86: Prohibit probing on exception masking instructions

Modified , adding the insn_masking_exception() function.

Sync the tooling version of the header to it, to fix this warning:

  Warning: synced file at 'tools/objtool/arch/x86/include/asm/insn.h' differs from latest kernel version at 'arch/x86/include/asm/insn.h'

Cc: Peter Zijlstra 
Cc: Josh Poimboeuf 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Cc: Ricardo Neri 
Cc: Francis Deslauriers 
Cc: Oleg Nesterov 
Cc: Alexei Starovoitov 
Cc: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: "H . Peter Anvin" 
Cc: Yonghong Song 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: "David S . Miller" 
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix "noreturn" detection for recursive sibling calls

2018-06-05T09:41:55+00:00

commit 0afd0d9e0e7879d666c1df2fa1bea4d8716909fe upstream.

Objtool has some crude logic for detecting static "noreturn" functions
(aka "dead ends").  This is necessary for being able to correctly follow
GCC code flow when such functions are called.

It's remotely possible for two functions to call each other via sibling
calls.  If they don't have RET instructions, objtool's noreturn
detection logic goes into a recursive loop:

  drivers/char/ipmi/ipmi_ssif.o: warning: objtool: return_hosed_msg()+0x0: infinite recursion (objtool bug!)
  drivers/char/ipmi/ipmi_ssif.o: warning: objtool: deliver_recv_msg()+0x0: infinite recursion (objtool bug!)

Instead of reporting an error in this case, consider the functions to be
non-dead-ends.

Reported-and-tested-by: Randy Dunlap 
Signed-off-by: Josh Poimboeuf 
Acked-by: Peter Zijlstra (Intel) 
Cc: Arnd Bergmann 
Cc: David Laight 
Cc: Greg KH 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: damian 
Link: http://lkml.kernel.org/r/7cc156408c5781a1f62085d352ced1fe39fe2f91.1525923412.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

objtool: Detect RIP-relative switch table references, part 2

2018-06-05T09:41:54+00:00

commit 7dec80ccbe310fb7e225bf21c48c672bb780ce7b upstream.

With the following commit:

  fd35c88b7417 ("objtool: Support GCC 8 switch tables")

I added a "can't find switch jump table" warning, to stop covering up
silent failures if add_switch_table() can't find anything.

That warning found yet another bug in the objtool switch table detection
logic.  For cases 1 and 2 (as described in the comments of
find_switch_table()), the find_symbol_containing() check doesn't adjust
the offset for RIP-relative switch jumps.

Incidentally, this bug was already fixed for case 3 with:

  6f5ec2993b1f ("objtool: Detect RIP-relative switch table references")

However, that commit missed the fix for cases 1 and 2.

The different cases are now starting to look more and more alike.  So
fix the bug by consolidating them into a single case, by checking the
original dynamic jump instruction in the case 3 loop.

This also simplifies the code and makes it more robust against future
switch table detection issues -- of which I'm sure there will be many...

Switch table detection has been the most fragile area of objtool, by
far.  I long for the day when we'll have a GCC plugin for annotating
switch tables.  Linus asked me to delay such a plugin due to the
flakiness of the plugin infrastructure in older versions of GCC, so this
rickety code is what we're stuck with for now.  At least the code is now
a little simpler than it was.

Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/f400541613d45689086329432f3095119ffbc328.1526674218.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman