linux.git/tools/objtool/check.c, branch v6.6.132

objtool: Handle Clang RSP musical chairs

2026-04-02T11:07:15+00:00

[ Upstream commit 7fdaa640c810cb42090a182c33f905bcc47a616a ]

For no apparent reason (possibly related to CONFIG_KMSAN), Clang can
randomly pass the value of RSP to other registers and then back again to
RSP.  Handle that accordingly.

Fixes the following warnings:

  drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: undefined stack state
  drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: unknown CFA base reg -1

Reported-by: Arnd Bergmann 
Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com
Link: https://patch.msgid.link/240e6a172cc73292499334a3724d02ccb3247fc7.1772818491.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

objtool: Fix standalone --hacks=jump_label

2026-01-11T14:21:13+00:00

[ Upstream commit be8374a5ba7cbab6b97df94b4ffe0b92f5c8a6d2 ]

The objtool command line 'objtool --hacks=jump_label foo.o' on its own
should be expected to rewrite jump labels to NOPs. This means the
add_special_section_alts() code path needs to run when only this option
is provided.

This is mainly relevant in certain debugging situations, but could
potentially also fix kernel builds in which objtool is run with
--hacks=jump_label but without --orc, --stackval, --uaccess, or
--hacks=noinstr.

Fixes: de6fbcedf5ab ("objtool: Read special sections with alts only when specific options are selected")
Signed-off-by: Dylan Hatch 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

objtool: Fix error handling inconsistencies in check()

2025-06-04T12:41:58+00:00

[ Upstream commit b745962cb97569aad026806bb0740663cf813147 ]

Make sure all fatal errors are funneled through the 'out' label with a
negative ret.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Brendan Jackman 
Link: https://lore.kernel.org/r/0f49d6a27a080b4012e84e6df1e23097f44cc082.1741975349.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin

objtool: Properly disable uaccess validation

2025-06-04T12:41:55+00:00

[ Upstream commit e1a9dda74dbffbc3fa2069ff418a1876dc99fb14 ]

If opts.uaccess isn't set, the uaccess validation is disabled, but only
partially: it doesn't read the uaccess_safe_builtin list but still tries
to do the validation.  Disable it completely to prevent false warnings.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/0e95581c1d2107fb5f59418edf2b26bba38b0cbb.1742852846.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin

objtool: Ignore end-of-section jumps for KCOV/GCOV

2025-05-02T05:51:04+00:00

commit 0d7597749f5a3ac67851d3836635d084df15fb66 upstream.

When KCOV or GCOV is enabled, dead code can be left behind, in which
case objtool silences unreachable and undefined behavior (fallthrough)
warnings.

Fallthrough warnings, and their variant "end of section" warnings, were
silenced with the following commit:

  6b023c784204 ("objtool: Silence more KCOV warnings")

Another variant of a fallthrough warning is a jump to the end of a
function.  If that function happens to be at the end of a section, the
jump destination doesn't actually exist.

Normally that would be a fatal objtool error, but for KCOV/GCOV it's
just another undefined behavior fallthrough.  Silence it like the
others.

Fixes the following warning:

  drivers/iommu/dma-iommu.o: warning: objtool: iommu_dma_sw_msi+0x92: can't find jump dest instruction at .text+0x54d5

Fixes: 6b023c784204 ("objtool: Silence more KCOV warnings")
Reported-by: Randy Dunlap 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/08fbe7d7e1e20612206f1df253077b94f178d93e.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/314f8809-cd59-479b-97d7-49356bf1c8d1@infradead.org/
Signed-off-by: Greg Kroah-Hartman

objtool: Stop UNRET validation on UD2

2025-05-02T05:50:59+00:00

[ Upstream commit 9f9cc012c2cbac4833746a0182e06a8eec940d19 ]

In preparation for simplifying INSN_SYSCALL, make validate_unret()
terminate control flow on UD2 just like validate_branch() already does.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/ce841269e7e28c8b7f32064464a9821034d724ff.1744095216.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin

objtool, panic: Disable SMAP in __stack_chk_fail()

2025-05-02T05:50:55+00:00

[ Upstream commit 72c774aa9d1e16bfd247096935e7dae194d84929 ]

__stack_chk_fail() can be called from uaccess-enabled code.  Make sure
uaccess gets disabled before calling panic().

Fixes the following warning:

  kernel/trace/trace_branch.o: error: objtool: ftrace_likely_update+0x1ea: call to __stack_chk_fail() with UACCESS enabled

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Kees Cook 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/a3e97e0119e1b04c725a8aa05f7bc83d98e657eb.1742852847.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin

objtool: Silence more KCOV warnings

2025-05-02T05:50:55+00:00

[ Upstream commit 6b023c7842048c4bbeede802f3cf36b96c7a8b25 ]

In the past there were issues with KCOV triggering unreachable
instruction warnings, which is why unreachable warnings are now disabled
with CONFIG_KCOV.

Now some new KCOV warnings are showing up with GCC 14:

  vmlinux.o: warning: objtool: cpuset_write_resmask() falls through to next function cpuset_update_active_cpus.cold()
  drivers/usb/core/driver.o: error: objtool: usb_deregister() falls through to next function usb_match_device()
  sound/soc/codecs/snd-soc-wcd934x.o: warning: objtool: .text.wcd934x_slim_irq_handler: unexpected end of section

All are caused by GCC KCOV not finishing an optimization, leaving behind
a never-taken conditional branch to a basic block which falls through to
the next function (or end of section).

At a high level this is similar to the unreachable warnings mentioned
above, in that KCOV isn't fully removing dead code.  Treat it the same
way by adding these to the list of warnings to ignore with CONFIG_KCOV.

Reported-by: Ingo Molnar 
Reported-by: kernel test robot 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/66a61a0b65d74e072d3dc02384e395edb2adc3c5.1742852846.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/Z9iTsI09AEBlxlHC@gmail.com
Closes: https://lore.kernel.org/oe-kbuild-all/202503180044.oH9gyPeg-lkp@intel.com/
Signed-off-by: Sasha Levin

objtool: Fix INSN_CONTEXT_SWITCH handling in validate_unret()

2025-04-25T08:45:05+00:00

[ Upstream commit a8df7d0ef92eca28c610206c6748daf537ac0586 ]

The !CONFIG_IA32_EMULATION version of xen_entry_SYSCALL_compat() ends
with a SYSCALL instruction which is classified by objtool as
INSN_CONTEXT_SWITCH.

Unlike validate_branch(), validate_unret() doesn't consider
INSN_CONTEXT_SWITCH in a non-function to be a dead end, so it keeps
going past the end of xen_entry_SYSCALL_compat(), resulting in the
following warning:

  vmlinux.o: warning: objtool: xen_reschedule_interrupt+0x2a: RET before UNTRAIN

Fix that by adding INSN_CONTEXT_SWITCH handling to validate_unret() to
match what validate_branch() is already doing.

Fixes: a09a6e2399ba ("objtool: Add entry UNRET validation")
Reported-by: Andrew Cooper 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/f5eda46fd09f15b1f5cde3d9ae3b92b958342add.1744095216.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin

objtool: Fix verbose disassembly if CROSS_COMPILE isn't set

2025-04-10T12:37:36+00:00

[ Upstream commit e77956e4e5c11218e60a1fe8cdbccd02476f2e56 ]

In verbose mode, when printing the disassembly of affected functions, if
CROSS_COMPILE isn't set, the objdump command string gets prefixed with
"(null)".

Somehow this worked before.  Maybe some versions of glibc return an
empty string instead of NULL.  Fix it regardless.

[ jpoimboe: Rewrite commit log. ]

Fixes: ca653464dd097 ("objtool: Add verbose option for disassembling affected functions")
Signed-off-by: David Laight 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/20250215142321.14081-1-david.laight.linux@gmail.com
Link: https://lore.kernel.org/r/b931a4786bc0127aa4c94e8b35ed617dcbd3d3da.1743481539.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin