objtool: Fix up some outdated references to ENTRY/ENDPROC

ENTRY and ENDPROC were deprecated years ago and replaced with
SYM_FUNC_{START,END}. Fix up a few outdated references in the objtool
documen

objtool: Fix up some outdated references to ENTRY/ENDPROC

ENTRY and ENDPROC were deprecated years ago and replaced with
SYM_FUNC_{START,END}. Fix up a few outdated references in the objtool
documentation and comments. Also fix a few typos.

Suggested-by: Brendan Jackman <[email protected]>
Suggested-by: Miroslav Benes <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/5eb7e06e1a0e87aaeda8d583ab060e7638a6ea8e.1742852846.git.jpoimboe@kernel.org

show more ...

objtool: Update documentation

Fix some outdated information in the objtool doc.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link

objtool: Update documentation

Fix some outdated information in the objtool doc.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/2552ee8b48631127bf269359647a7389edf5f002.1741975349.git.jpoimboe@kernel.org

show more ...

objtool: Improve __noreturn annotation warning

Clarify what needs to be done to resolve the missing __noreturn warning.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijl

objtool: Improve __noreturn annotation warning

Clarify what needs to be done to resolve the missing __noreturn warning.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/ab835a35d00bacf8aff0b56257df93f14fdd8224.1741975349.git.jpoimboe@kernel.org

show more ...

x86/alternatives, kvm: Fix a couple of CALLs without a frame pointer

objtool complains:

arch/x86/kvm/kvm.o: warning: objtool: .altinstr_replacement+0xc5: call without frame pointer save/setup
v

x86/alternatives, kvm: Fix a couple of CALLs without a frame pointer

objtool complains:

arch/x86/kvm/kvm.o: warning: objtool: .altinstr_replacement+0xc5: call without frame pointer save/setup
vmlinux.o: warning: objtool: .altinstr_replacement+0x2eb: call without frame pointer save/setup

Make sure %rSP is an output operand to the respective asm() statements.

The test_cc() hunk and ALT_OUTPUT_SP() courtesy of peterz. Also from him
add some helpful debugging info to the documentation.

Now on to the explanations:

tl;dr: The alternatives macros are pretty fragile.

If I do ALT_OUTPUT_SP(output) in order to be able to package in a %rsp
reference for objtool so that a stack frame gets properly generated, the
inline asm input operand with positional argument 0 in clear_page():

"0" (page)

gets "renumbered" due to the added

: "+r" (current_stack_pointer), "=D" (page)

and then gcc says:

./arch/x86/include/asm/page_64.h:53:9: error: inconsistent operand constraints in an ‘asm’

The fix is to use an explicit "D" constraint which points to a singleton
register class (gcc terminology) which ends up doing what is expected
here: the page pointer - input and output - should be in the same %rdi
register.

Other register classes have more than one register in them - example:
"r" and "=r" or "A":

‘A’
The ‘a’ and ‘d’ registers. This class is used for
instructions that return double word results in the ‘ax:dx’
register pair. Single word values will be allocated either in
‘ax’ or ‘dx’.

so using "D" and "=D" just works in this particular case.

And yes, one would say, sure, why don't you do "+D" but then:

: "+r" (current_stack_pointer), "+D" (page)
: [old] "i" (clear_page_orig), [new1] "i" (clear_page_rep), [new2] "i" (clear_page_erms),
: "cc", "memory", "rax", "rcx")

now find the Waldo^Wcomma which throws a wrench into all this.

Because that silly macro has an "input..." consume-all last macro arg
and in it, one is supposed to supply input *and* clobbers, leading to
silly syntax snafus.

Yap, they need to be cleaned up, one fine day...

Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Acked-by: Sean Christopherson <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/20240625112056.GDZnqoGDXgYuWBDUwu@fat_crate.local

show more ...

objtool: Move noreturn function list to separate file

This makes it a little cleaner and easier to maintain.

Suggested-by: Peter Zijlstra <[email protected]>
Reviewed-by: Miroslav Benes <mbenes@

objtool: Move noreturn function list to separate file

This makes it a little cleaner and easier to maintain.

Suggested-by: Peter Zijlstra <[email protected]>
Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lore.kernel.org/r/cecacf07a69a244c74474c18b7652627de67a528.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <[email protected]>

show more ...

objtool: Detect missing __noreturn annotations

Most "unreachable instruction" warnings these days seem to actually be
the result of a missing __noreturn annotation. Add an explicit check
for that.

objtool: Detect missing __noreturn annotations

Most "unreachable instruction" warnings these days seem to actually be
the result of a missing __noreturn annotation. Add an explicit check
for that.

Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lore.kernel.org/r/6e2b93d8c65eaed6c4166a358269dc0ef01f890c.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <[email protected]>

show more ...

objtool: Include backtrace in verbose mode

Include backtrace in verbose mode. This makes it easy to gather all the
information needed for diagnosing objtool warnings.

Reviewed-by: Miroslav Benes <

objtool: Include backtrace in verbose mode

Include backtrace in verbose mode. This makes it easy to gather all the
information needed for diagnosing objtool warnings.

Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lore.kernel.org/r/c255224fabcf7e64bac232fec1c77c9fc2d7d7ab.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <[email protected]>

show more ...

objtool: Add verbose option for disassembling affected functions

When a warning is associated with a function, add an option to
disassemble that function.

This makes it easier for reporters to subm

objtool: Add verbose option for disassembling affected functions

When a warning is associated with a function, add an option to
disassemble that function.

This makes it easier for reporters to submit the information needed to
diagnose objtool warnings.

Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lore.kernel.org/r/dd0fe13428ede186f09c74059a8001f4adcea5fc.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <[email protected]>

show more ...

docs: move x86 documentation into Documentation/arch/

Move the x86 documentation under Documentation/arch/ as a way of cleaning
up the top-level directory and making the structure of our docs more
c

docs: move x86 documentation into Documentation/arch/

Move the x86 documentation under Documentation/arch/ as a way of cleaning
up the top-level directory and making the structure of our docs more
closely match the structure of the source directories it describes.

All in-kernel references to the old paths have been updated.

Acked-by: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Borislav Petkov <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Jonathan Corbet <[email protected]>

show more ...

objtool: Check that module init/exit function is an indirect call target

Some out-of-tree modules still do not use module_init() / module_exit()
macros and simply create functions with magic names i

objtool: Check that module init/exit function is an indirect call target

Some out-of-tree modules still do not use module_init() / module_exit()
macros and simply create functions with magic names init_module() and
cleanup_module() instead. As a result, these functions are not recognized
as indirect call targets by objtool and such module fails to load into an
IBT enabled kernel.

This old way is not even documented any more but it is cleaner to issue
a warning than to let the module fail on load without obvious reason.

Signed-off-by: Michal Kubecek <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

objtool: Update documentation

The objtool documentation is very stack validation centric. Broaden the
documentation and describe all the features objtool supports.

Signed-off-by: Josh Poimboeuf <j

objtool: Update documentation

The objtool documentation is very stack validation centric. Broaden the
documentation and describe all the features objtool supports.

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Miroslav Benes <[email protected]>
Link: https://lkml.kernel.org/r/b6a84d301d9f73ec6725752654097f4e31fa1b69.1650300597.git.jpoimboe@redhat.com

show more ...