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 Fix up a few outdated references in the objtool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 <jackmanb@google.com>
Suggested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/5eb7e06e1a0e87aaeda8d583ab060e7638a6ea8e.1742852846.git.jpoimboe@kernel.org
Fix some outdated information in the objtool doc. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/2552ee8b48631127bf269359647a7389edf5f002.1741975349.git.jpoimboe@kernel.org
Clarify what needs to be done to resolve the missing __noreturn warning. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/ab835a35d00bacf8aff0b56257df93f14fdd8224.1741975349.git.jpoimboe@kernel.org
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/202406141648.jO9qNGLa-lkp@intel.com/ Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Sean Christopherson <seanjc@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240625112056.GDZnqoGDXgYuWBDUwu@fat_crate.local
This makes it a little cleaner and easier to maintain. Suggested-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/cecacf07a69a244c74474c18b7652627de67a528.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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 <mbenes@suse.cz> Link: https://lore.kernel.org/r/6e2b93d8c65eaed6c4166a358269dc0ef01f890c.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Include backtrace in verbose mode. This makes it easy to gather all the information needed for diagnosing objtool warnings. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/c255224fabcf7e64bac232fec1c77c9fc2d7d7ab.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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 <mbenes@suse.cz> Link: https://lore.kernel.org/r/dd0fe13428ede186f09c74059a8001f4adcea5fc.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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 <dave.hansen@linux.intel.com> Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: Borislav Petkov <bp@alien8.de> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20230315211523.108836-1-corbet@lwn.net/ Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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 <mkubecek@suse.cz> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20230118105215.B9DA960514@lion.mk-sys.cz