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2017-08-10x86/asm: Fix UNWIND_HINT_REGS macro for older binutilsJosh Poimboeuf1-4/+6
Apparently the binutils 2.20 assembler can't handle the '&&' operator in the UNWIND_HINT_REGS macro. Rearrange the macro to do without it. This fixes the following error: arch/x86/entry/entry_64.S: Assembler messages: arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 39358a033b2e ("objtool, x86: Add facility for asm code to provide unwind hints") Link: http://lkml.kernel.org/r/e2ad97c1ae49a484644b4aaa4dd3faa4d6d969b2.1502116651.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-18objtool, x86: Add facility for asm code to provide unwind hintsJosh Poimboeuf1-0/+103
Some asm (and inline asm) code does special things to the stack which objtool can't understand. (Nor can GCC or GNU assembler, for that matter.) In such cases we need a facility for the code to provide annotations, so the unwinder can unwind through it. This provides such a facility, in the form of unwind hints. They're similar to the GNU assembler .cfi* directives, but they give more information, and are needed in far fewer places, because objtool can fill in the blanks by following branches and adjusting the stack pointer for pushes and pops. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/0f5f3c9104fca559ff4088bece1d14ae3bca52d5.1499786555.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>