Messages in this thread | | | From | "H.J. Lu" <> | Date | Mon, 22 May 2017 07:39:57 -0700 | Subject | Re: [PATCH 7/7] DWARF: add the config option |
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On Mon, May 22, 2017 at 4:34 AM, Jiri Kosina <jikos@kernel.org> wrote: > On Sat, 20 May 2017, H.J. Lu wrote: > >> >>>> pushq %whatever >> >>>> .cfi_adjust_sp -8 >> >>>> ... >> >>>> popq %whatever >> >>>> .cfi_adjust_sp 8 >> >>>> >> >> >> >> Np. Compiler needs to generate this. >> >> >> > >> > How would the compiler generate this when inline asm is involved? For >> > the kernel, objtool could get around the need to have these >> > annotations, but not so much for user code? Is the compiler supposed >> > to parse the inline asm? Would the compiler provide some magic % code >> > to represent the current CFA base register? >> >> Here is one example of inline asm with call frame info: >> >> https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c;h=be058bac436d1cc9794b2b03107676ed99f6b872;hb=HEAD > > That brings us basically pretty close to square one though; having to > maintain "manual" anotations. Something we're pretty much trying to avoid > through this excercise.
Assembler only encodes instructions. You need to a different tool to figure out what an instruction does.
-- H.J.
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