From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>, Pavel Machek <pavel@ucw.cz>,
mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com,
x86@kernel.org, linux-kernel@vger.kernel.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
xen-devel@lists.xenproject.org,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>,
linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 02/10] x86: assembly, FUNC_START for fn, DATA_START for data
Date: Wed, 22 Mar 2017 10:33:36 -0500 [thread overview]
Message-ID: <20170322153336.srnce5vwq2727vuy@treble> (raw)
In-Reply-To: <049e6c03-8d7d-e869-96bd-0a98e6471227@suse.cz>
On Wed, Mar 22, 2017 at 04:01:08PM +0100, Jiri Slaby wrote:
> On 03/22/2017, 03:11 PM, Josh Poimboeuf wrote:
> > Or, here's a much easier way to do it, without involving objtool:
> >
> > --- a/include/linux/linkage.h
> > +++ b/include/linux/linkage.h
> > @@ -138,9 +138,17 @@
> > name:
> > #endif
> >
> > +#ifndef CHECK_DUP_SYM_END
> > +#define CHECK_DUP_SYM_END(name) \
> > + .pushsection .discard.sym_func_end ASM_NL \
> > + SYM_END_##name: .byte 0 ASM_NL \
> > + .popsection
> > +#endif
> > +
> > /* SYM_END -- use only if you have to */
> > #ifndef SYM_END
> > #define SYM_END(name, sym_type) \
> > + CHECK_DUP_SYM_END(name) ASM_NL \
> > .type name sym_type ASM_NL \
> > .size name, .-name
> > #endif
>
> I tried this approach and it didn't work for me inside .macros. Oh,
> well, the name cannot be first, so now, we can have a check for both
> correct pairing _and_ duplicate ends in one:
>
> #define SYM_CHECK_START(name) \
> .pushsection .rodata.bubak ASM_NL \
> .long has_no_SYM_END_##name - . ASM_NL \
> .popsection
>
> #define SYM_CHECK_END(name) \
> has_no_SYM_END_##name:
>
> /* SYM_START -- use only if you have to */
> #ifndef SYM_START
> #define SYM_START(name, align, visibility, entry) \
> SYM_CHECK_START(name) ASM_NL \
> visibility(name) ASM_NL \
> align ASM_NL \
> name: ASM_NL \
> entry
> #endif
>
> /* SYM_END -- use only if you have to */
> #ifndef SYM_END
> #define SYM_END(name, sym_type, exit) \
> exit ASM_NL \
> SYM_CHECK_END(name) ASM_NL \
> .type name sym_type ASM_NL \
> .size name, .-name
> #endif
>
>
> So for the ftrace mistake I did:
>
> AS arch/x86/kernel/mcount_64.o
> /home/latest/linux/arch/x86/kernel/mcount_64.S: Assembler messages:
> /home/latest/linux/arch/x86/kernel/mcount_64.S:192: Error: symbol
> `has_no_SYM_END_ftrace_caller' is already defined
>
>
> or if I remove SYM_END_FUNC completely:
> LD vmlinux.o
> MODPOST vmlinux.o
> arch/x86/built-in.o:(.rodata.bubak+0x130): undefined reference to
> `has_no_SYM_END_ftrace_stub'
>
>
> Sad is that this occurs only during linking, so I cannot put it in the
> .discard section -- ideas?
Ah, interesting idea but I can't think of a way to do the missing end
check before link time.
But it would be easy for objtool to check for a missing end because the
symbol would have a zero size.
--
Josh
next prev parent reply other threads:[~2017-03-22 15:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-17 10:47 [PATCH 01/10] x86: assembly, ENTRY for fn, GLOBAL for data Jiri Slaby
2017-02-17 10:47 ` [PATCH 02/10] x86: assembly, use ENDPROC for functions Jiri Slaby
2017-02-17 11:08 ` Juergen Gross
2017-02-17 11:06 ` [PATCH 01/10] x86: assembly, ENTRY for fn, GLOBAL for data Juergen Gross
2017-03-01 9:38 ` Ingo Molnar
2017-03-01 9:50 ` Jiri Slaby
2017-03-01 10:09 ` Thomas Gleixner
2017-03-01 10:27 ` Ingo Molnar
2017-03-03 12:22 ` Jiri Slaby
2017-03-03 18:20 ` hpa
2017-03-06 14:09 ` Jiri Slaby
2017-03-07 7:57 ` Ingo Molnar
2017-03-03 18:24 ` hpa
2017-03-07 8:27 ` Ingo Molnar
2017-03-07 17:24 ` [RFC] linkage: new macros for functions and data Jiri Slaby
2017-03-16 8:02 ` Ingo Molnar
2017-03-16 8:13 ` Jiri Slaby
2017-03-20 12:32 ` [PATCH v2 01/10] linkage: new macros for assembler symbols Jiri Slaby
2017-03-20 12:32 ` [PATCH v2 02/10] x86: assembly, FUNC_START for fn, DATA_START for data Jiri Slaby
2017-03-20 13:32 ` Josh Poimboeuf
2017-03-20 15:32 ` Jiri Slaby
2017-03-20 16:07 ` Josh Poimboeuf
2017-03-21 14:08 ` Pavel Machek
2017-03-22 7:25 ` Ingo Molnar
2017-03-22 7:39 ` Jiri Slaby
2017-03-22 7:46 ` Ingo Molnar
2017-03-22 14:11 ` Josh Poimboeuf
2017-03-22 15:01 ` Jiri Slaby
2017-03-22 15:33 ` Josh Poimboeuf [this message]
2017-03-23 7:38 ` Ingo Molnar
2017-03-23 13:24 ` Josh Poimboeuf
2017-03-22 12:06 ` Jiri Slaby
2017-03-22 15:52 ` Pavel Machek
2017-03-20 12:32 ` [PATCH v2 03/10] x86: assembly, use SYM_FUNC_END for functions Jiri Slaby
2017-03-21 14:48 ` Josh Poimboeuf
2017-03-22 7:29 ` Ingo Molnar
2017-03-22 14:26 ` Josh Poimboeuf
2017-03-22 15:44 ` Jiri Slaby
2017-04-10 11:23 ` Jiri Slaby
2017-04-10 19:35 ` Josh Poimboeuf
2017-04-12 6:24 ` Jiri Slaby
2017-04-12 6:52 ` Ingo Molnar
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