Re: [PATCH v2 02/10] x86: assembly, FUNC_START for fn, DATA_START for data

From: Pavel Machek <pavel@ucw.cz>
To: Jiri Slaby <jslaby@suse.cz>
Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com,
	x86@kernel.org, jpoimboe@redhat.com,
	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 16:52:45 +0100	[thread overview]
Message-ID: <20170322155245.GA27894@amd> (raw)
In-Reply-To: <fd0cb783-b07f-f636-04a8-d8a115de1a17@suse.cz>

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On Wed 2017-03-22 13:06:54, Jiri Slaby wrote:
> Hi,
> 
> On 03/21/2017, 03:08 PM, Pavel Machek wrote:
> >> -ENTRY(saved_rbp)	.quad	0
> >> -ENTRY(saved_rsi)	.quad	0
> >> -ENTRY(saved_rdi)	.quad	0
> >> -ENTRY(saved_rbx)	.quad	0
> >> +SYM_DATA_START(saved_rbp)		.quad	0
> >> +SYM_DATA_START(saved_rsi)		.quad	0
> >> +SYM_DATA_START(saved_rdi)		.quad	0
> >> +SYM_DATA_START(saved_rbx)		.quad	0
> > 
> > Does it make sense to call it SYM_DATA_*START* when there's no
> > corresponding end?
> > 
> > Plus... it looks like saved_rsi (and friends) are only used inside
> > wakeup_64.S. Could we just delete the "ENTRY" annotations?
> 
> 
> So, now I have:
> 
> === linkage.h ===
> 
> /* SYM_DATA_SIMPLE -- start+end wrapper around simple global data */
> #ifndef SYM_DATA_SIMPLE
> #define SYM_DATA_SIMPLE(name, data)                             \
>         SYM_DATA_START(name) ASM_NL                             \
>         data ASM_NL                                             \
>         SYM_DATA_END(name)
> #endif
> 
> /* SYM_DATA_SIMPLE_LOCAL -- start+end wrapper around simple local data */
> #ifndef SYM_DATA_SIMPLE_LOCAL
> #define SYM_DATA_SIMPLE_LOCAL(name, data)                       \
>         SYM_DATA_START_LOCAL(name) ASM_NL                       \
>         data ASM_NL                                             \
>         SYM_DATA_END(name)
> #endif
> 
> === wakeup_64.S ===
> 
> SYM_DATA_SIMPLE_LOCAL(saved_rbp, .quad 0)
> SYM_DATA_SIMPLE_LOCAL(saved_rsi, .quad 0)
> SYM_DATA_SIMPLE_LOCAL(saved_rdi, .quad 0)
> SYM_DATA_SIMPLE_LOCAL(saved_rbx, .quad 0)
> 
> SYM_DATA_SIMPLE_LOCAL(saved_rip, .quad 0)
> SYM_DATA_SIMPLE_LOCAL(saved_rsp, .quad 0)
> 
> SYM_DATA_SIMPLE_LOCAL(saved_magic, .quad 0)
> 
> === original ===
> 
>     10: 0000000000000060     0 NOTYPE  GLOBAL DEFAULT    3 saved_magic
>     11: 0000000000000050     0 NOTYPE  GLOBAL DEFAULT    3 saved_rsp
>     12: 0000000000000030     0 NOTYPE  GLOBAL DEFAULT    3 saved_rbx
>     13: 0000000000000020     0 NOTYPE  GLOBAL DEFAULT    3 saved_rdi
>     14: 0000000000000010     0 NOTYPE  GLOBAL DEFAULT    3 saved_rsi
>     15: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    3 saved_rbp
>     16: 0000000000000040     0 NOTYPE  GLOBAL DEFAULT    3 saved_rip
> 
> === new ===
> 
>      4: 0000000000000030     8 OBJECT  LOCAL  DEFAULT    3 saved_magic
>      6: 0000000000000028     8 OBJECT  LOCAL  DEFAULT    3 saved_rsp
>      7: 0000000000000018     8 OBJECT  LOCAL  DEFAULT    3 saved_rbx
>      8: 0000000000000010     8 OBJECT  LOCAL  DEFAULT    3 saved_rdi
>      9: 0000000000000008     8 OBJECT  LOCAL  DEFAULT    3 saved_rsi
>     10: 0000000000000000     8 OBJECT  LOCAL  DEFAULT    3 saved_rbp
>     11: 0000000000000020     8 OBJECT  LOCAL  DEFAULT    3 saved_rip
> 
> === EOF ===
> 
> BTW, ENTRY() aligned the data to 2^4 = 16 as we can see in the original.
> But I see no point aligning data like this.

Yep, that's a bug, too. I guess it hurts even more on 32-bit....

Thanks for fixing this,
									Pavel

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