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

Pavel Machek
2017-03-22T15:52:49Z

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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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