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From: Marcel Moolenaar <marcel@xcllnt.net>
Date: Wed, 1 Jun 2005 22:38:04 -0700
To: Richard Henderson <rth@twiddle.net>
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Cc: freebsd-alpha@freebsd.org
Subject: Re: reloc_non_plt_obj buggy
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On Jun 1, 2005, at 10:24 AM, Richard Henderson wrote:

>> From src/libexec/rtld-elf/alpha/reloc.c:
>
> ---------------------
> #define load64(p) ({						\
> 	Elf_Addr __res;						\
> 	__asm__("ldq_u %0,%1" : "=r"(__res) : "m"(*(p)));	\
> 	__res; })
>
> #define store64(p, v)						\
> 	__asm__("stq_u %1,%0" : "=m"(*(p)) : "r"(v))
> ---------------------
>
> Someone wasn't very clear on what ldq_u/stq_u actually does.
> You're not actually modifying the unaligned address, you're
> modifying (address & ~7), and corrupting the dwarf2 data in
> the process.

You're absolutely right.

> You need to use
>
> struct ualong {
>   Elf_Addr x __attribute__((packed));
> };
>
> #define load64(p)	(((struct ualong *)(p))->x)
> #define store64(p,v)	(((struct ualong *)(p))->x = (v))

Committed as-is. Thanks,

-- 
  Marcel Moolenaar         USPA: A-39004          marcel@xcllnt.net