kernel_optimize_test/arch/i386/boot/mca.c
H. Peter Anvin 5593eaa854 [x86 setup] Fix assembly constraints
Fix incorrect assembly constraints.  In particular, fix memory
constraints used inside push..pop, which can cause invalid operation
since gcc may generate %esp-relative references.

Additionally:

outl() should have "dN" not "dn".

query_mca() shouldn't listen 16/32-bit registers in an 8-bit only
context.

has_eflag(): the "mask" is only used well after both the stack pointer
and the output registers have been touched; this requires the output
registers to be earlyclobbers (=&) and the input to exclude memory (so
"ri", not "g").

Thanks to Etienne Lorrain and Chuck Ebbert for prompting this review.

Cc: Etienne Lorrain <etienne_lorrain@yahoo.fr>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2007-07-18 11:36:17 -07:00

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C

/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/mca.c
*
* Get the MCA system description table
*/
#include "boot.h"
int query_mca(void)
{
u8 err;
u16 es, bx, len;
asm("pushw %%es ; "
"int $0x15 ; "
"setc %0 ; "
"movw %%es, %1 ; "
"popw %%es"
: "=acd" (err), "=acdSD" (es), "=b" (bx)
: "a" (0xc000));
if (err)
return -1; /* No MCA present */
set_fs(es);
len = rdfs16(bx);
if (len > sizeof(boot_params.sys_desc_table))
len = sizeof(boot_params.sys_desc_table);
copy_from_fs(&boot_params.sys_desc_table, bx, len);
return 0;
}