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[MIPS] More uaccess.h fixes with gcc >= 4.0.1. 

From Richard Sandiford <richard@codesourcery.com>:
    
This patch caused a miscompilation of the restore_gp_regs() block
in restore_sigcontext().  This was in a 32-bit kernel compiled with
GCC CVS head.
    
restore_gp_regs() copies 64-bit user fields into 32-bit variables,
and in this combination, the new __get_user_asm_ll32() clobbers too
many registers.  It says:
    
/*
 * Get a long long 64 using 32 bit registers.
 */
{									\
	__asm__ __volatile__(						\
	"1:	lw	%1, (%3)				\n"	\
	"2:	lw	%D1, 4(%3)				\n"	\
	"	move	%0, $0					\n"	\
	"3:	.section	.fixup,\"ax\"			\n"	\
	"4:	li	%0, %4					\n"	\
	"	move	%1, $0					\n"	\
	"	move	%D1, $0					\n"	\
	"	j	3b					\n"	\
	"	.previous					\n"	\
	"	.section	__ex_table,\"a\"		\n"	\
	"	" __UA_ADDR "	1b, 4b				\n"	\
	"	" __UA_ADDR "	2b, 4b				\n"	\
	"	.previous					\n"	\
	: "=r" (__gu_err), "=&r" (val)					\
	: "0" (0), "r" (addr), "i" (-EFAULT));				\
}

and this requires val (%1) to be a 64-bit value.  In the case I saw,
gcc was using $3 for the 32-bit val, and wasn't expecting $4 to be
clobbered.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle 2006-02-10 01:31:24 +00:00
parent 41700e7399
commit 3218357c94
1 changed files with 4 additions and 1 deletions
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5
include/asm-mips/uaccess.h
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@ -266,6 +266,8 @@ do { \
*/
#define __get_user_asm_ll32(val, addr) \
{ \
unsigned long long __gu_tmp; \
\
__asm__ __volatile__( \
"1: lw %1, (%3) \n" \
"2: lw %D1, 4(%3) \n" \
@ -280,8 +282,9 @@ do { \
" " __UA_ADDR " 1b, 4b \n" \
" " __UA_ADDR " 2b, 4b \n" \
" .previous \n" \
: "=r" (__gu_err), "=&r" (val) \
: "=r" (__gu_err), "=&r" (__gu_tmp) \
: "0" (0), "r" (addr), "i" (-EFAULT)); \
(val) = __gu_tmp; \
}
/*