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sh: Fix up xchg/cmpxchg corruption with gUSA RB. 

gUSA special cases r15 for part of its login/out sequence, meaning that
any parameters need to be explicitly prohibited from accidentally being
assigned that particular register, and the compiler ultimately needs to
use a temporary instead.

Certain configurations have begun generating code paths that do indeed
get allocated r15, resulting in immediate corruption of the exchanged
value. This was observed in (amongst others) exit_mm() code generation
where the xchg_u32 call was immediately corrupting a structure address.

As this is a general gUSA restriction, the rest of the users likewise
need to be updated to ensure sensible constraints.

References: https://bugzilla.stlinux.com/show_bug.cgi?id=11229
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Reviewed-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Srinivas KANDAGATLA 2011-06-08 15:22:39 +09:00 committed by Paul Mundt
parent 363e9f05cb
commit 5bdbd4fa4d
1 changed files with 12 additions and 9 deletions
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21
arch/sh/include/asm/cmpxchg-grb.h
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@ -15,8 +15,9 @@ static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val)
" mov.l %2, @%1 \n\t" /* store new value */
"1: mov r1, r15 \n\t" /* LOGOUT */
: "=&r" (retval),
"+r" (m)
: "r" (val)
"+r" (m),
"+r" (val) /* inhibit r15 overloading */
:
: "memory", "r0", "r1");
return retval;
@ -36,8 +37,9 @@ static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val)
" mov.b %2, @%1 \n\t" /* store new value */
"1: mov r1, r15 \n\t" /* LOGOUT */
: "=&r" (retval),
"+r" (m)
: "r" (val)
"+r" (m),
"+r" (val) /* inhibit r15 overloading */
:
: "memory" , "r0", "r1");
return retval;
@ -54,13 +56,14 @@ static inline unsigned long __cmpxchg_u32(volatile int *m, unsigned long old,
" nop \n\t"
" mov r15, r1 \n\t" /* r1 = saved sp */
" mov #-8, r15 \n\t" /* LOGIN */
" mov.l @%1, %0 \n\t" /* load old value */
" cmp/eq %0, %2 \n\t"
" mov.l @%3, %0 \n\t" /* load old value */
" cmp/eq %0, %1 \n\t"
" bf 1f \n\t" /* if not equal */
" mov.l %3, @%1 \n\t" /* store new value */
" mov.l %2, @%3 \n\t" /* store new value */
"1: mov r1, r15 \n\t" /* LOGOUT */
: "=&r" (retval)
: "r" (m), "r" (old), "r" (new)
: "=&r" (retval),
"+r" (old), "+r" (new) /* old or new can be r15 */
: "r" (m)
: "memory" , "r0", "r1", "t");
return retval;