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csky: Fixup futex SMP implementation 

Arnd said:
I would guess that for csky, this is a mistake, as the architecture
is fairly new and should be able to implement it.

Guo reply:
The c610, c807, c810 don't support SMP, so futex_cmpxchg_enabled = 1
with asm-generic's implementation.
For c860, there is no HAVE_FUTEX_CMPXCHG and cmpxchg_inatomic/inuser
implementation, so futex_cmpxchg_enabled = 0.

Thx for point it out, we'll implement cmpxchg_inatomic/inuser for
C860 and still use asm-generic for non-smp CPUs.

LTP test:
futex_wait01    1  TPASS  :  futex_wait(): errno=ETIMEDOUT(110): Connection timed out
futex_wait01    2  TPASS  :  futex_wait(): errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable
futex_wait01    3  TPASS  :  futex_wait(): errno=ETIMEDOUT(110): Connection timed out
futex_wait01    4  TPASS  :  futex_wait(): errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable
futex_wait02    1  TPASS  :  futex_wait() woken up
futex_wait03    1  TPASS  :  futex_wait() woken up
futex_wait04    1  TPASS  :  futex_wait() returned -1: errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/lkml/CAK8P3a3+WaQNyJ6Za2qfu6=0mBgU1hApnRXrdp1b1=P7wwyRUg@mail.gmail.com/
This commit is contained in:
Guo Ren 2020-12-20 01:35:09 +00:00
parent 8d11f21a73
commit d6c5cb9f8c
2 changed files with 122 additions and 0 deletions
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1
arch/csky/Kconfig
View File

@ -48,6 +48,7 @@ config CSKY
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUTEX_CMPXCHG if FUTEX && SMP
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZO

121
arch/csky/include/asm/futex.h Normal file
View File

@ -0,0 +1,121 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_CSKY_FUTEX_H
#define __ASM_CSKY_FUTEX_H
#ifndef CONFIG_SMP
#include <asm-generic/futex.h>
#else
#include <linux/atomic.h>
#include <linux/futex.h>
#include <linux/uaccess.h>
#include <linux/errno.h>
#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
{ \
u32 tmp; \
\
__atomic_pre_full_fence(); \
\
__asm__ __volatile__ ( \
"1: ldex.w %[ov], %[u] \n" \
" "insn" \n" \
"2: stex.w %[t], %[u] \n" \
" bez %[t], 1b \n" \
" br 4f \n" \
"3: mov %[r], %[e] \n" \
"4: \n" \
" .section __ex_table,\"a\" \n" \
" .balign 4 \n" \
" .long 1b, 3b \n" \
" .long 2b, 3b \n" \
" .previous \n" \
: [r] "+r" (ret), [ov] "=&r" (oldval), \
[u] "+m" (*uaddr), [t] "=&r" (tmp) \
: [op] "Jr" (oparg), [e] "jr" (-EFAULT) \
: "memory"); \
\
__atomic_post_full_fence(); \
}
static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
{
int oldval = 0, ret = 0;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op("mov %[t], %[ov]",
ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
__futex_atomic_op("add %[t], %[ov], %[op]",
ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
__futex_atomic_op("or %[t], %[ov], %[op]",
ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op("and %[t], %[ov], %[op]",
ret, oldval, uaddr, ~oparg);
break;
case FUTEX_OP_XOR:
__futex_atomic_op("xor %[t], %[ov], %[op]",
ret, oldval, uaddr, oparg);
break;
default:
ret = -ENOSYS;
}
if (!ret)
*oval = oldval;
return ret;
}
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
int ret = 0;
u32 val, tmp;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
__atomic_pre_full_fence();
__asm__ __volatile__ (
"1: ldex.w %[v], %[u] \n"
" cmpne %[v], %[ov] \n"
" bt 4f \n"
" mov %[t], %[nv] \n"
"2: stex.w %[t], %[u] \n"
" bez %[t], 1b \n"
" br 4f \n"
"3: mov %[r], %[e] \n"
"4: \n"
" .section __ex_table,\"a\" \n"
" .balign 4 \n"
" .long 1b, 3b \n"
" .long 2b, 3b \n"
" .previous \n"
: [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr),
[t] "=&r" (tmp)
: [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "Jr" (-EFAULT)
: "memory");
__atomic_post_full_fence();
*uval = val;
return ret;
}
#endif /* CONFIG_SMP */
#endif /* __ASM_CSKY_FUTEX_H */