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x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()

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Lift stac/clac pairs from __futex_atomic_op{1,2} into arch_futex_atomic_op_inuser(),
fold them with access_ok() in there.  The switch in arch_futex_atomic_op_inuser()
is what has required the previous (objtool) commit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-02-16 13:10:42 -05:00
parent 36b1c70067
commit 0ec33c0171
1 changed files with 36 additions and 26 deletions
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62
arch/x86/include/asm/futex.h
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@ -12,26 +12,33 @@
#include <asm/processor.h>
#include <asm/smap.h>
#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg) \
asm volatile("\t" ASM_STAC "\n" \
"1:\t" insn "\n" \
"2:\t" ASM_CLAC "\n" \
#define unsafe_atomic_op1(insn, oval, uaddr, oparg, label) \
do { \
int oldval = 0, ret; \
asm volatile("1:\t" insn "\n" \
"2:\n" \
"\t.section .fixup,\"ax\"\n" \
"3:\tmov\t%3, %1\n" \
"\tjmp\t2b\n" \
"\t.previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
: "i" (-EFAULT), "0" (oparg), "1" (0))
: "i" (-EFAULT), "0" (oparg), "1" (0)); \
if (ret) \
goto label; \
*oval = oldval; \
} while(0)
#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \
asm volatile("\t" ASM_STAC "\n" \
"1:\tmovl %2, %0\n" \
#define unsafe_atomic_op2(insn, oval, uaddr, oparg, label) \
do { \
int oldval = 0, ret, tem; \
asm volatile("1:\tmovl %2, %0\n" \
"\tmovl\t%0, %3\n" \
"\t" insn "\n" \
"2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \
"\tjnz\t1b\n" \
"3:\t" ASM_CLAC "\n" \
"3:\n" \
"\t.section .fixup,\"ax\"\n" \
"4:\tmov\t%5, %1\n" \
"\tjmp\t3b\n" \
@ -40,41 +47,44 @@
_ASM_EXTABLE_UA(2b, 4b) \
: "=&a" (oldval), "=&r" (ret), \
"+m" (*uaddr), "=&r" (tem) \
: "r" (oparg), "i" (-EFAULT), "1" (0))
: "r" (oparg), "i" (-EFAULT), "1" (0)); \
if (ret) \
goto label; \
*oval = oldval; \
} while(0)
static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
u32 __user *uaddr)
{
int oldval = 0, ret, tem;
if (!access_ok(uaddr, sizeof(u32)))
if (!user_access_begin(uaddr, sizeof(u32)))
return -EFAULT;
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
break;
case FUTEX_OP_ADD:
__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
uaddr, oparg);
unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
uaddr, oparg, Efault);
break;
case FUTEX_OP_OR:
__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
break;
case FUTEX_OP_XOR:
__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
break;
default:
ret = -ENOSYS;
user_access_end();
return -ENOSYS;
}
if (!ret)
*oval = oldval;
return ret;
user_access_end();
return 0;
Efault:
user_access_end();
return -EFAULT;
}
static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,