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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 ARM Ltd.
*/
#ifndef __ASM_FUTEX_H
#define __ASM_FUTEX_H
#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/errno.h>
#include <asm/lsui.h>
#define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
#define LLSC_FUTEX_ATOMIC_OP(op, insn) \
static __always_inline int \
__llsc_futex_atomic_##op(int oparg, u32 __user *uaddr, int *oval) \
{ \
unsigned int loops = FUTEX_MAX_LOOPS; \
int ret, oldval, newval; \
\
uaccess_enable_privileged(); \
asm volatile("// __llsc_futex_atomic_" #op "\n" \
" prfm pstl1strm, %[uaddr]\n" \
"1: ldxr %w[oldval], %[uaddr]\n" \
insn "\n" \
"2: stlxr %w[ret], %w[newval], %[uaddr]\n" \
" cbz %w[ret], 3f\n" \
" sub %w[loops], %w[loops], %w[ret]\n" \
" cbnz %w[loops], 1b\n" \
" mov %w[ret], %w[err]\n" \
"3:\n" \
" dmb ish\n" \
_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w[ret]) \
_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w[ret]) \
: [ret] "=&r" (ret), [oldval] "=&r" (oldval), \
[uaddr] "+Q" (*uaddr), [newval] "=&r" (newval), \
[loops] "+r" (loops) \
: [oparg] "r" (oparg), [err] "Ir" (-EAGAIN) \
: "memory"); \
uaccess_disable_privileged(); \
\
if (!ret) \
*oval = oldval; \
\
return ret; \
}
LLSC_FUTEX_ATOMIC_OP(add, "add %w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(or, "orr %w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(and, "and %w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(eor, "eor %w[newval], %w[oldval], %w[oparg]")
LLSC_FUTEX_ATOMIC_OP(set, "mov %w[newval], %w[oparg]")
static __always_inline int
__llsc_futex_cmpxchg(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
int ret = 0;
unsigned int loops = FUTEX_MAX_LOOPS;
u32 val, tmp;
uaccess_enable_privileged();
asm volatile("//__llsc_futex_cmpxchg\n"
" prfm pstl1strm, %[uaddr]\n"
"1: ldxr %w[curval], %[uaddr]\n"
" eor %w[tmp], %w[curval], %w[oldval]\n"
" cbnz %w[tmp], 4f\n"
"2: stlxr %w[tmp], %w[newval], %[uaddr]\n"
" cbz %w[tmp], 3f\n"
" sub %w[loops], %w[loops], %w[tmp]\n"
" cbnz %w[loops], 1b\n"
" mov %w[ret], %w[err]\n"
"3:\n"
" dmb ish\n"
"4:\n"
_ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w[ret])
_ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w[ret])
: [ret] "+r" (ret), [curval] "=&r" (val),
[uaddr] "+Q" (*uaddr), [tmp] "=&r" (tmp),
[loops] "+r" (loops)
: [oldval] "r" (oldval), [newval] "r" (newval),
[err] "Ir" (-EAGAIN)
: "memory");
uaccess_disable_privileged();
if (!ret)
*oval = val;
return ret;
}
#ifdef CONFIG_ARM64_LSUI
/*
* Wrap LSUI instructions with uaccess_ttbr0_enable()/disable(), as
* PAN toggling is not required.
*/
#define LSUI_FUTEX_ATOMIC_OP(op, asm_op) \
static __always_inline int \
__lsui_futex_atomic_##op(int oparg, u32 __user *uaddr, int *oval) \
{ \
int ret = 0; \
int oldval; \
\
uaccess_ttbr0_enable(); \
\
asm volatile("// __lsui_futex_atomic_" #op "\n" \
__LSUI_PREAMBLE \
"1: " #asm_op "al %w[oparg], %w[oldval], %[uaddr]\n" \
"2:\n" \
_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w[ret]) \
: [ret] "+r" (ret), [uaddr] "+Q" (*uaddr), \
[oldval] "=r" (oldval) \
: [oparg] "r" (oparg) \
: "memory"); \
\
uaccess_ttbr0_disable(); \
\
if (!ret) \
*oval = oldval; \
return ret; \
}
LSUI_FUTEX_ATOMIC_OP(add, ldtadd)
LSUI_FUTEX_ATOMIC_OP(or, ldtset)
LSUI_FUTEX_ATOMIC_OP(andnot, ldtclr)
LSUI_FUTEX_ATOMIC_OP(set, swpt)
static __always_inline int
__lsui_cmpxchg64(u64 __user *uaddr, u64 *oldval, u64 newval)
{
int ret = 0;
uaccess_ttbr0_enable();
asm volatile("// __lsui_cmpxchg64\n"
__LSUI_PREAMBLE
"1: casalt %[oldval], %[newval], %[uaddr]\n"
"2:\n"
_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w[ret])
: [ret] "+r" (ret), [uaddr] "+Q" (*uaddr),
[oldval] "+r" (*oldval)
: [newval] "r" (newval)
: "memory");
uaccess_ttbr0_disable();
return ret;
}
static __always_inline int
__lsui_cmpxchg32(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
u64 __user *uaddr64;
bool futex_pos, other_pos;
u32 other, orig_other;
union {
u32 futex[2];
u64 raw;
} oval64, orig64, nval64;
uaddr64 = (u64 __user *)PTR_ALIGN_DOWN(uaddr, sizeof(u64));
futex_pos = !IS_ALIGNED((unsigned long)uaddr, sizeof(u64));
other_pos = !futex_pos;
oval64.futex[futex_pos] = oldval;
if (get_user(oval64.futex[other_pos], (u32 __user *)uaddr64 + other_pos))
return -EFAULT;
orig64.raw = oval64.raw;
nval64.futex[futex_pos] = newval;
nval64.futex[other_pos] = oval64.futex[other_pos];
if (__lsui_cmpxchg64(uaddr64, &oval64.raw, nval64.raw))
return -EFAULT;
oldval = oval64.futex[futex_pos];
other = oval64.futex[other_pos];
orig_other = orig64.futex[other_pos];
if (other != orig_other)
return -EAGAIN;
*oval = oldval;
return 0;
}
static __always_inline int
__lsui_futex_atomic_and(int oparg, u32 __user *uaddr, int *oval)
{
/*
* Undo the bitwise negation applied to the oparg passed from
* arch_futex_atomic_op_inuser() with FUTEX_OP_ANDN.
*/
return __lsui_futex_atomic_andnot(~oparg, uaddr, oval);
}
static __always_inline int
__lsui_futex_atomic_eor(int oparg, u32 __user *uaddr, int *oval)
{
u32 oldval, newval, val;
int ret, i;
if (get_user(oldval, uaddr))
return -EFAULT;
/*
* there are no ldteor/stteor instructions...
*/
for (i = 0; i < FUTEX_MAX_LOOPS; i++) {
newval = oldval ^ oparg;
ret = __lsui_cmpxchg32(uaddr, oldval, newval, &val);
switch (ret) {
case -EFAULT:
return ret;
case -EAGAIN:
continue;
}
if (val == oldval) {
*oval = val;
return 0;
}
oldval = val;
}
return -EAGAIN;
}
static __always_inline int
__lsui_futex_cmpxchg(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
/*
* Callers of futex_atomic_cmpxchg_inatomic() already retry on
* -EAGAIN, no need for another loop of max retries.
*/
return __lsui_cmpxchg32(uaddr, oldval, newval, oval);
}
#endif /* CONFIG_ARM64_LSUI */
#define FUTEX_ATOMIC_OP(op) \
static __always_inline int \
__futex_atomic_##op(int oparg, u32 __user *uaddr, int *oval) \
{ \
return __lsui_llsc_body(futex_atomic_##op, oparg, uaddr, oval); \
}
FUTEX_ATOMIC_OP(add)
FUTEX_ATOMIC_OP(or)
FUTEX_ATOMIC_OP(and)
FUTEX_ATOMIC_OP(eor)
FUTEX_ATOMIC_OP(set)
static __always_inline int
__futex_cmpxchg(u32 __user *uaddr, u32 oldval, u32 newval, u32 *oval)
{
return __lsui_llsc_body(futex_cmpxchg, uaddr, oldval, newval, oval);
}
static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
{
int ret;
u32 __user *uaddr;
if (!access_ok(_uaddr, sizeof(u32)))
return -EFAULT;
uaddr = __uaccess_mask_ptr(_uaddr);
switch (op) {
case FUTEX_OP_SET:
ret = __futex_atomic_set(oparg, uaddr, oval);
break;
case FUTEX_OP_ADD:
ret = __futex_atomic_add(oparg, uaddr, oval);
break;
case FUTEX_OP_OR:
ret = __futex_atomic_or(oparg, uaddr, oval);
break;
case FUTEX_OP_ANDN:
ret = __futex_atomic_and(~oparg, uaddr, oval);
break;
case FUTEX_OP_XOR:
ret = __futex_atomic_eor(oparg, uaddr, oval);
break;
default:
ret = -ENOSYS;
}
return ret;
}
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
u32 oldval, u32 newval)
{
u32 __user *uaddr;
if (!access_ok(_uaddr, sizeof(u32)))
return -EFAULT;
uaddr = __uaccess_mask_ptr(_uaddr);
return __futex_cmpxchg(uaddr, oldval, newval, uval);
}
#endif /* __ASM_FUTEX_H */
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