diff options
| -rw-r--r-- | arch/um/include/asm/Kbuild | 1 | ||||
| -rw-r--r-- | arch/um/include/asm/futex.h | 14 | ||||
| -rw-r--r-- | arch/um/kernel/skas/uaccess.c | 136 |
3 files changed, 150 insertions, 1 deletions
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild index 0c31d19a7a9c..e5a7b552bb38 100644 --- a/arch/um/include/asm/Kbuild +++ b/arch/um/include/asm/Kbuild @@ -9,7 +9,6 @@ generic-y += exec.h generic-y += extable.h generic-y += fb.h generic-y += ftrace.h -generic-y += futex.h generic-y += hw_irq.h generic-y += irq_regs.h generic-y += irq_work.h diff --git a/arch/um/include/asm/futex.h b/arch/um/include/asm/futex.h new file mode 100644 index 000000000000..780aa6bfc050 --- /dev/null +++ b/arch/um/include/asm/futex.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_UM_FUTEX_H +#define _ASM_UM_FUTEX_H + +#include <linux/futex.h> +#include <linux/uaccess.h> +#include <asm/errno.h> + + +int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr); +int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval); + +#endif diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c index 2dec915abe6f..6c76df96e858 100644 --- a/arch/um/kernel/skas/uaccess.c +++ b/arch/um/kernel/skas/uaccess.c @@ -11,6 +11,7 @@ #include <asm/current.h> #include <asm/page.h> #include <kern_util.h> +#include <asm/futex.h> #include <os.h> pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr) @@ -248,3 +249,138 @@ long __strnlen_user(const void __user *str, long len) return 0; } EXPORT_SYMBOL(__strnlen_user); + +/** + * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant + * argument and comparison of the previous + * futex value with another constant. + * + * @encoded_op: encoded operation to execute + * @uaddr: pointer to user space address + * + * Return: + * 0 - On success + * -EFAULT - User access resulted in a page fault + * -EAGAIN - Atomic operation was unable to complete due to contention + * -ENOSYS - Operation not supported + */ + +int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) +{ + int oldval, ret; + struct page *page; + unsigned long addr = (unsigned long) uaddr; + pte_t *pte; + + ret = -EFAULT; + if (!access_ok(uaddr, sizeof(*uaddr))) + return -EFAULT; + preempt_disable(); + pte = maybe_map(addr, 1); + if (pte == NULL) + goto out_inuser; + + page = pte_page(*pte); +#ifdef CONFIG_64BIT + pagefault_disable(); + addr = (unsigned long) page_address(page) + + (((unsigned long) addr) & ~PAGE_MASK); +#else + addr = (unsigned long) kmap_atomic(page) + + ((unsigned long) addr & ~PAGE_MASK); +#endif + uaddr = (u32 *) addr; + oldval = *uaddr; + + ret = 0; + + switch (op) { + case FUTEX_OP_SET: + *uaddr = oparg; + break; + case FUTEX_OP_ADD: + *uaddr += oparg; + break; + case FUTEX_OP_OR: + *uaddr |= oparg; + break; + case FUTEX_OP_ANDN: + *uaddr &= ~oparg; + break; + case FUTEX_OP_XOR: + *uaddr ^= oparg; + break; + default: + ret = -ENOSYS; + } +#ifdef CONFIG_64BIT + pagefault_enable(); +#else + kunmap_atomic((void *)addr); +#endif + +out_inuser: + preempt_enable(); + + if (ret == 0) + *oval = oldval; + + return ret; +} +EXPORT_SYMBOL(arch_futex_atomic_op_inuser); + +/** + * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the + * uaddr with newval if the current value is + * oldval. + * @uval: pointer to store content of @uaddr + * @uaddr: pointer to user space address + * @oldval: old value + * @newval: new value to store to @uaddr + * + * Return: + * 0 - On success + * -EFAULT - User access resulted in a page fault + * -EAGAIN - Atomic operation was unable to complete due to contention + * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG) + */ + +int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval) +{ + struct page *page; + pte_t *pte; + int ret = -EFAULT; + + if (!access_ok(uaddr, sizeof(*uaddr))) + return -EFAULT; + + preempt_disable(); + pte = maybe_map((unsigned long) uaddr, 1); + if (pte == NULL) + goto out_inatomic; + + page = pte_page(*pte); +#ifdef CONFIG_64BIT + pagefault_disable(); + uaddr = page_address(page) + (((unsigned long) uaddr) & ~PAGE_MASK); +#else + uaddr = kmap_atomic(page) + ((unsigned long) uaddr & ~PAGE_MASK); +#endif + + *uval = *uaddr; + + ret = cmpxchg(uaddr, oldval, newval); + +#ifdef CONFIG_64BIT + pagefault_enable(); +#else + kunmap_atomic(uaddr); +#endif + ret = 0; + +out_inatomic: + preempt_enable(); + return ret; +} +EXPORT_SYMBOL(futex_atomic_cmpxchg_inatomic); |