diff options
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
| -rw-r--r-- | arch/arm/kernel/entry-armv.S | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index d401d908c46..964cd717506 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -333,10 +333,14 @@ __pabt_svc: @ from the exception stack #if __LINUX_ARM_ARCH__ < 6 && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG) +#ifndef CONFIG_MMU +#warning "NPTL on non MMU needs fixing" +#else @ make sure our user space atomic helper is aborted cmp r2, #TASK_SIZE bichs r3, r3, #PSR_Z_BIT #endif +#endif @ @ We are now ready to fill in the remaining blanks on the stack: @@ -705,7 +709,12 @@ __kuser_memory_barrier: @ 0xffff0fa0 * The C flag is also set if *ptr was changed to allow for assembly * optimization in the calling code. * - * Note: this routine already includes memory barriers as needed. + * Notes: + * + * - This routine already includes memory barriers as needed. + * + * - A failure might be transient, i.e. it is possible, although unlikely, + * that "failure" be returned even if *ptr == oldval. * * For example, a user space atomic_add implementation could look like this: * @@ -756,12 +765,18 @@ __kuser_cmpxchg: @ 0xffff0fc0 * exception happening just after the str instruction which would * clear the Z flag although the exchange was done. */ +#ifdef CONFIG_MMU teq ip, ip @ set Z flag ldr ip, [r2] @ load current val add r3, r2, #1 @ prepare store ptr teqeq ip, r0 @ compare with oldval if still allowed streq r1, [r3, #-1]! @ store newval if still allowed subs r0, r2, r3 @ if r2 == r3 the str occured +#else +#warning "NPTL on non MMU needs fixing" + mov r0, #-1 + adds r0, r0, #0 +#endif mov pc, lr #else |