/* * Copyright (C) 2010 Imagination Technologies Ltd. * * This file contains code that can be accessed from userspace and can * access certain kernel data structures without the overhead of a system * call. */ #include <asm/metag_regs.h> #include <asm/user_gateway.h> /* * User helpers. * * These are segment of kernel provided user code reachable from user space * at a fixed address in kernel memory. This is used to provide user space * with some operations which require kernel help because of unimplemented * native feature and/or instructions in some Meta CPUs. The idea is for * this code to be executed directly in user mode for best efficiency but * which is too intimate with the kernel counter part to be left to user * libraries. The kernel reserves the right to change this code as needed * without warning. Only the entry points and their results are guaranteed * to be stable. * * Each segment is 64-byte aligned. This mechanism should be used only for * for things that are really small and justified, and not be abused freely. */ .text .global ___user_gateway_start ___user_gateway_start: /* get_tls * Offset: 0 * Description: Get the TLS pointer for this process. */ .global ___kuser_get_tls .type ___kuser_get_tls,function ___kuser_get_tls: MOVT D1Ar1,#HI(USER_GATEWAY_PAGE + USER_GATEWAY_TLS) ADD D1Ar1,D1Ar1,#LO(USER_GATEWAY_PAGE + USER_GATEWAY_TLS) MOV D1Ar3,TXENABLE AND D1Ar3,D1Ar3,#(TXENABLE_THREAD_BITS) LSR D1Ar3,D1Ar3,#(TXENABLE_THREAD_S - 2) GETD D0Re0,[D1Ar1+D1Ar3] ___kuser_get_tls_end: /* Beyond this point the read will complete */ MOV PC,D1RtP .size ___kuser_get_tls,.-___kuser_get_tls .global ___kuser_get_tls_end /* cmpxchg * Offset: 64 * Description: Replace the value at 'ptr' with 'newval' if the current * value is 'oldval'. Return zero if we succeeded, * non-zero otherwise. * * Reference prototype: * * int __kuser_cmpxchg(int oldval, int newval, unsigned long *ptr) * */ .balign 64 .global ___kuser_cmpxchg .type ___kuser_cmpxchg,function ___kuser_cmpxchg: #ifdef [31mCONFIG_SMP[0m /* * We must use LNKGET/LNKSET with an SMP kernel because the other method * does not provide atomicity across multiple CPUs. */ 0: LNKGETD D0Re0,[D1Ar3] CMP D0Re0,D1Ar1 LNKSETDZ [D1Ar3],D0Ar2 BNZ 1f DEFR D0Re0,TXSTAT ANDT D0Re0,D0Re0,#HI(0x3f000000) CMPT D0Re0,#HI(0x02000000) BNE 0b #ifdef [31mCONFIG_METAG_LNKGET_AROUND_CACHE[0m DCACHE [D1Ar3], D0Re0 #endif 1: MOV D0Re0,#1 XORZ D0Re0,D0Re0,D0Re0 MOV PC,D1RtP #else GETD D0Re0,[D1Ar3] CMP D0Re0,D1Ar1 SETDZ [D1Ar3],D0Ar2 ___kuser_cmpxchg_end: /* Beyond this point the write will complete */ MOV D0Re0,#1 XORZ D0Re0,D0Re0,D0Re0 MOV PC,D1RtP #endif /* CONFIG_SMP */ .size ___kuser_cmpxchg,.-___kuser_cmpxchg .global ___kuser_cmpxchg_end .global ___user_gateway_end ___user_gateway_end: |