ArmPkg/ArmSmcLib: fix stack handling in .asm version of SMC wrapper

[mirror_edk2.git] / ArmPkg / Library / ArmSmcLib / Arm / ArmSmc.asm

//\r
//  Copyright (c) 2012-2014, ARM Limited. All rights reserved.\r
//\r
//  This program and the accompanying materials\r
//  are licensed and made available under the terms and conditions of the BSD License\r
//  which accompanies this distribution.  The full text of the license may be found at\r
//  http://opensource.org/licenses/bsd-license.php\r
//\r
//  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
//  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
//\r
//\r
\r
    EXPORT ArmCallSmc\r
\r
    AREA   ArmSmc, CODE, READONLY\r
\r
ArmCallSmc\r
    push    {r4-r8}\r
    // r0 will be popped just after the SMC call\r
    push     {r0}\r
\r
    // Load the SMC arguments values into the appropriate registers\r
    ldr     r7, [r0, #28]\r
    ldr     r6, [r0, #24]\r
    ldr     r5, [r0, #20]\r
    ldr     r4, [r0, #16]\r
    ldr     r3, [r0, #12]\r
    ldr     r2, [r0, #8]\r
    ldr     r1, [r0, #4]\r
    ldr     r0, [r0, #0]\r
\r
    smc     #0\r
\r
    // Pop the ARM_SMC_ARGS structure address from the stack into r8\r
    pop     {r8}\r
\r
    // Load the SMC returned values into the appropriate registers\r
    // A SMC call can return up to 4 values - we do not need to store back r4-r7.\r
    str     r3, [r8, #12]\r
    str     r2, [r8, #8]\r
    str     r1, [r8, #4]\r
    str     r0, [r8, #0]\r
\r
    mov     r0, r8\r
\r
    // Restore the registers r4-r8\r
    pop     {r4-r8}\r
\r
    bx      lr\r
\r
    END\r