Introduce `el3_runtime` and `PSCI` libraries

This patch moves the PSCI services and BL31 frameworks like context
management and per-cpu data into new library components `PSCI` and
`el3_runtime` respectively. This enables PSCI to be built independently from
BL31. A new `psci_lib.mk` makefile is introduced which adds the relevant
PSCI library sources and gets included by `bl31.mk`. Other changes which
are done as part of this patch are:

* The runtime services framework is now moved to the `common/` folder to
  enable reuse.
* The `asm_macros.S` and `assert_macros.S` helpers are moved to architecture
  specific folder.
* The `plat_psci_common.c` is moved from the `plat/common/aarch64/` folder
  to `plat/common` folder. The original file location now has a stub which
  just includes the file from new location to maintain platform compatibility.

Most of the changes wouldn't affect platform builds as they just involve
changes to the generic bl1.mk and bl31.mk makefiles.

NOTE: THE `plat_psci_common.c` FILE HAS MOVED LOCATION AND THE STUB FILE AT
THE ORIGINAL LOCATION IS NOW DEPRECATED. PLATFORMS SHOULD MODIFY THEIR
MAKEFILES TO INCLUDE THE FILE FROM THE NEW LOCATION.

Change-Id: I6bd87d5b59424995c6a65ef8076d4fda91ad5e86
diff --git a/lib/el3_runtime/aarch64/context.S b/lib/el3_runtime/aarch64/context.S
new file mode 100644
index 0000000..7982e50
--- /dev/null
+++ b/lib/el3_runtime/aarch64/context.S
@@ -0,0 +1,405 @@
+/*
+ * Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <context.h>
+
+	.global	el1_sysregs_context_save
+	.global	el1_sysregs_context_restore
+#if CTX_INCLUDE_FPREGS
+	.global	fpregs_context_save
+	.global	fpregs_context_restore
+#endif
+	.global	save_gp_registers
+	.global	restore_gp_registers_eret
+	.global	restore_gp_registers_callee_eret
+	.global	el3_exit
+
+/* -----------------------------------------------------
+ * The following function strictly follows the AArch64
+ * PCS to use x9-x17 (temporary caller-saved registers)
+ * to save EL1 system register context. It assumes that
+ * 'x0' is pointing to a 'el1_sys_regs' structure where
+ * the register context will be saved.
+ * -----------------------------------------------------
+ */
+func el1_sysregs_context_save
+
+	mrs	x9, spsr_el1
+	mrs	x10, elr_el1
+	stp	x9, x10, [x0, #CTX_SPSR_EL1]
+
+	mrs	x15, sctlr_el1
+	mrs	x16, actlr_el1
+	stp	x15, x16, [x0, #CTX_SCTLR_EL1]
+
+	mrs	x17, cpacr_el1
+	mrs	x9, csselr_el1
+	stp	x17, x9, [x0, #CTX_CPACR_EL1]
+
+	mrs	x10, sp_el1
+	mrs	x11, esr_el1
+	stp	x10, x11, [x0, #CTX_SP_EL1]
+
+	mrs	x12, ttbr0_el1
+	mrs	x13, ttbr1_el1
+	stp	x12, x13, [x0, #CTX_TTBR0_EL1]
+
+	mrs	x14, mair_el1
+	mrs	x15, amair_el1
+	stp	x14, x15, [x0, #CTX_MAIR_EL1]
+
+	mrs	x16, tcr_el1
+	mrs	x17, tpidr_el1
+	stp	x16, x17, [x0, #CTX_TCR_EL1]
+
+	mrs	x9, tpidr_el0
+	mrs	x10, tpidrro_el0
+	stp	x9, x10, [x0, #CTX_TPIDR_EL0]
+
+	mrs	x13, par_el1
+	mrs	x14, far_el1
+	stp	x13, x14, [x0, #CTX_PAR_EL1]
+
+	mrs	x15, afsr0_el1
+	mrs	x16, afsr1_el1
+	stp	x15, x16, [x0, #CTX_AFSR0_EL1]
+
+	mrs	x17, contextidr_el1
+	mrs	x9, vbar_el1
+	stp	x17, x9, [x0, #CTX_CONTEXTIDR_EL1]
+
+	/* Save AArch32 system registers if the build has instructed so */
+#if CTX_INCLUDE_AARCH32_REGS
+	mrs	x11, spsr_abt
+	mrs	x12, spsr_und
+	stp	x11, x12, [x0, #CTX_SPSR_ABT]
+
+	mrs	x13, spsr_irq
+	mrs	x14, spsr_fiq
+	stp	x13, x14, [x0, #CTX_SPSR_IRQ]
+
+	mrs	x15, dacr32_el2
+	mrs	x16, ifsr32_el2
+	stp	x15, x16, [x0, #CTX_DACR32_EL2]
+
+	mrs	x17, fpexc32_el2
+	str	x17, [x0, #CTX_FP_FPEXC32_EL2]
+#endif
+
+	/* Save NS timer registers if the build has instructed so */
+#if NS_TIMER_SWITCH
+	mrs	x10, cntp_ctl_el0
+	mrs	x11, cntp_cval_el0
+	stp	x10, x11, [x0, #CTX_CNTP_CTL_EL0]
+
+	mrs	x12, cntv_ctl_el0
+	mrs	x13, cntv_cval_el0
+	stp	x12, x13, [x0, #CTX_CNTV_CTL_EL0]
+
+	mrs	x14, cntkctl_el1
+	str	x14, [x0, #CTX_CNTKCTL_EL1]
+#endif
+
+	ret
+endfunc el1_sysregs_context_save
+
+/* -----------------------------------------------------
+ * The following function strictly follows the AArch64
+ * PCS to use x9-x17 (temporary caller-saved registers)
+ * to restore EL1 system register context.  It assumes
+ * that 'x0' is pointing to a 'el1_sys_regs' structure
+ * from where the register context will be restored
+ * -----------------------------------------------------
+ */
+func el1_sysregs_context_restore
+
+	ldp	x9, x10, [x0, #CTX_SPSR_EL1]
+	msr	spsr_el1, x9
+	msr	elr_el1, x10
+
+	ldp	x15, x16, [x0, #CTX_SCTLR_EL1]
+	msr	sctlr_el1, x15
+	msr	actlr_el1, x16
+
+	ldp	x17, x9, [x0, #CTX_CPACR_EL1]
+	msr	cpacr_el1, x17
+	msr	csselr_el1, x9
+
+	ldp	x10, x11, [x0, #CTX_SP_EL1]
+	msr	sp_el1, x10
+	msr	esr_el1, x11
+
+	ldp	x12, x13, [x0, #CTX_TTBR0_EL1]
+	msr	ttbr0_el1, x12
+	msr	ttbr1_el1, x13
+
+	ldp	x14, x15, [x0, #CTX_MAIR_EL1]
+	msr	mair_el1, x14
+	msr	amair_el1, x15
+
+	ldp	x16, x17, [x0, #CTX_TCR_EL1]
+	msr	tcr_el1, x16
+	msr	tpidr_el1, x17
+
+	ldp	x9, x10, [x0, #CTX_TPIDR_EL0]
+	msr	tpidr_el0, x9
+	msr	tpidrro_el0, x10
+
+	ldp	x13, x14, [x0, #CTX_PAR_EL1]
+	msr	par_el1, x13
+	msr	far_el1, x14
+
+	ldp	x15, x16, [x0, #CTX_AFSR0_EL1]
+	msr	afsr0_el1, x15
+	msr	afsr1_el1, x16
+
+	ldp	x17, x9, [x0, #CTX_CONTEXTIDR_EL1]
+	msr	contextidr_el1, x17
+	msr	vbar_el1, x9
+
+	/* Restore AArch32 system registers if the build has instructed so */
+#if CTX_INCLUDE_AARCH32_REGS
+	ldp	x11, x12, [x0, #CTX_SPSR_ABT]
+	msr	spsr_abt, x11
+	msr	spsr_und, x12
+
+	ldp	x13, x14, [x0, #CTX_SPSR_IRQ]
+	msr	spsr_irq, x13
+	msr	spsr_fiq, x14
+
+	ldp	x15, x16, [x0, #CTX_DACR32_EL2]
+	msr	dacr32_el2, x15
+	msr	ifsr32_el2, x16
+
+	ldr	x17, [x0, #CTX_FP_FPEXC32_EL2]
+	msr	fpexc32_el2, x17
+#endif
+	/* Restore NS timer registers if the build has instructed so */
+#if NS_TIMER_SWITCH
+	ldp	x10, x11, [x0, #CTX_CNTP_CTL_EL0]
+	msr	cntp_ctl_el0, x10
+	msr	cntp_cval_el0, x11
+
+	ldp	x12, x13, [x0, #CTX_CNTV_CTL_EL0]
+	msr	cntv_ctl_el0, x12
+	msr	cntv_cval_el0, x13
+
+	ldr	x14, [x0, #CTX_CNTKCTL_EL1]
+	msr	cntkctl_el1, x14
+#endif
+
+	/* No explict ISB required here as ERET covers it */
+	ret
+endfunc el1_sysregs_context_restore
+
+/* -----------------------------------------------------
+ * The following function follows the aapcs_64 strictly
+ * to use x9-x17 (temporary caller-saved registers
+ * according to AArch64 PCS) to save floating point
+ * register context. It assumes that 'x0' is pointing to
+ * a 'fp_regs' structure where the register context will
+ * be saved.
+ *
+ * Access to VFP registers will trap if CPTR_EL3.TFP is
+ * set.  However currently we don't use VFP registers
+ * nor set traps in Trusted Firmware, and assume it's
+ * cleared
+ *
+ * TODO: Revisit when VFP is used in secure world
+ * -----------------------------------------------------
+ */
+#if CTX_INCLUDE_FPREGS
+func fpregs_context_save
+	stp	q0, q1, [x0, #CTX_FP_Q0]
+	stp	q2, q3, [x0, #CTX_FP_Q2]
+	stp	q4, q5, [x0, #CTX_FP_Q4]
+	stp	q6, q7, [x0, #CTX_FP_Q6]
+	stp	q8, q9, [x0, #CTX_FP_Q8]
+	stp	q10, q11, [x0, #CTX_FP_Q10]
+	stp	q12, q13, [x0, #CTX_FP_Q12]
+	stp	q14, q15, [x0, #CTX_FP_Q14]
+	stp	q16, q17, [x0, #CTX_FP_Q16]
+	stp	q18, q19, [x0, #CTX_FP_Q18]
+	stp	q20, q21, [x0, #CTX_FP_Q20]
+	stp	q22, q23, [x0, #CTX_FP_Q22]
+	stp	q24, q25, [x0, #CTX_FP_Q24]
+	stp	q26, q27, [x0, #CTX_FP_Q26]
+	stp	q28, q29, [x0, #CTX_FP_Q28]
+	stp	q30, q31, [x0, #CTX_FP_Q30]
+
+	mrs	x9, fpsr
+	str	x9, [x0, #CTX_FP_FPSR]
+
+	mrs	x10, fpcr
+	str	x10, [x0, #CTX_FP_FPCR]
+
+	ret
+endfunc fpregs_context_save
+
+/* -----------------------------------------------------
+ * The following function follows the aapcs_64 strictly
+ * to use x9-x17 (temporary caller-saved registers
+ * according to AArch64 PCS) to restore floating point
+ * register context. It assumes that 'x0' is pointing to
+ * a 'fp_regs' structure from where the register context
+ * will be restored.
+ *
+ * Access to VFP registers will trap if CPTR_EL3.TFP is
+ * set.  However currently we don't use VFP registers
+ * nor set traps in Trusted Firmware, and assume it's
+ * cleared
+ *
+ * TODO: Revisit when VFP is used in secure world
+ * -----------------------------------------------------
+ */
+func fpregs_context_restore
+	ldp	q0, q1, [x0, #CTX_FP_Q0]
+	ldp	q2, q3, [x0, #CTX_FP_Q2]
+	ldp	q4, q5, [x0, #CTX_FP_Q4]
+	ldp	q6, q7, [x0, #CTX_FP_Q6]
+	ldp	q8, q9, [x0, #CTX_FP_Q8]
+	ldp	q10, q11, [x0, #CTX_FP_Q10]
+	ldp	q12, q13, [x0, #CTX_FP_Q12]
+	ldp	q14, q15, [x0, #CTX_FP_Q14]
+	ldp	q16, q17, [x0, #CTX_FP_Q16]
+	ldp	q18, q19, [x0, #CTX_FP_Q18]
+	ldp	q20, q21, [x0, #CTX_FP_Q20]
+	ldp	q22, q23, [x0, #CTX_FP_Q22]
+	ldp	q24, q25, [x0, #CTX_FP_Q24]
+	ldp	q26, q27, [x0, #CTX_FP_Q26]
+	ldp	q28, q29, [x0, #CTX_FP_Q28]
+	ldp	q30, q31, [x0, #CTX_FP_Q30]
+
+	ldr	x9, [x0, #CTX_FP_FPSR]
+	msr	fpsr, x9
+
+	ldr	x10, [x0, #CTX_FP_FPCR]
+	msr	fpcr, x10
+
+	/*
+	 * No explict ISB required here as ERET to
+	 * switch to secure EL1 or non-secure world
+	 * covers it
+	 */
+
+	ret
+endfunc fpregs_context_restore
+#endif /* CTX_INCLUDE_FPREGS */
+
+/* -----------------------------------------------------
+ * The following functions are used to save and restore
+ * all the general purpose registers. Ideally we would
+ * only save and restore the callee saved registers when
+ * a world switch occurs but that type of implementation
+ * is more complex. So currently we will always save and
+ * restore these registers on entry and exit of EL3.
+ * These are not macros to ensure their invocation fits
+ * within the 32 instructions per exception vector.
+ * clobbers: x18
+ * -----------------------------------------------------
+ */
+func save_gp_registers
+	stp	x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
+	stp	x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
+	stp	x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
+	stp	x6, x7, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X6]
+	stp	x8, x9, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X8]
+	stp	x10, x11, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X10]
+	stp	x12, x13, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X12]
+	stp	x14, x15, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X14]
+	stp	x16, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X16]
+	stp	x18, x19, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X18]
+	stp	x20, x21, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X20]
+	stp	x22, x23, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X22]
+	stp	x24, x25, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X24]
+	stp	x26, x27, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X26]
+	stp	x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
+	mrs	x18, sp_el0
+	str	x18, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_SP_EL0]
+	ret
+endfunc save_gp_registers
+
+func restore_gp_registers_eret
+	ldp	x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
+	ldp	x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
+	b	restore_gp_registers_callee_eret
+endfunc restore_gp_registers_eret
+
+func restore_gp_registers_callee_eret
+	ldp	x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
+	ldp	x6, x7, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X6]
+	ldp	x8, x9, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X8]
+	ldp	x10, x11, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X10]
+	ldp	x12, x13, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X12]
+	ldp	x14, x15, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X14]
+	ldp	x18, x19, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X18]
+	ldp	x20, x21, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X20]
+	ldp	x22, x23, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X22]
+	ldp	x24, x25, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X24]
+	ldp	x26, x27, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X26]
+	ldp	x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
+	ldp	 x30, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
+	msr	sp_el0, x17
+	ldp	x16, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X16]
+	eret
+endfunc	restore_gp_registers_callee_eret
+
+	/* -----------------------------------------------------
+	 * This routine assumes that the SP_EL3 is pointing to
+	 * a valid context structure from where the gp regs and
+	 * other special registers can be retrieved.
+	 * -----------------------------------------------------
+	 */
+func el3_exit
+	/* -----------------------------------------------------
+	 * Save the current SP_EL0 i.e. the EL3 runtime stack
+	 * which will be used for handling the next SMC. Then
+	 * switch to SP_EL3
+	 * -----------------------------------------------------
+	 */
+	mov	x17, sp
+	msr	spsel, #1
+	str	x17, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP]
+
+	/* -----------------------------------------------------
+	 * Restore SPSR_EL3, ELR_EL3 and SCR_EL3 prior to ERET
+	 * -----------------------------------------------------
+	 */
+	ldr	x18, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
+	ldp	x16, x17, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
+	msr	scr_el3, x18
+	msr	spsr_el3, x16
+	msr	elr_el3, x17
+
+	/* Restore saved general purpose registers and return */
+	b	restore_gp_registers_eret
+endfunc el3_exit