context.S

/*
 * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#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
	.global	restore_gp_registers_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]

	mrs	x10, pmcr_el0
	str	x10, [x0, #CTX_PMCR_EL0]

	/* 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]
#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

	ldr	x10, [x0, #CTX_PMCR_EL0]
	msr	pmcr_el0, x10

	/* 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
#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]

#if CTX_INCLUDE_AARCH32_REGS
	mrs	x11, fpexc32_el2
	str	x11, [x0, #CTX_FP_FPEXC32_EL2]
#endif
	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

#if CTX_INCLUDE_AARCH32_REGS
	ldr	x11, [x0, #CTX_FP_FPEXC32_EL2]
	msr	fpexc32_el2, x11
#endif
	/*
	 * 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

/*
 * This function restores all general purpose registers except x30 from the
 * CPU context. x30 register must be explicitly restored by the caller.
 */
func restore_gp_registers
	ldp	x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
	ldp	x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
	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	x16, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X16]
	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]
	ldr	x28, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_SP_EL0]
	msr	sp_el0, x28
	ldp	x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
	ret
endfunc restore_gp_registers

/*
 * Restore general purpose registers (including x30), and exit EL3 via. ERET to
 * a lower exception level.
 */
func restore_gp_registers_eret
	bl	restore_gp_registers
	ldr	x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]

#if IMAGE_BL31 && RAS_EXTENSION
	/*
	 * Issue Error Synchronization Barrier to synchronize SErrors before
	 * exiting EL3. We're running with EAs unmasked, so any synchronized
	 * errors would be taken immediately; therefore no need to inspect
	 * DISR_EL1 register.
	 */
	esb
#endif
	eret
endfunc	restore_gp_registers_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

#if IMAGE_BL31 && DYNAMIC_WORKAROUND_CVE_2018_3639
	/* Restore mitigation state as it was on entry to EL3 */
	ldr	x17, [sp, #CTX_CVE_2018_3639_OFFSET + CTX_CVE_2018_3639_DISABLE]
	cmp	x17, xzr
	beq	1f
	blr	x17
#endif

1:
	/* Restore saved general purpose registers and return */
	b	restore_gp_registers_eret
endfunc el3_exit