From 3e3616ab216df37d610bbd5d2d7aee662bdc717b Mon Sep 17 00:00:00 2001
From: Soby Mathew <soby.mathew@arm.com>
Date: Thu, 5 May 2016 12:53:53 +0100
Subject: [PATCH] AArch32: Add SMCC context

This patch defines a SMCC context to save and restore
registers during a SMC call. It also adds appropriate helpers
to save and restore from this context for use by AArch32
secure payload and BL stages.

Change-Id: I64c8d6fe1d6cac22e1f1f39ea1b54ee1b1b72248
---
 include/lib/aarch32/smcc_helpers.h | 171 +++++++++++++++++++++++++++++
 include/lib/aarch32/smcc_macros.S  | 118 ++++++++++++++++++++
 2 files changed, 289 insertions(+)
 create mode 100644 include/lib/aarch32/smcc_helpers.h
 create mode 100644 include/lib/aarch32/smcc_macros.S

diff --git a/include/lib/aarch32/smcc_helpers.h b/include/lib/aarch32/smcc_helpers.h
new file mode 100644
index 000000000..5aeca2239
--- /dev/null
+++ b/include/lib/aarch32/smcc_helpers.h
@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 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.
+ */
+
+#ifndef __SMCC_HELPERS_H__
+#define __SMCC_HELPERS_H__
+
+#include <smcc.h>
+
+/* These are offsets to registers in smc_ctx_t */
+#define SMC_CTX_GPREG_R0	0x0
+#define SMC_CTX_GPREG_R1	0x4
+#define SMC_CTX_GPREG_R2	0x8
+#define SMC_CTX_GPREG_R3	0xC
+#define SMC_CTX_GPREG_R4	0x10
+#define SMC_CTX_SP_USR		0x34
+#define SMC_CTX_SPSR_MON	0x78
+#define SMC_CTX_LR_MON		0x7C
+#define SMC_CTX_SIZE		0x80
+
+#ifndef __ASSEMBLY__
+#include <cassert.h>
+#include <types.h>
+
+/*
+ * The generic structure to save arguments and callee saved registers during
+ * an SMC. Also this structure is used to store the result return values after
+ * the completion of SMC service.
+ */
+typedef struct smc_ctx {
+	u_register_t r0;
+	u_register_t r1;
+	u_register_t r2;
+	u_register_t r3;
+	u_register_t r4;
+	u_register_t r5;
+	u_register_t r6;
+	u_register_t r7;
+	u_register_t r8;
+	u_register_t r9;
+	u_register_t r10;
+	u_register_t r11;
+	u_register_t r12;
+	/* spsr_usr doesn't exist */
+	u_register_t sp_usr;
+	u_register_t lr_usr;
+	u_register_t spsr_irq;
+	u_register_t sp_irq;
+	u_register_t lr_irq;
+	u_register_t spsr_fiq;
+	u_register_t sp_fiq;
+	u_register_t lr_fiq;
+	u_register_t spsr_svc;
+	u_register_t sp_svc;
+	u_register_t lr_svc;
+	u_register_t spsr_abt;
+	u_register_t sp_abt;
+	u_register_t lr_abt;
+	u_register_t spsr_und;
+	u_register_t sp_und;
+	u_register_t lr_und;
+	u_register_t spsr_mon;
+	/* No need to save 'sp_mon' because we are already in monitor mode */
+	u_register_t lr_mon;
+} smc_ctx_t;
+
+/*
+ * Compile time assertions related to the 'smc_context' structure to
+ * ensure that the assembler and the compiler view of the offsets of
+ * the structure members is the same.
+ */
+CASSERT(SMC_CTX_GPREG_R0 == __builtin_offsetof(smc_ctx_t, r0), \
+	assert_smc_ctx_greg_r0_offset_mismatch);
+CASSERT(SMC_CTX_GPREG_R1 == __builtin_offsetof(smc_ctx_t, r1), \
+	assert_smc_ctx_greg_r1_offset_mismatch);
+CASSERT(SMC_CTX_GPREG_R2 == __builtin_offsetof(smc_ctx_t, r2), \
+	assert_smc_ctx_greg_r2_offset_mismatch);
+CASSERT(SMC_CTX_GPREG_R3 == __builtin_offsetof(smc_ctx_t, r3), \
+	assert_smc_ctx_greg_r3_offset_mismatch);
+CASSERT(SMC_CTX_GPREG_R4 == __builtin_offsetof(smc_ctx_t, r4), \
+	assert_smc_ctx_greg_r4_offset_mismatch);
+CASSERT(SMC_CTX_SP_USR == __builtin_offsetof(smc_ctx_t, sp_usr), \
+	assert_smc_ctx_sp_usr_offset_mismatch);
+CASSERT(SMC_CTX_LR_MON == __builtin_offsetof(smc_ctx_t, lr_mon), \
+	assert_smc_ctx_lr_mon_offset_mismatch);
+CASSERT(SMC_CTX_SPSR_MON == __builtin_offsetof(smc_ctx_t, spsr_mon), \
+	assert_smc_ctx_spsr_mon_offset_mismatch);
+
+CASSERT(SMC_CTX_SIZE == sizeof(smc_ctx_t), assert_smc_ctx_size_mismatch);
+
+/* Convenience macros to return from SMC handler */
+#define SMC_RET0(_h) {				\
+	return (uintptr_t)(_h);			\
+}
+#define SMC_RET1(_h, _r0) {			\
+	((smc_ctx_t *)(_h))->r0 = (_r0);	\
+	SMC_RET0(_h);				\
+}
+#define SMC_RET2(_h, _r0, _r1) {		\
+	((smc_ctx_t *)(_h))->r1 = (_r1);	\
+	SMC_RET1(_h, (_r0));			\
+}
+#define SMC_RET3(_h, _r0, _r1, _r2) {		\
+	((smc_ctx_t *)(_h))->r2 = (_r2);	\
+	SMC_RET2(_h, (_r0), (_r1));		\
+}
+#define SMC_RET4(_h, _r0, _r1, _r2, _r3) {	\
+	((smc_ctx_t *)(_h))->r3 = (_r3);	\
+	SMC_RET3(_h, (_r0), (_r1), (_r2));	\
+}
+
+/* Return a UUID in the SMC return registers */
+#define SMC_UUID_RET(_h, _uuid) \
+	SMC_RET4(handle, ((const uint32_t *) &(_uuid))[0], \
+			 ((const uint32_t *) &(_uuid))[1], \
+			 ((const uint32_t *) &(_uuid))[2], \
+			 ((const uint32_t *) &(_uuid))[3])
+
+/*
+ * Helper macro to retrieve the SMC parameters from smc_ctx_t.
+ */
+#define get_smc_params_from_ctx(_hdl, _r1, _r2, _r3, _r4) {	\
+		_r1 = ((smc_ctx_t *)_hdl)->r1;		\
+		_r2 = ((smc_ctx_t *)_hdl)->r2;		\
+		_r3 = ((smc_ctx_t *)_hdl)->r3;		\
+		_r4 = ((smc_ctx_t *)_hdl)->r4;		\
+		}
+
+/* ------------------------------------------------------------------------
+ * Helper APIs for setting and retrieving appropriate `smc_ctx_t`.
+ * These functions need to implemented by the BL including this library.
+ * ------------------------------------------------------------------------
+ */
+
+/* Get the pointer to `smc_ctx_t` corresponding to the security state. */
+void *smc_get_ctx(int security_state);
+
+/* Set the next `smc_ctx_t` corresponding to the security state. */
+void smc_set_next_ctx(int security_state);
+
+/* Get the pointer to next `smc_ctx_t` already set by `smc_set_next_ctx()`. */
+void *smc_get_next_ctx(void);
+
+#endif /*__ASSEMBLY__*/
+#endif /* __SMCC_HELPERS_H__ */
diff --git a/include/lib/aarch32/smcc_macros.S b/include/lib/aarch32/smcc_macros.S
new file mode 100644
index 000000000..c80c3e473
--- /dev/null
+++ b/include/lib/aarch32/smcc_macros.S
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 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.
+ */
+#ifndef __SMCC_MACROS_S__
+#define __SMCC_MACROS_S__
+
+#include <arch.h>
+
+/*
+ * Macro to save the General purpose registers including the banked
+ * registers to the SMC context on entry due a SMC call. On return, r0
+ * contains the pointer to the `smc_context_t`.
+ */
+	.macro smcc_save_gp_mode_regs
+	push	{r0-r3, lr}
+
+	ldcopr	r0, SCR
+	and	r0, r0, #SCR_NS_BIT
+	bl	smc_get_ctx
+
+	/* Save r4 - r12 in the SMC context */
+	add	r1, r0, #SMC_CTX_GPREG_R4
+	stm	r1!, {r4-r12}
+
+	/*
+	 * Pop r0 - r3, lr to r4 - r7, lr from stack and then save
+	 * it to SMC context.
+	 */
+	pop	{r4-r7, lr}
+	stm	r0, {r4-r7}
+
+	/* Save the banked registers including the current SPSR and LR */
+	mrs	r4, sp_usr
+	mrs	r5, lr_usr
+	mrs	r6, spsr_irq
+	mrs	r7, sp_irq
+	mrs	r8, lr_irq
+	mrs	r9, spsr_fiq
+	mrs	r10, sp_fiq
+	mrs	r11, lr_fiq
+	mrs	r12, spsr_svc
+	stm	r1!, {r4-r12}
+
+	mrs	r4, sp_svc
+	mrs	r5, lr_svc
+	mrs	r6, spsr_abt
+	mrs	r7, sp_abt
+	mrs	r8, lr_abt
+	mrs	r9, spsr_und
+	mrs	r10, sp_und
+	mrs	r11, lr_und
+	mrs	r12, spsr
+	stm	r1!, {r4-r12, lr}
+
+	.endm
+
+/*
+ * Macro to restore the General purpose registers including the banked
+ * registers from the SMC context prior to exit from the SMC call.
+ * r0 must point to the `smc_context_t` to restore from.
+ */
+	.macro smcc_restore_gp_mode_regs
+
+	/* Restore the banked registers including the current SPSR and LR */
+	add	r1, r0, #SMC_CTX_SP_USR
+	ldm	r1!, {r4-r12}
+	msr	sp_usr, r4
+	msr	lr_usr, r5
+	msr	spsr_irq, r6
+	msr	sp_irq, r7
+	msr	lr_irq, r8
+	msr	spsr_fiq, r9
+	msr	sp_fiq, r10
+	msr	lr_fiq, r11
+	msr	spsr_svc, r12
+
+	ldm	r1!, {r4-r12, lr}
+	msr	sp_svc, r4
+	msr	lr_svc, r5
+	msr	spsr_abt, r6
+	msr	sp_abt, r7
+	msr	lr_abt, r8
+	msr	spsr_und, r9
+	msr	sp_und, r10
+	msr	lr_und, r11
+	msr	spsr, r12
+
+	/* Restore the rest of the general purpose registers */
+	ldm	r0, {r0-r12}
+	.endm
+
+#endif /* __SMCC_MACROS_S__ */
-- 
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