Implement an assert() callable from assembly code

The patch implements a macro ASM_ASSERT() which can
be invoked from assembly code. When assertion happens,
file name and line number of the check is written
to the crash console.

Fixes ARM-software/tf-issues#95

Change-Id: I6f905a068e1c0fa4f746d723f18df60daaa00a86

Makefile

@@ -60,7 +60,9 @@ CTX_INCLUDE_FPREGS		:= 0
 # Determine the version of ARM GIC architecture to use for interrupt management
 # in EL3. The platform port can change this value if needed.
 ARM_GIC_ARCH		:=	2
-
+# Flag used to indicate if ASM_ASSERTION should be enabled for the build.
+# This defaults to being present in DEBUG builds only.
+ASM_ASSERTION		:=	${DEBUG}
 
 # Checkpatch ignores
 CHECK_IGNORE		=	--ignore COMPLEX_MACRO
@@ -92,6 +94,7 @@ VERSION_STRING		:=	v${VERSION_MAJOR}.${VERSION_MINOR}(${BUILD_TYPE}):${BUILD_STR
 BL_COMMON_SOURCES	:=	common/bl_common.c			\
 				common/debug.c				\
 				common/tf_printf.c			\
+				common/aarch64/assert.S			\
 				lib/aarch64/cache_helpers.S		\
 				lib/aarch64/misc_helpers.S		\
 				lib/aarch64/xlat_helpers.c		\
@@ -207,6 +210,9 @@ $(eval $(call add_define,CTX_INCLUDE_FPREGS))
 # Process ARM_GIC_ARCH flag
 $(eval $(call add_define,ARM_GIC_ARCH))
 
+# Process ASM_ASSERTION flag
+$(eval $(call assert_boolean,ASM_ASSERTION))
+$(eval $(call add_define,ASM_ASSERTION))
 
 ASFLAGS			+= 	-nostdinc -ffreestanding -Wa,--fatal-warnings	\
 				-Werror -Wmissing-include-dirs			\

common/aarch64/assert.S

+/*
+ * Copyright (c) 2014, 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>
+
+	.globl	asm_print_str
+	.globl	asm_print_hex
+	.globl	asm_assert
+	.globl	do_panic
+
+/* Since the max decimal input number is 65536 */
+#define MAX_DEC_DIVISOR		10000
+/* The offset to add to get ascii for numerals '0 - 9' */
+#define ASCII_OFFSET_NUM	0x30
+
+#if ASM_ASSERTION
+.section .rodata.assert_str, "aS"
+assert_msg1:
+	.asciz "ASSERT: File "
+assert_msg2:
+	.asciz " Line "
+
+	/*
+	 * This macro is intended to be used to print the
+	 * line number in decimal. Used by asm_assert macro.
+	 * The max number expected is 65536.
+	 * In: x4 = the decimal to print.
+	 * Clobber: x30, x0, x1, x2, x5, x6
+	 */
+	.macro asm_print_line_dec
+	mov	x6, #10		/* Divide by 10 after every loop iteration */
+	mov	x5, #MAX_DEC_DIVISOR
+1:
+	udiv	x0, x4, x5		/* Get the quotient */
+	msub	x4, x0, x5, x4		/* Find the remainder */
+	add	x0, x0, #ASCII_OFFSET_NUM		/* Convert to ascii */
+	bl	plat_crash_console_putc
+	udiv	x5, x5, x6		/* Reduce divisor */
+	cbnz	x5, 1b
+	.endm
+
+
+/* ---------------------------------------------------------------------------
+ * Assertion support in assembly.
+ * The below function helps to support assertions in assembly where we do not
+ * have a C runtime stack. Arguments to the function are :
+ * x0 - File name
+ * x1 - Line no
+ * Clobber list : x30, x0, x1, x2, x3, x4, x5, x6.
+ * ---------------------------------------------------------------------------
+ */
+func asm_assert
+	mov	x5, x0
+	mov	x6, x1
+	/* Ensure the console is initialized */
+	bl	plat_crash_console_init
+	/* Check if the console is initialized */
+	cbz	x0, _assert_loop
+	/* The console is initialized */
+	adr	x4, assert_msg1
+	bl	asm_print_str
+	mov	x4, x5
+	bl	asm_print_str
+	adr	x4, assert_msg2
+	bl	asm_print_str
+	/* Check if line number higher than max permitted */
+	tst	x6, #~0xffff
+	b.ne	_assert_loop
+	mov	x4, x6
+	asm_print_line_dec
+_assert_loop:
+	b	_assert_loop
+#endif
+
+/*
+ * This function prints a string from address in x4.
+ * In: x4 = pointer to string.
+ * Clobber: x30, x0, x1, x2, x3
+ */
+func asm_print_str
+	mov	x3, x30
+1:
+	ldrb	w0, [x4], #0x1
+	cbz	x0, 2f
+	bl	plat_crash_console_putc
+	b	1b
+2:
+	ret	x3
+
+/*
+ * This function prints a hexadecimal number in x4.
+ * In: x4 = the hexadecimal to print.
+ * Clobber: x30, x0, x5, x1, x2, x3
+ */
+func asm_print_hex
+	mov	x3, x30
+	mov	x5, #64  /* No of bits to convert to ascii */
+1:
+	sub	x5, x5, #4
+	lsrv	x0, x4, x5
+	and	x0, x0, #0xf
+	cmp	x0, #0xA
+	b.lo	2f
+	/* Add by 0x27 in addition to ASCII_OFFSET_NUM
+	 * to get ascii for characters 'a - f'.
+	 */
+	add	x0, x0, #0x27
+2:
+	add	x0, x0, #ASCII_OFFSET_NUM
+	bl	plat_crash_console_putc
+	cbnz	x5, 1b
+	ret	x3
+

docs/user-guide.md

@@ -181,6 +181,11 @@ performed.
     BL3-1. This option defaults to the value of `DEBUG` - i.e. by default
     this is only enabled for a debug build of the firmware.
 
+*   `ASM_ASSERTION`: This flag determines whether the assertion checks within
+    assembly source files are enabled or not. This option defaults to the
+    value of `DEBUG` - i.e. by default this is only enabled for a debug
+    build of the firmware.
+
 ### Creating a Firmware Image Package
 
 FIPs are automatically created as part of the build instructions described in

include/common/assert_macros.S

+/*
+ * Copyright (c) 2014, 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.
+ */
+
+	/*
+	 * Assembler macro to enable asm_assert. Use this macro wherever
+	 * assert is required in assembly.
+	 */
+#define ASM_ASSERT(_cc) \
+.ifndef .L_assert_filename ;\
+	.pushsection .rodata.str1.1, "aS" ;\
+	.L_assert_filename: ;\
+			.string	__FILE__ ;\
+	.popsection ;\
+.endif ;\
+	b._cc	1f ;\
+	adr	x0, .L_assert_filename ;\
+	mov	x1, __LINE__ ;\
+	b	asm_assert ;\
+1:

lib/aarch64/misc_helpers.S

@@ -30,6 +30,7 @@
 
 #include <arch.h>
 #include <asm_macros.S>
+#include <assert_macros.S>
 
 	.globl	get_afflvl_shift
 	.globl	mpidr_mask_lower_afflvls
@@ -46,7 +47,6 @@
 	.globl	enable_vfp
 #endif
 
-
 func get_afflvl_shift
 	cmp	x0, #3
 	cinc	x0, x0, eq
@@ -79,6 +79,10 @@ func smc
  * -----------------------------------------------------------------------
  */
 func zeromem16
+#if ASM_ASSERTION
+	tst	x0, #0xf
+	ASM_ASSERT(eq)
+#endif
 	add	x2, x0, x1
 /* zero 16 bytes at a time */
 z_loop16:
@@ -105,6 +109,11 @@ z_end:	ret
  * --------------------------------------------------------------------------
  */
 func memcpy16
+#if ASM_ASSERTION
+	orr	x3, x0, x1
+	tst	x3, #0xf
+	ASM_ASSERT(eq)
+#endif
 /* copy 16 bytes at a time */
 m_loop16:
 	cmp	x2, #16
@@ -145,7 +154,6 @@ func disable_mmu_icache_el3
 	mov	x1, #(SCTLR_M_BIT | SCTLR_C_BIT | SCTLR_I_BIT)
 	b	do_disable_mmu
 
-
 /* ---------------------------------------------------------------------------
  * Enable the use of VFP at EL3
  * ---------------------------------------------------------------------------