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

1 files changed, 141 insertions, 0 deletions

diff --git a/common/aarch64/assert.S b/common/aarch64/assert.S
new file mode 100644
index 00000000..a62c8f51
--- /dev/null
+++ b/common/aarch64/assert.S
@@ -0,0 +1,141 @@
+/*
+ * 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
+