Simplify assert() to reduce memory usage

The behaviour of assert() now depends on the value of the new optional
platform define `PLAT_LOG_LEVEL_ASSERT`. This defaults to `LOG_LEVEL` if
not defined by the platform.

- If `PLAT_LOG_LEVEL_ASSERT` >= `LOG_LEVEL_VERBOSE`, it prints the file
  name, line and asserted expression.
- If `PLAT_LOG_LEVEL_ASSERT` >= `LOG_LEVEL_INFO`, it prints the file
  name and line.
- If not, it doesn't print anything.

Note the old behaviour was to print the function name whereas now it
prints the file name. This reduces memory usage because the file name is
shared between all assert calls in a given file. Also, the default
behaviour in debug builds is to no longer print the asserted expression,
greatly reducing the string usage.

For FVP debug builds this change saves approximately:

              No TBBR    TBBR
        BL1    1.6 KB   2.2 KB
        BL2    1.7 KB   2.1 KB
        BL31   2.6 KB   3.3 KB

Change-Id: I2947569d593df0b25611dc3c7a6096f42155c115
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

3 files changed, 53 insertions, 14 deletions

diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index 0189ec40..4d7a5ead 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -535,6 +535,17 @@ optionally be defined:
     PLAT_PARTITION_MAX_ENTRIES	:=	12
     $(eval $(call add_define,PLAT_PARTITION_MAX_ENTRIES))
 
+The following constant is optional. It should be defined to override the default
+behaviour of the `assert()` function (for example, to save memory).
+
+*   **PLAT_LOG_LEVEL_ASSERT**
+    If `PLAT_LOG_LEVEL_ASSERT` is higher or equal than `LOG_LEVEL_VERBOSE`,
+    `assert()` prints the name of the file, the line number and the asserted
+    expression. Else if it is higher than `LOG_LEVEL_INFO`, it prints the file
+    name and the line number. Else if it is lower than `LOG_LEVEL_INFO`, it
+    doesn't print anything to the console. If `PLAT_LOG_LEVEL_ASSERT` isn't
+    defined, it defaults to `LOG_LEVEL`.
+
 
 ### File : plat_macros.S [mandatory]
 
diff --git a/include/lib/stdlib/assert.h b/include/lib/stdlib/assert.h
index 1bcd1ead..db567dbb 100644
--- a/include/lib/stdlib/assert.h
+++ b/include/lib/stdlib/assert.h
@@ -42,19 +42,36 @@
 #ifndef _ASSERT_H_
 #define _ASSERT_H_
 
+#include <debug.h>
+#include <platform_def.h>
 #include <sys/cdefs.h>
 
+#ifndef PLAT_LOG_LEVEL_ASSERT
+#define PLAT_LOG_LEVEL_ASSERT	LOG_LEVEL
+#endif
+
 #if ENABLE_ASSERTIONS
 #define	_assert(e)	assert(e)
-#define	assert(e)	((e) ? (void)0 : __assert(__func__, __FILE__, \
-			    __LINE__, #e))
+# if PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_VERBOSE
+#  define	assert(e)	((e) ? (void)0 : __assert(__FILE__, __LINE__, #e))
+# elif PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_INFO
+#  define	assert(e)	((e) ? (void)0 : __assert(__FILE__, __LINE__))
+# else
+#  define	assert(e)	((e) ? (void)0 : __assert())
+# endif
 #else
 #define	assert(e)	((void)0)
 #define	_assert(e)	((void)0)
 #endif /* ENABLE_ASSERTIONS */
 
 __BEGIN_DECLS
-void __assert(const char *, const char *, int, const char *) __dead2;
+#if PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_VERBOSE
+void __assert(const char *, unsigned int, const char *) __dead2;
+#elif PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_INFO
+void __assert(const char *, unsigned int) __dead2;
+#else
+void __assert(void) __dead2;
+#endif
 __END_DECLS
 
 #endif /* !_ASSERT_H_ */
diff --git a/lib/stdlib/assert.c b/lib/stdlib/assert.c
index 5220ad8f..41f70703 100644
--- a/lib/stdlib/assert.c
+++ b/lib/stdlib/assert.c
@@ -4,22 +4,33 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <assert.h>
 #include <console.h>
 #include <debug.h>
 #include <platform.h>
 
-void __assert(const char *function, const char *file, unsigned int line,
-		const char *assertion)
-{
-#if LOG_LEVEL >= LOG_LEVEL_INFO
-	/*
-	 * Only print the output if LOG_LEVEL is higher or equal to
-	 * LOG_LEVEL_INFO, which is the default value for builds with DEBUG=1.
-	 */
-	tf_printf("ASSERT: %s <%d> : %s\n", function, line, assertion);
+/*
+* Only print the output if PLAT_LOG_LEVEL_ASSERT is higher or equal to
+* LOG_LEVEL_INFO, which is the default value for builds with DEBUG=1.
+*/
 
+#if PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_VERBOSE
+void __assert(const char *file, unsigned int line, const char *assertion)
+{
+	tf_printf("ASSERT: %s <%d> : %s\n", file, line, assertion);
 	console_flush();
-#endif
-
 	plat_panic_handler();
 }
+#elif PLAT_LOG_LEVEL_ASSERT >= LOG_LEVEL_INFO
+void __assert(const char *file, unsigned int line)
+{
+	tf_printf("ASSERT: %s <%d>\n", file, line);
+	console_flush();
+	plat_panic_handler();
+}
+#else
+void __assert(void)
+{
+	plat_panic_handler();
+}
+#endif