dtc: Make asm output more portable and add testcases

This patch adds some testcases for dtc's -Oasm mode.  Specifically it
checks that building the asm will result in the same device tree blob
in memory as -Odtb mode would produce, for a variety of trees.  This
test uncovered two difficulties with our current -Oasm output, both of
which are addressed in this patch as well.

First, -Oasm output would only be correct if assembled for a
big-endian target.  Usually that would be the case, when building
device trees into a firmware or similar.  However this makes life
inconvenient for testing on a little-endian target, and one can think
up use cases where a program running on a little endian host might
want to embed a device tree for a big-endian target.  This patch
therefore changes -Oasm output to use .byte directives instead of
.long throughout in order to generate byte-for-byte identical trees
regardless of the endianness of the assembler target.

Second, -Oasm output emitted several #define statements which were
then used in the innards of the output - i.e. it assumed the output
would be processed by cpp before being assembled.  That may not be
convenient in all build environments, and in any case doesn't work
well with the above fix.  So, -Oasm output no longer needs to be
preprocessed before assembling.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 55 insertions, 37 deletions

diff --git a/flattree.c b/flattree.c
index 9197511..0ff8c45 100644
--- a/flattree.c
+++ b/flattree.c
@@ -127,11 +127,21 @@ static void emit_offset_label(FILE *f, const char *label, int offset)
 	fprintf(f, "%s\t= . + %d\n", label, offset);
 }
 
+#define ASM_EMIT_BELONG(f, fmt, ...) \
+	{ \
+		fprintf((f), "\t.byte\t((" fmt ") >> 24) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t((" fmt ") >> 16) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t((" fmt ") >> 8) & 0xff\n", __VA_ARGS__); \
+		fprintf((f), "\t.byte\t(" fmt ") & 0xff\n", __VA_ARGS__); \
+	}
+
 static void asm_emit_cell(void *e, cell_t val)
 {
 	FILE *f = e;
 
-	fprintf(f, "\t.long\t0x%x\n", val);
+	fprintf(f, "\t.byte 0x%02x; .byte 0x%02x; .byte 0x%02x; .byte 0x%02x\n",
+		(val >> 24) & 0xff, (val >> 16) & 0xff,
+		(val >> 8) & 0xff, val & 0xff);
 }
 
 static void asm_emit_string(void *e, char *str, int len)
@@ -169,8 +179,7 @@ static void asm_emit_data(void *e, struct data d)
 		emit_offset_label(f, m->ref, m->offset);
 
 	while ((d.len - off) >= sizeof(uint32_t)) {
-		fprintf(f, "\t.long\t0x%x\n",
-			fdt32_to_cpu(*((uint32_t *)(d.val+off))));
+		asm_emit_cell(e, fdt32_to_cpu(*((uint32_t *)(d.val+off))));
 		off += sizeof(uint32_t);
 	}
 
@@ -190,14 +199,16 @@ static void asm_emit_beginnode(void *e, const char *label)
 		fprintf(f, "\t.globl\t%s\n", label);
 		fprintf(f, "%s:\n", label);
 	}
-	fprintf(f, "\t.long\tFDT_BEGIN_NODE\n");
+	fprintf(f, "\t/* FDT_BEGIN_NODE */\n");
+	asm_emit_cell(e, FDT_BEGIN_NODE);
 }
 
 static void asm_emit_endnode(void *e, const char *label)
 {
 	FILE *f = e;
 
-	fprintf(f, "\t.long\tFDT_END_NODE\n");
+	fprintf(f, "\t/* FDT_END_NODE */\n");
+	asm_emit_cell(e, FDT_END_NODE);
 	if (label) {
 		fprintf(f, "\t.globl\t%s_end\n", label);
 		fprintf(f, "%s_end:\n", label);
@@ -212,7 +223,8 @@ static void asm_emit_property(void *e, const char *label)
 		fprintf(f, "\t.globl\t%s\n", label);
 		fprintf(f, "%s:\n", label);
 	}
-	fprintf(f, "\t.long\tFDT_PROP\n");
+	fprintf(f, "\t/* FDT_PROP */\n");
+	asm_emit_cell(e, FDT_PROP);
 }
 
 static struct emitter asm_emitter = {
@@ -458,39 +470,44 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version)
 		die("Unknown device tree blob version %d\n", version);
 
 	fprintf(f, "/* autogenerated by dtc, do not edit */\n\n");
-	fprintf(f, "#define FDT_MAGIC 0x%x\n", FDT_MAGIC);
-	fprintf(f, "#define FDT_BEGIN_NODE 0x%x\n", FDT_BEGIN_NODE);
-	fprintf(f, "#define FDT_END_NODE 0x%x\n", FDT_END_NODE);
-	fprintf(f, "#define FDT_PROP 0x%x\n", FDT_PROP);
-	fprintf(f, "#define FDT_END 0x%x\n", FDT_END);
-	fprintf(f, "\n");
 
 	emit_label(f, symprefix, "blob_start");
 	emit_label(f, symprefix, "header");
-	fprintf(f, "\t.long\tFDT_MAGIC\t\t\t\t/* magic */\n");
-	fprintf(f, "\t.long\t_%s_blob_abs_end - _%s_blob_start\t/* totalsize */\n",
-		symprefix, symprefix);
-	fprintf(f, "\t.long\t_%s_struct_start - _%s_blob_start\t/* off_dt_struct */\n",
+	fprintf(f, "\t/* magic */\n");
+	asm_emit_cell(f, FDT_MAGIC);
+	fprintf(f, "\t/* totalsize */\n");
+	ASM_EMIT_BELONG(f, "_%s_blob_abs_end - _%s_blob_start",
+			symprefix, symprefix);
+	fprintf(f, "\t/* off_dt_struct */\n");
+	ASM_EMIT_BELONG(f, "_%s_struct_start - _%s_blob_start",
 		symprefix, symprefix);
-	fprintf(f, "\t.long\t_%s_strings_start - _%s_blob_start\t/* off_dt_strings */\n",
+	fprintf(f, "\t/* off_dt_strings */\n");
+	ASM_EMIT_BELONG(f, "_%s_strings_start - _%s_blob_start",
 		symprefix, symprefix);
-	fprintf(f, "\t.long\t_%s_reserve_map - _%s_blob_start\t/* off_dt_strings */\n",
+	fprintf(f, "\t/* off_mem_rsvmap */\n");
+	ASM_EMIT_BELONG(f, "_%s_reserve_map - _%s_blob_start",
 		symprefix, symprefix);
-	fprintf(f, "\t.long\t%d\t\t\t\t\t/* version */\n", vi->version);
-	fprintf(f, "\t.long\t%d\t\t\t\t\t/* last_comp_version */\n",
-		vi->last_comp_version);
-
-	if (vi->flags & FTF_BOOTCPUID)
-		fprintf(f, "\t.long\t%i\t\t\t\t\t/* boot_cpuid_phys */\n",
-			bi->boot_cpuid_phys);
+	fprintf(f, "\t/* version */\n");
+	asm_emit_cell(f, vi->version);
+	fprintf(f, "\t/* last_comp_version */\n");
+	asm_emit_cell(f, vi->last_comp_version);
+
+	if (vi->flags & FTF_BOOTCPUID) {
+		fprintf(f, "\t/* boot_cpuid_phys */\n");
+		asm_emit_cell(f, bi->boot_cpuid_phys);
+	}
 
-	if (vi->flags & FTF_STRTABSIZE)
-		fprintf(f, "\t.long\t_%s_strings_end - _%s_strings_start\t/* size_dt_strings */\n",
-			symprefix, symprefix);
+	if (vi->flags & FTF_STRTABSIZE) {
+		fprintf(f, "\t/* size_dt_strings */\n");
+		ASM_EMIT_BELONG(f, "_%s_strings_end - _%s_strings_start",
+				symprefix, symprefix);
+	}
 
-	if (vi->flags & FTF_STRUCTSIZE)
-		fprintf(f, "\t.long\t_%s_struct_end - _%s_struct_start\t/* size_dt_struct */\n",
+	if (vi->flags & FTF_STRUCTSIZE) {
+		fprintf(f, "\t/* size_dt_struct */\n");
+		ASM_EMIT_BELONG(f, "_%s_struct_end - _%s_struct_start",
 			symprefix, symprefix);
+	}
 
 	/*
 	 * Reserve map entries.
@@ -512,12 +529,11 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version)
 			fprintf(f, "\t.globl\t%s\n", re->label);
 			fprintf(f, "%s:\n", re->label);
 		}
-		fprintf(f, "\t.long\t0x%08x, 0x%08x\n",
-			(unsigned int)(re->re.address >> 32),
-			(unsigned int)(re->re.address & 0xffffffff));
-		fprintf(f, "\t.long\t0x%08x, 0x%08x\n",
-			(unsigned int)(re->re.size >> 32),
-			(unsigned int)(re->re.size & 0xffffffff));
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.address >> 32));
+		ASM_EMIT_BELONG(f, "0x%08x",
+				(unsigned int)(re->re.address & 0xffffffff));
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.size >> 32));
+		ASM_EMIT_BELONG(f, "0x%08x", (unsigned int)(re->re.size & 0xffffffff));
 	}
 	for (i = 0; i < reservenum; i++) {
 		fprintf(f, "\t.long\t0, 0\n\t.long\t0, 0\n");
@@ -527,7 +543,9 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version)
 
 	emit_label(f, symprefix, "struct_start");
 	flatten_tree(bi->dt, &asm_emitter, f, &strbuf, vi);
-	fprintf(f, "\t.long\tFDT_END\n");
+
+	fprintf(f, "\t/* FDT_END */\n");
+	asm_emit_cell(f, FDT_END);
 	emit_label(f, symprefix, "struct_end");
 
 	emit_label(f, symprefix, "strings_start");