Zero BSS in hello world test

While trying to reduce U/X state issues, I notice that our BSS is not being initialised in the hello world test. Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
2 years ago · ff442d1bdb
parent ebdddcc402
commit ff442d1bdb
5 changed files with 181 additions and 153 deletions
--- a/hello_world/head.S
+++ b/hello_world/head.S
@ -60,11 +60,25 @@ _start:

 .global boot_entry
 boot_entry:
+	LOAD_IMM64(%r10,__bss_start)
+	LOAD_IMM64(%r11,__bss_end)
+	subf	%r11,%r10,%r11
+	addi	%r11,%r11,63
+	srdi.	%r11,%r11,6
+	beq	2f
+	mtctr	%r11
+1:	dcbz	0,%r10
+	addi	%r10,%r10,64
+	bdnz	1b
+
 	/* setup stack */
-	LOAD_IMM64(%r1, STACK_TOP - 0x100)
+2:	LOAD_IMM64(%r1,__stack_top)
+	li	%r0,0
+	stdu	%r0,-32(%r1)
 	LOAD_IMM64(%r12, main)
-	mtctr	%r12,
+	mtctr	%r12
 	bctrl
+	attn // terminate on exit
 	b .

 #define EXCEPTION(nr)		\
--- a/hello_world/hello_world.bin
+++ b/hello_world/hello_world.bin
--- a/hello_world/hello_world.elf
+++ b/hello_world/hello_world.elf
--- a/hello_world/hello_world.hex
+++ b/hello_world/hello_world.hex
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--- a/hello_world/powerpc.lds
+++ b/hello_world/powerpc.lds
@ -1,13 +1,27 @@
 SECTIONS
 {
-	_start = .;
 	. = 0;
+	_start = .;
 	.head : {
 		KEEP(*(.head))
 	}
 	. = 0x1000;
-	.text : { *(.text) }
+	.text : { *(.text) *(.text.*) *(.rodata) *(.rodata.*) }
 	. = 0x1800;
-	.data : { *(.data) }
-	.bss : { *(.bss) }
+	.data : { *(.data) *(.data.*) *(.got) *(.toc) }
+	. = ALIGN(0x80);
+	__bss_start = .;
+	.bss : {
+		*(.dynsbss)
+		*(.sbss)
+		*(.scommon)
+		*(.dynbss)
+		*(.bss)
+		*(.common)
+		*(.bss.*)
+	}
+	. = ALIGN(0x80);
+	__bss_end = .;
+	. = . + 0x2000;
+	__stack_top = .;
 }