diff options
| author | Nicolas Pitre <nicolas.pitre@linaro.org> | 2011-06-12 01:07:33 -0400 |
|---|---|---|
| committer | Nicolas Pitre <nicolas.pitre@linaro.org> | 2011-06-23 02:37:20 -0400 |
| commit | a6cfe326d080c6280c1c3867ff36e2f51e1e0842 (patch) | |
| tree | f1d7bbae4606dfe255ad55d333744fb495adb62b | |
| parent | 11204ad50e0239dd2e3d52f2f64ac1cf14613aa9 (diff) | |
ARM: zImage: make sure appended DTB doesn't get overwritten by kernel .bss
The appended DTB gets relocated with the decompressor code to get out
of the way of the decompressed kernel. However the kernel's .bss section
may be larger than the relocated code and data, and then the DTB gets
overwritten. Let's make sure the relocation takes care of moving zImage
far enough so no such conflict with .bss occurs.
Thanks to Tony Lindgren <tony@atomide.com> for figuring out this issue.
While at it, let's clean up the code a bit so that the wont_overwrite
symbol is used while determining if a conflict exists, making the above
change more precise as well as eliminating some ARM/THUMB alternates.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
| -rw-r--r-- | arch/arm/boot/compressed/Makefile | 3 | ||||
| -rw-r--r-- | arch/arm/boot/compressed/head.S | 19 |
2 files changed, 18 insertions, 4 deletions
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 23aad072230..48bead99ea4 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -98,6 +98,9 @@ endif ccflags-y := -fpic -fno-builtin asflags-y := -Wa,-march=all +# Supply kernel BSS size to the decompressor via a linker symbol. +KBSS_SZ = $(shell size $(obj)/../../../../vmlinux | awk 'END{print $$3}') +LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ) # Supply ZRELADDR to the decompressor via a linker symbol. ifneq ($(CONFIG_AUTO_ZRELADDR),y) LDFLAGS_vmlinux += --defsym zreladdr=$(ZRELADDR) diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 3ce5738ddb9..ba5c552f8c6 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -248,6 +248,18 @@ restart: adr r0, LC0 mov r8, r6 @ use the appended device tree + /* + * Make sure that the DTB doesn't end up in the final + * kernel's .bss area. To do so, we adjust the decompressed + * kernel size to compensate if that .bss size is larger + * than the relocated code. + */ + ldr r5, =_kernel_bss_size + adr r1, wont_overwrite + sub r1, r6, r1 + subs r1, r5, r1 + addhi r9, r9, r1 + /* Get the dtb's size */ ldr r5, [r6, #4] #ifndef __ARMEB__ @@ -276,15 +288,14 @@ dtb_check_done: * r10 = end of this image, including bss/stack/malloc space if non XIP * We basically want: * r4 - 16k page directory >= r10 -> OK - * r4 + image length <= current position (pc) -> OK + * r4 + image length <= address of wont_overwrite -> OK */ add r10, r10, #16384 cmp r4, r10 bhs wont_overwrite add r10, r4, r9 - ARM( cmp r10, pc ) - THUMB( mov lr, pc ) - THUMB( cmp r10, lr ) + adr r9, wont_overwrite + cmp r10, r9 bls wont_overwrite /* |