diff mbox

ARM: zImage: ensure header in LE format for BE8 kernels

Message ID 1397147232-28516-1-git-send-email-taras.kondratiuk@linaro.org
State Superseded
Headers show

Commit Message

Taras Kondratiuk April 10, 2014, 4:27 p.m. UTC
From: Nico Pitre <nico@fluxnic.net>

All known BE8-capable systems have LE bootloaders, so we need to ensure
that the magic number and image start/end values are in little endian
format.

[ben.dooks@codethink.co.uk: from nico's original email on this subject]
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
[taras.kondratiuk@linaro.org: removed lds.S->lds rule, added target to extra-y]
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
---
Nico, should I add your Signed-off-by?

Discussion about the patch:
http://www.spinics.net/lists/arm-kernel/msg320670.html

Based on v3.14+ master commit 39de65aa2c3eee901db020a4f1396998e09602a3

 arch/arm/boot/compressed/.gitignore     |    1 +
 arch/arm/boot/compressed/Makefile       |    4 ++--
 arch/arm/boot/compressed/head.S         |    7 ++++---
 arch/arm/boot/compressed/vmlinux.lds.in |   14 ++++++++++++++
 4 files changed, 21 insertions(+), 5 deletions(-)

Comments

Nicolas Pitre April 10, 2014, 5:03 p.m. UTC | #1
On Thu, 10 Apr 2014, Taras Kondratiuk wrote:

> From: Nico Pitre <nico@fluxnic.net>

Please use "Nicolas Pitre" as my full name.

> All known BE8-capable systems have LE bootloaders, so we need to ensure
> that the magic number and image start/end values are in little endian
> format.
> 
> [ben.dooks@codethink.co.uk: from nico's original email on this subject]
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
> [taras.kondratiuk@linaro.org: removed lds.S->lds rule, added target to extra-y]
> Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
> ---
> Nico, should I add your Signed-off-by?

Sure.

> 
> Discussion about the patch:
> http://www.spinics.net/lists/arm-kernel/msg320670.html
> 
> Based on v3.14+ master commit 39de65aa2c3eee901db020a4f1396998e09602a3
> 
>  arch/arm/boot/compressed/.gitignore     |    1 +
>  arch/arm/boot/compressed/Makefile       |    4 ++--
>  arch/arm/boot/compressed/head.S         |    7 ++++---
>  arch/arm/boot/compressed/vmlinux.lds.in |   14 ++++++++++++++
>  4 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm/boot/compressed/.gitignore b/arch/arm/boot/compressed/.gitignore
> index 0714e03..6a26e7b 100644
> --- a/arch/arm/boot/compressed/.gitignore
> +++ b/arch/arm/boot/compressed/.gitignore
> @@ -10,6 +10,7 @@ piggy.xzkern
>  piggy.lz4
>  vmlinux
>  vmlinux.lds
> +vmlinux.lds.S
>  
>  # borrowed libfdt files
>  fdt.c
> diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
> index 68c9183..8a80906 100644
> --- a/arch/arm/boot/compressed/Makefile
> +++ b/arch/arm/boot/compressed/Makefile
> @@ -114,7 +114,7 @@ targets       := vmlinux vmlinux.lds \
>  # Make sure files are removed during clean
>  extra-y       += piggy.gzip piggy.lzo piggy.lzma piggy.xzkern piggy.lz4 \
>  		 lib1funcs.S ashldi3.S bswapsdi2.S $(libfdt) $(libfdt_hdrs) \
> -		 hyp-stub.S
> +		 hyp-stub.S vmlinux.lds.S
>  
>  ifeq ($(CONFIG_FUNCTION_TRACER),y)
>  ORIG_CFLAGS := $(KBUILD_CFLAGS)
> @@ -199,7 +199,7 @@ CFLAGS_font.o := -Dstatic=
>  $(obj)/font.c: $(FONTC)
>  	$(call cmd,shipped)
>  
> -$(obj)/vmlinux.lds: $(obj)/vmlinux.lds.in arch/arm/boot/Makefile $(KCONFIG_CONFIG)
> +$(obj)/vmlinux.lds.S: $(obj)/vmlinux.lds.in arch/arm/boot/Makefile $(KCONFIG_CONFIG)
>  	@sed "$(SEDFLAGS)" < $< > $@
>  
>  $(obj)/hyp-stub.S: $(srctree)/arch/$(SRCARCH)/kernel/hyp-stub.S
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 066b034..8ea1773 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -130,9 +130,10 @@ start:
>   THUMB(		adr	r12, BSYM(1f)	)
>   THUMB(		bx	r12		)
>  
> -		.word	0x016f2818		@ Magic numbers to help the loader
> -		.word	start			@ absolute load/run zImage address
> -		.word	_edata			@ zImage end address
> +		.word	_magic_sig	@ Magic numbers to help the loader
> +		.word	_magic_start	@ absolute load/run zImage address
> +		.word	_magic_end	@ zImage end address
> +
>   THUMB(		.thumb			)
>  1:
>   ARM_BE8(	setend	be )			@ go BE8 if compiled for BE8
> diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
> index 4919f2a..6016223 100644
> --- a/arch/arm/boot/compressed/vmlinux.lds.in
> +++ b/arch/arm/boot/compressed/vmlinux.lds.in
> @@ -7,6 +7,16 @@
>   * it under the terms of the GNU General Public License version 2 as
>   * published by the Free Software Foundation.
>   */
> +
> +#ifdef CONFIG_CPU_ENDIAN_BE8
> +#define ZIMAGE_MAGIC(x) ( (((x) >> 24) & 0x000000ff) | \
> +			  (((x) >>  8) & 0x0000ff00) | \
> +			  (((x) <<  8) & 0x00ff0000) | \
> +			  (((x) << 24) & 0xff000000) )
> +#else
> +#define ZIMAGE_MAGIC(x) (x)
> +#endif
> +
>  OUTPUT_ARCH(arm)
>  ENTRY(_start)
>  SECTIONS
> @@ -57,6 +67,10 @@ SECTIONS
>    .pad			: { BYTE(0); . = ALIGN(8); }
>    _edata = .;
>  
> +  _magic_sig = ZIMAGE_MAGIC(0x016f2818);
> +  _magic_start = ZIMAGE_MAGIC(_start);
> +  _magic_end = ZIMAGE_MAGIC(_edata);
> +
>    . = BSS_START;
>    __bss_start = .;
>    .bss			: { *(.bss) }
> -- 
> 1.7.9.5
> 
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Nicolas Pitre June 17, 2014, 4:07 p.m. UTC | #2
On Tue, 17 Jun 2014, Russell King - ARM Linux wrote:

> Given that we're now passing the linker script through GCC for C
> preprocessing, it seems to me that we don't need to do the sed trick
> anymore - we can pass TEXTADDR and ZBSSADDR into GCC via definitions
> instead, so I've committed this patch after this one.  No changes to
> the vmlinux.lds.* file, it's just a pure rename.  Ack?
> 
> From: Russell King <rmk+kernel@arm.linux.org.uk>
> Subject: [PATCH] ARM: Simplify generation of compressed vmlinux.lds file
> 
> As we are now using the C preprocessor, we do not need to use sed to
> edit constants in this file, and then pass the resulting file through
> the C preprocessor.  Instead, rely solely on the C preprocessor to
> rewrite TEXT_START and BSS_ADDR.
> 
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> ---
>  arch/arm/boot/compressed/.gitignore     |  1 -
>  arch/arm/boot/compressed/Makefile       |  5 +-
>  arch/arm/boot/compressed/vmlinux.lds.S  | 90 +++++++++++++++++++++++++++++++++
>  arch/arm/boot/compressed/vmlinux.lds.in | 90 ---------------------------------

Would be easier to review with git diff -M.

> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
> new file mode 100644
> index 000000000000..60162231c7ea
[...]
> diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
> deleted file mode 100644
> index 60162231c7ea..000000000000

OK, the SHA1 is the same so both files are identical.

> --- a/arch/arm/boot/compressed/vmlinux.lds.in
> +++ /dev/null
> @@ -1,90 +0,0 @@
> -/*
> - *  linux/arch/arm/boot/compressed/vmlinux.lds.in

You might want to update this comment though.

Other than that...

Acked-by: Nicolas Pitre <nico@linaro.org>


Nicolas
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Kevin Hilman June 18, 2014, 5:55 p.m. UTC | #3
On Thu, Apr 10, 2014 at 9:27 AM, Taras Kondratiuk
<taras.kondratiuk@linaro.org> wrote:
> From: Nico Pitre <nico@fluxnic.net>
>
> All known BE8-capable systems have LE bootloaders, so we need to ensure
> that the magic number and image start/end values are in little endian
> format.
>
> [ben.dooks@codethink.co.uk: from nico's original email on this subject]
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
> [taras.kondratiuk@linaro.org: removed lds.S->lds rule, added target to extra-y]
> Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>

This patch has now hit -next (as of next-20140618) and I noticed all
my big-endian boot tests failed[1].  Turns out they failed because I'm
deciding whether to pass a big-endian or little-endian initramfs based
on the magic number of the zImage.  Since it's now always little
endian, even the big-endian kernels were boot tested with a little
endian initramfs.  And guess what.... they failed.

I like this patch for several reasons, including the fact that
u-boot's bootz support checks the magic number and failed before this
patch.

All of that to say, with this patch applied, I need a new (and
reliable) way to determine the endianness of a kernel just by looking
at the zImage.  Recommendations welcome.

Thanks,

Kevin

[1] http://lists.linaro.org/pipermail/kernel-build-reports/2014-June/004059.html
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diff mbox

Patch

diff --git a/arch/arm/boot/compressed/.gitignore b/arch/arm/boot/compressed/.gitignore
index 0714e03..6a26e7b 100644
--- a/arch/arm/boot/compressed/.gitignore
+++ b/arch/arm/boot/compressed/.gitignore
@@ -10,6 +10,7 @@  piggy.xzkern
 piggy.lz4
 vmlinux
 vmlinux.lds
+vmlinux.lds.S
 
 # borrowed libfdt files
 fdt.c
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index 68c9183..8a80906 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -114,7 +114,7 @@  targets       := vmlinux vmlinux.lds \
 # Make sure files are removed during clean
 extra-y       += piggy.gzip piggy.lzo piggy.lzma piggy.xzkern piggy.lz4 \
 		 lib1funcs.S ashldi3.S bswapsdi2.S $(libfdt) $(libfdt_hdrs) \
-		 hyp-stub.S
+		 hyp-stub.S vmlinux.lds.S
 
 ifeq ($(CONFIG_FUNCTION_TRACER),y)
 ORIG_CFLAGS := $(KBUILD_CFLAGS)
@@ -199,7 +199,7 @@  CFLAGS_font.o := -Dstatic=
 $(obj)/font.c: $(FONTC)
 	$(call cmd,shipped)
 
-$(obj)/vmlinux.lds: $(obj)/vmlinux.lds.in arch/arm/boot/Makefile $(KCONFIG_CONFIG)
+$(obj)/vmlinux.lds.S: $(obj)/vmlinux.lds.in arch/arm/boot/Makefile $(KCONFIG_CONFIG)
 	@sed "$(SEDFLAGS)" < $< > $@
 
 $(obj)/hyp-stub.S: $(srctree)/arch/$(SRCARCH)/kernel/hyp-stub.S
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 066b034..8ea1773 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -130,9 +130,10 @@  start:
  THUMB(		adr	r12, BSYM(1f)	)
  THUMB(		bx	r12		)
 
-		.word	0x016f2818		@ Magic numbers to help the loader
-		.word	start			@ absolute load/run zImage address
-		.word	_edata			@ zImage end address
+		.word	_magic_sig	@ Magic numbers to help the loader
+		.word	_magic_start	@ absolute load/run zImage address
+		.word	_magic_end	@ zImage end address
+
  THUMB(		.thumb			)
 1:
  ARM_BE8(	setend	be )			@ go BE8 if compiled for BE8
diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
index 4919f2a..6016223 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.in
+++ b/arch/arm/boot/compressed/vmlinux.lds.in
@@ -7,6 +7,16 @@ 
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+
+#ifdef CONFIG_CPU_ENDIAN_BE8
+#define ZIMAGE_MAGIC(x) ( (((x) >> 24) & 0x000000ff) | \
+			  (((x) >>  8) & 0x0000ff00) | \
+			  (((x) <<  8) & 0x00ff0000) | \
+			  (((x) << 24) & 0xff000000) )
+#else
+#define ZIMAGE_MAGIC(x) (x)
+#endif
+
 OUTPUT_ARCH(arm)
 ENTRY(_start)
 SECTIONS
@@ -57,6 +67,10 @@  SECTIONS
   .pad			: { BYTE(0); . = ALIGN(8); }
   _edata = .;
 
+  _magic_sig = ZIMAGE_MAGIC(0x016f2818);
+  _magic_start = ZIMAGE_MAGIC(_start);
+  _magic_end = ZIMAGE_MAGIC(_edata);
+
   . = BSS_START;
   __bss_start = .;
   .bss			: { *(.bss) }