The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net --- arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in little endian */ - image_size = le32_to_cpup((void *)&__image_end - 4); + image_size = get_unaligned_le32((void *)&__image_end - 4);
/* copy dtb to where the booted kernel will expect it */ memcpy((void *)VMLINUX_LOAD_ADDRESS_ULL + image_size,
On Wed, Dec 16, 2020 at 3:40 PM Paul Cercueil paul@crapouillou.net wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
Should it be get_unaligned_le32()?
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
Hi Paul, thanks for the patch (and for testing with Clang)! Alternatively, we could re-align __image_end to the next 4B multiple via:
diff --git a/arch/mips/boot/compressed/ld.script b/arch/mips/boot/compressed/ld.script index 0ebb667274d6..349919eff5fb 100644 --- a/arch/mips/boot/compressed/ld.script +++ b/arch/mips/boot/compressed/ld.script @@ -27,6 +27,7 @@ SECTIONS /* Put the compressed image here */ __image_begin = .; *(.image) + . = ALIGN(4); __image_end = .; CONSTRUCTORS . = ALIGN(16);
The tradeoff being up to 3 wasted bytes of padding in the compressed image, vs fetching one value slower (assuming unaligned loads are slower than aligned loads MIPS, IDK). I doubt decompress_kernel is called repeatedly, so let's take the byte saving approach of yours by using unaligned loads!
Reviewed-by: Nick Desaulniers ndesaulniers@google.com
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in little endian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void *)&__image_end - 4); /* copy dtb to where the booted kernel will expect it */ memcpy((void *)VMLINUX_LOAD_ADDRESS_ULL + image_size,-- 2.29.2
Hi Nick,
Le mer. 16 déc. 2020 à 18:08, Nick Desaulniers ndesaulniers@google.com a écrit :
On Wed, Dec 16, 2020 at 3:40 PM Paul Cercueil paul@crapouillou.net wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
Should it be get_unaligned_le32()?
Indeed.
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
Hi Paul, thanks for the patch (and for testing with Clang)! Alternatively, we could re-align __image_end to the next 4B multiple via:
diff --git a/arch/mips/boot/compressed/ld.script b/arch/mips/boot/compressed/ld.script index 0ebb667274d6..349919eff5fb 100644 --- a/arch/mips/boot/compressed/ld.script +++ b/arch/mips/boot/compressed/ld.script @@ -27,6 +27,7 @@ SECTIONS /* Put the compressed image here */ __image_begin = .; *(.image)
. = ALIGN(4); __image_end = .; CONSTRUCTORS . = ALIGN(16);
Actually that would not work (I did try that), since the 4-byte size appended to the compressed payload is inside the *(.image) section. The code that appends it (in scripts/Makefile.lib, I think) doesn't seem to take care about aligning it to a 4-byte offset. I have no idea why it does with GCC and doesn't with Clang, and I have no idea why the compressed payload's size isn't aligned either.
The tradeoff being up to 3 wasted bytes of padding in the compressed image, vs fetching one value slower (assuming unaligned loads are slower than aligned loads MIPS, IDK). I doubt decompress_kernel is called repeatedly, so let's take the byte saving approach of yours by using unaligned loads!
Reviewed-by: Nick Desaulniers ndesaulniers@google.com
Thanks.
Cheers, -Paul
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in littleendian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void*)&__image_end - 4);
/* copy dtb to where the booted kernel will expectit */ memcpy((void *)VMLINUX_LOAD_ADDRESS_ULL + image_size, -- 2.29.2
-- Thanks, ~Nick Desaulniers
On Thu, Dec 17, 2020 at 12:41 AM Paul Cercueil paul@crapouillou.net wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Philippe Mathieu-Daudé f4bug@amsat.org
On Wed, Dec 16, 2020 at 11:39:56PM +0000, Paul Cercueil wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb); /* last four bytes is always image size in little endian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void *)&__image_end - 4);
gives me following error
arch/mips/boot/compressed/decompress.c:120:16: error: implicit declaration of function ‘get_unaligned_le32’ [-Werror=implicit-function-declaration] image_size = get_unaligned_le32((void *)&__image_end - 4);
I've added
#include <asm/unaligned.h>
which fixes the compile error, but I'm wondering why the patch compiled for you ?
Thomas.
Hi Thomas,
Le lun. 28 déc. 2020 à 23:25, Thomas Bogendoerfer tsbogend@alpha.franken.de a écrit :
On Wed, Dec 16, 2020 at 11:39:56PM +0000, Paul Cercueil wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in little endian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void *)&__image_end - 4);gives me following error
arch/mips/boot/compressed/decompress.c:120:16: error: implicit declaration of function ‘get_unaligned_le32’ [-Werror=implicit-function-declaration] image_size = get_unaligned_le32((void *)&__image_end - 4);
I've added
#include <asm/unaligned.h>
which fixes the compile error, but I'm wondering why the patch compiled for you ?
No idea - but it does compile fine without the include here. Probably a defconfig difference.
Cheers, -Paul
On Mon, Dec 28, 2020 at 10:30:36PM +0000, Paul Cercueil wrote:
Le lun. 28 déc. 2020 à 23:25, Thomas Bogendoerfer tsbogend@alpha.franken.de a écrit :
On Wed, Dec 16, 2020 at 11:39:56PM +0000, Paul Cercueil wrote:
The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in little endian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void *)&__image_end - 4);gives me following error
arch/mips/boot/compressed/decompress.c:120:16: error: implicit declaration of function ‘get_unaligned_le32’ [-Werror=implicit-function-declaration] image_size = get_unaligned_le32((void *)&__image_end - 4);
I've added
#include <asm/unaligned.h>
which fixes the compile error, but I'm wondering why the patch compiled for you ?
No idea - but it does compile fine without the include here. Probably a defconfig difference.
# CONFIG_KERNEL_LZO is not set # CONFIG_KERNEL_LZ4 is not set
this makes the difference. Both decompress.c files include asm/unaligned.h.
I've added the #include, fixed the get_unaligned_le32 in the description and applied it to mips-fixes.
Thomas.
Hi Thomas,
Le mar. 29 déc. 2020 à 16:08, Thomas Bogendoerfer tsbogend@alpha.franken.de a écrit :
On Mon, Dec 28, 2020 at 10:30:36PM +0000, Paul Cercueil wrote:
Le lun. 28 déc. 2020 à 23:25, Thomas Bogendoerfer tsbogend@alpha.franken.de a écrit :
On Wed, Dec 16, 2020 at 11:39:56PM +0000, Paul Cercueil wrote:
The compressed payload is not necesarily 4-byte aligned, at
least
when compiling with Clang. In that case, the 4-byte value appended
to the
compressed payload that corresponds to the uncompressed kernel
image
size must be read using get_unaligned_le().
This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board).
Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the
end of
the kernel") Cc: stable@vger.kernel.org # v4.7 Signed-off-by: Paul Cercueil paul@crapouillou.net
arch/mips/boot/compressed/decompress.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index c61c641674e6..47c07990432b 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb);
/* last four bytes is always image size in little endian */
image_size = le32_to_cpup((void *)&__image_end - 4);
image_size = get_unaligned_le32((void *)&__image_end - 4);gives me following error
arch/mips/boot/compressed/decompress.c:120:16: error: implicit declaration of function ‘get_unaligned_le32’ [-Werror=implicit-function-declaration] image_size = get_unaligned_le32((void *)&__image_end - 4);
I've added
#include <asm/unaligned.h>
which fixes the compile error, but I'm wondering why the patch
compiled
for you ?
No idea - but it does compile fine without the include here. Probably a defconfig difference.
# CONFIG_KERNEL_LZO is not set # CONFIG_KERNEL_LZ4 is not set
this makes the difference. Both decompress.c files include asm/unaligned.h.
I've added the #include, fixed the get_unaligned_le32 in the description and applied it to mips-fixes.
Alright, great! Thanks!
Cheers, -Paul
linux-stable-mirror@lists.linaro.org
-
Nick Desaulniers -
Paul Cercueil -
Philippe Mathieu-Daudé -
Thomas Bogendoerfer