Subject: [PATCH v6] MIPS: Truncate link address into 32bit for 32bit kernel
In-Reply-To: <[email protected]>
LLD failed to link vmlinux with 64bit load address for 32bit ELF
while bfd will strip 64bit address into 32bit silently.
To fix LLD build, we should truncate load address provided by platform
into 32bit for 32bit kernel.
Signed-off-by: Jiaxun Yang <[email protected]>
Link: https://github.com/ClangBuiltLinux/linux/issues/786
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25784
Reviewed-by: Fangrui Song <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Cc: Maciej W. Rozycki <[email protected]>
---
V2: Take MaskRay's shell magic.
V3: After spent an hour on dealing with special character issue in
Makefile, I gave up to do shell hacks and write a util in C instead.
Thanks Maciej for pointing out Makefile variable problem.
v4: Finally we managed to find a Makefile method to do it properly
thanks to Kees. As it's too far from the initial version, I removed
Review & Test tag from Nick and Fangrui and Cc instead.
v5: Care vmlinuz as well.
v6: Rename to LIKER_LOAD_ADDRESS
---
arch/mips/Makefile | 13 ++++++++++++-
arch/mips/boot/compressed/Makefile | 2 +-
arch/mips/kernel/vmlinux.lds.S | 2 +-
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index e1c44aed8156..68c0f22fefc0 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -288,12 +288,23 @@ ifdef CONFIG_64BIT
endif
endif
+# When linking a 32-bit executable the LLVM linker cannot cope with a
+# 32-bit load address that has been sign-extended to 64 bits. Simply
+# remove the upper 32 bits then, as it is safe to do so with other
+# linkers.
+ifdef CONFIG_64BIT
+ load-ld = $(load-y)
+else
+ load-ld = $(subst 0xffffffff,0x,$(load-y))
+endif
+
KBUILD_AFLAGS += $(cflags-y)
KBUILD_CFLAGS += $(cflags-y)
-KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
+KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y) -DLINKER_LOAD_ADDRESS=$(load-ld)
KBUILD_CPPFLAGS += -DDATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)
bootvars-y = VMLINUX_LOAD_ADDRESS=$(load-y) \
+ LINKER_LOAD_ADDRESS=$(load-ld) \
VMLINUX_ENTRY_ADDRESS=$(entry-y) \
PLATFORM="$(platform-y)" \
ITS_INPUTS="$(its-y)"
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index 0df0ee8a298d..3d391256ab7e 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -90,7 +90,7 @@ ifneq ($(zload-y),)
VMLINUZ_LOAD_ADDRESS := $(zload-y)
else
VMLINUZ_LOAD_ADDRESS = $(shell $(obj)/calc_vmlinuz_load_addr \
- $(obj)/vmlinux.bin $(VMLINUX_LOAD_ADDRESS))
+ $(obj)/vmlinux.bin $(LINKER_LOAD_ADDRESS))
endif
UIMAGE_LOADADDR = $(VMLINUZ_LOAD_ADDRESS)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index a5f00ec73ea6..5226cd8e4bee 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -55,7 +55,7 @@ SECTIONS
/* . = 0xa800000000300000; */
. = 0xffffffff80300000;
#endif
- . = VMLINUX_LOAD_ADDRESS;
+ . = LINKER_LOAD_ADDRESS;
/* read-only */
_text = .; /* Text and read-only data */
.text : {
On Tue, May 5, 2020 at 10:52 PM Jiaxun Yang <[email protected]> wrote:
>
> Subject: [PATCH v6] MIPS: Truncate link address into 32bit for 32bit kernel
> In-Reply-To: <[email protected]>
>
> LLD failed to link vmlinux with 64bit load address for 32bit ELF
> while bfd will strip 64bit address into 32bit silently.
> To fix LLD build, we should truncate load address provided by platform
> into 32bit for 32bit kernel.
>
> Signed-off-by: Jiaxun Yang <[email protected]>
> Link: https://github.com/ClangBuiltLinux/linux/issues/786
> Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25784
> Reviewed-by: Fangrui Song <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Tested-by: Nathan Chancellor <[email protected]>
> Cc: Maciej W. Rozycki <[email protected]>
Cool, this revision looks a bit simpler. Thanks for chasing this.
Tested-by: Nick Desaulniers <[email protected]>
> ---
> V2: Take MaskRay's shell magic.
>
> V3: After spent an hour on dealing with special character issue in
> Makefile, I gave up to do shell hacks and write a util in C instead.
> Thanks Maciej for pointing out Makefile variable problem.
>
> v4: Finally we managed to find a Makefile method to do it properly
> thanks to Kees. As it's too far from the initial version, I removed
> Review & Test tag from Nick and Fangrui and Cc instead.
>
> v5: Care vmlinuz as well.
>
> v6: Rename to LIKER_LOAD_ADDRESS
> ---
> arch/mips/Makefile | 13 ++++++++++++-
> arch/mips/boot/compressed/Makefile | 2 +-
> arch/mips/kernel/vmlinux.lds.S | 2 +-
> 3 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/arch/mips/Makefile b/arch/mips/Makefile
> index e1c44aed8156..68c0f22fefc0 100644
> --- a/arch/mips/Makefile
> +++ b/arch/mips/Makefile
> @@ -288,12 +288,23 @@ ifdef CONFIG_64BIT
> endif
> endif
>
> +# When linking a 32-bit executable the LLVM linker cannot cope with a
> +# 32-bit load address that has been sign-extended to 64 bits. Simply
> +# remove the upper 32 bits then, as it is safe to do so with other
> +# linkers.
> +ifdef CONFIG_64BIT
> + load-ld = $(load-y)
> +else
> + load-ld = $(subst 0xffffffff,0x,$(load-y))
> +endif
> +
> KBUILD_AFLAGS += $(cflags-y)
> KBUILD_CFLAGS += $(cflags-y)
> -KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
> +KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y) -DLINKER_LOAD_ADDRESS=$(load-ld)
> KBUILD_CPPFLAGS += -DDATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)
>
> bootvars-y = VMLINUX_LOAD_ADDRESS=$(load-y) \
> + LINKER_LOAD_ADDRESS=$(load-ld) \
> VMLINUX_ENTRY_ADDRESS=$(entry-y) \
> PLATFORM="$(platform-y)" \
> ITS_INPUTS="$(its-y)"
> diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
> index 0df0ee8a298d..3d391256ab7e 100644
> --- a/arch/mips/boot/compressed/Makefile
> +++ b/arch/mips/boot/compressed/Makefile
> @@ -90,7 +90,7 @@ ifneq ($(zload-y),)
> VMLINUZ_LOAD_ADDRESS := $(zload-y)
> else
> VMLINUZ_LOAD_ADDRESS = $(shell $(obj)/calc_vmlinuz_load_addr \
> - $(obj)/vmlinux.bin $(VMLINUX_LOAD_ADDRESS))
> + $(obj)/vmlinux.bin $(LINKER_LOAD_ADDRESS))
> endif
> UIMAGE_LOADADDR = $(VMLINUZ_LOAD_ADDRESS)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index a5f00ec73ea6..5226cd8e4bee 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -55,7 +55,7 @@ SECTIONS
> /* . = 0xa800000000300000; */
> . = 0xffffffff80300000;
> #endif
> - . = VMLINUX_LOAD_ADDRESS;
> + . = LINKER_LOAD_ADDRESS;
> /* read-only */
> _text = .; /* Text and read-only data */
> .text : {
>
> --
--
Thanks,
~Nick Desaulniers
On Wed, May 06, 2020 at 01:52:45PM +0800, Jiaxun Yang wrote:
> Subject: [PATCH v6] MIPS: Truncate link address into 32bit for 32bit kernel
> In-Reply-To: <[email protected]>
>
> LLD failed to link vmlinux with 64bit load address for 32bit ELF
> while bfd will strip 64bit address into 32bit silently.
> To fix LLD build, we should truncate load address provided by platform
> into 32bit for 32bit kernel.
>
> Signed-off-by: Jiaxun Yang <[email protected]>
> Link: https://github.com/ClangBuiltLinux/linux/issues/786
> Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25784
> Reviewed-by: Fangrui Song <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Tested-by: Nathan Chancellor <[email protected]>
> Cc: Maciej W. Rozycki <[email protected]>
> ---
> V2: Take MaskRay's shell magic.
>
> V3: After spent an hour on dealing with special character issue in
> Makefile, I gave up to do shell hacks and write a util in C instead.
> Thanks Maciej for pointing out Makefile variable problem.
>
> v4: Finally we managed to find a Makefile method to do it properly
> thanks to Kees. As it's too far from the initial version, I removed
> Review & Test tag from Nick and Fangrui and Cc instead.
>
> v5: Care vmlinuz as well.
>
> v6: Rename to LIKER_LOAD_ADDRESS
> ---
> arch/mips/Makefile | 13 ++++++++++++-
> arch/mips/boot/compressed/Makefile | 2 +-
> arch/mips/kernel/vmlinux.lds.S | 2 +-
> 3 files changed, 14 insertions(+), 3 deletions(-)
applied to mips-next.
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]