| Message ID | 1374510833-25716-5-git-send-email-ben.dooks@codethink.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/22, Ben Dooks wrote: > To avoid having to make every text section swap the instruction order > of all instructions, make sure modules are built also built with --be8 > (as is the current kernel final link). > > If we do not do this, we would end up having to swap all instructions > when loading a module, instead of just the instructions that we are > applying ELF relocations to. > If someone tries to load a be8 module on a non-be8 kernel will it still work? Or should we add an extra version magic string in asm/module.h to prevent that?
On 22/07/13 18:05, Stephen Boyd wrote: > On 07/22, Ben Dooks wrote: >> To avoid having to make every text section swap the instruction order >> of all instructions, make sure modules are built also built with --be8 >> (as is the current kernel final link). >> >> If we do not do this, we would end up having to swap all instructions >> when loading a module, instead of just the instructions that we are >> applying ELF relocations to. >> > > If someone tries to load a be8 module on a non-be8 kernel will it > still work? Or should we add an extra version magic string in > asm/module.h to prevent that? The ELF header changes the EI_DATA field in the ei_ident from ELFDATA2LSB to ELFDATA2MSB when compiling so we should be able to detect these when loading. I have not checked to see if the kernel correctly checks for this. I do not think it currently checks the ei_flags field for the EF_ARM_BE8 in ABI 4 and 5. I am not sure if this is really important?
On Mon, 22 Jul 2013, Ben Dooks wrote: > On 22/07/13 18:05, Stephen Boyd wrote: > > On 07/22, Ben Dooks wrote: > > > To avoid having to make every text section swap the instruction order > > > of all instructions, make sure modules are built also built with --be8 > > > (as is the current kernel final link). > > > > > > If we do not do this, we would end up having to swap all instructions > > > when loading a module, instead of just the instructions that we are > > > applying ELF relocations to. > > > > > > > If someone tries to load a be8 module on a non-be8 kernel will it > > still work? Or should we add an extra version magic string in > > asm/module.h to prevent that? > > The ELF header changes the EI_DATA field in the ei_ident from > ELFDATA2LSB to ELFDATA2MSB when compiling so we should be able > to detect these when loading. > > I have not checked to see if the kernel correctly checks for this. > > I do not think it currently checks the ei_flags field for the > EF_ARM_BE8 in ABI 4 and 5. I am not sure if this is really important? If the information is already there and easily accessible, then it should be used. Nicolas
diff --git a/arch/arm/Makefile b/arch/arm/Makefile index ee4605f..8173883 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -16,6 +16,7 @@ LDFLAGS := LDFLAGS_vmlinux :=-p --no-undefined -X ifeq ($(CONFIG_CPU_ENDIAN_BE8),y) LDFLAGS_vmlinux += --be8 +LDFLAGS_MODULE += --be8 endif OBJCOPYFLAGS :=-O binary -R .comment -S
To avoid having to make every text section swap the instruction order of all instructions, make sure modules are built also built with --be8 (as is the current kernel final link). If we do not do this, we would end up having to swap all instructions when loading a module, instead of just the instructions that we are applying ELF relocations to. Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> --- arch/arm/Makefile | 1 + 1 file changed, 1 insertion(+)