| Message ID | 20220914154746.1122482-2-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: build / linker improvements | expand |
Le 14/09/2022 à 17:47, Nicholas Piggin a écrit : > Const function pointers live in .data.rel.ro rather than .rodata because > they must be relocated. This change prevents powerpc/32 from generating > R_PPC_UADDR32 relocations (which are not handled). The sys_call_table is > moved to writeable memory, but a later change will move it back. Aren't you missing commit c7acee3d2f12 ("powerpc: align syscall table for ppc32") ? I can't see any R_PPC_UADDR32 relocations generated by ppc4xx_defconfig + CONFIG_RELOCATABLE unless I revert that commit. > > After this patch, 44x_defconfig + CONFIG_RELOCATABLE boots to busybox. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/kernel/systbl.S | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.S > index cb3358886203..0bec33e86f50 100644 > --- a/arch/powerpc/kernel/systbl.S > +++ b/arch/powerpc/kernel/systbl.S > @@ -12,7 +12,11 @@ > > #include <asm/ppc_asm.h> > > +#ifdef CONFIG_RELOCATABLE > +.section .data.rel.ro,"aw" > +#else > .section .rodata,"a" > +#endif > > #ifdef CONFIG_PPC64 > .p2align 3
Christophe Leroy <christophe.leroy@csgroup.eu> writes: > Le 14/09/2022 à 17:47, Nicholas Piggin a écrit : >> Const function pointers live in .data.rel.ro rather than .rodata because >> they must be relocated. This change prevents powerpc/32 from generating >> R_PPC_UADDR32 relocations (which are not handled). The sys_call_table is >> moved to writeable memory, but a later change will move it back. > > Aren't you missing commit c7acee3d2f12 ("powerpc: align syscall table > for ppc32") ? That's in fixes. I'll sort it out when I apply this, or when I merge fixes into next. > I can't see any R_PPC_UADDR32 relocations generated by ppc4xx_defconfig > + CONFIG_RELOCATABLE unless I revert that commit. Presumably this change accidentally aligns the syscall table. >> After this patch, 44x_defconfig + CONFIG_RELOCATABLE boots to busybox. So that's probably just because of the alignment too. I think this patch should go after .data.rel.ro is made read only. cheers
On Thu Sep 15, 2022 at 10:51 PM AEST, Michael Ellerman wrote: > Christophe Leroy <christophe.leroy@csgroup.eu> writes: > > Le 14/09/2022 à 17:47, Nicholas Piggin a écrit : > >> Const function pointers live in .data.rel.ro rather than .rodata because > >> they must be relocated. This change prevents powerpc/32 from generating > >> R_PPC_UADDR32 relocations (which are not handled). The sys_call_table is > >> moved to writeable memory, but a later change will move it back. > > > > Aren't you missing commit c7acee3d2f12 ("powerpc: align syscall table > > for ppc32") ? > > That's in fixes. I'll sort it out when I apply this, or when I merge > fixes into next. Yeah that explains the relocations I was seeing, I should have dug further into that, so they're really unrelated to this patch. > > I can't see any R_PPC_UADDR32 relocations generated by ppc4xx_defconfig > > + CONFIG_RELOCATABLE unless I revert that commit. > > Presumably this change accidentally aligns the syscall table. > > >> After this patch, 44x_defconfig + CONFIG_RELOCATABLE boots to busybox. > > So that's probably just because of the alignment too. > > I think this patch should go after .data.rel.ro is made read only. Yeah that should be fine. Thanks, Nick
diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.S index cb3358886203..0bec33e86f50 100644 --- a/arch/powerpc/kernel/systbl.S +++ b/arch/powerpc/kernel/systbl.S @@ -12,7 +12,11 @@ #include <asm/ppc_asm.h> +#ifdef CONFIG_RELOCATABLE +.section .data.rel.ro,"aw" +#else .section .rodata,"a" +#endif #ifdef CONFIG_PPC64 .p2align 3
Const function pointers live in .data.rel.ro rather than .rodata because they must be relocated. This change prevents powerpc/32 from generating R_PPC_UADDR32 relocations (which are not handled). The sys_call_table is moved to writeable memory, but a later change will move it back. After this patch, 44x_defconfig + CONFIG_RELOCATABLE boots to busybox. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/systbl.S | 4 ++++ 1 file changed, 4 insertions(+)