Message ID | 20151026201611.GI12277@leverpostej (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
> Perhaps it would be better to have something like the following (with > PAGE_SHIFT sorted out to be includable in a linker script), so any > ALIGN_DEBUG_RO* correctly aligns things to whatever boundary is > required, and we don't need to over-align things in the !DEBUG_RO_DATA > case. Ignore the bit about PAGE_SHIFT and linker script. I'd got confused as I had a local typo breaking the build. With the below diff applied I can boot a defconfig +CONFIG_DEBUG_RODATA +CONFIG_ARM64_64K_PAGES v4.3-rc7 kernel on Juno Thanks, Mark. > ---->8---- > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 9807333..4d77757 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -60,9 +60,12 @@ PECOFF_FILE_ALIGNMENT = 0x200; > #define PECOFF_EDATA_PADDING > #endif > > -#ifdef CONFIG_DEBUG_ALIGN_RODATA > +#if defined(CONFIG_DEBUG_ALIGN_RODATA) > #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT); > #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO > +#elif defined(CONFIG_DEBUG_RODATA) > +#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT); > +#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO > #else > #define ALIGN_DEBUG_RO > #define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min);
On 10/26/15 1:26 PM, Mark Rutland wrote: >> Perhaps it would be better to have something like the following (with >> PAGE_SHIFT sorted out to be includable in a linker script), so any >> ALIGN_DEBUG_RO* correctly aligns things to whatever boundary is >> required, and we don't need to over-align things in the !DEBUG_RO_DATA >> case. > > Ignore the bit about PAGE_SHIFT and linker script. I'd got confused as I > had a local typo breaking the build. > > With the below diff applied I can boot a defconfig +CONFIG_DEBUG_RODATA > +CONFIG_ARM64_64K_PAGES v4.3-rc7 kernel on Juno > Most of the alignment was found by trial and error so I suspect it was just getting lucky before. I think this should be covering all the cases. Hopefully the protections will make it more restrictive instead of less to catch any more corner cases. For whoever ends up submitting the patch, Reviewed-by: Laura Abbott <laura@labbott.name> > Thanks, > Mark. > >> ---->8---- >> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S >> index 9807333..4d77757 100644 >> --- a/arch/arm64/kernel/vmlinux.lds.S >> +++ b/arch/arm64/kernel/vmlinux.lds.S >> @@ -60,9 +60,12 @@ PECOFF_FILE_ALIGNMENT = 0x200; >> #define PECOFF_EDATA_PADDING >> #endif >> >> -#ifdef CONFIG_DEBUG_ALIGN_RODATA >> +#if defined(CONFIG_DEBUG_ALIGN_RODATA) >> #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT); >> #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO >> +#elif defined(CONFIG_DEBUG_RODATA) >> +#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT); >> +#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO >> #else >> #define ALIGN_DEBUG_RO >> #define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min);
On Mon, Oct 26, 2015 at 02:09:58PM -0700, Laura Abbott wrote: > On 10/26/15 1:26 PM, Mark Rutland wrote: > >>Perhaps it would be better to have something like the following (with > >>PAGE_SHIFT sorted out to be includable in a linker script), so any > >>ALIGN_DEBUG_RO* correctly aligns things to whatever boundary is > >>required, and we don't need to over-align things in the !DEBUG_RO_DATA > >>case. > > > >Ignore the bit about PAGE_SHIFT and linker script. I'd got confused as I > >had a local typo breaking the build. > > > >With the below diff applied I can boot a defconfig +CONFIG_DEBUG_RODATA > >+CONFIG_ARM64_64K_PAGES v4.3-rc7 kernel on Juno > > > > Most of the alignment was found by trial and error so I suspect it was > just getting lucky before. I think this should be covering all the > cases. Hopefully the protections will make it more restrictive instead > of less to catch any more corner cases. Hopefully! On a somewhat related note, we should probably move .rodata away from .text; currently we give everything between _stext and _etext PAGE_KERNEL_EXEC permissions (i.e. !PXN), and .rodata has no reason to be executable. Doing so would also make it simpler to add .rodata to the mem_init notice, which I've been meaning to do for a while. I can take a look at shuffling sections for that tomorrow. > For whoever ends up submitting the patch, > > Reviewed-by: Laura Abbott <laura@labbott.name> Cheers; I'll spin this as a full patch momentarily. Thanks, Mark. > >>---->8---- > >>diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > >>index 9807333..4d77757 100644 > >>--- a/arch/arm64/kernel/vmlinux.lds.S > >>+++ b/arch/arm64/kernel/vmlinux.lds.S > >>@@ -60,9 +60,12 @@ PECOFF_FILE_ALIGNMENT = 0x200; > >> #define PECOFF_EDATA_PADDING > >> #endif > >> > >>-#ifdef CONFIG_DEBUG_ALIGN_RODATA > >>+#if defined(CONFIG_DEBUG_ALIGN_RODATA) > >> #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT); > >> #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO > >>+#elif defined(CONFIG_DEBUG_RODATA) > >>+#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT); > >>+#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO > >> #else > >> #define ALIGN_DEBUG_RO > >> #define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min); >
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 9807333..4d77757 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -60,9 +60,12 @@ PECOFF_FILE_ALIGNMENT = 0x200; #define PECOFF_EDATA_PADDING #endif -#ifdef CONFIG_DEBUG_ALIGN_RODATA +#if defined(CONFIG_DEBUG_ALIGN_RODATA) #define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT); #define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO +#elif defined(CONFIG_DEBUG_RODATA) +#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT); +#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO #else #define ALIGN_DEBUG_RO #define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min);