| Message ID | 1368809021-25130-1-git-send-email-will.deacon@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/17/2013 09:43 AM, Will Deacon wrote: > As is done for other architectures, sort the exception table at > build-time rather than during boot. > > Since sortextable appears to be a standalone C program relying on the > host elf.h to provide EM_AARCH64, I've had to add a conditional check in > order to allow cross-compilation on machines that aren't running a > bleeding-edge libc-dev. > > Signed-off-by: Will Deacon <will.deacon@arm.com> > --- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/vmlinux.lds.S | 15 +++++++-------- > scripts/sortextable.c | 5 +++++ > 3 files changed, 13 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 48347dc..fb8fd90 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -7,6 +7,7 @@ config ARM64 > select ARM_AMBA > select ARM_ARCH_TIMER > select ARM_GIC > + select BUILDTIME_EXTABLE_SORT > select CLONE_BACKWARDS > select COMMON_CLK > select GENERIC_CLOCKEVENTS > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 3fae2be..3d527726 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -57,6 +57,13 @@ SECTIONS > > RO_DATA(PAGE_SIZE) > > + . = ALIGN(8); > + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { > + __start___ex_table = .; > + *(__ex_table) > + __stop___ex_table = .; > + } > + > _etext = .; /* End of text and rodata section */ You have moved this to rodata. o Will the runtime sort still work like this? o Do we care? Maybe not. David Daney > > . = ALIGN(PAGE_SIZE); > @@ -99,14 +106,6 @@ SECTIONS > READ_MOSTLY_DATA(64) > > /* > - * The exception fixup table (might need resorting at runtime) > - */ > - . = ALIGN(32); > - __start___ex_table = .; > - *(__ex_table) > - __stop___ex_table = .; > - > - /* > * and the usual data section > */ > DATA_DATA > diff --git a/scripts/sortextable.c b/scripts/sortextable.c > index 1f10e89..f9ce116 100644 > --- a/scripts/sortextable.c > +++ b/scripts/sortextable.c > @@ -31,6 +31,10 @@ > #include <tools/be_byteshift.h> > #include <tools/le_byteshift.h> > > +#ifndef EM_AARCH64 > +#define EM_AARCH64 183 > +#endif > + > static int fd_map; /* File descriptor for file being modified. */ > static int mmap_failed; /* Boolean flag. */ > static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */ > @@ -249,6 +253,7 @@ do_file(char const *const fname) > custom_sort = sort_relative_table; > break; > case EM_ARM: > + case EM_AARCH64: > case EM_MIPS: > break; > } /* end switch */ >
On Fri, May 17, 2013 at 05:43:41PM +0100, Will Deacon wrote: > As is done for other architectures, sort the exception table at > build-time rather than during boot. > > Since sortextable appears to be a standalone C program relying on the > host elf.h to provide EM_AARCH64, I've had to add a conditional check in > order to allow cross-compilation on machines that aren't running a > bleeding-edge libc-dev. > > Signed-off-by: Will Deacon <will.deacon@arm.com> > --- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/vmlinux.lds.S | 15 +++++++-------- > scripts/sortextable.c | 5 +++++ > 3 files changed, 13 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 48347dc..fb8fd90 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -7,6 +7,7 @@ config ARM64 > select ARM_AMBA > select ARM_ARCH_TIMER > select ARM_GIC > + select BUILDTIME_EXTABLE_SORT > select CLONE_BACKWARDS > select COMMON_CLK > select GENERIC_CLOCKEVENTS > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 3fae2be..3d527726 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -57,6 +57,13 @@ SECTIONS > > RO_DATA(PAGE_SIZE) > > + . = ALIGN(8); > + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { > + __start___ex_table = .; > + *(__ex_table) > + __stop___ex_table = .; > + } Here you could use: EXCEPTION_TABLE(align) (From include/asm-generic/vmlinux.lds.h) Sam
Hi David, On Fri, May 17, 2013 at 07:33:53PM +0100, David Daney wrote: > On 05/17/2013 09:43 AM, Will Deacon wrote: > > As is done for other architectures, sort the exception table at > > build-time rather than during boot. > > > > Since sortextable appears to be a standalone C program relying on the > > host elf.h to provide EM_AARCH64, I've had to add a conditional check in > > order to allow cross-compilation on machines that aren't running a > > bleeding-edge libc-dev. > > > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > arch/arm64/Kconfig | 1 + > > arch/arm64/kernel/vmlinux.lds.S | 15 +++++++-------- > > scripts/sortextable.c | 5 +++++ > > 3 files changed, 13 insertions(+), 8 deletions(-) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 48347dc..fb8fd90 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -7,6 +7,7 @@ config ARM64 > > select ARM_AMBA > > select ARM_ARCH_TIMER > > select ARM_GIC > > + select BUILDTIME_EXTABLE_SORT > > select CLONE_BACKWARDS > > select COMMON_CLK > > select GENERIC_CLOCKEVENTS > > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > > index 3fae2be..3d527726 100644 > > --- a/arch/arm64/kernel/vmlinux.lds.S > > +++ b/arch/arm64/kernel/vmlinux.lds.S > > @@ -57,6 +57,13 @@ SECTIONS > > > > RO_DATA(PAGE_SIZE) > > > > + . = ALIGN(8); > > + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { > > + __start___ex_table = .; > > + *(__ex_table) > > + __stop___ex_table = .; > > + } > > + > > _etext = .; /* End of text and rodata section */ > > > You have moved this to rodata. I don't think I have moved this to rodata. The RO_DATA macro expands to a bunch of sections, but it doesn't leave any of them open at the end. > o Will the runtime sort still work like this? > > o Do we care? Maybe not. For arm64 we'd be moving exclusively to build-time sorting, so I guess we *could* stick the thing in rodata if we wanted to. Not sure it's worth the linker script munging though. Will
On Fri, May 17, 2013 at 07:49:50PM +0100, Sam Ravnborg wrote: > On Fri, May 17, 2013 at 05:43:41PM +0100, Will Deacon wrote: > > + . = ALIGN(8); > > + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { > > + __start___ex_table = .; > > + *(__ex_table) > > + __stop___ex_table = .; > > + } > > Here you could use: > EXCEPTION_TABLE(align) > > (From include/asm-generic/vmlinux.lds.h) Good spot, I'll spin a v2 using that. Looks like we don't use that for arch/arm/ because we want to discard the section ifdef CONFIG_MMU. Maybe we could change the generic macro to expand to nothing if !MMU, but I'm not sure if other MMU-less architectures are playing tricks with this. Will
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 48347dc..fb8fd90 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -7,6 +7,7 @@ config ARM64 select ARM_AMBA select ARM_ARCH_TIMER select ARM_GIC + select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS select COMMON_CLK select GENERIC_CLOCKEVENTS diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 3fae2be..3d527726 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -57,6 +57,13 @@ SECTIONS RO_DATA(PAGE_SIZE) + . = ALIGN(8); + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { + __start___ex_table = .; + *(__ex_table) + __stop___ex_table = .; + } + _etext = .; /* End of text and rodata section */ . = ALIGN(PAGE_SIZE); @@ -99,14 +106,6 @@ SECTIONS READ_MOSTLY_DATA(64) /* - * The exception fixup table (might need resorting at runtime) - */ - . = ALIGN(32); - __start___ex_table = .; - *(__ex_table) - __stop___ex_table = .; - - /* * and the usual data section */ DATA_DATA diff --git a/scripts/sortextable.c b/scripts/sortextable.c index 1f10e89..f9ce116 100644 --- a/scripts/sortextable.c +++ b/scripts/sortextable.c @@ -31,6 +31,10 @@ #include <tools/be_byteshift.h> #include <tools/le_byteshift.h> +#ifndef EM_AARCH64 +#define EM_AARCH64 183 +#endif + static int fd_map; /* File descriptor for file being modified. */ static int mmap_failed; /* Boolean flag. */ static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */ @@ -249,6 +253,7 @@ do_file(char const *const fname) custom_sort = sort_relative_table; break; case EM_ARM: + case EM_AARCH64: case EM_MIPS: break; } /* end switch */
As is done for other architectures, sort the exception table at build-time rather than during boot. Since sortextable appears to be a standalone C program relying on the host elf.h to provide EM_AARCH64, I've had to add a conditional check in order to allow cross-compilation on machines that aren't running a bleeding-edge libc-dev. Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/vmlinux.lds.S | 15 +++++++-------- scripts/sortextable.c | 5 +++++ 3 files changed, 13 insertions(+), 8 deletions(-)