| Message ID | 20180509130001.24276-5-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | LD_DEAD_CODE_DATA_ELIMINATION fixes and enabling for powerpc | expand |
Nicholas Piggin <npiggin@gmail.com> writes: > This requires further changes to linker script to KEEP some tables > and wildcard compiler generated sections into the right place. This > includes pp32 modifications from Christophe Leroy. > > When compiling powernv_defconfig with this option, the resulting > kernel is almost 400kB smaller (and still boots): > > text data bss dec filename > 11827621 4810490 1341080 17979191 vmlinux > 11752437 4598858 1338776 17690071 vmlinux.dcde > > Mathieu's numbers for custom Mac Mini G4 config has almost 200kB > saving. It also had some increase in vmlinux size for as-yet > unknown reasons. > > text data bss dec filename > 7461457 2475122 1428064 11364643 vmlinux > 7386425 2364370 1425432 11176227 vmlinux.dcde > > Tested-by: Christophe Leroy <christophe.leroy@c-s.fr> [8xx] > Tested-by: Mathieu Malaterre <malat@debian.org> [32-bit powermac] > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/Kconfig | 1 + > arch/powerpc/kernel/vmlinux.lds.S | 22 +++++++++++----------- > 2 files changed, 12 insertions(+), 11 deletions(-) I'm happy for this to go in via the kbuild tree. As long as it's in linux-next it will get tested by my CI which should hopefully shake out any bugs. Acked-by: Michael Ellerman <mpe@ellerman.id.au> cheers
On Wed, May 9, 2018 at 3:00 PM, Nicholas Piggin <npiggin@gmail.com> wrote: > This requires further changes to linker script to KEEP some tables > and wildcard compiler generated sections into the right place. This > includes pp32 modifications from Christophe Leroy. > > When compiling powernv_defconfig with this option, the resulting > kernel is almost 400kB smaller (and still boots): > > text data bss dec filename > 11827621 4810490 1341080 17979191 vmlinux > 11752437 4598858 1338776 17690071 vmlinux.dcde > > Mathieu's numbers for custom Mac Mini G4 config has almost 200kB Technically this is an oldconfig from debian original config file (debian official powerpc kernel package)... tested on a mac mini g4. > saving. It also had some increase in vmlinux size for as-yet > unknown reasons. > > text data bss dec filename > 7461457 2475122 1428064 11364643 vmlinux > 7386425 2364370 1425432 11176227 vmlinux.dcde > > Tested-by: Christophe Leroy <christophe.leroy@c-s.fr> [8xx] > Tested-by: Mathieu Malaterre <malat@debian.org> [32-bit powermac] > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/Kconfig | 1 + > arch/powerpc/kernel/vmlinux.lds.S | 22 +++++++++++----------- > 2 files changed, 12 insertions(+), 11 deletions(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index c32a181a7cbb..ee6dbe2efc8b 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -205,6 +205,7 @@ config PPC > select HAVE_KPROBES > select HAVE_KPROBES_ON_FTRACE > select HAVE_KRETPROBES > + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION > select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS > select HAVE_MEMBLOCK > select HAVE_MEMBLOCK_NODE_MAP > diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S > index c8af90ff49f0..52a93cdd04bc 100644 > --- a/arch/powerpc/kernel/vmlinux.lds.S > +++ b/arch/powerpc/kernel/vmlinux.lds.S > @@ -89,7 +89,7 @@ SECTIONS > */ > .text BLOCK(0) : AT(ADDR(.text) - LOAD_OFFSET) { > #ifdef CONFIG_LD_HEAD_STUB_CATCH > - *(.linker_stub_catch); > + KEEP(*(.linker_stub_catch)); > . = . ; > #endif > > @@ -98,7 +98,7 @@ SECTIONS > ALIGN_FUNCTION(); > #endif > /* careful! __ftr_alt_* sections need to be close to .text */ > - *(.text.hot .text .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); > + *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); > SCHED_TEXT > CPUIDLE_TEXT > LOCK_TEXT > @@ -170,10 +170,10 @@ SECTIONS > .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { > INIT_DATA > __vtop_table_begin = .; > - *(.vtop_fixup); > + KEEP(*(.vtop_fixup)); > __vtop_table_end = .; > __ptov_table_begin = .; > - *(.ptov_fixup); > + KEEP(*(.ptov_fixup)); > __ptov_table_end = .; > } > > @@ -194,26 +194,26 @@ SECTIONS > . = ALIGN(8); > __ftr_fixup : AT(ADDR(__ftr_fixup) - LOAD_OFFSET) { > __start___ftr_fixup = .; > - *(__ftr_fixup) > + KEEP(*(__ftr_fixup)) > __stop___ftr_fixup = .; > } > . = ALIGN(8); > __mmu_ftr_fixup : AT(ADDR(__mmu_ftr_fixup) - LOAD_OFFSET) { > __start___mmu_ftr_fixup = .; > - *(__mmu_ftr_fixup) > + KEEP(*(__mmu_ftr_fixup)) > __stop___mmu_ftr_fixup = .; > } > . = ALIGN(8); > __lwsync_fixup : AT(ADDR(__lwsync_fixup) - LOAD_OFFSET) { > __start___lwsync_fixup = .; > - *(__lwsync_fixup) > + KEEP(*(__lwsync_fixup)) > __stop___lwsync_fixup = .; > } > #ifdef CONFIG_PPC64 > . = ALIGN(8); > __fw_ftr_fixup : AT(ADDR(__fw_ftr_fixup) - LOAD_OFFSET) { > __start___fw_ftr_fixup = .; > - *(__fw_ftr_fixup) > + KEEP(*(__fw_ftr_fixup)) > __stop___fw_ftr_fixup = .; > } > #endif > @@ -226,7 +226,7 @@ SECTIONS > . = ALIGN(8); > .machine.desc : AT(ADDR(.machine.desc) - LOAD_OFFSET) { > __machine_desc_start = . ; > - *(.machine.desc) > + KEEP(*(.machine.desc)) > __machine_desc_end = . ; > } > #ifdef CONFIG_RELOCATABLE > @@ -274,7 +274,7 @@ SECTIONS > .data : AT(ADDR(.data) - LOAD_OFFSET) { > DATA_DATA > *(.data.rel*) > - *(.sdata) > + *(SDATA_MAIN) > *(.sdata2) > *(.got.plt) *(.got) > *(.plt) > @@ -289,7 +289,7 @@ SECTIONS > > .opd : AT(ADDR(.opd) - LOAD_OFFSET) { > __start_opd = .; > - *(.opd) > + KEEP(*(.opd)) > __end_opd = .; > } > > -- > 2.17.0 >
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index c32a181a7cbb..ee6dbe2efc8b 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -205,6 +205,7 @@ config PPC select HAVE_KPROBES select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_MEMBLOCK select HAVE_MEMBLOCK_NODE_MAP diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index c8af90ff49f0..52a93cdd04bc 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -89,7 +89,7 @@ SECTIONS */ .text BLOCK(0) : AT(ADDR(.text) - LOAD_OFFSET) { #ifdef CONFIG_LD_HEAD_STUB_CATCH - *(.linker_stub_catch); + KEEP(*(.linker_stub_catch)); . = . ; #endif @@ -98,7 +98,7 @@ SECTIONS ALIGN_FUNCTION(); #endif /* careful! __ftr_alt_* sections need to be close to .text */ - *(.text.hot .text .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); + *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); SCHED_TEXT CPUIDLE_TEXT LOCK_TEXT @@ -170,10 +170,10 @@ SECTIONS .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { INIT_DATA __vtop_table_begin = .; - *(.vtop_fixup); + KEEP(*(.vtop_fixup)); __vtop_table_end = .; __ptov_table_begin = .; - *(.ptov_fixup); + KEEP(*(.ptov_fixup)); __ptov_table_end = .; } @@ -194,26 +194,26 @@ SECTIONS . = ALIGN(8); __ftr_fixup : AT(ADDR(__ftr_fixup) - LOAD_OFFSET) { __start___ftr_fixup = .; - *(__ftr_fixup) + KEEP(*(__ftr_fixup)) __stop___ftr_fixup = .; } . = ALIGN(8); __mmu_ftr_fixup : AT(ADDR(__mmu_ftr_fixup) - LOAD_OFFSET) { __start___mmu_ftr_fixup = .; - *(__mmu_ftr_fixup) + KEEP(*(__mmu_ftr_fixup)) __stop___mmu_ftr_fixup = .; } . = ALIGN(8); __lwsync_fixup : AT(ADDR(__lwsync_fixup) - LOAD_OFFSET) { __start___lwsync_fixup = .; - *(__lwsync_fixup) + KEEP(*(__lwsync_fixup)) __stop___lwsync_fixup = .; } #ifdef CONFIG_PPC64 . = ALIGN(8); __fw_ftr_fixup : AT(ADDR(__fw_ftr_fixup) - LOAD_OFFSET) { __start___fw_ftr_fixup = .; - *(__fw_ftr_fixup) + KEEP(*(__fw_ftr_fixup)) __stop___fw_ftr_fixup = .; } #endif @@ -226,7 +226,7 @@ SECTIONS . = ALIGN(8); .machine.desc : AT(ADDR(.machine.desc) - LOAD_OFFSET) { __machine_desc_start = . ; - *(.machine.desc) + KEEP(*(.machine.desc)) __machine_desc_end = . ; } #ifdef CONFIG_RELOCATABLE @@ -274,7 +274,7 @@ SECTIONS .data : AT(ADDR(.data) - LOAD_OFFSET) { DATA_DATA *(.data.rel*) - *(.sdata) + *(SDATA_MAIN) *(.sdata2) *(.got.plt) *(.got) *(.plt) @@ -289,7 +289,7 @@ SECTIONS .opd : AT(ADDR(.opd) - LOAD_OFFSET) { __start_opd = .; - *(.opd) + KEEP(*(.opd)) __end_opd = .; }
This requires further changes to linker script to KEEP some tables and wildcard compiler generated sections into the right place. This includes pp32 modifications from Christophe Leroy. When compiling powernv_defconfig with this option, the resulting kernel is almost 400kB smaller (and still boots): text data bss dec filename 11827621 4810490 1341080 17979191 vmlinux 11752437 4598858 1338776 17690071 vmlinux.dcde Mathieu's numbers for custom Mac Mini G4 config has almost 200kB saving. It also had some increase in vmlinux size for as-yet unknown reasons. text data bss dec filename 7461457 2475122 1428064 11364643 vmlinux 7386425 2364370 1425432 11176227 vmlinux.dcde Tested-by: Christophe Leroy <christophe.leroy@c-s.fr> [8xx] Tested-by: Mathieu Malaterre <malat@debian.org> [32-bit powermac] Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/Kconfig | 1 + arch/powerpc/kernel/vmlinux.lds.S | 22 +++++++++++----------- 2 files changed, 12 insertions(+), 11 deletions(-)