* [PATCH v2 0/1] Enable Dead Code Elimination @ 2024-08-29 20:11 Kele Zhang 2024-08-29 20:12 ` [PATCH v2 1/1] Makefile: enable --gc-sections Kele Zhang 0 siblings, 1 reply; 7+ messages in thread From: Kele Zhang @ 2024-08-29 20:11 UTC (permalink / raw) To: opensbi This patch enables `--gc-sections`. Dead Code Elimination (DCE) can reduce binary size and the attack surface without introducing side effects, and it has been used in the Linux kernel for many years. After testing, enabling DCE does not affect the normal functionality of OpenSBI. --- v1: https://lists.infradead.org/pipermail/opensbi/2024-August/007286.html --- Changes in v2: - Move --gc-sections to ELFFLAGS - Remove redundant KEEP() Kele Zhang (1): Makefile: enable --gc-sections Makefile | 5 +++-- firmware/fw_base.ldS | 1 + 2 files changed, 4 insertions(+), 2 deletions(-) base-commit: c4940a9517486413cd676fc8032bb55f9d4e2778 -- 2.34.1 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-08-29 20:11 [PATCH v2 0/1] Enable Dead Code Elimination Kele Zhang @ 2024-08-29 20:12 ` Kele Zhang 2024-08-30 16:13 ` Xiang W 2024-09-01 11:12 ` Bin Meng 0 siblings, 2 replies; 7+ messages in thread From: Kele Zhang @ 2024-08-29 20:12 UTC (permalink / raw) To: opensbi The --gc-sections option enables the linker to perform garbage collection of unreferenced code and data, thereby reducing the binary size. The -ffunction-sections option will place each function into a separate section, so it is necessary to add .text.* to the linker script. Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> Signed-off-by: Yuan Tan <tanyuan@tinylab.org> Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- Makefile | 5 +++-- firmware/fw_base.ldS | 1 + 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index e5a0f19..44db5d4 100644 --- a/Makefile +++ b/Makefile @@ -355,9 +355,9 @@ GENFLAGS += $(libsbiutils-genflags-y) GENFLAGS += $(platform-genflags-y) GENFLAGS += $(firmware-genflags-y) -CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing +CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata-sections ifneq ($(DEBUG),) -CFLAGS += -O0 +CFLAGS += -O0 -Wl,--print-gc-sections else CFLAGS += -O2 endif @@ -406,6 +406,7 @@ ASFLAGS += $(firmware-asflags-y) ARFLAGS = rcs ELFFLAGS += $(USE_LD_FLAG) +ELFFLAGS += -Wl,--gc-sections ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) ELFFLAGS += -Wl,--exclude-libs,ALL endif diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS index fb47984..a33746a 100644 --- a/firmware/fw_base.ldS +++ b/firmware/fw_base.ldS @@ -20,6 +20,7 @@ PROVIDE(_text_start = .); *(.entry) *(.text) + *(.text.*) . = ALIGN(8); PROVIDE(_text_end = .); } -- 2.34.1 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-08-29 20:12 ` [PATCH v2 1/1] Makefile: enable --gc-sections Kele Zhang @ 2024-08-30 16:13 ` Xiang W 2024-09-01 11:12 ` Bin Meng 1 sibling, 0 replies; 7+ messages in thread From: Xiang W @ 2024-08-30 16:13 UTC (permalink / raw) To: opensbi ? 2024-08-29???? 20:12 +0000?Kele Zhang??? > The --gc-sections option enables the linker to perform garbage > collection of unreferenced code and data, thereby reducing the binary > size. > > The -ffunction-sections option will place each function into a separate > section, so it is necessary to add .text.* to the linker script. > > Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> > Signed-off-by: Yuan Tan <tanyuan@tinylab.org> > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> LGTM Reviewed-by: Xiang W <wxjstz@126.com> > --- > ?Makefile???????????? | 5 +++-- > ?firmware/fw_base.ldS | 1 + > ?2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index e5a0f19..44db5d4 100644 > --- a/Makefile > +++ b/Makefile > @@ -355,9 +355,9 @@ GENFLAGS += $(libsbiutils-genflags-y) > ?GENFLAGS += $(platform-genflags-y) > ?GENFLAGS += $(firmware-genflags-y) > ? > -CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing > +CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata- > sections > ?ifneq ($(DEBUG),) > -CFLAGS += -O0 > +CFLAGS += -O0 -Wl,--print-gc-sections > ?else > ?CFLAGS += -O2 > ?endif > @@ -406,6 +406,7 @@ ASFLAGS += $(firmware-asflags-y) > ?ARFLAGS = rcs > ? > ?ELFFLAGS += $(USE_LD_FLAG) > +ELFFLAGS += -Wl,--gc-sections > ?ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) > ?ELFFLAGS += -Wl,--exclude-libs,ALL > ?endif > diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS > index fb47984..a33746a 100644 > --- a/firmware/fw_base.ldS > +++ b/firmware/fw_base.ldS > @@ -20,6 +20,7 @@ > ? PROVIDE(_text_start = .); > ? *(.entry) > ? *(.text) > + *(.text.*) > ? . = ALIGN(8); > ? PROVIDE(_text_end = .); > ? } ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-08-29 20:12 ` [PATCH v2 1/1] Makefile: enable --gc-sections Kele Zhang 2024-08-30 16:13 ` Xiang W @ 2024-09-01 11:12 ` Bin Meng 2024-09-01 11:51 ` cola zhang 1 sibling, 1 reply; 7+ messages in thread From: Bin Meng @ 2024-09-01 11:12 UTC (permalink / raw) To: opensbi On Fri, Aug 30, 2024 at 4:12?AM Kele Zhang <zhangcola2003@gmail.com> wrote: > > The --gc-sections option enables the linker to perform garbage > collection of unreferenced code and data, thereby reducing the binary > size. > > The -ffunction-sections option will place each function into a separate > section, so it is necessary to add .text.* to the linker script. > > Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> > Signed-off-by: Yuan Tan <tanyuan@tinylab.org> > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> > --- > Makefile | 5 +++-- > firmware/fw_base.ldS | 1 + > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index e5a0f19..44db5d4 100644 > --- a/Makefile > +++ b/Makefile > @@ -355,9 +355,9 @@ GENFLAGS += $(libsbiutils-genflags-y) > GENFLAGS += $(platform-genflags-y) > GENFLAGS += $(firmware-genflags-y) > > -CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing > +CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata-sections > ifneq ($(DEBUG),) > -CFLAGS += -O0 > +CFLAGS += -O0 -Wl,--print-gc-sections This should be put into the ELF flags too. > else > CFLAGS += -O2 > endif > @@ -406,6 +406,7 @@ ASFLAGS += $(firmware-asflags-y) > ARFLAGS = rcs > > ELFFLAGS += $(USE_LD_FLAG) > +ELFFLAGS += -Wl,--gc-sections > ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) > ELFFLAGS += -Wl,--exclude-libs,ALL > endif > diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS > index fb47984..a33746a 100644 > --- a/firmware/fw_base.ldS > +++ b/firmware/fw_base.ldS > @@ -20,6 +20,7 @@ > PROVIDE(_text_start = .); > *(.entry) > *(.text) > + *(.text.*) > . = ALIGN(8); > PROVIDE(_text_end = .); > } Regards, Bin ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-09-01 11:12 ` Bin Meng @ 2024-09-01 11:51 ` cola zhang 2024-09-01 12:14 ` Xiang W 0 siblings, 1 reply; 7+ messages in thread From: cola zhang @ 2024-09-01 11:51 UTC (permalink / raw) To: opensbi Bin Meng <bmeng.cn@gmail.com> ?2024?9?1??? 19:12??? > > On Fri, Aug 30, 2024 at 4:12?AM Kele Zhang <zhangcola2003@gmail.com> wrote: > > > > The --gc-sections option enables the linker to perform garbage > > collection of unreferenced code and data, thereby reducing the binary > > size. > > > > The -ffunction-sections option will place each function into a separate > > section, so it is necessary to add .text.* to the linker script. > > > > Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> > > Signed-off-by: Yuan Tan <tanyuan@tinylab.org> > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> > > --- > > Makefile | 5 +++-- > > firmware/fw_base.ldS | 1 + > > 2 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index e5a0f19..44db5d4 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -355,9 +355,9 @@ GENFLAGS += $(libsbiutils-genflags-y) > > GENFLAGS += $(platform-genflags-y) > > GENFLAGS += $(firmware-genflags-y) > > > > -CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing > > +CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata-sections > > ifneq ($(DEBUG),) > > -CFLAGS += -O0 > > +CFLAGS += -O0 -Wl,--print-gc-sections > > This should be put into the ELF flags too. Are ELFflags the flags that take effect during linking? -ffunction-sections -fdata-sections will take effect during compilation. Enabling them will generate different .s files and will not affect the behavior of the linker. So isn't it better to put them in cflags? > > > else > > CFLAGS += -O2 > > endif > > @@ -406,6 +406,7 @@ ASFLAGS += $(firmware-asflags-y) > > ARFLAGS = rcs > > > > ELFFLAGS += $(USE_LD_FLAG) > > +ELFFLAGS += -Wl,--gc-sections > > ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) > > ELFFLAGS += -Wl,--exclude-libs,ALL > > endif > > diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS > > index fb47984..a33746a 100644 > > --- a/firmware/fw_base.ldS > > +++ b/firmware/fw_base.ldS > > @@ -20,6 +20,7 @@ > > PROVIDE(_text_start = .); > > *(.entry) > > *(.text) > > + *(.text.*) > > . = ALIGN(8); > > PROVIDE(_text_end = .); > > } > > Regards, > Bin ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-09-01 11:51 ` cola zhang @ 2024-09-01 12:14 ` Xiang W 2024-09-01 12:35 ` cola zhang 0 siblings, 1 reply; 7+ messages in thread From: Xiang W @ 2024-09-01 12:14 UTC (permalink / raw) To: opensbi ? 2024-09-01???? 19:51 +0800?cola zhang??? > Bin Meng <bmeng.cn@gmail.com> ?2024?9?1??? 19:12??? > > > > On Fri, Aug 30, 2024 at 4:12?AM Kele Zhang <zhangcola2003@gmail.com> wrote: > > > > > > The --gc-sections option enables the linker to perform garbage > > > collection of unreferenced code and data, thereby reducing the binary > > > size. > > > > > > The -ffunction-sections option will place each function into a separate > > > section, so it is necessary to add .text.* to the linker script. > > > > > > Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> > > > Signed-off-by: Yuan Tan <tanyuan@tinylab.org> > > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> > > > --- > > > ?Makefile???????????? | 5 +++-- > > > ?firmware/fw_base.ldS | 1 + > > > ?2 files changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/Makefile b/Makefile > > > index e5a0f19..44db5d4 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -355,9 +355,9 @@ GENFLAGS??? +=????? $(libsbiutils-genflags-y) > > > ?GENFLAGS?????? +=????? $(platform-genflags-y) > > > ?GENFLAGS?????? +=????? $(firmware-genflags-y) > > > > > > -CFLAGS???????? =?????? -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing > > > +CFLAGS???????? =?????? -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata- > > > sections > > > ?ifneq ($(DEBUG),) > > > -CFLAGS???????? +=????? -O0 > > > +CFLAGS???????? +=????? -O0 -Wl,--print-gc-sections > > > > This should be put into the ELF flags too. > > Are ELFflags the flags that take effect during linking? > -ffunction-sections -fdata-sections will take effect during compilation. > Enabling them will generate different .s files and will not affect the behavior > of the linker. So isn't it better to put them in cflags? -Wl,--print-gc-sections move to ELFFLAGS Regards, Xiang W > > > > > > ?else > > > ?CFLAGS???????? +=????? -O2 > > > ?endif > > > @@ -406,6 +406,7 @@ ASFLAGS???????????? +=????? $(firmware-asflags-y) > > > ?ARFLAGS??????????????? =?????? rcs > > > > > > ?ELFFLAGS?????? +=????? $(USE_LD_FLAG) > > > +ELFFLAGS?????? +=????? -Wl,--gc-sections > > > ?ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) > > > ?ELFFLAGS?????? +=????? -Wl,--exclude-libs,ALL > > > ?endif > > > diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS > > > index fb47984..a33746a 100644 > > > --- a/firmware/fw_base.ldS > > > +++ b/firmware/fw_base.ldS > > > @@ -20,6 +20,7 @@ > > > ??????????????? PROVIDE(_text_start = .); > > > ??????????????? *(.entry) > > > ??????????????? *(.text) > > > +?????????????? *(.text.*) > > > ??????????????? . = ALIGN(8); > > > ??????????????? PROVIDE(_text_end = .); > > > ??????? } > > > > Regards, > > Bin ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/1] Makefile: enable --gc-sections 2024-09-01 12:14 ` Xiang W @ 2024-09-01 12:35 ` cola zhang 0 siblings, 0 replies; 7+ messages in thread From: cola zhang @ 2024-09-01 12:35 UTC (permalink / raw) To: opensbi Xiang W <wxjstz@126.com> ?2024?9?1??? 20:15??? > > ? 2024-09-01???? 19:51 +0800?cola zhang??? > > Bin Meng <bmeng.cn@gmail.com> ?2024?9?1??? 19:12??? > > > > > > On Fri, Aug 30, 2024 at 4:12?AM Kele Zhang <zhangcola2003@gmail.com> wrote: > > > > > > > > The --gc-sections option enables the linker to perform garbage > > > > collection of unreferenced code and data, thereby reducing the binary > > > > size. > > > > > > > > The -ffunction-sections option will place each function into a separate > > > > section, so it is necessary to add .text.* to the linker script. > > > > > > > > Signed-off-by: Kele Zhang <zhangcola2003@gmail.com> > > > > Signed-off-by: Yuan Tan <tanyuan@tinylab.org> > > > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org> > > > > --- > > > > Makefile | 5 +++-- > > > > firmware/fw_base.ldS | 1 + > > > > 2 files changed, 4 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/Makefile b/Makefile > > > > index e5a0f19..44db5d4 100644 > > > > --- a/Makefile > > > > +++ b/Makefile > > > > @@ -355,9 +355,9 @@ GENFLAGS += $(libsbiutils-genflags-y) > > > > GENFLAGS += $(platform-genflags-y) > > > > GENFLAGS += $(firmware-genflags-y) > > > > > > > > -CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing > > > > +CFLAGS = -g -Wall -Werror -ffreestanding -nostdlib -fno-stack-protector -fno-strict-aliasing -ffunction-sections -fdata- > > > > sections > > > > ifneq ($(DEBUG),) > > > > -CFLAGS += -O0 > > > > +CFLAGS += -O0 -Wl,--print-gc-sections > > > > > > This should be put into the ELF flags too. > > > > Are ELFflags the flags that take effect during linking? > > -ffunction-sections -fdata-sections will take effect during compilation. > > Enabling them will generate different .s files and will not affect the behavior > > of the linker. So isn't it better to put them in cflags? > > -Wl,--print-gc-sections move to ELFFLAGS Sorry, I didn't see clearly. This indeed needs to be modified. > > Regards, > Xiang W > > > > > > > > > else > > > > CFLAGS += -O2 > > > > endif > > > > @@ -406,6 +406,7 @@ ASFLAGS += $(firmware-asflags-y) > > > > ARFLAGS = rcs > > > > > > > > ELFFLAGS += $(USE_LD_FLAG) > > > > +ELFFLAGS += -Wl,--gc-sections > > > > ifeq ($(OPENSBI_LD_EXCLUDE_LIBS),y) > > > > ELFFLAGS += -Wl,--exclude-libs,ALL > > > > endif > > > > diff --git a/firmware/fw_base.ldS b/firmware/fw_base.ldS > > > > index fb47984..a33746a 100644 > > > > --- a/firmware/fw_base.ldS > > > > +++ b/firmware/fw_base.ldS > > > > @@ -20,6 +20,7 @@ > > > > PROVIDE(_text_start = .); > > > > *(.entry) > > > > *(.text) > > > > + *(.text.*) > > > > . = ALIGN(8); > > > > PROVIDE(_text_end = .); > > > > } > > > > > > Regards, > > > Bin > ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2024-09-01 12:35 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2024-08-29 20:11 [PATCH v2 0/1] Enable Dead Code Elimination Kele Zhang 2024-08-29 20:12 ` [PATCH v2 1/1] Makefile: enable --gc-sections Kele Zhang 2024-08-30 16:13 ` Xiang W 2024-09-01 11:12 ` Bin Meng 2024-09-01 11:51 ` cola zhang 2024-09-01 12:14 ` Xiang W 2024-09-01 12:35 ` cola zhang
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